Messier-Bugatti-Dowty
Airbus Single Aisle Family Landing Gear
IN-SERVICE EXPERIENCE
Issue 4 A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
Foreword This “In-Service Experience” is Messier-Bugatti-Dowty proprietary Its use is strictly limited to Messier-Bugatti-Dowty customers It shall never be copied nor transmitted to any other organisation without Messier-Bugatti-Dowty authorisation The information given in the “In-Service Experience” is not contractual In no case may it supersede the applicable Messier-Bugatti-Dowty Technical Publication (e.g. Component Maintenance Manual, Service Bulletin, Service Letter, Product Deviation Authorisation etc..) for operation and/or maintenance purpose. The inclusion of a topic within the ISE does not mean that it is can be considered to occur on a fleetwide or repetitive basis unless specifically mentioned within the slide. In no circumstance can the ISE content be used against MBD in any claim 1 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
Airbus Single Aisle Family Landing Gear CONTENTS
/01/ Solutions In Development 1. Nose Landing Gear 2. Main Landing Gear
/03/ Best Maintenance Practices 1. Lubrication of the Landing Gears 2. Cleaning 3. General Checks
/02/ Recommended Solutions 1. Nose Landing Gear 2. Main Landing Gear
/04/ Landing Gear Product Information 1. A320/321 Serialisation SBs 2. Restoration Information 3. Tracking the safe life of parts 4. New Products 5.EV Tooling Information
Note 1 : Revised or New Slides are identified with • Note 2 : On wing repair documentation previously known as RDAS is now known as RDDAS 2 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development 1- Nose Landing Gear
1.5 – Barrel Top Face 1.4 - Harnesses
1.1 - Electrical Box
1.3 – Barrel Bush Migration 1.2 - Shock Absorber
1.6 – Proximity Sensor
3 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development 1.1 - NLG Electrical Box
CONTENTS Electrical Box P/N affected: D23119750-1, D23119751119
4 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development 1.1 - NLG Electrical Box Description/ Context •
Several cases of unscheduled removal were reported by various airlines; In addition, few cases of NLG electrical box re-connection during operation have been reported A MISP was opened in 2011 on these issues
• •
Consequence • Several cases of overpressure in the steering system potentially due to hydraulic system reactivation or non-deactivation during towing phase.
Root Cause Investigation •
Reconnection issue
•
Analysis of MBD MRO and supplier repair feedback and in-service
•
screening to identify candidate and then a root cause; 13 electrical boxes investigated (coming from warranty and in-service) => Electrical box not determined as the cause of the in-service issue
•
• • •
Solution/Mitigation • Introduction of AMM task in order to allow replacement of lamp bulb on-wing avoiding unscheduled removal of the electrical box • Reliability improvement with introduction of LED instead of incandescent light
Status Update • AMM task now available • LED introduction on-going (will be covered by dedicated MBD SB 580-32-3177) => aim is to perform modification on-wing • MISP has been considered closed
Reliability
Reliability analysis performed showing good behaviour of electrical box in-service for several years Analysis of MBD MRO and supplier repair feedback to determine potential reliability improvements Lamp identified as the main contributor to unscheduled removal
No link determined between electrical box and reconnection issue. Reliability improvement w ith introduction of LED 5 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development 1.2 - NLG Shock Absorber
CONTENTS Shock Absorber Leakage - Dynamic Seal Dynamic Seal P/N affected: S34852-343P99
Sliding Tube Chrome Flaking Sliding Tube P/N affected: D66679
6 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development 1.2 - NLG Shock Absorber Leakage - Dynamic Seal Description/ Context
Root Cause Investigation
Dynamic seal leakages have been reported across the fleet.
Consequence
In service investigation showed premature wear of the dynamic seals.
Grounding of aircraft for removal of shock absorber to replace dynamic seal.
• The average number of cycles performed by seals before leakage occurs is approximately 6500 cycles • 46% of seals never cause leakage
Solution/Mitigation •
Specific AMM task for dynamic seal replacement with leg at 45 degrees
•
MBD recommends pro-active replacement as per SL 580-32-3150
SCRAPER
Status Update • • •
• •
Redesign of the dynamic seal taking into account experience of various dynamic seals used in MBD shock absorbers Test results have shown increased reliability with the new seal MBD and Airbus launched an in service evaluation (ISE) of the new dynamic seal in order to validate the seal behaviour during aircraft operation: 1 MBD SB will be issued for installation of the new dynamic seal 16 aircrafts participate to this ISE without any leakage reported so far (with around 17404 FC accumulated) MBD/Airbus are looking for airline candidates for In service evaluation trial. Contact MBD/Airbus for participation in trial .
New dynamic seal
In service evaluation trial of the new dynamic seal in progress. Future actions w ill be determined based on the ISE results. 7 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development h 1.2 - NLG Sliding Tube Chrome Flaking Description/ Context
Root Cause Investigation
Operators reported chrome flaking on the sliding tube. MBD identified a specific batch. Note: Not all chrome detachments are linked to t his batch i s s ue .
Investigation determined that during the manufacturing process, cleaning and sand blasting at one source of supply was not consistently applied, leading to variability of chrome adhesion.
Consequence
• Population of 200 sliding tubes identified across 60 operators
Grounding of aircraft for temporary repair until sliding tube replacement
Solution/Mitigation • MBD has issued RDDAS temporary repairs for this type of damage. • Contact AOG CSC (
[email protected]) if this damage occurs. • RDDAS issued by MBD can allow continued A/C operation – around 45 days/200FC • Dedicated support provided and communicated to all 60 operators • MBD MRO network used to support the regions with rotable sliders
Status Update Retrofit ongoing and support available Warranty extended up to 1st overhaul for sliders concerned by Quality batch.
Retrofit progressing and dedicated RDDAS support available on request. 8 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development 1.3 - NLG Barrel
CONTENTS Barrel Bush Migration Barrel P/N affected: All
9 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development 1.3 - NLG Barrel Bush Migration Description/ Context
Root Cause Investigation
Around 60 cases of migration were reported on barrel at the actuating cylinder/barrel interface
The migration occurs during the operation of actuating cylinder The combination of : • Significant offset of actuating cylinder kinematic • Stiffness of the lug bush flange
Consequence • Cracked sealant noticed • Burden in maintenance (bush replacement / TA request)
Then, axle bending leads to bush migration in this particular configuration
Mitigation • MBD issued a Service Letter 580-32-3185 to mitigate the phenomenon in-service. The mitigation consist to remove the sealant, inspect and clean the area and renew the sealant.
Solution Some technical proposals are under discussion between MBD & Airbus engineering to determine if design should be improved
Status Update MBD Service Letter 580-32-3185 issued in December 2014 to mitigate the phenomenon inservice
Embodiment of MBD Service Letter 580-32-3185 will permit to mitigate this phenomenon and avoid any bush replacement 10 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development 1.4 – NLG Harnesses
CONTENTS Harness Connector Corrosion A/C affected: A318/ A319/A320/A321
11 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
P/N affected: All P/Ns
/01/ Solutions In Development 1.4 – Harness Connector Corrosion Description/ Context Some operators have reported corrosion of NLG / MLG electrical connectors to MBD and Airbus.
Consequence Corrosion may result in connector replacement in service or at overhaul.
Status Update The connectors comply to Airbus Supplier Equipment Specification MBD are supporting Airbus in the solution development
Refer to Airbus TFU 32.00.00.007 R14 12 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development 1.5 – NLG Barrel Top Face
CONTENTS Barrel Top Face Corrosion
13 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ In Service Experience 1.5 - NLG Barrel top f ace corrosion Description/ Context
Root cause investigation
Several cases of corrosion have been reported on the top face of barrel and on barrel bolt holes in service and in shop
Based on feedback from in-service and in shop, the main contributor is degradation of the sealant around the barrel bolts. After degradation of the sealant, moisture is able to go through the barrel bolts leading then to protective treatment degradation and corrosion development.
Consequence The corrosion has to be removed by re-machining the top face or the holes leading to higher overhaul costs (additional repair or part replacement).
Recommendation
This sealant degradation could be due to several contributors: • Improper sealant application during potential previous maintenance tasks • Protective treatment degradation between Barrel and Upper support
• Airbus ISI 32.31.00004 has been developed with MBD to provide information about inspection of sensitive areas. •detect Regular inspection onsealant this area allow any visual damage on rubber and could prevent anyto corrosion development
Mitigation • Segregation in the RC analysis between CIS and nonCIS operation is under study with Airbus. • Target for this new disposition is Q3 2016 • Life limitation at 1 TBO is under investigation on non-CIS aircraft
Segregation of life limitations via RC under study to reduce Pre EV Barrel scrap 14 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ In Service Experience 1.6 - NLG Proximity Sensor System
CONTENTS NLG Proximity Sensor Proximity sensor mechanism P/N affected: Post SB 580-32-3155 / 3157
15 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ In Service Experience 1.6 - NLG Proximity Sensor System Description/ Context
Root cause investigation
Some airlines reported abnormal play on NLG Proximity sensor mechanism (post-SB 580-32-3155 / 3157) either during maintenance check or after troubleshooting (in case of 24/25Ga fault triggered).
Some proximity sensor mechanism have been recovered from maintenance check for laboratory analysis: • Wear is mainly noticed at level of bushed lever and greased pin
Consequence • High rate of parts replacement during maintenance check • Potential risk of Operational Interruption linked to proximity sensor mechanism issue
Analysis is still on going to correlate in-service data with mechanism free play leading to loss of signal. Sample analysis is on-going via MRO to assess level of wear at Overhaul.
Mitigation • Replacement of worn or damaged parts • Preventive maintenance according to Airbus AMM Task 32-21-00-210-802-A
Status Update Engineering analysis on-going. MRO sampling on-going. Investigation report to be shared between MBD and Airbus in Q1 2016 Report conclusion will drive decision on the way forward Feedback from Customer is needed in case of event related to 24/25GA
Investigations on going. MBD to gather additional data from operators 16 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development 2 - Main Landing Gear
2.6 Pintle Pins 2.5 - Lockstay Actuator
2.4 - Sliding Tube
2.3 - Quick Release Coupling
17 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
2.1 - Harnesses
2.2 - Torque Link Damper
/01/ Solutions In Development 2.1 - Harnesses
CONTENTS Harness Connector Corrosion A/C affected: A318/ A319/A320/A321
18 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
P/N affected: All P/Ns
/01/ Solutions In Development 2.2 – Harness Connector Corrosion Description/ Context Some operators have reported corrosion of NLG / MLG electrical connectors to MBD and Airbus.
Consequence Corrosion may result in connector replacement in service or at overhaul.
Status Update The connectors comply to Airbus Supplier Equipment Specification MBD are supporting Airbus in the solution development
Refer to Airbus TFU 32.00.00.007 R14 19 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development 2.2 - Torque Link Damper CONTENTS MLG Torque Link Damper Loose Bolts A/C affected: A319/A320/A321
20 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
P/N affected: 201404001
/01/ Solutions In Development 2.2 - Torque Link Damper Loose Bolts Description/ Context There have been reports of the bolts that attach the torque link damper becoming loose. These bolts attach the torque link damper to the upper torque link. The torque link damper is also attached by the torque link apex pin.
5mm additional material added to the face.
Consequence Corrosion to the bolts and the bolts becoming loose, although the torque link damper cannot become detached as it is also attached by the torque link apex pin.
Root Cause Investigation Thread tapping was in some cases not to the full depth required. The thread inserts when installed in these holes became tapered. When the bolts for the torque link damper were installed in the tapered insert the bolts would not torque correctly.
Solution A revised damper with increased depth of the tapped holes had been produced for the EV MLG, the revised damper will also be available as a modification to the Enhanced MLG. The modification to apply the revised torque link damper is under final approval, VSB expected Q3 2016.
The modification to apply the revised torque link damper is under approval. 21 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development 2.3 - Quick Release Coupling CONTENTS MLG Quick Release Coupling Hydraulic Leaks A/C affected: A318/ A319/A320
22 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
P/N affected: 201042031
/01/ Solutions In Development 2.3 - Quick Release Coupling Hydraulic Leaks Description/ Context MBD have received a number of reports of hydraulic fluid leakage from above the union nut on the brake flexible hydraulic hose elbow at the junction of the Quick Release Coupling.
Consequence Hydraulic fluid spilling on hot brakes may cause brake smoke or brake fire during taxi-in or parking phases .
Root Cause Investigation • On parts returned to MBD, galling damage was observed on the non threaded parts of the mating faces of the QRC and flexible hose which can be caused by vibration. • Some coincide with piston housing loose on MBDand brakescases Ref: VSB C20225-32-3391, SL F6137-32-3389 Airbus TFU 32.42.27.037 due to non-compliant locking bolt assemblies
Galling damage
Mitigation
Airbus Alert Operators Transmission -A32N005-14 dated 11 Sep 2014 calls for a one-time visual inspection of the QRC and the MLG brake piston housing bolts on A318, A319 and A320 aircraft equipped with MBD MLG Brake assemblies PN C20225508, C20225509 and C20225510. Status Update
MBD is continuing to monitor occurrences in service.
MISP closed. 23 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development 2.4 - MLG Sliding Tube CONTENTS MLG Sliding Tube Thermal Damage and Cracking A/C affected: A318/A319/A320/A321
P/N affected: All P/Ns
Axle Overheating Damage A/C affected: A321
P/N affected: All P/Ns
Slave Link Lug Crack A/C affected: A318/A319/A320/A321
P/N affected: 201271304, 201522353
24 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development 2.4 - MLG Sliding Tube Thermal Damage And Cracking Root Cause Investigation
Description/ Context
• •
Operators have reported local chromium plate detachment and base material cracks on the main barrel diameter. A/C Flying into CIS Regions have been particularly affected and a low numbers of operators outside of the CIS region have also been affected.
Consequence • Increased risk of unserviceable Sliding Tubes at next shop visit. • Cracking to the sliding tube. • Increased risk of Shock Absorber fluid leakage.
Investigation has shown increased Shock Absorber velocity and Bearing friction between the Sliding Tube and Lower Bearing can lead to this damage. Damage typically occurs in the working region of the Lower Bearing during the taxi phase of operation. Runways and taxiways with increased surface roughness can increase the probability and severity of damage. Base metal thermal damage on rear of slider
Mitigation • MBD has provided RDDAS temporary repairs for this type of damage. Contact AOG CSC (
[email protected]) if this damage occurs. • Repetitive inspections for CIS operators including DVI and MPI inspections. • Operators may choose to reduce greasing intervals in this area. Particularly if flying into CIS region where it is recommended to grease weekly.
Solution
Chromium plate detachment on rear of slider
Solution
Mitigation actions and a solution are available. 25 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development 2.4 - MLG Sliding Tube Thermal Damage And Cracking Solution MBD SB 200-32-307, 201-32-58, 200-32310, and 201-32-60. The new standard of bearing includes: • A new low friction inner liner and shorter retaining pins • The inner liner consists of a lead impregnated PTFE layer mounted on a bronze backing • Existing Lower Bearing assemblies can be modified at overhaul
•
The embodiment of the new Lower Bearing is currently controlled by Airbus, affected operators out of the CIS region can request the solution from Airbus.
New lower bearing subassembly 201587212
Inner liner
Area of wear
201646300
Status Update •
Endurance limits to be published by Airbus into Airbus SB A320-23-1386.
• •
•
The life of the bearing in the CIS region will be 5800 FC. Further analysis of bearings is not expected to allow any improvements on this.
Post Mod Lower Bearing
Acceptable In-service condition
Liners are being returned by some operators outside of the CIS region for wear analysis.
Back to Description
Solution available to remove need for repetitive inspections and prevent in-service damage 26 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development 2.4 - MLG Axle Overheating Damage Description/ Context
Mitigation
MBD has received reports of local chromium plating detachment and base metal overheating on the innermost chromium plated Axle diameter (next to the Brake Flange). Damage is found to be more common on A321 Aircraft.
• On all A321 aircraft, a regular greasing of the MLG Axle outer diameter and Axle Sleeve inner diameter is recommended to be performed every 2000 FC. Refer to TFU 32.11.00.005 and Airbus SIL 32-130.
Consequence Risk of Sliding Tube being deemed unserviceable.
Root Cause Investigation Most likely cause of overheating is fretting between the Axle Sleeve and innermost chromium plated Axle land. Subsequent heat generation can, in some cases, be sufficient to change the microstructure and properties of the base metal.
• MBD has issued RDDAS temporary repairs for this type of damage which requires at minimum acid etch to PCS 3600. Contact AOG CSC (
[email protected]) if this damage occurs. • Repair off-wing is covered by applicable CMM repairs. For damage exceeding this a repair solution has been developed but is subject to approval by a Repair Concession.
Status Update
•
All MBD information on root cause effects has been passed to Airbus to assist with solution development at interface level.
MBD recommend regular greasing of Axle – refer to Airbus SIL and TFU. 27 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development MLG Sliding Tube Slave Link Lug Crack 2.4 - MLG Sliding Tube Slave Link Lug Crack Description/Context
Root Cause Investigation
At overhaul 2 sliding tubes from different operators were found to have a crack in the Sliding Tube slave link lug area when NDT tested at overhaul
The fracture propagated from a burr in 1 of the 4 slave link lug holes. The fracture did not extend into the barrel of the sliding tube
Possible Consequence
•
Suspect population identified, MBD VSB to be updated with the population expected Q2 2016.
• Scrapping of Sliding Tube if crack found • Crack in Principle Structural Element therefore airworthiness directive expected
Slave Link Lug location (aft)
Mitigation / Solution
•
MBD VSB released to check for burrs at overhaul, Airbus SB and Airworthiness Directive Expected to Mandate Inspection at overhaul or on-wing. • De-burring operation at manufacture has been improved.
Inspection and Mitigation in development for Enh sliding tubes in service 28 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development 2.5 - Lockstay Actuator CONTENTS Lockstay Actuator Leakages A/C affected: A318/A319/A320/A321
29 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
P/N affected: 114095 series
/01/ Solutions In Development 2.5- Lockstay Actuator Leakages Description/ Context
Mitigation
A number of warranty claims have been received by MBD for Lock-stay Actuator Leak ages. Typical findings on actuators are; cracked / pockmarked seal elastomer and worn / torn atmospheric side back-up ring.
MBD recommends frequent completion of the below (as often as weekly or even daily) and immediately after actuator installation. 1. Ensure the MLG is in the down locked position and is safe in accordance with AMM procedures 2. Using a Lint free cloth and a small amount of cleaning fluid; clean the Lockstay Actuator Piston Rod OD to remove any old Hydraulic Fluid, Dirt, Debris or Contamination. Ensure that no cleaning fluid gets inside the actuator past the scraper seal assembly. 3. Using a Lint free cloth dry the Lockstay Actuator Piston Rod OD 4. Using a Lint free cloth apply a layer of Hydraulic fluid onto the Lockstay Actuator Piston Rod Chrome Plated Diameter
Consequence • Potential for hydraulic fluid leakage and unscheduled maintenance • Economic burden to repair leaking units
Root Cause Investigation Primary Factor • Use of Skydrol LD-4, Hyjet IV-A+, Skydrol PE-5, and
NOTE: MBD recommends using the same Hydraulic Fluid as used in the Aircraft Hydraulic System to ensure compatibility.
Status Update
• MBD will investigate another actuator to investigate for any possible regional or environmental effects, depending on the results a solution for fluid in-compatibility may be implemented.
• Operators are invited to contact MBD regarding repeat cases of lockstay actuator leakages so that another actuator can be investigated.
Hyjet V may result in a gland fill percentage greater than 100% increasing the risk of back-up ring extrusion and / or frictional related damage to the seal. Possible geographic / environmental factors have been identified, suggesting further investigation of another actuator is required to confirm the correct root cause. Secondary Factors (cannot individually cause a leakage) 1. The Piston Rod Surface Finish is smoother than recommended. Which reduces the amount of fluid that can sit in “troughs” on the piston rod OD increasing seal friction 2. Piston Rod ‘wiping’ (with and without cleaning fluids) in scenarios where the seal is not allowing sufficient fluid to pass and form a lubricating layer on the piston rod increases seal friction
Cracked / pockmarked seal Worn / torn back-up ring
Root cause identified and mitigating actions available to operators 30 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/01/ Solutions In Development 2.6 - Forward Pintle Pin Retaining Bolts
CONTENTS Forward Pintle Pin Retaining Bolts A/C affected: A318/A319/A320/A321
31 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.6 – Forward Pintle Pin Description/ Context MBD has received a report from an operator of multiple occurrences of Chrome plate detachment and base metal corrosion on A320 and A321 MLG Forward Pintle Pins. Another operator found a Forward Pintle Pin that was rotated and had fractured lugs.
Consequence In all cases the damages were discovered during routine inspections and did not result in any direct impact on the operation of the aircraft. However if the base metal of the pin is corroded there is an increased risk of fracture of the Forward Pintle Pin which could lead to collapse of the MLG.
Solution/Mitigation MBD recommend the following: •
Check for signs of c orrosion product when performing maintenance or inspections in the area
•
When greasing at this location, ensure that greasing is performed effectively and check the condition of the extruded grease for signs of metallic particles
•
If there is doubt about the condition of the Pintle Pin then consider investigating further.
Root Cause Investigation The investigation into the root cause of the damage is on-going however it is expected that ineffective lubrication in the region may be causing increased friction between the Forward Pintle Pin and the Aircraft Spherical Bearing.
Regular and effective greasing is effective mitigation. 32 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 1- Nose Landing Gear 1.7 - Retraction Actuator
1.1 - Unlock Actuator Inspection
1.4 -Panel and Barrel Greasing Ducts
1.2 - Shock Absorber Cylinder Colouration
1.5 - Turning Tube 1.3 - Proximity Sensor System 1.6 NLG ICY Modification
1.8 - Torque Links
NLG Leg P/N affected: All P/N 33 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 1.1 - NLG Unlock actuator
CONTENTS Unlock actuator Inspection P/N affected: D23076000 series
34 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 1.1 - NLG Unlock Actuator Inspection Description/ Context
Root Cause Investigation
Cases of spherical ball partial or complete migration.
Root cause a combination of:
Consequence
• Insufficient swaging and/or
Risk of incomplete NLG retraction or down-locking.
• Installation of specific “long” bolts P/N D62597
Solution • Bolt P/N D62597 must be replaced as per MBD SB 580-32-3169 • SB contains instructions for correct swaging and check improvements • MBD SB 589-32-3169 available on MBD portal
Embodiment of MBD SB will prevent bearing migration and unlock actuator damage. 35 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 1.2 - NLG Shock Absorber Cylinder
CONTENTS Shock Absorber Cylinder Colouration P/N affected: D65519
36 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 1.2 - NLG Shock Absorber Cylinder Colouration Description/ Context During scheduled shock absorber removal, a few cases of marks noticed on the cylinder has been reported by operators.
Consequence • Customer requests for technical recommendation • Potential delay in maintenance schedule
Root Cause Investigation • Marks are due to friction, bronze deposit or heating • Brownish marks do not require any further action • Bluish marks require NDT (FPI + Stress Scan)
Solution Service Letter 580-32-3172 available on MBD portal.
Brownish mark on sliding tube
MBD SIL provides the procedures necessary for different colour indications 37 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions h 1.3 - NLG Proximity Sensor System
CONTENTS NLG Proximity Sensor
38 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions h 1.3 - NLG Proximity Sensor System Description/ Context Cases of Lever Pin showing wear.
pre-mod
Consequence • Risk of seizure leading to rod-link bending or rupture • Potential In Flight Turn Back linked to proximity sensor issue
Solution/Mitigation • Pin lubrication ducts introduction; • Rod link reinforcement (from aluminium to steel)
Status Update • MBD SB 580-32-3155 available on MBD portal • MBD SB 580-32-3157 available on MBD portal
post-mod
Embodiment of MBD SB’s will reduce risk of rod-link bending and potential for In Flight Turn Back 39 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 1.4 - NLG Barrel & Panel
Panel Greasing Ducts and Barrel Greasing Ducts A/C affected: A318/A319/A320/A321
40 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
P/N affected: All
/02/ Recommended Solutions h 1.4 - NLG Barrel & Panel Greasing Ducts Description/ Context • Grease could be accumulated on Barrel and Panel hinge pin leading to grease overpressure inside the blanking cap cavity
Consequence • Lack of grease on outside area of pintle pins • Presence of dried grease inside the greasing duct
Solution/Mitigation •
Modification of grease duct to improve the way out for the grease • •
•
Machining of current greasing ducts Replacement by new one
Improvement of pintle pins greasing
Status Update •
MBD SB 580-32-3179 available on MBD portal
•
Airbus issued a covering SB 32-1417
Embodiment of MBD SB will reduce risk of lack of grease or presence of dried grease 41 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 1.5 - NLG Turning Tube
CONTENTS Turning Tube Lug Corrosion Turning Tube P/N affected:D65520 ; D59418 ;D62385
42 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 1.5 - NLG Turning Tube Lug Corrosion Description/ Context
Root Cause Investigation
Corrosion has been found on the inner diameter of the turning tube lug at the upper torque link attachment.
The corrosion seen in this area is a result of moisture ingress between the bush and the turning tube lug inner diameter
Consequence Repair required for removal of corrosion.
Solution/Mitigation • Preventative maintenance practices are outlined in the Airbus SIL 32-144 to mitigate such corrosion:
Turning tube lug
• Grease lubrication points frequently between the turning tube and upper torque link- MBD recommendation is every 200 FC • Check sealant is continuous around the bushes within the turning tube lugs area • Check sealant is continuous and well coated in the nut and around the head of the pin between the barrel and the upper torque link
• MBD have included a local repair into relevant CMM’s • If repair is outside of CMM scope, contact AOG CSC (
[email protected] ), to apply for a RDDAS Temporary Repair. • MBD SIL 580-32-3184 has been issued to inform operator about CIC application to help prevent corrosion (CMM will be updated accordingly in September 2015)
Status Update Use of anti-corrosion compound for the affected area is under analysis.
Water/moisture ingress path
SIL 580-32-3184 released and CMMs repair will be updated in September 2015 to introduce corrosion inhibiting compound in area 43 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions h 1.6 - NLG New Configuration Leg (ICY) Description/ Context More than 20 versions of NLG legs in service, depending on weight variants. ICY requested by operators at FAIR Working Group.
New LRU’s created:
Consequence • Technical adaptation could be needed on AOG basis • Management of different versions of spares • Various CMM/AMM documentation to refer in service
Solution/Mitigation •
A modification kit has been produced to create a common NLG • 4 to 6 man hours required 3 new LRU are created: •Servicing placard kit •Green or yellow circuit kits •TPIS or Non TPIS kits • Configuration harmonization (Reduction in NLG versions, ICY with old parts increased, ease in spares management); • Flexibility for customers (new LRU managed through AMM tasks) •
Status Update • MBD SB 580-32-3173 embodiment subject to a dedicated support – CSC & CSM to be contacted • MBD SB 580-32-3173 issued to cover this new configuration • CMM documentation created/updated to include new P/N standard (post MBD SB 580-32-3173) • Airbus issued a covering SB 32-1392 & SIL 32-136
1Dependant
on weight variant compliance
Implementation will lead to an ease in configuration management. Post SB spares can be used on any A320 Aircraft1. Customization possible with optional kits. MBD SB is a prerequisite of any further modification. 44 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 1.7 - NLG Retraction Actuator
CONTENTS Retraction Actuator Leakage P/N affected: D23613000
45 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 1.7 - NLG Retraction Actuator Leakage Description/ Context • Cases of premature leakages (recently delivered actuators) have been noticed in service, and through warranty claims since 2010.
Consequence • Potential operational impacts able to create AOG situation and/or flights cancelled – not experienced to date
Root Cause Investigation •
Investigations have been performed on several actuators recovered from in-service
•
Static leakage has been highlighted during investigation
•
Quality investigation performed permitting to determine 2 contributors of the static leakage :
Solution/Mitigation • Components affected are NLG actuating cylinders P/N D23613000 Serial Numbers from MA 0723 up to and including MA 1418 • Replacement of the affected static seal NAS1611-233 is sufficient to prevent similar leakage.
Status Update • MBD Service Letter 580-32-3183 released in April 2014 to cover technical and commercial aspects
1. Squeeze of a specific static seal NAS1611-233 batch below MBD specification 2. Inner diameter of the actuator cylinder P/N D65540 with a specific tolerance in the static seal area •
These 2 contributors taken separately would not cause any leakage of the actuating cylinder from the static seal area and no specific preventive or corrective action is required in that case.
Replacement of the affected sea l enough to prevent similar leakage. MBD SIL released to cover technical and commercial aspects 46 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 1.8 - NLG Torque Links
CONTENTS Torque Link Apex Pin Rupture Torque Link Apex Pin P/N affected: D64433
47 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions H 1.8 - NLG Torque Link Apex Pin Rupture Description/ Context
Root Cause Investigation
Several cases of apex pin rupture have been reported during aircraft operation.
Investigation has identified :
Consequence
• External bending loads in Apex pin due to contact with towbarless tractor doors
Possible NLG overload, and/or damage to NLG Tyres or torque links.
• No free-play within locking mechanism (nut over-torquing)
Solution/Mitigation The following solutions were established: • New locking system which provides adequate free-play avoiding pin overloading • Shorter torque link apex pin to increase clearance to the tractor
Figure showing shorter pin and new locking mechanism
Status Update MBD SB 580-32-3178 has been approved by Airbus, MBD SB 580-323173 is a prerequisite.
Fracture at thread
Embodiment of MBD SB will significantly reduce the possibility of apex pin rupture. 48 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2 - Main Landing Gear 2.1 - Retraction Actuator 2.10 - Main Fitting 2.2 - Pintle Pins 2.9 - Lockstay Actuator Hoses 2.8 – Side Stay 2.3 - New Charging Labels 2.7 - Sliding Tube 2.4 - Lower Bearing 2.6 - Torque Link Damper Disk Spring 2.5 - Harnesses
49 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.1 - MLG Retraction Actuator
CONTENTS Hydraulic Ports P/N affected: 201590 & 114193 series
Cylinder Corrosion P/N affected: 201590 series
50 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions h 2.1 - MLG Retraction Actuator Hydraulic Ports Description/ Context Repetitive inspections of retraction actuators were introduced by Airbus ISB A320-32-1298 to check the condition of the hydraulic ports at the open end of retraction actuators.
Open end of Retraction Actuator
Diameter increased
Consequence • Possibility of hydraulic leakage. • Repetitive inspections required .
Root Cause Investigation MBD testing using updated in-service data introduced the possibility of cracks occurring in the hydraulic ports at the
Piston Rod
open end of the retraction actuator.
Solution/Mitigation
Hydraulic Ports
• A solution is available to modify the affected hydraulic ports and remove repeat inspection requirements by expanded the diameter of hydraulic ports using a cold working method. • A new production standard cylinder is available that does not require the repeat inspections. • Rework of existing units is available (MBD SB 200-32-299 & MBD SB 201-32-51) • Recommended before 20,000 FC, embodiment after 20,000 FC risks causing damage to cylinder
Embodiment of MBD SBs will remove the need for inspections and reduce the risk of hydraulic leakage. 51 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.1 - MLG Retraction Actuator Cylinder Corrosion Description/ Context Corrosion has been found in the retaining ring groove of enhanced in-service retraction actuator cylinders.
Consequence There is limited reparability in this location, and likely that corroded cylinders will be considered unserviceable.
Root Cause Investigation
Corrosion
Three factors combine to cause the corrosion. • Sealant application can allow voids in sealant to remain. •
Moisture from scraper seal will tend to flow into any voids present in the assembly.
•
Galvanic difference between the base materials in the assembly causes an electrochemical reaction.
Design mitigates risk of galvanic corrosion
To reduce risk of moisture ingress
Thin Chromium Plate added To add corrosion protection to base metal
ROD
Solution/Mitigation
GLAND
• EASA AD No.: 2013-0283R1, FAA AD No.: 2014-2305, and Airbus SB A320-32-1408 require replacement and overhaul of affected actuators within 18 months (from 13/12/13). • MBD SB 200-32-318 & 201-32-66 introduce a new standard of cylinder which is repairable with improved protective treatments. • MBD SB 200-32-311 & 201-32-61 modifies the existing cylinder with improved protective treatments.
Sealant Application Improved
Increased chamfer
RETAINING RING • Material Change • Addition protection of Cadmium Plate & Primer Paint To increase corrosion resistance
To suit chromium plate
CYLINDER Sealant Introduced
Production Solution Increased Cylinder O/D providing more reparability
Primer Paint added to cylinder ID For corrosion resistance
Embodiment of MBD Service Bulletins will reduce corrosion. 52 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
To reduce risk of moisture ingress
/02/ Recommended Solutions 2.2 - MLG A320/A321 Forward Pintle Pin Retaining Bolts
CONTENTS A320/A321 Forward Pintle Pin Retaining Bolts A/C affected: A318/A319/A320/A321
53 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.2 - MLG A320/A321 Forward Pintle Pin Retaining Bolts Description/ Context
Pre - mod
Cases of cross bolt fracture which retains the pintle pin
Consequence • Could result in subsequent loss of pintle pin.
Root Cause Investigation Additional external loads caused fractures of the cross bolt in the pintle pin.
Solution/Mitigation A320 A321 Post - mod
• MBD Service Bulletin introduces 2 stub bolts to replace the one cross bolt that secures the pintle pin. • MBD SB 200-32-261 parts are superseded by serialised parts from SB 200-32-271.
A320 Post - mod
Solution/Mitigation A321 • MBD Service Bulletin introduces new stub bolts connected by a bowden cable to replace the one cross bolt that secures the pintle pin. • MBD SB 201-32-22 parts are superseded by serialised parts from MBD SB 201-32-40.
Embodiment of MBD SB 201-32-22 will reduce the risk of loss of the pintle pin 54 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.3 - MLG New Charging Labels
CONTENTS MLG New Charging Labels A/C affected: A318/A319/A320/A321
55 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.3 - MLG New Charging Labels Description/ Context Labels that show the weight on wheels inflation pressures were deemed to be unclear
Consequence Possible incorrect servicing of the shock absorber
Root Cause Investigation Based on in-service feedback from operators, the charging labels were unclear.
Solution MBD SB 200-32-302 and MBD SB 201-32-53 (A321) introduces new charging labels with increased clarity.
New charging labels introduced with increased clarity 56 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.4 - MLG Lower Bearing
CONTENTS Lower Bearing Outer Diameter Corrosion Lower Bearing P/N affected: Pre SB 200-32-297
Lower Bearing Inner Diameter Corrosion Lower Bearing P/N affected: 201587213 only
57 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.4 - MLG Lower Bearing OD Corrosion Description/ Context Fretting and corrosion has been found on the outer diameter of the lower bearing during seal change and scheduled maintenance.
Consequence Potential hydraulic fluid leakage, replacement of lower bearing in extreme cases and possible damage to main fitting at interface.
Root Cause Investigation Investigations have determined that the root cause of this corrosion is fretting of the OD of the lower bearing and liner, this results in degradation of the anodised coating and exposes the base material.
Mitigation Possible repairs available on application of MBD RDDAS Note: In some cases bearings are required to be replaced
Solution MBD SB 200-32-297 & 201-32-49 issued. • Introduction of a new lower bearing sub assembly with an extended liner which reduces the possibility of fretting and corrosion on the OD of the Lower Bearing. Improved corrosion resistance noted from post mod lower bearings in service.
Pre-mod
Post-mod
New lower bearing available. Improvement in corrosion performance evident. 58 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.5 - Corrosion of LB IDs behind DU-B Liners Description An operator has reported that during DU-B liner replacements their bronze lower bearings suffer from corrosion at the interface with the DU-B liner. The corrosion is de-alloying corrosion which removes the zinc, aluminium and manganese alloying components from the lower bearing ID and deposits them on the OD of the DU-B Liner.
Consequence • On-wing RDDASs can be requested from MBD for temporary repair to remove the corrosion. • Or replacement of Lower Bearings Assembly and then subsequent replacement of bronze bushing at MRO.
Root Cause The corrosion has been caused by excessive moisture present in the region as a result of contamination of grease with an aqueous fluid before the grease is pumped into the lower bearing, or introduction of moisture into the Lower Bearing region during other Landing Gear maintenance activities (such as cleaning or de-icing operations). Solution / Mitigation This can be avoided by taking care not to contaminate grease before use on the aircraft. Additional care should be taken during cleaning / de -icing operations to ensure that there is no moisture ingress past the sliding tube scraper seal.
59 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.5 - MLG New 1M And 2M Axle Harnesses CONTENTS MLG New 1M and 2M Axle Harnesses A/C affected: A318/A319/A320/A321
Overhauled 2M Harnesses A/C affected: A318/A319/A320/A321
P/N affected: Enhanced only
60 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.5 - MLG New 1M And 2M Axle Harnesses Description/ Context There have been cases reported where the tachometer connectors have been installed to the wrong sensor.
Consequence • Incorrect reading of the wheel revolutions to the BCSU
Root Cause Investigation • Incorrect installation between the tachometer connectors and the sensor
Solution/Mitigation • MBD SB 200-32-304 (A318/A319/A320) /201-32-56 (A321) Service Bulletin introduces yellow sleeves on all the cables to all the inboard connections for clearer identification.
Axle
Embodiment of MBD SB will reduce the risk of incorrect installation 61 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ RECOMMENDED SOLUTIONS 2.5 - Overhauled 2M Harnesses Description/ Context Some overhauled 2M MLG Leg harnesses have had arcing events in the area below the center of the torque links.
FWD
Consequence There is a cockpit warning that the auto brake system is disabled. There are no structural consequences.
Root Cause Investigation Investigation found that the contractor that overhauled the harnesses had used cables of an incorrect specification and that the cables were shorter than required. Also the lower conduit subassembly did not have the drain holes in the correct position.
Clamp block Area where 2M Harness has had damage
Solution • MBD has identified the affected population • The contractor for the harness repair has updated their procedures
•
MBD SL A320-A33 has been released to provide guidance on the desired physical condition of the 2m harness following any refurbishment , repair, or restoration.
Retrofit actions completed by MBD MRO for affected Airlines and SL released. 62 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.6 - MLG Torque Link Damper Disk Spring
CONTENTS MLG Torque Link Damper Disk Spring A/C affected: A319/A320/A321
63 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.6 - MLG Torque Link Damper Disk Spring Description/ Context Some torque link damper springs have fractured when the torque link damper has been disassembled for inspection.
Consequence • Potential internal damage to the damper • No effect on MLG operation.
Root Cause Investigation The disk springs a fatigue mode were found to have fractured in
Solution/Mitigation MBD SB 200-32-268 (A319/A320) / 201-32-28 (A321) introduces new disk springs which have increased fatigue life. Affected Disk Springs
Embodiment of MBD SB will reduce the risk of fracture of the disk springs 64 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.7 - MLG Sliding Tube
CONTENTS Axle End Cracks Sliding Tube P/N affected: All P/Ns
Dowel Hole Deformation and cracks Sliding Tube P/N affected: All P/Ns
65 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.7 - MLG Axle End Cracks Description/ Context MBD has received some reports of cracks at the threaded end of the Sliding Tube Axle. Cracks have been located at the Axle Nut Locking Bolt holes and also in the plain section between the holes.
Consequence Risk of Sliding Tube being un-repairable at the next shop visit.
Solution/Mitigation • MBD recommends care is taken not to impact the ends of the MLG Axles. Use the Axle Thread Protector mentioned in the AMM. The following notes are included in the AMM:
Root Cause Investigation On a number of occasions deformation has been observed on the end of the Axle in the cracked areas. This indicates an impact has occurred. No evidence of crack propagation by fatigue has been observed in components investigated by MBD. It is most likely that cracking has formed due to the presence of residual stress. Residual stress is most likely to have been imparted through impact at the end of the Axle.
• MBD has provided off wing Repair Concessions for a number of instances where this damage has been found. • Contact AOG CSC (
[email protected]) if this damage occurs on wing.
Take care to protect Axle ends. Use the Axle Thread Protector specified in the AMM. 66 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.7 Dowel Holes Deformation and Cracks Description/ Context
Root Cause Investigation
MBD has investigated a case of deformation and cracking around the dowel holes at the top end of the Sliding Tube. The damage was found by the operator during scheduled maintenance and did not have any direct operational impact.
The investigation revealed that all 6 dowel holes were cracked and that there was higher than normal stress scan readings in the base material of the sliding tube. The deformation and cracking observed was caused by higher than normal velocity collisions of the Retaining Collar with the Upper Diaphragm Tube following extension of the Sliding Tube during take off. These high velocity collisions are the result of underdamped extensions of the Sliding Tube which are caused by an incorrect balance of hydraulic fluid.
Consequence Following the investigation intothe reported case the Sliding Tube and several Shock Absorber internal components were unserviceable due to the damage sustained. In the theoretical extreme case of rupture of all 6 dowel holes, the Sliding Tube would be retained within the main fitting by the Torque Links. Although retraction of the gear would not be possible, the gear would still be able to support the aircraft during a subsequent landing.
Solution / Mitigation Ensure that the servicing is performed correctly in accordance with the AMM, so that the correct balance of hydraulic fluid and Nitrogen is m aintained at all times. Keep records of all shock absorber maintenance.
Upper Diaphragm Tube
Retaining Collar
Dowel Pin
Pitot Tube
Sliding Tube
Visible Crack and MPI image of further cracking
Main Fitting
Upper Bearing Subassembly
Caused by ineffective maintenance – simple preventive measures can be taken. 67 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.8 – Side Stay CONTENTS Lower Side-Stay Detachment Applicability: All Upper & Lower Side Stay Attachment Pins : 201521xxx 201584xxx 201659xxx
MLG Cuff Link and Banana Link Side Stay Double Locking A/C affected: A318/A319/A320/A321
Upper Cardan Pin Life Limit A/C affected: A320 Pre-EV
68 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
P/N affected: 201163620 only
/02/ Recommended Solutions 2.8 - Low er Side-stay Detachment Location of Upper attachment pin
Description / Context One incident has occurred where the lower side stay attachment pin detached from the landing gear during landing.
Consequence In this case, the aircraft taxied safely to the gate. However, there is a risk of landing gear collapse. Location of Lower attachment pin
Root Cause Investigation • Probable root cause: insecure fastening of the lower side stay attachment pin. • After the incident, only the pin was found. The associated fastening components were not found.
Mitigation / Solution Operators are reminded that Aircraft Maintenance Manual (AMM) procedures must be followed to ensure correct assembly and disassembly of the side stay.
Unlocked washer tabs before locking and sealant application
Follow AMM procedures for assembly and disassembly of side stay 69 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.8 - MLG Cuff Link And Banana Link Description/ Context Operators have reported 4 fractures of the cuff subassemblies
Consequence • Potential for incorrect locking of the lock spring. • Inspection requirements to Airbus SB A320-32A1224
Root Cause Investigation • Investigations have shown that the cuff fractures were due to stress corrosion cracks which were possibly induced by moisture ingress.
Solution/Mitigation • MBD SB 200-32-267 & SB 201-32-27 introduces reinforced cuff and banana links which gives improved resistance to stress corrosion and improved strength properties.
Banana Link
Banana Link
Cuff subassembly
Embodiment of MBD SB will reduce the risk of fractures of the cuff and remove the requirement for inspection 70 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.8 Sidestay Cardan Double Locking Description/ Context
Status Update
New locking end caps and bolts for the upper and lower Sidestay Cardan joints - To introduce double locking to the Joints.
AD released to mandate the installation of new end caps and bolts. MBD SBs 200-32-315 and 201-32-63 released. Kits available, contact
[email protected] to place orders – see table for applicability • Please note availability of kits is staggered over the AD Compliance Time (currently June 2021).
Affects all A320/A321 MLG with the exception of EV
Commercial Policy Kits discounted time, by 50% duration of the AD compliance seefor SBs for prices.
MLG Type
Kit number
Comments
A320
MAF2175A320-200
Upper and Lower Joints
A321-200
MAF2175A321-200
Upper Joint Only
A321-100
MAF2175A321-100
Upper and Lower Joints
MBD SBs released. Kits available - Contact MBD Retrofit to order. 71 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.8 - Sidestay Upper Cardan Life Limit Description/ Context
Mitigation
During an A320-200 77T main landing gear fatigue test, an upper cardan PN 201163620 was found with a crack, emanating from the grease hole / main lug intersection.
certain i ns tallations of the P/N 201163620 MLG upper cardan (see below
Consequence This condition, if not corrected, could lead to MLG upper cardan fracture and in worse case MLG collapse.
An AD has been released, it has been decided to reduce the life limit for table for information). This AD requires implementation of the new life limits, as applicable, and replacement of any affected MLG upper cardan units that have already exceeded the reduced limit.
Status Update AD 2014-0141 released. MBD SB 200-32-312 has been published with rework instructions to achieve full life.
Root Cause Investigation Fatigue crack emanated from grease hole
Crack
Grease holes
AD 2014-0141 and MBD SB 200-32-312 released. 72 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.9 - MLG Lock Stay Actuator Hoses
CONTENTS Lockstay Actuator Hose Corrosion Hose Leakage Near Swivel Coupling Hoses
A/C affected:
P/N affected:
A318/A319/A320/A321
20165519(3/4/5/6)
73 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.9 - MLG Lockstay Actuator Hose Corrosion Description/ Context Operators have reported corrosion to hose end fittings
End fittings
Consequence Hydraulic leakage
Root Cause Investigation
Hoses
Corrosion was found to be in the threads of the swivel housing
Solution MBD SB 200-32-300 and MBD SB 201-32-52 (A321) introduces a more corrosion resistant material of the end fittings.
Crack on swivel housing
MBD SBs introduce new end fittings which are more resistant to corrosion 74 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.9 - MLG Lockstay Actuator Hose Leakage Near Swivel Coupling Description/Context 2 Cases of Post SB 200-32-300 Lockstay Actuator Hose leakages near the swivel coupling location on the hose.
Possible Consequence • If leak occurs whilst aircraft on ground may result in an AOG and delays to source a spare hose. • If leak occurs in flight then may result in in-ability to retract MLG and an in flight turn back.
Root Cause Investigation The hose leakage on the subject aircraft is a result of an attempt to undo the 13/16” Hex or 11/16” Hex of the Swivel coupling endfitting to disconnect the Swivel coupling from the hose socket during AC maintenance. This joint should only be used during hose production.
Mitigation/Solution Operators should not use the 11/16” and the 13/16” Hex when removing or installing the Lockstay actuator hoses . AMM will be updated to include these notes due Q4 2016.
Swivel coupling
Hose Socket
SimpleMBD solution available,new AMM to fittings be updated risk of future occurrence. SBs introduce end which to arereduce more resistant to corrosion 75 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.10 - MLG Main Fitting
CONTENTS Main Fitting Inner Bore Corrosion A/C affected: A318/A319/A320/A321
P/N affected: All PNs
Main Fitting Inner Bore Corrosion RDDAS Guidelines Main Fitting Inner Bore Corrosion FAQs
76 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.10 - MLG Main Fitting Inner Bore Corrosion Description/Context Estimated ~3% of fleet affected and ~50 cases of Main Fitting corrosion have been reported since the introduction of a modified Lower Bearing with a longer outer liner in 2008 (MBD SBs 200-32-297 & 201-32-49). All cases have been repairable.
Possible Consequences • •
Shock absorber fluid leakage and consequent unscheduled maintenance. A requirement to perform an on-wing repair, to remove corrosion damage. •
Extreme cases of corrosion may necessitate MRO repair .
Root Cause Investigation The root cause of the corrosion is a combination of: • Inherent micro-cracking of the flash chrome plus moisture ingress can lead to corrosion . This corrosion causes chrome lift/detachment. • Fretting between the Lower Bearing and Main Fitting, which (in the presence of lifted/detached chrome) damages the attached flash chrome and exposes the base metal further.
Mitigation • Refer to Airbus SIL 32-144(especially page 45) for Corrosion Prevention Recommendations. • On-Wing: • If you find this damage, make an RDDAS request to MBD AOG CSC (
[email protected]) and request the current reporting template. • RDDAS limitation : next overhaul • MBD SLs A320-A31 & A321-A19 (application of a CIC Wipe) may be performed at any convenient opportunity (RDDAS or no RDDAS) to increase inspection interval. • Maximum RDDAS inspection interval : 8000FC/48 months.
Solution At overhaul Main Fittings are modifiable (MBD SB 200-32-371 & 201-32-65): • Main Fitting bore machined to accommodate a thicker layer of chrome • Chrome wiped with primer paint to fill surface micro-cracks This will be embodied on new manufacture in August 2015. On-Wing MBD SLs A31 & A19 issued Sep. 2014 to apply CIC wipe to area
RDDAS Guide
MISP Closed, S olutions Available 77 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.10 - MLG Main Fitting Inner Bore Corrosion RDDAS Guidelines General Guidelines Main Fitting Inner Bore Corrosion RDDASs must take a number of variables into account before a RDDAS can be issued. FAQs • Blends in the sealing lands must provide enough material support to maintain the shock absorber sealing function. • Blends in the locating bore must provide enough support for the lower bearing during landing gear operation and maintain fatigue stresses within acceptable limits, where the support has been removed or is not sufficient the RDDAS would be rejected and off-wing repaired would be required (including installation of an overseize bearing).
Case
Case Description
Blend Size
Max Depth Seen
1
Locating Bore Deep Blend
Height 80mm x Width 140mm
0.9mm
2
Primary Seal Land Deep Blend
Height 37mm x Width 23mm
0.7mm
Blend is near seals and RDDAS is subject to satisfactory sealing of the shock absorber.
3
Long Blend in Locating bore
Height 50mm x Width 250mm
0.42mm
Remaining bearing. section above blend provides support for
Case 1
Comments
Case 2
Case 3
Note: this slide is for information only and is not authorisation for future repairs 78 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.10 - MLG Main Fitting Inner Bore Corrosion FAQs Customer Question (Main Fitting):
Customer Question (Lower Bearing):
I need to repair a pre-SB* Main Fitting (at overhaul) in the area where the Lower Bearing locates, but the only CMM Repair is for a post-SB* Main Fitting. How do I process the repair? * SB 200-32-317 (A320), SB 201-32-65 (A321)
I have repaired a Main Fitting in the area where the Lower Bearing locates and want to install an oversize Lower Bearing with a “long” outer liner. However, SB 200-32-297 / SB 201-32-49 does not include the P/Ns of oversize Lower Bearings. How do I proceed?
MBD Response:
MBD Response:
You first need to embody the re-identification aspect of the SB*. In practice, this means you must assign the applicable post-SB P/N to the Main Fitting, both in documentation and on the part, in accordance with the SB* instructions. Then the CMM Repair will be applicable to your Main Fitting.
You first need to embody the re-identification aspect of the SB by cancelling the strike numbers on the applicable nameplates. Then you can refer to the CMM Repair for the Main Fitting, where the “Option 2 – Post SB” table contains the P/Ns of the “long” outer-liner oversize Lower Bearings.
Main Fitting Flow Chart
More FAQs
Lower Bearing Flow Chart
1. Embody the re-identification aspect of the SB:
1. Embody the re-identification aspect of the SB:
Assign the applicable post-SB P/N to the Main Fitting (both in documentation and on the part), in accordance with the SB*.
Cancel the strike numbers on the applicable nameplates in accordance with SB instructions.
2. Perform the CMM Repair:
2. Refer to the CMM:
Now that your Main Fitting is identified with a postSB* P/N, you can perform the CMM Repair.
Now that your MLG is identified as being post-SB, refer to the “Option 2 – Post SB” table in the CMM Repair, which contains the P/Ns of the “long” outer -liner oversize Lower Bearings.
79 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/02/ Recommended Solutions 2.10 - MLG Main Fitting Inner Bore Corrosion FAQs Customer Question (Main Fitting):
Customer Question (Lower Bearing):
Is there any concern that the wet primer will mix with hydraulic fluid?
Is it possible to apply the SB on-wing?
MBD Response: No, the wet primer application procedure calls for the wet primer to be wiped ‘dry’. The objective is not for the primer to stay on the surface but to impregnate the microcracks.
Customer Question (Lower Bearing):
MBD Response: No because the chrome plating is a shop procedure. See the on-wing solution (Service Letter) for way forward.
Customer Question (Lower Bearing):
What will be the design in this area for the new EV MLGs?
What is the maximum allowable blend depth for a RDDAS if there are corrosion findings?
MBD Response:
MBD Response:
Same as existing solution i.e. Thicker chrome plating ( a small number of EV MLGs do not have the solution embodied).
Due to the number of variables (Blend W idth, Height, Depth and Location), MBD is currently processing RDDASs on a case by case basis.
Customer Question (Lower Bearing): Does CIC wipe need to be re-applied if the shock absorber is disassembled for any reason before overhaul?
MBD Response: MBD recommends the reapplication of CIC wipe in the area at any convenient opportunity, as a best practice.
80 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/03/ Best Maintenance Practices 3 - Landing Gear - Best Maintenance Practices Lubrication of Landing Gears • 3.1. NLG Lubrication Recommendations • 3.2. MLG Lubrication Recommendations • 3.3. General Lubrication Recommendations • 3.4. Signs of In-Effective Lubrication • 3.5. Lubrication of Threads • 3.6. Clay vs Lithium Grease Cleaning •
3.6. General Recommendations
General Checks • 3.7. Sealant • 3.8. Protective Treatments • 3.9. Hoses and Harnesses
Effective preventative maintenance will reduce the risk of part degradation and improve gear reliability 81 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/03/ Best Maintenance Practices 3.1 - NLG Lubrication Recommendations Upper panel & barrel hinge pintle
The greasing intervals given in Airbus MPD are the minimum requirement. MBD, on advice from operators has highlighted sensitive areas where operators may wish to reduce their greasing intervals should they feel the need (proactively or through previous experience).
24/25 GA target lever pin Torque links and apex pins Lower Bearing
Effective greasing will reduce the risk of part degradation and improve gear reliability 82 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/03/ Best Maintenance Practices 3.2 - MLG Lubrication Recommendations The greasing intervals given in Airbus MPD are the minimum requirement. MBD, on advice from operators has highlighted sensitive areas where operators may wish to reduce their greasing intervals should they feel the need (proactively or through previous experience).
Retraction Actuator Pins
Pintle Bearings Aft Forward and Lower Bearing Dowel Pins, particularly if flying into the CIS region where weekly greasing is recommended Very dynamic location and operation on rough runways and taxiways has been proven to reduce grease longevity therefore more frequent grease replenishment is recommended.
Upper and Lower Torque Links
Effective greasing will reduce the risk of part degradation and improve gear reliability 83 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/03/ Best Maintenance Practices 3.3 - General Lubrication Recommendations Lubrication Information: •
Greasing operations are expected to fulfill two different functions: •
Lubrication
•
Indirect protection of metallic parts against corrosion
•
Greasing minimises friction in joints and expels trapped moisture dirt and debris from joints interface locations.
•
Greasing and lubrication of the landing gear need to be performed as per MPD Greasing intervals as a minimum
Recommendation during Greasing •
•
Fully replenish all old grease at every greasing interval, by injecting grease until only fresh grease is seen to extrude (purging) for full grease renewal •
Replenishing grease throughout a path/joint will prevent solidification of the grease inside the greasing paths
•
Note:- This is only possible for joints where grease is expelled externally
Do not mix greases of different types / specifications •
•
If grease is changed, fully purge joint with new grease and reduce greasing interval for a short period of time
Use only approved lubricants from the Airbus Consumable Materials List •
Ensure grease is within its shelf life
•
Ensure grease is kept in sealed containers before use
84 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/03/ Best Maintenance Practices 3.4 - Signs of In-Effective Lubrication Signs of In-Effective Lubrication
Signs that a grease path is blocked
•
• •
• •
During Greasing Application extruded grease may contain debris Excessively worn protective treatments, chromium plate and possible exposure of base metal. Base material may be corroded.
• •
In-effective lubrication excessive wear and base metal exposure.
Grease gun give excessive back pressure Excessive grease may extrude from around grease adaptor.. During disassembly greasing path may be visibly blocked No grease extrude from joint or orifice
Effective Lubrication, normal wear.
Blocked Greasing path – lack of effective lubrication 85 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/03/ Best Maintenance Practices 3.5 - Lubrication of Threads
•
Application of jointing compound on threads and splines is important to prevent degradation.
•
An application of suitable lubricant/ Jointing compound on to threads before assembly as per AMM/ CMM practices (i.e Molykote DX paste as per below image) will lubricate the thread interface and prevent protective treatment damage during assembly.
•
Lubricants and jointing compounds used for this application are not resistant to hydraulic oils and will absorb moisture over time, so ensure that a fillet of sealant is always present to provide additional protection.
86 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/03/ Best Maintenance Practices 3.6 - Clay vs Lithium Grease MBD has received frequent questions and requests regarding lithium based greases for use on all families of landing gear. The Airbus AMM currently allows use of either Lithium or Clay based greases. MBD documentation and deliveries currently complies wi th the grease specified on the purchase order from the Type Certificate Holder of the aircraft. For Single Aisle Aircraft this is currently Clay Based Gr ease Mobil 28. MBD recognizes that some operators have a preference for Lithium grease over Clay based grease; however the introduction of Lithium grease into MBD documentation will not take place until requested by the Type Certificate Holder.
87 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/03/ Best Maintenance Practices 3.6 - General Cleaning Recommendations DO NOT USE Vapour cleaning or high pressure spraying equipment (MBD also recommends operators DO NOT use low pressure spraying equipment). These cleaning methods lead to potential moisture ingress, sealant damage and part corrosion in particular: • Removal of protective treatments and damage to fillets of sealant on Structural Parts resulting in corrosion • Moisture ingress inside Interference Fits (Lug and Bush Interfaces) resulting in lug corrosion • Damage to Electrical Equipment resulting in short circuiting or false indications • Damage or degradation to Sealed (Hydraulic) Units (see below) If you do use low pressure spray equipment when washing Sealed (Hydraulic units) then: • Do not direct the jet to the gland ID: This could force water past the scraper seal lead to moisture ingress result in corrosion on internal parts. • Do not direct the jet to external valves: this may remove sealant and lead to moisture ingress. Follow and use only AMM approved cleaning methods and fluids. • AMM External Cleaning • AMM Main Landing Gear Cleaning
Washing of Hydraulic Units - Do not direct jet to this location (Gland ID)
88 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/03/ Best Maintenance Practices 3.7 - General Checks - Sealant •
Inspection and repair is recommended at regular intervals and/or when damage is noted during any visual inspection.
•
Visually Inspect joints to ensure sealant is present and forms a continuous unbroken profile. Any damage to sealant should be repaired / replaced in line with relevant AMM/CMM.
Cracked sealant could identify bush migration / rotation.
•
Cracked sealant could indicated bush/Migration or rotation.
Ensure sealant is present and continuous
• If Migration or bush rotation has occurred then refer to applicable AMM/CMM or approved documentation (In some cases this is covered in a service bulletin)
89 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/03/ Best Maintenance Practices 3.8 - General Checks - Protective Treatments •
Protective Treatment prevents base material from corrosion. Any damage to protective treatment could result in corrosion and part degradation.
•
Signs that a Protective Treatment is Damaged • Visual defects present • Old exuded grease may include particles of protective treatments • Corrosion / corrosion product evident in the area • Base material exposed
•
Causes of Protective Treatment Damage • Ingress of moisture into a joint, Stagnant water in a joint, Abrasive damage (Internal wear and external chaffing), General weather damage FOD damage, Chemical damage/attack (deicing fluids, hydraulic fluids, etc), Physical damage from mishandling
•
Replenishment of Protective Treatments • Follow relevant AMM/CMM to reapply the protective treatment
90 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
Paint Loss has resulted in corrosion on this MLG
/03/ Best Maintenance Practices 3.9 - General Checks - Hoses and Harnesses •
Damage to the Harness and protective treatment could occur when these two components come in contact with each other during the operation
•
When inspecting hoses and harnesses, look out for worn sections, leakages, deformation, kinks, scratches, FOD / protective treatment damage. Also ensure that the back shells are not cracked or damaged. If any of these damages are encountered, the part must be replaced, refer to the relevant AMM / CMM. Do not perform unauthorised modifications or repairs to harness and hoses as this can have unforeseen results and consequences.
•
91 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/04/ Landing Gear Product Information
1. A320/321 Serialisation SBs
2. Restoration Information
3. Tracking the safe life of parts
4. New Products
5. EV Tooling Information
92 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/04/ Landing Gear Production Information 4.1 - MLG A320 Serialisation Service Bulletins
It is a requirement of the Airbus MPD that all the life l imited parts can be tracked •
This was introduced by a number of Service Bulletins: • 200-32-271 (Retraction actuator pins and forward pintle pin cross bolts) • Refer to Airbus SB A320-32-1213 for compliance • Introduction of a new serialised parts from SB 200-32-271 will also accomplish SB 200-32-261 • 200-32-282 (Torque link apex pin nut) • 200-32-283 (Side stay parts) • Introduction of the new serialised Cuff and Banana link subassemblies from SB 20032-283 will also accomplish SB 200-32-267 • 200-32-284 (Retraction actuator)
• •
The Serialisation Service Bulletins include a method to produce the unique tracking numbers The operators should make sure that the applicable strike numbers are marked on the strike plates Embodiment of MBD SB’s will help to track the safe life of the parts
93 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/04/ Landing Gear Production Information 4.1 - MLG A321 Serialisation Service Bulletins
It is a requirement of the Airbus MPD that all the life l imited parts can be tracked •
This was introduced by a number of Service Bulletins: • 201-32-29 (Retraction actuator pins and forward pintle pin cross bolts) • Refer to Airbus SB A320-32-1213 for compliance • Introduction of a new serialised parts from SB 200-32-29 will also accomplish SB 20132-22 • 201-32-39 (Torque link apex pin nut) • 201-32-40 (Side stay parts) • Introduction of the new serialised Cuff and Banana link subassemblies from SB 20132-40 will also accomplish SB 201-32-27 • 201-32-41 (Retraction actuator)
• •
The Serialisation Service Bulletins include a method to produce the unique tracking numbers The operators should make sure that the applicable strike numbers are marked on the strike plates Continued Embodiment of MBD SB’s will help to track the safe life of the parts
94 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/04/ Landing Gear Production Information 4.2 - NLG Restoration Information •
Based on MBD experience and in-service feedback, MBD has issued a SB which provides the recommended restoration tasks to perform at the end of the TBO period (during overhaul process)
•
The recommendations provided in this MBD SB advise on the restoration activity that needs to be performed to maintain continued safe and reliable operation.
•
2 categories have been defined : • Concept A => parts requiring a complete overhaul as per the relevant CMM • Concept B => parts submitted only to visual inspection and tests as per relevant CMM; if a finding is noticed during visual inspection or the test then the part should be submitted to a complete overhaul as per relevant CMM Continued
MBD SB 580-32-3170 provides all restoration tasks to perform on NLG 95 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/04/ Landing Gear Production Information 4.2 - MLG Restoration Information • The Restoration Service Bulletins were produced by MBD to define the minimum requirements that need to be achieved at an overhaul • These Service Bulletins must be used in conjunction with the Airbus MRBR and MPD documents • The Service Bulletins list the items that are identified with a life limitation that require a full restoration • On condition units that are accepted after a satisfactory test at overhaul will not have had a full restoration
MBD SB 200-32-295 and 201-32-48 provides all restoration tasks to perform on MLG 96 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/04/ Landing Gear Production Information 4.3 - MLG Tracking the Safe Life of Parts •
The Service Bulletins are issued to help Operators to track the safe life of the parts
•
The safe life data is included in the Airbus Airworthiness Limitations Section (ALS) and the SBs
•
The data in the MBD SB is in three sections • Parts which tests indicate have not achieved the full design life are listed in Appendix A, the Safe Life Limits for these parts are listed in the Airbus ALS Part 1 (ALS Part 4 contains system equipment). • Parts which tests indicate have achieved the full design life are listed in Appendix B, the Safe Life Limits for these parts are listed in the Airbus ALS Part 1 (ALS Part 4 contains system equipment). • Parts with a recommended replacement within 60,000 landings are listed in Appendix C of the MBD SBs, with the recommended replacement data, these parts are not included in the ALS
MBD SB 200-32-230 and 201-32-08 (A321) will help to track the safe life of the parts 97 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/04/ Landing Gear Production Information 4.4 - A320 Landing Gear New Products - Context •
New NLG and MLG are under development • Driven by new specifications encompassing product improvement and new programme requirements • 1 NLG version (common across all AC variants) and 2 MLG versions (A320 & A321) • Will be applicable to both current A320 family aircrafts and the NEO aircraft.
•
The new landing gears are derived from the current production standards with improvements where required
Continued 98 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/04/ Landing Gear Production Information 4.4 - Interchangeability • The new gears will be compatible with some existing A320 Aircraft. • Higher structural requirements mean existing A320 gears are NOT compatible with A320 NEO airframe. • MBD and Airbus are w orking together to deliver the latest improvements to the existing fleet.
Continued 99 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/04/ Landing Gear Production Information 4.4 - NLG & MLG Structural Reinforcements •
NLG structural improvements • • • • • • •
Main Fitting Dragstay Sliding Tube Turning Tube Torque link Shock absorber internals Secondary structural items •
•
(pins, wheel axle nut, uplock assembly…)
MLG structural improvements • • •
Main Fitting Sliding Tube Sidestay
Continued 100 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/04/ Landing Gear Production Information 4.4 - NLG In-Service Corrosion Protection Improvements •
Upper Support / column interface •
•
Change of column material to Corrosion Resistant Steel
Articulation points • •
Corrosion inhibitor compound in lug cavities Improved bush assembly techniques (thicker cadmium on bushes and wet primer assembly)
•
Axle / Sliding Tube (spacer) interface • •
Corrosion inhibitor compound / jointing compound Improved sealant scheme
Continued 101 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/04/ A320 Landing Gear New Products 4.4 - NLG Operational Improvements •
Harness chaffing resolution • •
•
•
New routing of Upper 1M and 2M harnesses New junction box technology
Retraction Actuator bearing •
Change of rod material to Corrosion Resistant
•
Steel Caged split spherical bearing
Towing indications •
Painted visual indication of the 2 angular limits
Continued 102 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/04/ Landing Gear Production Information 4.4 - In-service Corrosion Protection Improvements •
Bushes •
•
Change of assembly process to use wet primer method
Main Fitting to Upper Diaphragm Tube Interface • •
New environmental seal Improved corrosion prevention methods applied to area
•
Jacking Dome • •
Improved protection scheme and assembly methods Design change to improve drainage
Continued 103 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/04/ Landing Gear Production Information 4.4 - MLG Operational Improvements •
New Upper Bearing Assembly for A320 MLG •
•
Changeover valve indicator •
•
Threaded assembly to harmonize A320 & A321
Improved visual aid for identification of secondary seal activation
Improved Damper and Torque Link interface • •
New wire inserts Longer bolts
104 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/04/ Landing Gear Production Information 4.5 – EV Tooling Information
A320 EV NLG socket for use with new barrel nut.
A320 CMM 32-27-70 – T46934
105 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/04/ Landing Gear Production Information 4.5 – EV Tooling Information
A320 and A321 EV MLG Upper Cardan Nut Socket to torque the new Lower Cardan Nut
A320 CMM 32-12-79 – DRT69679 A321 CMM 32-12-80 – DRT69681
A320 and A321 EV MLG Lower Cardan Nut Socket to torque the new Lower Cardan Nut
A320 CMM 32-12-79 - DRT69678 A321 CMM 32-12-80 - DRT69680
106 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/04/ Landing Gear Production Information 4.5 – EV Tooling Information
A320 EV MLG fixture to drill locking plate 55-450501600 for threaded upper bearing assembly.
A320 EV MLG spanner to torque the Upper Bearing onto the Slider
CMM 32-12-82 – F28183000
CMM 32-12-82 – T47412
Upper Bearing
Locking Plate
A320 EV MLG threaded cone to protect sliding tube threads during lower bearing
CMM 32-12-82 – T47411 Sliding Tube
107 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
/04/ Landing Gear Production Information 4.5 – EV Tooling Information Piston Nut
A320 and A321 EV MLG torque adaptor for use on Retraction Actuator Piston
CMM 32-31-04 - PN 144465
108 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
END
109 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016 This document and the information therein are the property of Messier-Bugatti-Dowty, They must not be copied or communicated to a third party without the prior written authorization of Messier-Bugatti-Dowty.
