Lockheed Field Service Digest FSD Vol.4 No.1 Intro L1649 Starliner Part 3 of 3

LOCKHEED

field service digest

This IS the Digest and it belongs in your file of copies - right next to your copy of Vol. 3. No.6. To mark the beginning of our fourth year of publication in English (second year in Spanish), the familiar bars and graph lines on the Digest's front couer haue been replaced by a new design. The inside front couer has also been reuised to include "Change of Address" information and to present a more attractiue appearance. We hope you will like the new look.

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AVIATOR'S OXYGEN COMMERCIAL SERVICE BULLETINS PENDING THE STARLINER (PART

III) .

HYDRAULIC SYSTEM . LANDING GEAR, WHEELS, AND BRAKES FLIGHT CONTROLS FUEL SYSTEM . AIR CONDITIONING SYSTEM REMOVE AND REPLACE TRADE TIPS READING LIGHT ALIGNMENT KIT

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13 14 22 24

26 28

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CLEANING SUCTION RELIEF VALVES AND SCREENS SHUR-LoK NUTS FOR SUPERCHARGER DISCONNECT .

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AIRCRAFT EMERGENCY ESCAPE LADDER . TECHNICAL PUBLICATIONS FOR TRANSPORT AIRCRAFT

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The President's Preference. President Dwight D. Eisenhower's Super Constellation, Columbine III, is his personal preference for long-range transportation. This "Flying White House" is the third Constellation he has used - the first when he was Commander of SHAPE in Europe; the other two in his present office as President. All three were named the Columbine for the state flower of Mrs. Eisenhower's home state, Colorado. The President states, "The present Columbine, like the other two, is trustworthy, reliable and, above all for me, it is comfortable."

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what it is ... why it requires pecial treatment . .. how to handle it ... Maintenance personnel know that any component of an oxygen system must be kept clean and free of foreign matter, particularly of hydrocarbons such as greases and oils (both mineral and vegetable base), thread lube, trim cements, gums, and like substances. However, the reason behind this demand for absolute cleanliness is not always fully appreciated. 049, 749, 1049, 1649 SERIES

It is the purpose of this article to acquaint, or reacquaint, maintenance personnel who handle oxygen with its characteristics, to explain why all foreign matter must be kept out of oxygen systems, and to provide a few details regarding the Constellation and 1649A systems.

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WHAT IS OXYGEN? Oxygen (0 2 ) is a colorless, odorless, and very active gas which will combine chemically with a great number of elements. When it does. combine with another element, the amount of heat liberated will depend upon the chemical nature of the other element or substance involved. Although oxygen by itself is noncombustible, it supports combustion and makes other materials burn rapidly. This property is often put to use by foundries or metallurgicallaboratories when extremely high temperatures are required for a smelting process. The use of an oxy-hydrogen torch for cutting thick steel plates in underwater salvage operations is a dramatic example of the extent to which oxygen supports combustion.

AN AID TO COMBUSTION

It is also possible for lint, dust, and other such foreign particles to create a tiny spark during their travels through the metal tubing, and since oxygen will greatly increase the extent of any combustion, a serious fire or e'xplosion may result. Fires may even be caused by a jet of high-pressure oxygen impinging upon soiled cabin trim materials or greasy metal structure. The hazards described above are increased in aircraft applications because the oxygen is under great pressure and is of relatively high purity. Shortly after an aircraft was placed on ground display at an air show, the attending mechanic heard a hissing sound coming from the aircraft. He thought that the valves on the oxygen bottles might be open alld he started to close them. As he did, a fire broke out, burning him and severely damaging the aircraft.

AN ACTUAL CASE

The subsequent investigation of this incident disclosed that there had been a small amount of grease in a fitting in the oxygen overboard discharge system, and the hissing sound the mechanic heard was oxygen escaping through this discharge. When the oxygen contacted the grease in the fitting, a fire resulted. The heat generated by the oxygen-fed fire was so great that the fitting was burned through as though cut with an oxy-acetylene torch. Although a picture of the burned fitting is not available, Figure 1 shows what a similar fire did to one of the most rugged components of an oxygen system, a distribution manifold. In most cases of fire or explosion involving oxygen, the investigations have revealed that faulty maintenance of oxygen systems or careless and improper handling of oxygen was the cause.

STORAGE OF OXYGEN CYLINDERS FIRE AND EXPLOSION Oxygen's ability to support combustion, when added to its characteristic of combining chemically with many other elements, can lead to trouble under certain conditions. As an example, when oxygen and any quantity of oil or grease are brought together they can combinemaybe EXPLOSIVELY! It is not possible to predict exactly what will happen. Perhaps a fire will result. Or perhaps nothing will happen at that particular time-maybe later. But it must be borne in mind that when oxygen and hydrocarbons combine to produce a fire or explosion, they may do so spontaneously as a result of chemical reaction-no spark or other form of ignition need be present.

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Proper storage of oxygen cylinders is an important part of oxygen handling. Members of United States military organizations should use T.O. 42B5-1-2 for instructions in the use, handling, and maintenance of oxygen cylinders. However, we feel that a short review of the principles and safety rules affecting storage of oxygen cylinders will be of interest to all concerned. First of all, make certain that the cylinders which are to be used for bulk ground storage of aviator's oxygen have been cleaned and properly purged by an approved oxygen servicing facility if they have been used for any compressed gas other than oxygen. Purging is also required if cylinder pressure

has been completely exhausted, because outside air may have entered, and moisture may condense inside the cylinder.

Figure 1 Oxygen Distribution Manifold Burned Through by Spontaneous Combustion of Grease and Oxygen

Next, make sure that the cylinders are recharged only with Aviator's Breathing Oxygen, Federal Specification BB-O-925, Grade A, or equivalent. Grade A Aviator's Breathing Oxygen is dehydrated more than Grade B during processing and bottling. Grade A must be 99.570 pure oxygen by volume, and must not contain more than 0.02 milligrams of water vapor per liter of gas at 760 millimeters Hg and 70°F. Grade B maybe used if necessary, but is not recommended for regular operations.

Figure 2 Recharging Operations at Modern Oxygen Servicing Facility Showing Properly Identified Cylinders

It is not possible for maintenance personnel to

determine the grade and purity of oxygen without special laboratory equipment. If there is a question as to whether a cylinder contains breathing oxygen or some other gas, don't use that cylinder to recharge an aircraft oxygen system. Make sure that storage cylinders are completely painted to protect them from rust and to identify the contents. Unfortunately, a standard method for color coding of compressed gas cylinders to indicate the contents has not yet been adopted in the United States. In the interest of safety, we recommend that breathing oxygen ground storage cylinders be identified with a coat of green paint. The words "OXYGEN AVIATOR'S" or "AVIATOR'S BREATHING OXYGEN" should be stenciled on the cylinder parallel to its longitudinal axis. These words should be painted white and should be at least 1% inches high. Oxygen cylinders lettered in this manner are shown during recharging operations at a properly equipped oxygen servicing facility (see Figure 2).

caps should remain installed on cylinders not in use, to prevent damage to the valves. If a valve is broken off, the cylinder will become an exceedingly dangerous unguided missile of destruction. All other normal precautions concerning the storage of any compressed gas should also be observed. In the specific case of oxygen, cylinders should be separated from flammable gases or materials by a fire-resistant partition. If such a partition is not available in the storage area, oxygen cylinders should be placed approximately 50 feet from any flammable gas or material. If oxygen cylinders are properly marked and stored, there will be less chance of a landing gear shock strut or tire being inflated with oxygen. This has happened several times and in some ·cases, has resulted in disastrous explosions and fire.

MAINTAINING THE AIRCRAFT OXYGEN SYSTEM

Figure 3 Oxygen Cylinders Stored Indoors in Clean, Dry, Ventilated Area with Protective Caps Installed This color coding and lettering conforms generally to U.S. military requirements, and is also becoming accepted as a standard identification by most commercial operators in the United States. With translation of the wording, it could be used internationally. Breathing oxygen cylinders must be protected against exposure to temperature extremes and should be stored inside whenever possible. If the cylinders are stored in the open, they must be protected from direct contact with the ground to avoid rusting. They should be covered to prevent an accumulation of ice or snow in winter and to shade against the direct rays of the sun in summer. Figure 3 shows oxygen bottles stored on a concrete floor in a clean, dry, indoor area. While oxygen cylinders are in storage, proper ventilation must be provided to prevent an accumulation of oxygen from leaking cylinders which might become a fire or explosion hazard. Cylinders should be stored standing upright and a chain or fence should be used to prevent them from falling over. Protective 6

Constellation and Starliner oxygen systems are basically similar. However, individual aircraft may vary considerably in detail to suit the requirements of the operator. All models are equipped with one or more storage cylinders which feed a multiple outlet manifold system. A typical Super Constellation oxygen system is shown in Figure 4. In addition to the central system, one or more portable oxygen cylinders are carried for emergencies. The storage and the portable cylinders are high-pressure oxygen cylinders (1800 psi at 70°F [21°C]). Model 049 and 149 airplanes are the exception to this rule. They use a low pressure system (425 psi). CLEANING Before installing any tube assembly in the oxygen system, it must be thoroughly degreased, cleaned, and dried. The method we use in production assembly is to submerge the entire tube assembly in a tank of clean trichlorethylene (Spec MIL-T7003), as shown in Figure 5. After drying with clean, dry, water-pumped compressed air*, the tubing assembly is capped with plastic caps, identified, inspected, and stored until ready for use. Cylinders of dry, water-pumped compressed air are available from most vendors of bottled gases.

for cleaning lines prior to installation is to flush the affected lines thoroughly with naphtha (Federal Spec TT-N-95). Naphtha is highly flammable and care must be taken to prevent an accumulation of vapors during flushing. Only An alternate procedure

*Water-pumped air is air which has been compressed by water pressure to avoid the presence of oil particles from an oil-lubricated compressor, and then dehydrated by chemical or physical means.

CREW COMPARTMENT

fLIGHT STATION

MAIN PASSENGER COMPARTMENT

FORWARO PASSENGER COMPARTMENT

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A

AfT PASSENGER COMPARTMENT

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16 TWO-PORT SUPPLEMENTARY MANIFOLDS

c::::::J

OXYGEN SUPPLY CREW OXYGEN PASSENGER OXYGEN

l.

o

Filler check valve

2. Pressure reducer

OXYGEN REPLENISHING LINES OVERBOARD DISCHAR"GE LINES DILUTER DEMAND REGULATOR

[EJ RELIEF VALVE ~ CHECK VALVE CJ SUPPLEMENTARY OXY OUTLET

5. Continuous flow pressure regulators 6. Relief valves

3. High pressure gage

1. Overboard discharge indicator

4. Line shut-off valve

8. Oxygen supply cylinders

Figure 4 Schematic Diagram of Typical Super Constellation Oxygen System

Figure 5 Degreasing Tubing in a Trichlorethylene Dip Tank

approved vapor-proof lights should be used near naphtha. The lines should then be dried with clean, dry, water-pumped compressed air. Following the naphtha flushing and drying operations, the lines should be flushed either with antiicing fluid which conforms to Spec MIL-F-5566, or with anhydrous ethyl alcohol. Rinse the lines thoroughly with fresh water and once again dry them with water-pumped compressed air. using trichlorethylene as the cleaning agent may also be used to clean oxygen system components. To ensure proper cleaning, follow the instructions provided by the manufacturer of the degreasing unit. A vapor degreaser

When replacing an oxygen system fitting, clean the new fitting carefully by any of the above methods prior to installation. We do not recommend the use of cadmium plated mild-steel fittings because they are often grease coated for storage. If even a small amount of this grease has entered the interior of the fitting, an explosion or fire may result when the oxygen is turned on. Also, particles of cadmium may contaminate the system. 8

For these reasons, Starliners and Constellations use fittings made from corrosion-resistant steel or anodized aluminum which do not require grease coating for storage. As an additional safety measure, we specify that no grease, oil, or preservative compound may be applied to any fitting intended for use in oxygen systems. In any case, it is good practice to clean shelf stock items before installation on the airplane, using one of the methods outlined above. Following complete degreasing by any of the recommended methods, every precaution must be taken to ensure that the components are thoroughly dried as described earlier. Moisture in an oxygen system may cause serious corrosion, or it may freeze in valves and regulators and prevent their proper operation. IMPORTANCE OF DRYING

Breathing oxygen (Federal Spec BB-O-925, Grade A) may also be used as a drying agent if no other method is available. No trace of trichlorethylene should remain in any oxygen component, as fumes from this chemical may act as an anesthetic on flight crews or passengers.

Following the cleaning and drying process, all oxygen lines and fittings which are not to be installed immediately should be covered with clean, dry, plastic caps. Do not use masking, adhesive, friction, or any other kind of tape to cover the open ends of oxygen lines. Maintenance personnel should make certain that their hands, as well as any tools to be used on oxygen system components, are completely clean and free from oil or grease. APPROVED THREAD COMPOUNDS Because of the explosive nature of an oxygen/grease mixture, none of the standard thread lubricants can be used on oxygen fittings. Lockheed has approved three thread compounds which meet the requirements of Spec MIL-T-5542: Key AbsoLute, Type B (E. A. Key Co., 1947 Santa Fe Ave., Los Angeles 21, California); DAG #217 (Acheson Colloids Co., Port Huron, Michigan) ; and Recto Seal # 15 (Rector Well Equipment Co., 2215 Commerce St., Houston 2, Texas).

These compounds may be used only to prevent thread seizure and should be applied sparingly and carefully to the male pipe threads only, coating just the first three threads from the end of the fitting. Do not dip a fitting into the thread lubricant. Thread compound should not be used on flared tube fitting straight threads, coupling sleeves, or on the outside of tube flares.

SERVICING AIRCRAFT SYSTEMS EXTERNAL FILLER CONNECTION Many Constellations and Super Constellations are provided with an external filler connection to which a portable oxygen cart may be attached and the oxygen system recharged without the removal of any components. Figure 6 shows the locally-made adapter which must be used between the oxygen output hose of the portable cart and the filler connection. The Super Constellation maintenance manual contains step-by-step instructions for the recharging operation.

Removing and replacing a discharged oxygen cylinder with a fully charged one is a satisfactory alternate to using the external filler on Constellations. It is standard procedure on the Model 1649A, since no external filler is provided to date. The changeover operation must be completed in the shortest possible time and with extreme care. Since the oxygen distribution lines are open during the changeover operation, any delay increases the chances for contamination of the system. To avoid this, it is recommended that any oxygen tube or fitting that must be disconnected and left open for any length of time be covered with a clean, dry, plastic cap. REPLACEMENT OF DISCHARGED CYLINDERS

Copper plumbing used at the supply cylinders will become work hardened in time because of vibration

Figure 6 Adapter Fitting and Shut·Off Valve Installed on High Pressure Oxygen Filler Hose. Note that adapter is connected to blanked· off fitting to prevent internal contamination when not in use. 9

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Graph starts at approximately 70°F ambient temperature.

Add pressure change if ambient temperature rises above 70°F.

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. ....

Subtract pressure change if ambient temperature falls below 70°F.

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Graph is based on 1800 psi charged cylinders.

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= ....

20 15 10

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60

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1,10

120

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CHANGE IN PRESSURE IN PSI

Figure 7 Relationship Between Oxygen System Pressure and Ambient Temperature. Use of this chart ensures correctly charged cylinders regardless of temperature variations.

and frequent bending during servicing operations. It should be removed and annealed, then cleaned and reinstalled at periodic inspections to prevent cracking. If flexible metal hose has been installed instead of copper lines, make sure that the hose is not subjected to a longitudinal twist (torsion) when it is connected to the supply cylinders. EFFECTS OF TEMPERATURE When recharging through the external filler connection or when making any check of the installed system, open the applicable valves very slowly. Rapid opening of valves in a high pressure oxygen system allows oxygen to flow into the system faster than it can pass through restrictions or around sharp bends in fittings of the system. This creates a condition known as shock compression, which may result in a temperature rise sufficient to ignite any small particles of dust, metal, etc., in the system and cause a fire or explosion. The damage to the manifold shown in Figure 1 may have resulted from shock compression.

Temperature changes will affect the indicated pressure shown on the system pressure gage. The oxygen 10

cylinders in the Cons.tellation and 1649A Starliner are designed to be filled to an indicated 1800 (-+- 50) psi at an oxygen temperature of 70°F (21°C). If the aircraft system is to be recharged from an oxygen supply in which the oxygen is at a lower or higher temperature than the specified temperature, care must be taken to avoid overfilling or underfilling the cyllinders. Figure 7 shows the pressure/temperature relationship which should be maintained during recharging operations to ensure full oxygen cylinders at temperatures greater or less than 70°F (21°C). PORTABLE CYLINDERS The portable oxygen cylinders require frequent inspection for indicated pressure and general operating condition. When the 1800 ( -+- 50) psi fully charged pressure of the portable cylinder drops to an indicated 50 to 60 psi, the cylinder should be removed, cleaned, inspected, and recharged. CHECKING FOR FLOW After the oxygen system has been recharged, all oxygen outlets available to the flight crew and passengers must be checked for proper operation of the flow indicators and for free flow of

oxygen with no indication of clogging. If a valve cannot be completely closed by hand, it may indicate that there is some corrosion in the valve. Do not use a wrench on the valve. If a wrench is used, this resistance will be easily overcome and the presence of corrosion will be undetected. The use of a wrench may also damage the valve seats. Damaged valves and cylinders should be returned to a servicing organization qualified to repair such items. Detailed instructions concerning this flow test procedure are set forth in the applicable maintenance manuals. Following the recharging operation and flow test, any parts of the oxygen system which were disconnected or replaced should be pressure-checked for leaks. Do this by brushing each of the affected connections with a bubble-free solution of a mild, neutral (Castile-type) cake or liquid soap and water. Wash off all traces of the solution with clear water immediately after testing, then wipe dry with a clean cloth. CHECKING FOR LEAKS

If soap solutions are not removed completely by thorough washing, they may cause corrosion on plumbing lines. An alternate leak-testing solution which we use at Lockheed is MIL-L-25567 Compound, which does not cause corrosion. Detailed instructions for the leak check are set forth in the applicable maintenance manuals.

the filler hose. The gases generated by the fire were then forced into the aircraft's oxygen system, but no further check was made on the system after the fire. When the pilot took a deep breath through the oxygen mask, highly toxic gases were drawn into his lungs. The aircraft was on the ground and no serious consequences resulted, but the potential danger in this incident is obvious. The entire affair could have' been avoided if the airplane's oxygen cylinders had been removed and replaced with properly charged cylinders and the oxygen system flushed with dry ail or breathing oxygen. Then the system should have been checked for operation in accordance with the maintenance manual. These are precautions which must always be taken after a fire in the oxygen filler equipment.

I,--------------------HANDLE WITH CARE I I We would like to re-emphasize the importance of

I system. The following list of Do's and Don'ts might I serve as a reminder: •

•

•

POISON ON DEMAND Here is an example of what can happen because of careless oxygen servicing. Not long ago an airline pilot climbed into an aircraft, put on an oxygen mask, took -a deep breath, and almost passed out. Fortunately he recovered after a few minutes of semi-consciousness. The oxygen cylinder was removed from the aircraft system. Chemical analysis showed that it contained a mixture of oxygen, hydrogen sulfide, carbon monoxide, carbon dioxide, and another gaseous, hydrogen by-product. The investigation disclosed that a fire had taken place in the oxygen cart's servicing line during the previous day's recharging operation. The fire appeared to have been caused by a small amount of oil or grease in the fittings of the service line. When the oxygen valve on the service cart was opened, the oil and grease ignited and began to hurn the inside of

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Iproper caution when handling any part of an oxygen I

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• •

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Do store spare, charged oxygen cylinders in a cool place, protected from direct sunlight or any source of heat. Do mark all oxygen cylinders plainly to show the contents, and store separately from other gas storage cylinders. Do mark all depleted cylinders "EMPTY" and isolate from other cylinders to avoid the possibility of installing an empty cylinder in the aircraft. Do open and close oxygen valves slowly and by hand only. Don't use oxygen for other than its intended purpose; i.e., don't use it for filling shock struts or charging hydraulic accumulators. Don't allow foreign material to enter any component of the system. Don't test or charge an oxygen system with any gas other than aviator's breathing oxygen (Federal Spec BB-O-925, Grade A) or equivalent. Don't store or handle cylinders so that they can tip over or be dropped. Keep protective valve caps in place except when cylinders are connected to plumbing. Don't attempt any service or repair of the oxygen system unless you are fully qualified and authorized to do so. .A .A

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COMMERCIAL SERVICE BULLETINS PENDING Service Bulletins 1049/2928 and 1049/2976 listed in Vol. 3, No.6 of the Digest have been rescheduled to an approximate release date of July 1957. There are no additions to the list at this time. 11

HIS IS the third of three introductory articles on the Starliner. In previous issues we have given a general description of the airplane and described in detail the wing, powerplant, fuselage, empennage, and ground handling provisions. In this issue we will discuss the hydraulic system, landing gear and brakes, flight controls, fuel system, and the air conditioning system.

T

THE

Since it is not feasible to include each minor system in these initial presentations, and because some systems such as the electrical system are essentially the same as on previous models, we have confined the introductory material on the Starliner to the subjects noted above. More information on pertinent subjects concerning the Starliner will appear in future issues of the Digest.

PART THREE

HYDRAULIC SYSTEM An entirely new hydraulic system is installed in the 1649A. Complete schematic diagrams of the new system are included on the fold-out pages in this issue. The principal features of the Starliner system which differ from hydraulic systems used on Constellation· models are as follows: • The Starliner has two independent main hydraulic systems, designated No. 1 and No.2, each with a normal operating pressure of 3000 psi. • No crossover operation of any type is provided between the two systems. • There are four engine-driven hydraulic pumps on the Starliner. These are variable volume, piston type pumps, each incorporating a built in pressure regulator, flow control (compensator), and solenoid operated blocking valve in the pressure port. • Power is supplied to Hydraulic system No. 1 from the pumps on engines No.1 and No.3. Hydraulic system No.2 is powered by the pumps on engines No. 2 and No.4. The two systems supply equal power to the surface control boosters, wing flaps, brakes and nose gear actuating cylinders. System No. 1 provides 100 per cent power to the main gear actuators and nose steering mechanism. System No. 2 provides 100 per cent power to the reserve engine oil transfer system and the autopilot control of the control surface booster valves. • The left wing primary and secondary heat exchanger fan motors are driven exclusively by the hydraulic pump on engine No. 1. The right wing primary and secondary heat exchanger fan motors are driven exclusively by the hydraulic pump on engine No.4. • No electric pumps for auxiliary booster operation are necessary, since each main hydraulic system supplies 50 per cent of the power to the surface control booster systems. However, either system is capable of supplying the hydraulic power necessary for control booster operation in the event pressure is lost in one system. • The 1649A auxiliary hydraulic system is powered by an electrically driven pump with output controlled by system pressure. • Most main hydraulic units are located in the forward service area in the 1649A. This is a nonpressurized compartment which provides quick access to the system components through a door on the underside of the fuselage just forward of the wing (see " 1649A Maintenance and Service Areas" in Vol. 3, No.5 of the Digest).

RESERVOIRS AND FILTERS After leaving the enginedriven hydraulic pumps, the hydraulic fluid is directed past a pulsation filter (accumulator), through a stainless steel wire-mesh pressure filter, and is then routed through check valves to a manifold. The fluid is then directed to the various hydraulically operated systems. To prevent contamination of the hydraulic system in case of pump failure, bypass relief valves are not incorporated in the pressure line filters. Each pressure line from the engine-driven pumps contains a low-pressure warning switch downstream of the filter. Each of the two main hydraulic system reservoirs in the service area incorporates easily removable micronic filters and bypass relief valves at the reservoir fluid return port. The fluid and air lines to the aspirators have filters (screens) which require infrequent servicing.

Each main system reservoir is pressurized by its aspirator to an air pressure of 15 to 19 psi. A relief valve is set to open at 22 psi and relieves through an overboard drain. A reservoir air pressure regulator valve senses air pressure in the reservoir and controls aspirator flow to the reservoir. The two system reservoirs and the auxiliary reservoir may be replenished from a reserve filler tank located between the pilot's rudder pedals below the floor (see Figure 1). Fluid is transferred by means of a selector valve and a wobble pump, which has priming provisions. (Continued on next page) 1649A Reserve Hydraulic Filler Tank

HYDRAULIC PLUMBING LINES All rigid hydraulic pressure lines are made from 304 YaH stainless steel and use Ermeto flareless fittings. AlII-inch and larger suction lines are made from 5052-0 material and use Wig-O-Flex fittings outside Zone 3 and AN fittings within Zone 3. Suction lines and return lines smaller than I-inch are made from 6061-T6 material. WigO-Flex fittings are also used on %-inch suction lines on both sides of No.2 and No.4 hydraulic suction shutoff valves. All other hydraulic lines use Ermeto fittings. AUXILIARY POWER SYSTEM An electrically driven hydraulic pump supplies power for the auxiliary hydraulic system. The brake and auxiliary nose gear extension reservoir (called the emergency extension and brake tank on 1049 airplanes) is located in the forward service area on the 1649A. Fluid for the electric pump is taken from the auxiliary reservoir and sent through a check valve, filter, pressure transmitter and pressure switch, and a cylindrical accumulator, to a selector valve. This valve selects pressure for either of the two following operations: emergency or ground operation of the No.1 brake system; or emergency extension of the nose landing gear 14

through No. 1 hydraulic system nose gear actuating cylinder. An additional line incorporating a relief valve is in the system between the accumulator and the selector valve to relieve pump pressure if pump operation is continuous or if the pressure switch is faulty.

LANDING GEAR, WHEELS, AND BRAKES Because of the Starliner's new thin wing and gross take-off weight of 156,000 pounds, it was necessary to design a completely new main landing gear. Coupled with this change are redesigned iocking mechanisms. The uplocks on all landing gears, although normally hydraulically operated, can be opened by manual release cables in the event of system hydraulic failure. The nose landing gear is otherwise essentially the same as on Constellation models, except that there are two actuating cylinders each operated by separate main hydraulic systems. MAIN GEAR Refer to Figure 2. Manufactured by the Menasco Company to Lockheed design, the new gear is fabricated of high heat treat steel (260,000 to 280,000 psi). It can be installed as a complete

assembly with actuating cylinder, linkage, locks, etc., thereby permitting complete gear build-up and adjustment prior to installation on the airplane. In the new main gear the fulcrum is an integral part of the strut cylinder to minimize deflection and reduce weight. Fulcrum ends are attached to the main landing gear support structure truss with split bearing caps which house large spherical ball bearings. Landing gear side thrust loads are shared by the inboard and outboard fulcrum bearings. Parallel drag braces connect the fulcrum to a hanger mounted on the wing front beam. A drag strut damper similar to that used on the 1049G is mounted between the main landing gear strut and the upper drag strut. This damper is installed with the piston rod-end at the strut, a position which is reversed from that of the 1049 installation. The total damper stroke is 1.25 inches and the minimum preload in the damper spring is 4500 pounds. The 1649A main gear is an over-center design. Thus, when the airplane is in a normal position on the ground, the axle is aft of the fulcrum and the drag strut damper is extended. Vertical strut loads then add to the drag load and tend to hold the gear in the down position. Static grounding is provided by a rubber grounding strap on each main gear rather than by the grounding wire used on Constellation models. Actuating Cylinder. Each main gear is actuated by a hydraulic cylinder supplied from the No. 1 hydraulic system. The actuating cylinder is attached between the drag strut crosshead and an eccentric crank arm supported by the fulcrum (see Figure 3). For main landing gear extension the cylinder piston rod retracts into the cylinder. The larger piston head area of the actuating cylinder piston is used for gear retraction, and no runaround line is needed. Downlock Assembly. No hydraulic force is needed to actuate the downlock; its action is purely mechanical and is designed on the over-center principle. A bungee assembly containing a heavy coil spring connects to the downlock linkage to ensure latching of the downlock during free-fall and locking of the main landing gear. The downlock bungee mechanism is illustrated in Figure 4. A hole is provided in the main landing gear downlock assembly for the insertion of a Ys-inch diameter ground safety lock pin. Uplock Assembly. Refer to Figure 5. A completely new uplock assembly, also of over-center design, is attached to the drag strut crosshead. Each main gear uplock hook is normally opened by hydraulic release cylinders fed from the landing gear DOWN line. The uplocks can also be opened by a manual release (Continued on next page)

Figure 6 Main Gear Wheels Showing Provisions for Brakes

cable system. The main gear is designed to free-fall and lock in the DOWN position without the benefit of hydraulic pressure. Because of this free-fall feature, one-way restrictors are incorporated in landing gear DOWN lines. Flow regulators installed in each main gear UP line assist to equalize the speed at which the gears retract. Speed Brake. The incorporation of the manual release cable system for the main gear uplocks, together with other design features, allows the 1649A main gear to be used as a speed brake. Actuating the speed brake control handle located on the pilots instrument panel glare shield opens the main gear uplock hooks by means of the cable system and the main gear free-falls and locks in the extended position. This speed brake feature can be used at indicated air speeds up to 234 knots. MAIN GEAR WHEELS AND BRAKES Forged magnesium wheels are used on the main landing gear. Wheels are made in two halves and assembled with a seal between the halves for the Type III 17.00 by 20 tubeless tires (24 ply-rating nylon) which are normally used. Conventional tires with tubes can be installed by removing the valve mounted on the wheel. BRAKES Single Goodyear "Trimetallic" multiple disc brakes are mounted on the strut side only of each main landing gear wheel. No brake assembly is mounted in the outer side of the wheels (see Figure 6). Each brake assembly is comprised of nine rotating discs, eight stationary discs, one pressure plate, and one backing plate. A brake assembly is illustrated in Figure 7. All brake discs are approximately ;4-inch thick. Stationary discs are made of steel and rotating

16

Figure 7 1649A Multiple-Disc Brake Assembly

discs have a steel core with a bonded friction facing material. Brakes are actuated by dual magnesium pistons which move in forged aluminum housings. These pistons are ported to the No. 1 and No.2 hydraulic systems so that approximately half of the actuating force of each brake is supplied by each hydraulic system. Brake System. Two completely independent relay brake systems are installed. Advantages of this type system are-less brake lag, reduced weight, and the elimination of long lengths of high pressure tubing. Brake control is provided by a master cylinder and brake relay valve system. Two 25-cubic inch master cylinder reservoirs are installed in the left side of the airplane nose and supply oil to the master cyl(Continued on pa/!,e 21)

LOCKHEED FIELD SERVICE DIGEST July-August 1957 Vol. 4, No.1

NOTE RIGHT OUTBOARD NACELLE EQUIPMENT IDENTIFIED LEFT OUTBOARD NACELLE EQUIPMENT IDENTICAL.

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NOTE LEFT FILlET EQUIPfIlNT IDENTIFIED RIGHT FILlET EQUIPMENT IDENTICAL. LEFT INNER WING EQUIPMENT IDENTIFIED RIGHT INNER WING EQUIPMENT IDENTICAL.

1 PILOTS AND COPILOTS FOOT WARMERS AND CONTROLS 2 COPILOTS FACE OUTlET AND CONTROL KNOB 3 FLIGHT ENGINEERS OUTlET AND CONTROL LEVER 4 AIR CONDITIONING AND PRESSURIZATION CONTROL (260) PANEl 5 CIRCUIT BREAKER PANEL (STA 260) 6 INDIVIDUAL COLD AIR OUTlETS (TYPl 7 FORWARD LAVATORY VENTUR I 8 RIGHT FORWARD COLD AIR DUCT 9 RIGHT CABIN SUPERCHARGER AIR INLET AND PLENUM CtiAMBER 10 REFRIGERATION TURBINE UNIT 11 SUPERCHARGER DUMP VALVE 12 RIGHT CABIN SUPERCHARGER 13 PRIMARY HEATEXCHANGER, EXIT DOOR AND COOLING FAN 14 RIGHT PRIMARY HEATEXCHANGER AIR INLET (RAM) 15 SECONDARY HEAT EXCHANGER, EX IT DOOR AND COOLING FAN 16 RIGHT SECONDARY, HEAT EXCHANGER AIR INlET SCOOP 17 PRESSURE RATIO LIMITER VALVE LOCATION 18 CABIN AIR MIXING AND SELECTOR VALVE (4-WAY VALVE) 19 FORWARD OVERHEAD HOTWALL DISTRIBUTION DUCT 20 HOTWALL LATERAL DUCT, "NO WINDOW" BAY (TYP) 21 HOTWALLLATERAL DUCT, "WINDOW" BAY (TYP) 22 RIGHT AUXILIARY VENTILATION INLET DUCT 23 R.H. AUXILIARY VENTILATION INlET VALVE 24 COLD AIR (FORWARD) RISER 25 CABIN AIR RISER 26 FLIGHT STATION AIR MIXING VALVE 27 HOTWALL RISER 28 LOW PRESSURE GROUND AIR CONNECTION (AFT SERVICE AREAl 29 SUPERCHARGER CROSSOVER DUCT 30 HEATER CROSSOVER DUCT (FLIGHT STATION AIR) 31 HOTWALL SHUTOFF VALVE AND CONTROL 32 GALLEY VENTURI AND CONTROL& 33 AFT OVER HEAD CAB IN AIR DI STR I BUTI ON DUCT 34 AFT OVERHEAD HOTWALL DI STR IBUTION DUCT 35 AFT COLD AIR DI STRI BUTION DUCT (INDIVI DUAL OUTlETS) 36 AFT LAVATORY VENTURI 37 CABIN PRESSURE SAFETY RELIEF, NEGATIVE PRESSURE RELIEF AND DUMP VALVE 38 CABIN NEGATIVE PRESSURE RELIEF VALVE 39 AUXILIARY VENTILATION EXIT VALVE 40 THERMI STOR BLOWER AND VENTUR I 41 RECIRCULATION AIR INLET AND CHECK VALVES 42 AIR MIXING CHAMBER AND MANIFOLD 43 FRESH AIR INlET (GROUND) 44 RECIRCULATION FAN 45 CABIN HEATER PACKAGE 46 CABIN HEATER EXHAUST 47 COLO AIR RESTRICTOR VALVE 48 GROUND TEST BLOCKING PROVISION 49 SUPERCHARGER DUCT CHECK VALVE AND PILOT VALVE 50 ANTI-ICING VALVE (PNEUMATIC THERMOSTAT) 51 GROUND TEST PRESSURE FITTING 52 WATER SEPARATOR 53 SUPERCHARGER DUCT RELIEF VALVE 54 L.H. AUXILIARY VENTILATION INlET VALVE 55 LEFT AUXILIARY VENTILATION AIR INLET 56 COMBUSTION AIR DUCT CONNECTION (TO CABIN HEATER) 57 LEFT AUXILIARY VENTILATION INlET DUCT 58 FLIGHT STATION BOOSTER FAN 59 CABIN PRESSURE REGULATOR CONTROL VALVE (SENSING HEAD) PNEUMATIC RELAY, AUXILIARY PRESSURE REGULATOR VALVES (OUT flOW) 60 RADIO RACK VENTURI AND CONTROL 61 RADIO RACK COOLING BLOWER 62 FLIGHT STATION AUXILIARY HEATER 63 PILOTS FACE OUTLET AND CONTROL KNOB

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&. 1649AAir Conditioning Dueting

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TWA galley venturi is located under the floor structure. TWA and Air France only.

17

LOCKHEED FIELD SERVICE DIGEST

July-August 1957

~ ACCUMULATOR WITH AIR GUAGE AND AIR CHARGE VALVE BUILT-IN PUMP SOLENOID PILOT AND BLOCKING VALVE RELIEF VALVE FLOW REGULATOR (ARROW DENOTES REGULATED FLOW, FREE FLOW OPPOS IT[ DIRECTIONI

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~ORIFICETYPE

PULSATION FILTER (TYPICAL)

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PUMP PRESSURE LINE ""( FILTER (TYPICAL)

ENGINE PUMP DRIVEN HYDRAULIC PUMP (TYPICAl)

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RIGHT HEAT EXCHANGERS - - -...,

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AUXILIARY MOTOR DRIVEN HYDRAULI C PUMP PRESSURE SWITCH

PRESSURE TRANSMlmR< ~ AND RESTR I CTOR

MANUAL GROUND TEST SHUTOFF VALVE

AIR PRESSURE REliEF VALVE

rr===========(W;:IT;:H;:TR::=AN,;;S;,;;M;;,ITT;,;,ER:=)=;t AUXILIARY ACCUMULATOR (WITH AIR GUAGE AND VALVE)

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PUMP LOW PRESSURE WARNING SWITCH