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VOL. 5, NO. 3, JULY · SEPTEMBER 1978

A SERVICE: PU6L ICATI ON OF LOCKHEED·GEOAGIA cor.1PANY, A DIV ISION OF LOCKHEED CORPORATION

Hercules LOX System

A SERVICE PUBLICATION OFLOCKHEED-GEORGIA COMPANYA DIVISION OFLOCKHEED CORPORATION

EditorJay V. Roy

Associate EditorsCharles I. GaleDon H. HungateJames A. Loftin

Art Direction & ProductionAnne G. Anderson

Cover : A U.S. Coast GuardHercules is the subject of the coverpainting by Robert Karr of ourTechnical Information Depart-ment, Coastal surveillance is amongthe many missions of the CoastGuard Hercules. Search and rescueefforts are aided by the sea/searchradar in the Hercules’ nose whichserves not only as a weather radar,but also has the capability of de-tecting small boats, even in high seaconditions,

Pubhshed by Lockheed-Georgia Company, a Division ofLockheed Corpora t ton . Information contained in this

issue IS considered by Lockheed-Ceorgta Company to beaccurate and authoritative it should not be assumed, how-

ever, that this material has received approval from anygovernmental agency or military service unless it is

specif ical ly noted. This publication IS for planning andinformation purposes only, and it IS not to be construed

as authortty for making changes on atrcraft or equipment,

or as superseding any established operational or main-

tenance procedures or policies. The following marks areregistered and owned by Lockheed Corporation

“ “, “Lockheed”, “Hercules”, and “JetStar”.Wrttten permission must be obtained from Lockheed-

Georgia Company before republishing any material in this

periodical. Address all communications to Editor, ServiceNews, Department 64-22, Zone 278, Lockheed-GeorgiaCompany, Marietta, Georgia, 30063. Copyright 1978

Lockheed Corporation.

vol. 5, No. 3, July - September 1978CONTENTS

3 The Hercules Liquid Oxygen System3 Major Components8 Servicing

11 Safety

12

14

13

Solid State Componentsfor Hercules Air Conditioning Systems

Reclaiming Fuel Compensator Units

StarTi pNose Landing Gear Switch Adjustments

DIRECTOR T.J. CLELAND

MANAGER

FIELD SERVICE & INVENTORY MGMT

CUSTOMER TRAINING

JETSTAR SUPPORT

SPARES STORES & SHIPPlNG

O.L. BRAUND

A.H. McCRUM

E. L. PARKER

H.L. BURNETTE

C. C. HOPKINS

MANAGER M.M. HODNETT

SUPPLY PROCUREMENT

SUPPLY SYSTEMS & INVENTORY CONTROL

SUPPLY SALES & CONTRACTS

SUPPLY TECHNICAL SUPPORT

J.K. PIERCE

C.K. ALLEN

H.T. NISSLEY, JR.

J.L. THURMOND

by Fred Tatum, Flight Line MechanicJohn Walters, Design Engineer, Senior

Under normal operating conditions, anairplane’s pressurization equipment isused to maintain a safe and comfor-table cabin environment during flight.In certain circumstances, however, itmay not be possible or even desirableto pressurize the aircraft at high al-titudes. For such situations, there mustbe an oxygen system on board thatcan supply pure oxygen as needed toprotect the crew from the dangerouseffects of hypoxia. Every Herculesis equipped with a system designed todo this.

There are two basic kinds of oxygen systems in use onHercules aircraft. The differences between them stemprimarily from the way the oxygen supply is stored ineach case. One type relies on compressed oxygen gas insteel cylinders for its supply; the second type makes useof oxygen which has been cooled sufficiently to convert itinto a liquid. The liquified oxygen, which is at atemperature of -297’F (-183’C) or below, is carried in aspecially insulated container. It is with this second type ofoxygen system that we shall be concerned here.

Liquid oxygen (LOX) systems have several importantadvantages over those systems which depend upon gaseousoxygen : The heavy gas storage cylinders are not requiredin a LOX system; this saves both space and weight.Furthermore, since oxygen increases in volume over 860times when it changes from a liquid to a gas, a smallamount of LOX will yield a very large volume of oxygengas. A practical result of this fact of physics is that acomparatively compact LOX system can satisfy the

oxygen requirements of a given aircrew for a much longerperiod of time than would be possible using a gaseoussystem of equivalent size and weight. This can be asignificant safety factor, particularly on long overwaterflights.

The advantages offered by LOX systems for a variety offlight applications have made the installation of this typeof equipment on new aircraft increasingly more common-place. It is worth noting, however, that LOX systems dopresent special maintenance problems. A thorough under-standing of the operation and proper servicing of LOXequipment is necessary if the inherent advantages of thesesystems are to be fully realized.

MAJOR COMPONENTS

The operation of the Hercules LOX system can mostreadily be understood by first examining the functions ofthe major components of the system.

Right. The LOX converter with

protective cover removed. The con-

verter is located in the right aft

corner of the NLG wheel wel l .

Below. Fiberglass cover in place

over converter.

4 The heart of the LOX system is the converter assembly.It consists of a double-walled sphere that will hold 25liters (26.4 quarts) of liquid oxygen. The space betweenthe walls is evacuated, which in effect forms an insulatingbarrier that reduces the flow of heat into the interior ofthe vessel. A coil of tubing is wrapped around the sphereand serves as a heat exchanger. Specifically, this unit isknown as the buildup heat exchanger. Here the heat ofambient air converts the liquid oxygen present in thetubing to gas, and the gas pressure is allowed to build upin a controlled manner until it is sufficient to meet theoperating requirements of the system.

The converter is provided with a series of valves whichcontrol its operation and protect the system from pressureextremes.

The valvessystem may

and their most importantbe described as follows:

functions in the

Pressure Closing Valve - The purpose of this valve is tostop the flow of LOX through the buildup heat exchangerwhen the pressure reaches approximately 305 PSI.

Low Pressure Relief Valve - This valve opens at between330 and 380 PSI, and serves as the primary overpressureprotection for the inner sphere.

High Pressure Relief Valve - Pressure of 380 to 430 PSI isrequired to open this valve. It provides secondary

overpressure protection for the sphere, and primaryprotection for the supply tubing downstream of theconverter-mounted check valve.

Supply-line Check Valve - The function of this valve is to

prevent gas pressure in the supply line from backing upinto the sphere.

The converter also contains a capacitance probe totransmit data on the quantity of LOX in the sphere to aflight station gage.

In addition to the converter and related components, theLOX system includes a combination fill-buildup-ventvalve, external heat exchangers (two on most Herculesmodels), a manually operated shutoff valve, breathingregulators, masks, and interconnecting tubing.

The LOX system has two principal modesthe fill mode and the buildup-supply mode.

of operation ;

The system goes into the fill mode only when the transfercart filler valve is connected to the combination valve onthe aircraft. When the cart filler valve is disconnected, thecombination valve automatically shifts the system to thebuildup-supply mode. Figure 1 is a diagrammatic repre-sentation of the LOX system in the fill mode; Figure 2shows the buildup-supply mode. Refer to Figure 1 as weexamine the fill (or refill) operation.

~---

380-430 RELIEF VALVE

i

330-380 RELIEF VALVE

-OVERBOARD

VENT PORT

OVERBOARD VENT

+ TO REGULATORS

Fill IN PORT

-

CHECK VALVE

t

Figure I LIQUID OXYGEN FILL/RE Fl LL OPERATION

380.430 RELIEF VALVE

330 380 RELIEF VALVE

-

COMBINATION VALVE

t

-

OVERBOARD VENT PORT

FILL IN PORT

PORT lw/checl< volvol

OVERBOARD VENT

+ TO REGULATORS CHECK VALVE

HEAT EXCHANGER

ORAIN VALVE

HEAT EXCJ.IANGER

DRAIN VALVE

Figure 2 LIQUID OXYGEN BUI LOUP/SUPPLY OPERATION

PRESSURE CLOSING

VALVE

-

PRESSURE CLOSING

VALVE

s

t

-

6

Left: The LOX service panel is located in a recess in the lowerright surface of the nose section. Right: Plumbing on the backside of the LOX service panel showing the combination fill- buildup-

vent valve. Below: Connecting the service hose to the LOX servicepanel. Note tubing leading to the drip pan from the overboard vent.

When the service hose from the LOX transfer cart isconnected to the filler port of the combination valve, anygas pressure present in the converter is automaticallyvented to the atmosphere. This permits the liquid oxygenin the cart, which is under approximately 30 PSI pressure,to flow through the combination valve into the converter.

As the liquid enters the lower part of the sphere, gas fromthe upper part is forced out the overboard vent. When aclear stream of LOX begins to flow from the vent, thesphere has reached its full capacity and the fill isdiscontinued by shutting off the transfer cart filler valve.The transfer cart filler valve and the aircraft combinationvalve should, however, remain connected for approxi-mately 10 minutes to allow the LOX in the intercon-necting lines time to turn into gas and boil off. Then thefiller valve may be safely disconnected.

Now consider Figure 2 as we describe the buildup, andsubsequently, the supply operations.

Disconnecting the transfer cart filler valve from thecombination valve on the aircraft positions the system tothe buildup-supply mode. Initially, during buildup, theliquid in the buildup heat exchanger turns into a gas, thusincreasing the pressure as it flows through the pressureclosing valve. The pressure closing valve remains openuntil the pressure builds to about 305 PSI. Then it closes,halting the flow of liquid oxygen through the buildupheat exchanger.

At this point, the system is as relatively static as a LOXsystem can be. The excellent insulation of the spherehelps keep the LOX cold, and for a while whatever heatdoes penetrate to the interior of the sphere is absorbed inthe form of latent heat of vaporization; that is, the heatwhich is absorbed by a liquid - without an increase in itstemperature - as it changes from the liquid to the gaseousstate. The pressure in the converter will remain at about305 PSI during this period, and there will be no gasreleased from the aircraft’s overboard vent.

The system cannot remain static for long, however. Thesphere is actually a big thermos bottle, and even the bestthermos bottle will not keep its contents cold forever.There is a gradual transfer of heat into the LOX, andeventually the LOX will have absorbed all of the heat itcan and still remain in the liquid state. Any additionalheat at this point will cause some of it to change into gas.Then the pressure will begin to rise in the converter; it willcontinue to do so until the low-pressure relief valve opens

at somewhere between 330 and 380 PSI, and venting tothe atmosphere begins. It can take up to several hours forthis stage to be reached, depending on the ambienttemperature and other factors. Once venting has begun, itmay be continuous or cyclic, depending on the relief valveconfiguration. Either of these reactions is considerednormal.

The regulator pressure gages in the airplane will indicate atleast 330 PSI when the system is stabilized but not in use.The actual pressure reading may be much higher thanthis. If the gaseous oxygen in the supply lines betweenthe check valve and the breathing regulator is warmed byheat transferred from the surrounding atmosphere, ther-mal expansion occurs and the pressure can rise until thehigh-pressure relief valve opens (380 to 430 PSI). That iswhy a pressure of up to 430 PSI is considered normal. Inpractice, a reading on the regulator pressure gages of up to455 PSI can be considered normal since the gages have atolerance of +/- 25 PSI.

The pressure demand oxygen regulator.

High pressure readings are often seen after a high flowdemand has been imposed on the system. High flow canoccur when EMERGENCY or TEST MASK is selected atthe regulator, during the recharging of portable oxygenbottles, or when several people simultaneously breathe100% oxygen.

Liquid oxygen can flow past the check valve during veryhigh flow demand periods. When the flow is thenstopped, the liquid trapped between the check valve and

8the regulators will turn into gas and expand. Thehigh-pressure relief valve will limit the maximum pressurein the supply line by opening and allowing the excesspressure to bleed off.

Most Hercules aircraft have two flat-plate heat exchangersinstalled in the supply line adjacent to the underdeckelectronics rack on the right side of the aircraft. Theseplates, in addition to the aircraft supply tubing, serve towarm the cold gas to ambient, or near ambient, tempera-ture for comfortable breathing. This system configurationcan warm the oxygen required for ten people simul-taneously breathing normal oxygen at the altitude(25,000 feet) at which maximum consumption occurs. Aflow rate of approximately 70 cubic feet per minute isrequired for this.

There are several ways that excessive flow rates can beimposed on the system; i.e., flow rates that overtax thecapability of the system to turn LOX to gas and warm itto the ambient temperature: Selecting EMERGENCY at aregulator and allowing the gas emitted from the regulatorbreathing hose to flow freely into the atmosphere cancause LOX to enter the aircraft supply line. Similarly,recharging more than one portable oxygen bottle at a timewill also result in LOX flowing into the supply line fasterthan the system can convert it to gas.

As we have previously noted, LOX systems have severaladvantages over gaseous systems, but one of their dis-

advantages is the necessity of providing a means to changeLOX to a gas and warm it to comfortable temperaturesprior to breathing.

SERVICING

There are two things that must not be introduced into theLOX converter: solid contaminants (especially thosewhich are petroleum-based) and moisture. Solid con-taminants are visible to the naked eye and require onlynormal precautionary measures and due care. Moisture,however, presents a special problem. Moisture can be verytricky stuff. It changes from a liquid, or frost, whenoutside the system to solid ice when it gets inside. Once itturns into a solid, it remains in that state as long as it isinside the converter. If ice lodges under a valve seat, theresult is excessive release of oxygen gas from theoverboard vent. When, however, the converter is emptiedand removed from the aircraft for repair, the ice reverts towater and quietly drains off.

The bench functional test inspector is thus left with agood unit and a puzzle; the problem has literally drainedaway.

The single most important factor in keeping the operationof a LOX system free of dust, moisture, and trouble ingeneral is careful adherence to correct procedures whenfilling or refilling the system. You should, of course,always follow the procedures which have been approvedfor use by your organization when servicing a LOXsystem. For informational purposes, however, here is aprocedure that has given reliable results at Lockheed-Georgia:

Recharging the Liquid Oxygen System

1.

2.

3.

4.

Ensure that both aircraft and transfer cart aregrounded, and ground the cart to the aircraft. Insertthe drain tube into the overboard vent opening, andplace a clean, degreased drip pan on the ground underthe outlet of the tube.

Remove the filler cap from the “fill in” port of theaircraft combination valve.

Inspect the “fill in” port of the combination valve forcontamination. Remove contaminants, if present,with a clean, lint-free cloth. If frost is present,remove it, using isopropyl alcohol. Dry thoroughlyprior to making a hookup.

Inspect the transfer cart purge fitting for contamina-tion. Remove contaminants with a clean, lint-freecloth. If frost is present, remove it, using isopropylalcohol. Dry thoroughly prior to making a hookup.

Installing the drain tube between the overboard ventopening and the drip pan.

Cleaning hose connection fittings on the service panel.

9

Left: Inspecting and cleaning the fitting used for purging

the service cart system. Below: Typical LOX transfer cart.

Purging the transfer cart system.

5. Connect the transfer cart filler valve to the transfercart purge fitting. Build pressure in the transfer cartup to 30 (+/- 5) PSI as follows:

10

n Close transfer cart vent valve.n Open pressure buildup valve.n Close pressure buildup valve when the desired

pressure is reached.

6. Purge the transfer cart hose by opening the transfercart fill-drain valve until a steady stream of LOX isobserved coming from the purge fitting overflow line.

7. Close the transfer cart fill-drain valve. Release hosepressure by pulling the transfer cart hose pressurerelief valve knob.

8. Disconnect the transfer cart filler valve from thepurge fitting. If frost is present, remove it, usingisopropyl alcohol. Dry thoroughly prior to making ahookup to the airplane.

9. Connect the transfer cart hose’s clean, dry tiller valveto the aircraft’s clean, dry combination valve. Go toone of the aircraft oxygen regulators and place themask end of the breather hose out of a window ordoor. Position the regulator SUPPLY switch to ONand position the regulator emergency switch toEMERGENCY. Allow the LOX system pressure todecay to zero.

10. Position the regulator SUPPLY switch to OFF, andposition the regulator emergency switch to NOR-MAL; then immediately open the transfer cartfill-drain valve and transfer LOX.

11.

12.

Fill until a clear stream of LOX flows from theaircraft’s overboard vent and out the drain tube.

Shut the LOX transfer off by closing the transfer cartfill-drain valve. Wait 10 minutes and then disconnectthe filler valve from the combination valve. Be sureto restow the breather hose used in Step 9.

Watching for stream of liquid that indicates the converteris full of liquid oxygen.

Finally, there are two points that deserve special em-phasis. Assuming that the LOX being received from thedistributor is of high quality, and that all handlingequipment such as storage tanks and transfer carts areproperly maintained, service personnel can greatly in-fluence the reliability of aircraft LOX systems by rigidobservance of these rules:

n Always wash the transfer cart filler valve and theaircraft combination valve with isopropyl alcohol(FED SPEC TT-I-735A) and then wipe completelydry prior to making a hookup.

Allow the aircraft LOX system to deplete to zeropressure before opening the transfer cart fill-drainvalve. This ensures an immediate flow of LOX andhelps prevent ice from collecting and snowballingaround the valves.

SAFETY

Always keep safety uppermost in mind when you areworking with any type of oxygen system. The numberone area of concern in dealing with oxygen is always thedanger of fire. The problem is not so much that theoxygen might burn - strictly speaking, it won’t - butthat nearly everything else will burn so well in itspresence. A smoldering cigarette will erupt into flame inan oxygen atmosphere, and tiny sparks that woulddissipate harmlessly in ordinary air can set off fires andexplosions if supplied with a little extra oxygen.

In general, all of the safety rules that apply to gaseousoxygen also apply to the handling of liquid oxygen - andseveral more besides. If your job brings you into contactwith oxygen or oxygen systems, it’s a good idea to reviewall the safety regulations pertaining to oxygen handling ona regular basis. Keeping alert to potential dangers andknowing the correct measures to use in avoiding them iswhat safety is all about.

Here are some safety pointers in connection with LOXthat are worth special notice: When using liquid oxygen,the fire danger is aggravated by the fact that as a liquid,LOX is spillable. It can be splattered onto combustiblematerials, or accidently poured into containers of greaseor solvents. Make certain that accidents of this sort don’thappen by keeping all flammable substances far awayfrom areas where LOX systems are being serviced.

LOX also poses some unique handling hazards because itis so very cold. At -297’F (-183’C), liquid oxygen is acryogenic fluid that will instantly freeze solid anything itdoesn’t ignite. This, of course, includes human flesh.Even a small quantity spilled on the skin will causefrostbite “burns” which are extremely painful.

This protective clothing - with you inside it - is the firststep toward personal safety when handling LOX. Have acontainer of wash water handy to immediately thaw theskin should any of the liquid oxygen somehow come incontact with it.

folds that might tend to trap spilled liquid and hold it incontact with the skin. Clean, loose-fitting, tightly wovencotton coveralls plus a cotton cap offer satisfactory basic 11

protection, but make certain that the coveralls arewithout pockets or cuffs, and that the legs are longenough to extend over the shoe tops. The shoes shouldhave high tops and rubber soles and heels.

The hands and face are particularly subject to injuryduring the handling of LOX. Asbestos gloves, or rubbergloves with loose-fitting cotton liners should be used tocover the hands, and a face protector shield will provideprotection for the face and eyes.

Another point worth special notice is that stored LOX isalways releasing a certain amount of oxygen gas. Theambient air is so much warmer than the liquid oxygenthat some of the LOX is constantly boiling off. Thismeans that any container which is used to hold LOX mustbe provided with adequate safety valves, or left open sothe gas can escape. Don’t set the stage for a possibleexplosion by “bottling up” liquid oxygen.

The proper handling of LOX systems requires a com-bination of attention to correct procedures, cleanliness,safety-mindedness, and common sense. A balanced main-tenance approach combining these elements will ensureboth safe and reliable LOX system operation.

Be sure to use proper protective clothing when handlingLOX. Particularly avoid wearing anything with tucks or

for Herculesair conditioning systems

Solid-state devices are not exactly news any more and wehave all become rather accustomed to the reliability andlong life of these marvels of modern electronics.

Still, every once in a while we see some figures thatremind us just how much difference the conversion tosolid-state circuitry can make in the performance anddependability of a given system.

12

An excellent example can be found in our experience withthe air conditioning system of the Hercules aircraft.About two years ago, starting with aircraft serial numberLAC 4579, we began incorporating improved solid-statetemperature control boxes and resistive-type sensors inthe air conditioning systems. The data compiled from theaircraft equipped with the new components have beenmost impressive.

Air conditioning temperature control boxes located onthe aft side of the 245 bulkhead.

Table 1

The improved performance includes a quicker response todesired temperature changes, an increased range of tem-perature selections and, best of all, a mean time tounscheduled removal (MTUR) of up to nearly ten timesthat of the old-type components. This adds up to aworthwhile reduction in maintenance costs. The figuresin Table 1 show the improvement in reliability for specificunits.

Operators of older Hercules will be pleased to learn thatexisting aircraft can easily be retrofitted with the newsolid-state components. The only requirement is that allof the following solid-state components be installed as acomplete system: Temperature control box, cabin tem-perature sensor, duct temperature sensor, duct overheatsensor, and temperature selector. There are no changesrequired to the aircraft wiring or connectors.

The following table is a handy reference of both Lock-heed and vendor part numbers affected by this change.

For further information regarding price and availability ofthese parts, contact the Lockheed-Georgia Supply Salesand Contracts Department, D/65-1 1, Zone 287.

Other articles relating to the Hercules air conditioningsystem can be found in Service News issues Vol. 3, No. 2,April- June 1976, and Vol. 3, No. 3, July - September1976.

NOSE LANDING GEAR SWITCH ADJUSTMENTS

by C. E. Shuler, Field Service Representative

Both the nose gear upiock limit switch and thedownlock limit switch on the Hercules can beadjusted without jacking the airplane and operat-ing the gear. With the gear indicating down andlocked, perform the following steps:

1. Back off the downlock limit switch until theswitch plunger just contacts the actuating piston.The nose gear indicator in the cockpit should nowindicate “in-transit” (barber pole) and the gearhandle light should be illuminated.

Nose landing gear warning light switches. As shown, the

uplock switch is on the left and the downlock switch is on

the right.

2. Actuate the uplock assembly with a largescrewdriver. Back off the uplock limit switchuntil the switch plunger just contacts the actuatorplate, then advance the switch from 2 to 2-l/2threads or until the plunger measures 0.225 to0.275 inches in length. Lock and safety wire theswitch. The nose gear indicator should nowindicate UP. Release the uplock assembly bypushing back on the phenolic or aluminum blockfor the manual release of the uplock. The nosegear indicator should again indicate “in-transit”and the gear handle light should be illuminated.

3. Advance the downlock limit switch forward 2to 2-l/2 threads or until the plunger measures0.225 to 0.275 inches in length. Lock and safetywire the switch. The nose gear indicator shouldindicate wheels down and the gear handle lightshould be extinguished.

4. Make sure the switches are locked andsafetied and that all wires are properly secured.

This procedure checks both switches for stickingand proper operation and adjusts them for correctactuation and travel.

13

14

ReclaI

Iming Fue

Investigations have shown that fuel quantity com-pensators of the fiberglass type which have mal-functioned due to moisture contamination can bereclaimed and returned to service. This is accomp-

lished by cleaning and recoating the compensators.

The material used for coating is Laminar X-500.Laminar X-500 Flex Clean 7-C-27-36 coating

l Compensator Units

(essentially the same as 7C-27-40), has proven to besuccessful and is recommended by Lockheed. Thismaterial is available from Magna Coatings andChemical Corporation and is qualified to MIL-C-83019. It may be ordered under NSN8 0 3 0 - 0 0 - 2 4 1 - 2 4 9 8 f o r q u a r t s i z e s o r8030-00-496-9275 for gallon sizes.

When ordering, it is imperative to specify the entirenomenclature as “Flex Clear 7-C-27-36”. Inci-dentally, this is the same material used to coat theaircraft fuel tank sealant.

An outline of a procedure for reclaiming compen-sators is as follows:

Step 1. Wash compensators in a warm (1 20°F,49’C) detergent solution - a mild liquid dishwash-ing detergent will suffice - and rinse well in cleantap water.

Step 2. Flush compensators with methyl ethylketone and dry two to four hours at 160’F (71’C).

Step 3. Dip the compensator unit for 30seconds in a heated solution containing oneounce per gallon of water of chemical con-version coating material such as Alodine 1200,Iradite 14-2, Turco Alumigold or other ma-terials conforming to MILC-554 1.

The temperature of the solution should bemaintained at 120’F (49’C). Then rinse thecompensator with clear water and dry thor-roughly at ambient conditions.

Step 4. Dip coat the compensator portion ofthe probe with Laminar X-500 Flex Clean7-C-27-36, or - 40.

Step 5. Cure the coating for 38 hours at ambieconditions. After drying, bake at 140’F (6O’C) FUEL QUANTITYfrom two to four hours. This will improve the cure COMPENSATOR

and, at the same time, reveal any lack of adhesion PROBE

in the coating.

Step 6. Functionally test each compensator, utiliz-ing the TF-20 Test Set or equivalent, prior toreturning the compensator to service.

In the dipping operation, it is very important thatthe Laminax X-500 be allowed to stand forapproximately 15 minutes before the compensatoris dipped. This allows air bubbles in the mixture toescape. The manner in which the compensator isdipped is also important. It should be inserted atthe rate of approximately one inch per 15 secondsand removed at the same speed. A rapid or erraticdipping may allow air bubbles to form and thusresult in pin holes in the final coating. Oncedipped, compensators should be allowed to dry in adust free area in order to insure a perfect coating.

The procedure for calibrating the fuel quantitysystem is not affected as long as the preferredmethod of calibration is used (tanks empty, com-pensators dry); however, when the alternatemethod (tanks containing fuel) is used, a fulladjustment should be made with 62.5 mmf set forthe compensator. The average compensator drycapacitanceis increased approximately 0.5 mmfwhen coated with Laminar.

It should be noted that a malfunctioning fuelcompensator due to moisture accumulation isindicative of contaminated fuel or contami-nated fuel tanks. When it is determined thatthe fuel quantity indicating system is malfunc-tioning due to moisture accumulation, the fueltanks should be thoroughly inspected forcontamination and corrosion. In addition tothe inspection, a procedure should be initiatedto prevent recurrence of contaminated fuel orcontaminated fuel tank problems,

TO WALK

TO POINT

C 111 1V o1 4fY'.JtJClr ..,,., nc

FROM POINT

COULD TAKE THE REST OF YOUR LIFE!

- • tM,.1'Cld by lCOff R l ft~ VP-8 S.t.tv Otf.c.

CUSTOMER SERVICE DIVISIONLOCKHEED-GEORGIA COMPANY/\ DIVISION OF LOCKHEED CORPORATIONMARIETTA GEORGIA 30063

Lower fuel consumptionbrings new economy and versatility

Lower fuel consumption - especially important today - brings new economy and versatility to JetStar IIoperations.

The JetStar II has demonstrated its nonstop capability, flying 3,425 miles from Los Angeles to San Juan in6-1/2 hours. Other nonstop demonstration flights were made from New York to Mexico City, and fromHonolulu to El Paso.

The new JetStar II is powered by four TFE-731-3 engines to increase range while meeting federalregulations on both noise and pollution. There is good-neighbor quietness outside and a quieterenvironment inside the spacious cabin. The JetStar II fleet has acquired more than 6500 flight hours andhas traveled over 3-1/2 million statute miles since going into operational service in early 1977.