ata 73

Dornier 328 DORNIER LUFTFAHRT

TRAINING MANUAL LINE /BASE MAINTENANCE

ATA CHAPTER 73 ENGINE FUEL AND CONTROL 73-10 DISTRIBUTION

2

OPERATION ............................................................................................................................................ 2 Fuel System ........................................................................................................................................... 2 Fuel Filter/Heater Unit .......................................................................................................................... 4 Fuel Manifold Assy & Nozzles............................................................................................................. 7 Fuel Drain Ejector Tank........................................................................................................................ 8 OPERATION ............................................................................................................................................ 8

73-20 CONTROLLING

9

Hydro - Mechanical Fuel Control Unit (Hmu)..................................................................................... 9 Hmu Eec Mode.................................................................................................................................... 10 Hmu Manual Mode ............................................................................................................................. 12 Fault Detection System ....................................................................................................................... 13 EEC Features & TSC Features............................................................................................................ 15 EEC SAFETY FEATURES ................................................................................................................ 15 TSC FEATURES ................................................................................................................................ 15 Auto-Feather System........................................................................................................................... 16 NH Overspeed Test: ............................................................................................................................ 18 Engine Trim:........................................................................................................................................ 18

73-30 INDICATING

19

FUEL FLOW AND TEMPERATURE................................................................................................... 19 FUNCTIONAL DESCRIPTION ............................................................................................................ 19 OPERATION .......................................................................................................................................... 19 Fuel Flow Primary EICAS Page ......................................................................................................... 21 FUEL FILTER / PRESSURE.................................................................................................................. 22 FUNCTIONAL DESCRIPTION ............................................................................................................ 22 OPERATION .......................................................................................................................................... 22 Fuel -Flow / -Used / -Temperature / -Pressure and HP Filter on Fuel Page ....................................... 23 Fuel Flow on Engine Page................................................................................................................... 24 LP Fuel Filter on System Maintenance Page ...................................................................................... 25 Fuel Flow on RMU Page 2.................................................................................................................. 26

INDEX

27

LIST OF ILLUSTRATIONS

27

Effectivity: 328-100 Mod.10

- FOR TRAINING PURPOSES ONLY TM-Engine Fuel & Control

Page: 73-1 Issue: 08/95 ETM/ETX

Dornier 328 TRAINING MANUAL

DORNIER LUFTFAHRT

LINE /BASE MAINTENANCE

73-10 DISTRIBUTION OPERATION Fuel System

Fig. 1 Fuel System Fuel is pumped from the aircraft fuel tanks, to the engine fuel inlet, by either the electrical fuel booster pumps or by the ejector pumps. Fuel is introduced into the engine fuel system at the fuel heater unit. This unit consists of a filter and a fin type heater in two integral housings. The filter housing contains a bypass valve to ensure an adequate fuel flow in the event of blockage and an indicator to wam of impending blockage. The heater housing is divided into two circuits. RGB lubricating oil flows through one circuit to transfer heat to the fuel, which flows through the other circuit. A themnal sensor in the fuel circuit operates a valve to regulate the oil flow in order to maintain proper fuel temperature. The outlet port incorporates a switch to operate a low pressure waming and a retum port for the fuel drain tank. Fuel transfers to the fuel pump by an extemal transfer tube. The pump is a positive displacement type. The inlet contains a screen which, when blocked, lifts from it's seat to allow the fuel to bypass. The fuel passes through the inlet screen and is pumped through the outlet filter by a single stage gear type pump. The outlet filter has a bypass valve to divert the fuel flow in the event of filter blockage and an indicator to wam of impending blockage.

Page: 73-2 Issue: 08/95 ETM/ETX

- FOR TRAINING PURPOSES ONLY TM-Engine Fuel & Control

Effectivity: 328-100 Mod.10

Dornier 328 DORNIER LUFTFAHRT

TRAINING MANUAL LINE /BASE MAINTENANCE

To maintain fuel inlet pressure, an amount of fuel is retumed from the HMU to the inlet side of the pump through an ejector nozzle positioned ahead of the main inlet. Fuel is routed between the HMU and the pump by intemal passages which are sealed by prefommed packings. The hydromechanical metering unit (HMU) divides the high pressure fuel between the motive flow, metered flow and bypass flow circuits. The motive flow circuit is used to drive airframe ejectors and purge the fuel drain tank. The metered flow circuit provides fuel to the fuel nozzles. The bypass flow circuit retums excess fuel back to the fuel pump inlet. An airframe supplied fuel flow meter measures the amount of fuel flowing through the metered flow circuit. The flow divider splits metered fuel flow into the primary and the secondary circuits with the engine running. During shut down the dump valve purges remaining fuel, trapped within the manifolds, to the fuel drain tank. The primary and secondary fuel manifolds carries fuel to the 14 fuel nozzles and in the event of a defective packing, drains fuel leakage. The fuel nozzles delivers fuel to the combustion chamber. The fuel drain tank contains fuel from the previous engine shut down and will be purged, during the next engine run, into the low pressure fuel system at the fuel heater unit . Types of fuel and additives Ref.: SB20004 Use of AVGAS limited to 150 hours/TBO Hours on AVGAS = Amount of AVGAS / average fuel consumption

Effectivity: 328-100 Mod.10

- FOR TRAINING PURPOSES ONLY TM-Engine Fuel & Control

Page: 73-3 Issue: 08/95 ETM/ETX

Dornier 328 TRAINING MANUAL

DORNIER LUFTFAHRT

LINE /BASE MAINTENANCE

Fuel Filter/Heater Unit

Fig. 2 Fuel Filter/Heater Unit Purpose: Construction:

Operation:

Filter:

Impending bypass switch:

Page: 73-4 Issue: 08/95 ETM/ETX

Pre-heat the fuel to prevent ice crystal formation Consists of a low pressure fuel filter, an impending bypass indicator, a bypass valve (ref. fuel system), a heat exchanger, a thermal sensor and an oil flow control valve The heater housing has two circuits: lubricating oil and fuel. Heat transfers from oil to fuel. A thermal sensor in the fuel circuit operates an oil flow control valve to maintain the required fuel temperature. Fuel out temp. below 10°C = full oil flow, max. heating Fuel out temp. above 10°C = reduction of heat transfer Fuel out temp. above 32°C = full bypass, no heating 70 microns Cleanable Buble Point test Activates at 1.5 psid Field replaceable Bypass valve: Opens at 3 psid - FOR TRAINING PURPOSES ONLY TM-Engine Fuel & Control

Effectivity: 328-100 Mod.10

Dornier 328 DORNIER LUFTFAHRT

TRAINING MANUAL LINE /BASE MAINTENANCE

Fuel Pump

Fig. 3 Fuel Pump Purpose: Provide high pressure fuel flow to the mechanical control unit to meet engine fuel requirements at any operating conditions Description: Single stage gear type pump driven by the HP rotor through the accessory gearbox. The pump incorporates a 74 micron inlet strainer with integral bypass feature, a set of spur gears and a 10 micron outlet filter. The outlet filter is equiped with a bypass valve and an impending bypass switch. 100% NH = 3740 PPH (TYPICAL) Operation: Rotation of the pump gears draw the low pressure fuel through the inlet strainer. Restricton in the system causes the fuel to pressurize and flow through the outlet filter out to the hydromechanical fuel control (HMU). When blockage of the pump inlet strainer causes a pressure drop of 1.3 psid, the strainer lift off its seat and allow fuel to bypass the strainer. When blockage of the pump outlet filter causes a pressure drop of 25 psid, the impending bypass switch sends a warning signal. When the pressure drop reaches 50 psid the bypass valve opens and send unfiltered fuel to the HMU. Bypass fuel from the mechanical fuel control is returned to the inlet of the pump, through an ejector nozzle, to help maintain the inlet pressure to the pump gears. Inlet strainer: Outlet filter:

Effectivity: 328-100 Mod.10

cleanable (ELECTROSONIC) cleanable (ULTRASONIC) buble point test Buble point test:

- FOR TRAINING PURPOSES ONLY TM-Engine Fuel & Control

Page: 73-5 Issue: 08/95 ETM/ETX

Dornier 328 TRAINING MANUAL

DORNIER LUFTFAHRT

LINE /BASE MAINTENANCE

Flow Divider Valve

Fig. 4 Flow Divider Valve Purpose:

Divides flow between primary and secondary fuel manifolds and dumps fuel from the manifolds on shutdown Construction: Two concentric valves spring loaded to dump position Dump position: Purge fuel manifolds and nozzles from any remaining fuel Prevents contamination of nozzles Fuel returns to engine Primary flow position: 10 psi closes dump side of primary valve Opens flow to primary manifolds 10 nozzles begin to flow Primary and secondary flow position: 310 psi opens secondary valve Opens flow to secondary manifolds 14 additional nozzles begin to flow Page: 73-6 Issue: 08/95 ETM/ETX

- FOR TRAINING PURPOSES ONLY TM-Engine Fuel & Control

Effectivity: 328-100 Mod.10

Dornier 328 DORNIER LUFTFAHRT

TRAINING MANUAL LINE /BASE MAINTENANCE

Fuel Manifold Assy & Nozzles

Fig. 5 Fuel Manifold Assy & Nozzles Purpose: Construction:

Atomize and deliver fuel to the combustion chamber. Primary - secondary adapters Primary flow through center orifice Secondary flow through annular orifice Locating pin on adapter

Secondary adapters Secondary flow only Locating pin on gas generator case Positions # 1-4-8-12 Drain manifold Prevents fuel from leaking on the gas generator case Collects fuel manifold leakage and drains it overboard

Effectivity: 328-100 Mod.10

- FOR TRAINING PURPOSES ONLY TM-Engine Fuel & Control

Page: 73-7 Issue: 08/95 ETM/ETX

Dornier 328 TRAINING MANUAL

DORNIER LUFTFAHRT

LINE /BASE MAINTENANCE

Fuel Drain Ejector Tank

Fig. 6 Fuel Drain Ejector Tank Purpose:

Collect engine drain fuel and return it to the fuel heater upstream of the fuel pump.

Construction:

Tank Float Valve Lever Non- return valve Ejector pump

OPERATION Fuel drained from the nozzles raises the tank fuel level and the float rises. During its movement, the float body lifts the lever which unseats the valve from the plug orifice. The fuel pressure, acting on the upper end of the orifice, together with a small depression produced by the annulus at the orifice lower end, causes a pressure drop inside the plug orifice. The pressure drop unseats the non-return valve, permitting fuel to flow to the ejector pump. The fuel then is drawn by the ejector pump venturi action and returned to the engine low pressure fuel system.

Page: 73-8 Issue: 08/95 ETM/ETX

- FOR TRAINING PURPOSES ONLY TM-Engine Fuel & Control

Effectivity: 328-100 Mod.10

Dornier 328 DORNIER LUFTFAHRT

TRAINING MANUAL LINE /BASE MAINTENANCE

73-20 CONTROLLING Hydro - Mechanical Fuel Control Unit (Hmu)

Fig. 7 Hydro - Mechanical Fuel Control Unit (Hmu) Features: Provides metered flow for engine requirements Provides motiv flow for airframe ejector boost pomps Limits min / max fuel flow Limits acceleration and deceleration rate Back up Nh speed control (manual mode)

Effectivity: 328-100 Mod.10

- FOR TRAINING PURPOSES ONLY TM-Engine Fuel & Control

Page: 73-9 Issue: 08/95 ETM/ETX

Dornier 328 TRAINING MANUAL

DORNIER LUFTFAHRT

LINE /BASE MAINTENANCE

Hmu Eec Mode

Fig. 8 Hmu EEC Mode Motive flow valve: High pressure relief valve: Power lever valve: Potentiometer: P3 servo: Page: 73-10 Issue: 08/95 ETM/ETX

Opens to send fuel to airframe ejector boost pumps when supply pressure exceeds bypass pressure by 270 PSID. Opens at 1350 PSID to relieve excess pressure in HMU. Manually controls metering orifice A1 for "manual mode", and rotates potentiometer for "EEC mode". Connected to power lever valve, it reads position of lever and transmits (PLA) signal to EEC. Regulates Wf/P3. Travels up and down to control fuel flow. - FOR TRAINING PURPOSES ONLY TM-Engine Fuel & Control

Effectivity: 328-100 Mod.10

Dornier 328 DORNIER LUFTFAHRT

Pressure regulating valve: Torque motor: Enrichment solenoid:

Min. pressurizing valve: Cut-off valve:

TRAINING MANUAL LINE /BASE MAINTENANCE

UP Towards min. WF stop (90 PPH). Closes windows A2 and A3. DOWN Towards Max. WF stop (1350 PPH)Opens windows at A2 and A3. Maintains pressure differential of 23 PSID between supply pressure and regulator pressure. EEC controls torque motor. Increase current Torque motor valve opens. Decrease current Torque motor valve closes. Enriches or de-enriches HMU manual schedule. EEC on - De-enriched - Solenoid up.- Energized EEC off - Enriched - Solenoid down.- De-energized Maintains a minimum pressure of 110 PSID in HMU before allowing fuel flow to the engine. Shuts off flow to the engine, by forcing min pressurizing valve to close.

Note: EEC OFF BELOW 25% NH.

Effectivity: 328-100 Mod.10

- FOR TRAINING PURPOSES ONLY TM-Engine Fuel & Control

Page: 73-11 Issue: 08/95 ETM/ETX

Dornier 328 TRAINING MANUAL

DORNIER LUFTFAHRT

LINE /BASE MAINTENANCE

Hmu Manual Mode

Fig. 9 Hmu Manual Mode Manual mode: EEC off, torque motor de-energizes and closes. Enrichment solenoid de-energizes and moves down. Fixed fuel flow circuit then flows to Most Selector pushing it to the left and continuing to the pressure regulating valve. Differential pressure is now controlled via window A1 in the power lever valve. Enrichment solenoid: Up when EEC is on, blocking fixed fuel flow circuit to PRV, and allowing regulator pressure to control PRV via torque motor. Should the enrichment solenoid stay up (de-enriched) during a reversion to manual mode at take-off power, the engine would decelerate to min. flow. To prevent this, the solenoid is enriched (down) during take-off allowing the Most Selector to regulate the flow to the pressure regulating valve between the higher of two pressures. As the aircraft climbs to higher altitudes and the EEC lowers the fuel flow in an effort to maintain NH constant, it becomes possible for the Most Selector to switch from EEC regulator pressure to manual fixed fuel flow pressure. When this happens the EEC can no longer reduce the fuel to control NH since authority has been switched to the manual schedule. Therefore, the enrichment solenoid must be deenriched (up) after take-off. Page: 73-12 Issue: 08/95 ETM/ETX

- FOR TRAINING PURPOSES ONLY TM-Engine Fuel & Control

Effectivity: 328-100 Mod.10

Dornier 328 DORNIER LUFTFAHRT

TRAINING MANUAL LINE /BASE MAINTENANCE

Fault Detection System

Fig. 10 Fault Detection System The control software contains various fault detection routines which allow the EEC to identify and accommodate system faults. The built-in-test infomms the pilot of the fault by setting the fault indicator. EEC hardware faults are detected by self test routines executed upon control initiation and at regular intervals during nommal operation. Sensor and input signal processing faults are detected by comparison of the input data with normal operating range and rate of change limits. Discrete switch input faults are identified by comparison logical input and output combinations. The engine is controlled by the EEC (automatic mode) or by the pilot (manual mode) and a reversion from automatic to manual occurs under anyone of the following conditions: - EEC detects a fault within itself - EEC detects a fault in one of several components providing input pilot selection The ENG MANUAL light illuminates whenever a reversion has taken place. The EEC FAULT light illuminates when a fault has been detected within the EEC or within the HMU PLA system

Effectivity: 328-100 Mod.10

- FOR TRAINING PURPOSES ONLY TM-Engine Fuel & Control

Page: 73-13 Issue: 08/95 ETM/ETX

Dornier 328 TRAINING MANUAL

DORNIER LUFTFAHRT

LINE /BASE MAINTENANCE

There are two types of reversion to manual: latching and non-latching. Latching fault: - Once corrected, does not automatically result in the EEC resuming functioning - The EEC must be pilot reset by cycling the 28 volts reset breaker or the ENG MANUAL switch Non-latching fault: - Once corrected, results in the EEC resetting itself (ENG MANUAL light OFF) • Example: Loss of Nh signal when CLA is in feather • EEC resets itself at engine start-up when Nh is > 25% Minor fault: - Fault affecting accuracy but not integrity of control system Major fault: - Fault affection integrity of control system - Always revert to manual Fail fixed: - Ensures no power loss during reversion to manual when a minor is fault detected - Available when PLA and CLA are in the take-off range Operation: During takeoff, upon detection of a minor fault the EEC will freeze the torque motor current at the level it was an instant before detection of the fault. The EEC will then revert to manual but there will be no power loss if fault occurred in steady state.

Page: 73-14 Issue: 08/95 ETM/ETX

- FOR TRAINING PURPOSES ONLY TM-Engine Fuel & Control

Effectivity: 328-100 Mod.10

Dornier 328 DORNIER LUFTFAHRT

TRAINING MANUAL LINE /BASE MAINTENANCE

EEC Features & TSC Features

Fig. 11 EEC Features & TSC Features EEC FEATURES Command the handling bleed valve. Keeps NH constant during cruise through various ambient conditions. Controls accel and decel rate based on Nh. NP fuel governing functions Maintain minimum NP at low power. Schedule NP as a funciton of PLA in reverse. Limits maximum NP in reverse. EEC SAFETY FEATURES NH overspeed protection at 103%. -> EEC switches off. NP > 100% or NP accelerating faster than a predetermined rate, EEC will reduce fuel flow to control NP within 105%. -> Feature enabled when NP > 80%. TSC FEATURES Torque output to cockpit Auto-feather logic Effectivity: 328-100 Mod.10

- FOR TRAINING PURPOSES ONLY TM-Engine Fuel & Control

Page: 73-15 Issue: 08/95 ETM/ETX

Dornier 328 TRAINING MANUAL

DORNIER LUFTFAHRT

LINE /BASE MAINTENANCE

Auto-Feather System

Fig. 12 Auto-Feather System Purpose: Components: Arming:

Trigger:

Disarming:

Page: 73-16 Issue: 08/95 ETM/ETX

Detect an engine failure and signal airframe to feather the failed engine propeller. System is used during take off only TSC reads torque from sensor and manages auto-feather logic\ Auto-feather switch ON Both PLA's in TO range Both torque > 50.4% (+- 5.1%) "Ammed" light ON One engine torque < 19.4% (+-5.1%) Other engine torque > 50.4% (+-5.1%) 0.5 second later "Armed" light OFF, propeller feathers, auxiliary pump activates and local NP fuel goveming is cancelled Auto-feather switch OFF or One PLA < TO range or Both PLA's < TO range or Both engine torque < 50.4% (+- 5.1%) or Auto-feather triggered

- FOR TRAINING PURPOSES ONLY TM-Engine Fuel & Control

Effectivity: 328-100 Mod.10

Dornier 328 DORNIER LUFTFAHRT Test:

TRAINING MANUAL LINE /BASE MAINTENANCE

Both engines Nnning CLA at MAXIMUM rpm PLA's at flight idle Auto-feather switch ON A/F test switch 1 and 2 ON "Armed" light ON Release one A/F switch 0.5 second later "Arrned" light off, propeller feathers, auxiliary pump activates and local NP fuel goveming is cancelled

Governing PLA: Position of PLA represents a certain NH speed. The EEC will vary fuel flow to maintain NH as required by a schedule of a rating chart.

Cancel NP(T) Governing: -When feathering propeller NP(T) fuel governing feature must be cancelled to avoid an overtorque, since EEC would otherwise try and maintain a minimum NP. NP(T) fuel governing is cancelled whenever prop is feathered by 1. Auto-feather 2. Condition lever selecting electrical feather 3. Manual selecting feather (OHP) or 4. NPT falls below 6000 RPM (NP