A SERVICE PUBLICATION OFLOCKHEED-GEORGIA COMPANYA DIVISION OFLOCKHEED CORPORATION

EditorCharles I. Gale

Associate EditorsDaniel E. JolleyJames A. LoftinKathy T. Sherwin

Vol. 11, No. 2, April-June 1984

CONTENTS

2 Focal PointT. J_ ClelandDirector of Product Support

3 An Introduction to NondestructiveEvaluation

7 MLG Brake Application After Loss ofHydraulic Pressure

9 New FCS-105/C-12 Simulation Test Set

11 New Pin and Bushing for MLG ShelfBracket

13 StarTipImproving the General Purpose SlingAssemblv

15 C-130Hs for Japan

Cover: New U.S. Coast Guard HC-130H-7s patrol

the skies over Florida’s Gulf coast.

An Uncommon Achievement

This summer we at Lockheed-Georgia willmark the 30th anniversary of the first flight ofthe C-110. To date, over 1700 Hercules aircrafthave been delivered, and the airplane con-tinues in full production. From having just onecustomer for the C-130 in 1954-the U. S. AirForce-we have now provided this amazingairlifter to 55 countries throughout the world.It is a remarkable record, one which is un-precedented in the annals of aviation. T. J. CLELAND

The past 30 years have firmly established theHercules aircraft as one of the most successful airplanes in history, but much of the creditmust go to you, our customers.

Your achievements are evident on every page of the Hercules success story. It is ourcustomers who have shown us how tough and versatile this airplane really is. You havetaken the Hercules aircraft to every continent, probed every corner of the world from theoil fields of Alaska�s North Slope to the frozen wastes of Antarctica. Your aircraf t are theones that have brought relief and hope to disaster-ravaged towns and villages. It is you whohave challenged uncharted peaks to reach the jungles of the Amazon: it is your airplanesthat have tamed the burning sands of the central Sahara. It i s you who have shown theworld how a cargo plane can build a nation.

We salute you for what your enterprise has helped us accomplish as d company, but whatyou have done has much broader significance. With the Hercules aircraft. you have indi-vidually and collectively demonstrated the enormous potential of aerospace technologyfor the progress and betterment of mankind. Yours is truly an uncommon achievement.

Sincerely,

T. J. ClelandDirector of Product Support

T. J. CLELAND DIRECTOR

I

CUSTOMER INTEGRATEDSERVICE LOGISTICS SUPPORT

CUSTOMERSUPPLY

Nondestructive evaluation (NDE) assesses the resultsof performing nondestructive inspection (NDI) and non-destructive testing (NDT) techniques in conjunction withsystem requirements to determine the serviceability ofa component or assembly. NDE is the technique ofinspecting or testing materials and components withoutdestroying them or reducing their serviceability. Visualexamination is no longer the only means of ensuringadequate serviceability. NDE methods are used, forexample, to detect variations in the structure ofmaterials, to detect the presence of discontinuities, todetect flaws or changes in surface finish, and to deter-

mine physical properties of materials. NDE increasessystem and component reliability, helps to prevent acci-dents, lowers operating costs, and increases productutilization. In this article we will describe the basicmethods of NDE used on Hercules aircraft and otheraircraft in commercial and military inventories.

There are six NDE methods commonly in use todayto determine the integrity of aircraft materials and com-ponents: visual inspection, liquid penetrant evaluation,magnetic particle evaluation, eddy current evaluation,ultrasonic evaluation, and radiographic evaluation.

Lockheed SERVICE NEWS Vl 1 N2 3

Figure 1. Some of the items used in liquidpenetrant inspection.

Visual Inspection

Visual inspection was the first method of nondestruc-tive evaluation, and it is still the one most widely usedfor detecting discontinuities. Technical manual T.O.33B-1-1, Nondestructive Inspection Methods, definesdiscontinuities as interruptions in the normal physicalstructure or configuration of a part such as cracks, laps,seams, inclusions, and porosity. Discontinuities may ormay not affect the usefulness of a part. Visual inspec-tions are a quick and economical way of detectingvarious types of surface discontinuities before they pro-gress to failure. The reliability of visual inspectionsdepends on the ability, experience, and diligence of theinspector.

In order to perform a satisfactory visual inspectionor any other form of NDE, the surface of the test speci-men must be clean and dry. Foreign substances remain-ing on the part being tested may mask defects. Flash-lights, inspection mirrors, microscopes, magnifyingglasses, and borescopes are often used in conjunctionwith visual inspections to facilitate the detection of sur-face flaws.

Liquid Penetrant Evaluation

The liquid penetrant method is used to detect varioustypes of discontinuities open to the surface of a com-ponent. Most nonporous materials such as metal alloys,plastics, rubber, glass, and some ceramics can be in-spected by this method. All that is needed for thismethod is a penetrant, a cleaner, a developer, and asuitable light source (Figure 1).

The basic principle of penetrant testing is to increasethe visible contrast between a discontinuity and its back-ground. After cleaning the component surface, pene-trant is applied to the surface and capillary action causesit to enter surface imperfections. After a predeterminedtime, the excess surface penetrant is removed. A devel-

Figure 2. Parker contour probe, field indicator,and magnetic particles used in magnetic particleevaluation.

oper is then applied to the surface being inspected. Ifthere is a discontinuity present, the developer will actas a blotter and draw out any penetrant that has seepedinto it, highlighting the discontinuity. Best results aregenerally obtained by the use of fluorescent penetrants,which glow when exposed to ultraviolet (“black”) light.This makes discontinuities more readily visible.

Magnetic Particle Evaluation

Magnetic particle evaluation is also a widely employedNDE method. It is used to locate surface and subsurfacediscontinuities. This method has some limitations as faras the aerospace industry is concerned because it canonly be used on ferromagnetic materials.

Figure 3. M-500 mobile power pack used inmagnetic particle evaluation.

Figure 4. ED-520 eddy current test instrumentand reference standard.

Magnetic particle evaluation involves the use of ironfilings, a source of electric current, and a magnetic-fieldinducing device (Figures 2 and 3). A magnetic field isinduced in a test specimen, using either alternating cur-rent or pulsating direct current. After the magnetic fieldis established, iron filings are sprinkled over the testspecimen surface. When the magnetic field in the testarticle is interrupted by a discontinuity, some of the fieldis forced into the air above the discontinuity, forminga leakage field. The iron filings sprinkled over the sur-face will be attracted to the leakage field, indicating itslocation, size, and shape.

Eddy Current Evaluation

Eddy current evaluation is a nondestructive techniquedesigned to detect small discontinuities which are opento or just below the surface of a test specimen. It canalso be used for sorting metals, hardness testing, con-ductivity measurements, and coating thickness measure-ments. Eddy current testing is useful on all electricallyconductive test specimens, including those made of non-ferrous alloys. Since most aircraft are made primarilyof aluminum alloys, eddy current testing is widely usedin the aerospace industry.

The test equipment needed for this method consistsof an eddy current test instrument and reference stand-ards (Figures 4 and 5). The test instrument typically con-tains a test coil, an oscillator to generate AC current,a bridge circuit, a circuit to process returned signals, anda test meter.

Eddy current evaluation also makes use of a magneticfield. A test coil carrying alternating current is placednear the surface of a test article. The alternating cur-rent in the coil produces an alternating magnetic field.When the alternating magnetic field comes in contact

Figure 5. NDT-17 eddy current test instrument.

with the test material, circular electrical currents callededdy currents are established in the test specimen. Theseeddy currents will be parallel to the surface of the testarticle. When the eddy current path is disrupted by adiscontinuity, the current in the test coil will change. Thechange will be registered by a test meter attached to thecoil through a bridge circuit. Reference standards areused to calibrate the test instrument for the materialbeing tested. The width, depth, and length of the dis-continuity can often be determined by this technique.

Figure 6. Sonic Mark IV ultrasonic testinstrument.

Figure 7. Digi-Sonic 502 ultrasonic test instru-ment and reference standard.

Ultrasonic Evaluation

Ultrasonic evaluation uses high-frequency soundwaves to detect surface and subsurface discontinuities.It is a sensitive method for detecting small discon-tinuities, but requires that the operator be highly experi-enced for signal interpretation. Ultrasonic testing canbe used on many different materials including metals,composites, bonded honeycomb, plastics, rubber, andsynthetic materials. Ultrasonic testing can also be usedfor accurately measuring material thicknesses.

Ultrasonic test equipment includes an ultrasonic testinstrument and reference standards (Figures 6 and 7).The test instrument generally contains a power supply,

Figure 8. X-ray of aircraft part illuminated by ahigh-intensity viewer.

a transducer, a pulser/receiver, and a cathode ray tubeor other display device.

To determine if a test specimen has a discontinuity,high-frequency sound waves (above 20,000 Hz) are intro-duced into the material, using a transducer element. Asthe sound waves travel through a material, a discon-tinuity will reflect the waves. If the major axis of thediscontinuity is perpendicular to the sound beam, thewaves will be reflected back to the transducer, whichconverts the sound waves into an electrical signal. Thissignal is displayed on a cathode ray tube and interpretedby a trained technician, using reference standards toevaluate the indications.

Radiographic Evaluation

Radiographic evaluation is one of the oldest tech-niques of NDE and can be used to detect internal andexternal discontinuities in almost any type of material.Radiography uses high-energy X-ray radiation and radio-graphic film to examine a test specimen in the same waythat low-energy X-rays and radiographic film are usedto examine the human body (Figure 8). Radiographictesting can be used on almost any material or part aslong as the radiation has enough energy to penetrate thematerial and expose the film.

Radiography measures a change in material thicknessand density. Where the material is reduced in thicknessor less dense, more radiation will pass through that areaand the corresponding area on the film. When a testspecimen is irradiated, discontinuities will show up asdark images on the film since the total thickness thatthe radiation must pass through is reduced by the discon-tinuity. Radiographic testing is used extensively in theaerospace industry because of its ability to examine partsand areas not accessible to other techniques withoutextensive disassembly.

The six methods of nondestructive evaluation that wehave just described are by no means the only methods,but they are the ones that are currently being used mostextensively in the aerospace industry. In future issues ofService News we plan to discuss these techniques in moredetail, and their application to the Hercules aircraft.

6 Lockheed SERVICE NEWS Vl 1 N2

If you are a Hercules aircraft flight crew member orinvolved with hydraulic system maintenance, you maybe familiar with the paragraph in some of the flightmanuals in the section on brake system accumulatorsthat discusses the number of brake applications availablein case of a hydraulic system pressure failure. The gistof the statement is that the normal brake system accu-mulator, when fully charged with hydraulic fluid, iscapable of supplying pressure for about two brake appli-cations.

Some flight crews have put this statement to the testand discovered that the results do not always appear toagree with the above assertion. Instead of having suffi-cient pressure for two brake applications, the normalbrake system accumulator may provide for only one.This has been a source of concern for some personnel;in fact, occasionally aircraft have been refused by flightcrews because it had been determined that only onebrake application was available.

Actually, the braking system was probably workingproperly in these cases. The key point is the positionof the anti-skid system switch. If the normal brakesystem accumulator’s ability to provide hydraulicpressure for braking is tested with the anti-skid systemswitch in the ON position, one application is likely allthat will bc available.

Here is why. When the anti-skid system switch is inthe ON position, power from the main DC bus is sup-

plied to the parking brake off solenoids in the LH andRH anti-skid control valves (Figure I).

This in turn opens the solenoid-controlled shutoffvalve (Figure 2) in each anti-skid valve. Hydraulic fluidfrom each anti-skid valve will leak down at a rate ofabout 61 cubic inches per minute when the shutoff valveis open, for a total rate of 122 cubic inches per minutefor both anti-skid valves.

When the first brake application is made, approxi-mately 20 of the 50 cubic inches of hydraulic fluid storedin the normal brake system accumulator goes to fillbrake cylinders. This leaves approximately 30 cubicinches of fluid in the accumulator.

At a combined leak-down rate of 122 cubic inches perminute, the anti-skid valves can deplete the 30 cubicinches of fluid remaining in the accumulator in aboutI5 seconds. This accounts for the lack of pressurenecessary for a second brake application; after only 5seconds, there would be insufficient fluid available.

If the anti-skid system switch is in the OFF position,however, two brake applications will be available.

The explanation for this is as follows. From Figure3, it can be seen that power from the main DC bus can-not travel past the anti-skid system switch when theswitch is selected to OFF. Since no power is availableto the solenoid-controlled shutoff valve in each anti-skid

SELECT EMERGENCY BRAKESWITCH SELECTOR VALVE

BRAKE VALVE

FAIL-SAFE

ANTI -SKID

LIGHTINOPERATIVE

LIGHT

LH ANTI-SKID RH ANTI-SKIDCONTROL VALVE CONTROL VALVE

Figure I A. Anti-skid system switch on-parking brake off solenoids energized.

Figure 2 One half of dual anti-skid valve.

8 Lockheed SERVICE NEWS Vl 1 N2

OFF

NORMAL BRAKE BRAKESELECTOR SELECT E M E R G E N C Y BRAKE

PARKINGVALVE SWITCH SELECTOR VALVE

BRAKESWITCH

ESSDC

BUSBRAKE VALVE

LG UPLIMIT

SWITCHES

LG DOWN

FAIL-SAFELIGHT

INOPERATIVELIGHT

LH ANTI-SKID RH ANTI-SKIDCONTROL VALVE CONTROL VALVE

Figure 3. Anti-skid system switch off-parking brake off solenoid deenergized.

control valve, the shutoff valves remain closed. When Perhaps the old adage that appearances can be deceiv-the valves are closed, each anti-skid valve will only leak ing is appropriate here. You may think that you haveabout 10 drops of hydraulic fluid per minute. This means a brake problem when you don’t. A quick scan of thethat most of the 30 cubic inches of fluid still in the nor- anti-skid control panel and the switch position will givema1 brake accumulator after one brake application is you a clue. Just remember that the anti-skid controlavailable for another application and will remain so for switch should be in the OFFposition for the brakes tosome time.

_“perform as advertised?

A problem encountered by many Hercules aircraftoperators during routine ground maintenance has beenthe inability to effectively test the FCS-105 flight con-trol system. Conventional methods for evaluating thissystem have proven cumbersome and have involvedunacceptable levels of guesswork and expense.

In January 1983, a competition was held by the U.S.Air Force for the development and procurement of amore cost-effective method of testing this system. Thiscompetition ended with the selection of a new light-weight, carry-on-board FCS-105/C-12 Simulation TestSet (P/N 3402904-l, NSN 4920-01-156-4522) manufac-

tured by Lockheed-Georgia Company.

By following a step-by-step procedure, this test setenables a maintenance technician to simulate flight con-ditions heretofore not achievable during ground checks.As a result, a more complete and timely analysis of thesystem can be accomplished, avoiding unnecessarydowntime. The test set also enhances the technician’sability to accurately diagnose a malfunction, thusreducing the probability of replacing an operationalcomponent needlessly.

The test set, which operates on aircraft power, comesin two units weighing approximately 40 pounds each.Both are used on the flight deck. One is a simulationunit, which the technician uses for observations of thevarious instruments and manipulation of the controls.This unit provides the simulated heading, pitch, roll, andinstrument deviations necessary to operate the flightcontrol system.

Figure I. Simulation unit.

The other unit consists of the breakout panels, con-trols, and mounts for the mode selector, autopilot ampli-fier, and the flight director computer, and interfaces withthe appropriate aircraft equipment mounts. The test setcomes with all cables and data necessary to troubleshootthe FCS-105 flight control system.

Figure 2. Breakout panels.

The FCS-105/C-12 Simulation Test Set represents asignificant technological advancement in troubleshootingthe flight control system. If you would like additionaltechnical or procurement information about this test set,please direct inquiries to the Manager, Supply Sales andContracts Department, at the following address:

Lockheed-Georgia CompanySupply Sales and Contracts Dept.Department 65-11, Zone 451Marietta, Georgia 30063Telephone (404) 424-4214TELEX 542642

10

Those of you who are involved with landing gearmaintenance on the Hercules aircraft are undoubtedlywell acquainted with the vital role that the MLG shelfbracket plays in the proper operation of the main land-ing gear.

The shelf brackets are designed to provide a stableplatform to retain the MLG when the landing gear isfully extended. Each shelf bracket incorporates twoholes, provided with bushings, which accept drag pinsattached to the associated shock strut flange when thegear is fully extended. When properly engaged in thebushings, the drag pins prevent side loads from deflect-ing the main landing gear laterally during landings.

For many years, the method used to keep the retain-ing pin in place was to stake the top of the bushing intwo places and the bottom of the retainer in one place(see illustration). This approach was usually satisfactoryfor the initial factory installation, but it proved lessreliable when the original bushings wore out and hadto be replaced in the field. Unless the new parts werestaked in a rather precise way, wear and repeated land-ing gear operating cycles sometimes combined to causethe retaining pin to work free and drop out.

Without a retaining pin, the bushing can unscrewand separate from its retainer. If this occurs, the dragpin may pull the bushing out of the shelf bracket whenthe landing gear is retracted. The bushing usually dropsoff as soon as the drag pin clears the shelf bracket andthe side loads are removed, but more often than not itfalls back into its hole in a cocked position. With themisaligned bushing blocking the hole, the landing gearcannot be fully extended because the drag pins are pre-vented from engaging the shelf bracket in the normalway.

Securing the Bushings

The shelf bracket bushings are held in place byretainers. A retaining pin is used to help prevent thebushing and the retainer from unscrewing and separat-ing. The pin is installed through a predrilled hole in thebushing and seated in a hole in the retainer which mustbe specially drilled at the correct location for each instal-lation.

ELF BRACKET

STAKE MARKS

/ P I N

ORIGINAL PIN INSTALLATION

PIN

NEW PIN INSTALLATION

Figure I. Original and new shelf bracket and pin installations.

A Better Way

Lockheed has recently developed a new way of secur-ing the pin in the bushing retainer that helps avoid suchunpleasant possibilities. The new arrangement consistsof substituting a P/N 389438-3 bushing for a -1 bushingand using a headed retaining pin, P/N 3319688-l. Thepredrilled hole in the -3 bushing is countersunk toaccommodate the headed pin. You still must drill amatching hole (0.093 to 0.098-inch diameter) throughthe retainer. Instead of inserting the pin through thebushing and bushing retainer and then staking, the newpin is inserted through the bushing and retainer headup; it is then bent to a 45-degree angle where it exitsthe retainer (see illustration). This new arrangement vir-tually eliminates loss of the pin and resultant looseningof the bushing.

If you find it necessary to replace a bushing andbushing retainer with the headed pin, but do not havethe new -3 bushing in stock, a -1 can be reworked toaccept the headed pin. All that is required is to counter-drill the hole in the -1 bushing to a depth of 0.120 inchwith a l/S-inch diameter drill.

Regardless of which bushing you use, we think thatthe new pin arrangement will prove to be both time-saving and timely. The potential for MLG extensionproblems will be significantly reduced once the new pinconfiguration is installed on your aircraft.

12 Lockheed SERVICE NEWS Vl 1 N2

Improving the General Purpose Sling Assemblyby Earl D. Allen, Engineering Specialist

The General Purpose Sling Assembly, P/N 3400961-Lwas originally designed to be used in removing andinstalling ailerons, rudders, elevators, outboard wingflaps, vertical and horizontal stabilizers, and verticalstabilizer leading edges. Experience has shown that thissling assembly as presently configured is not ideallysuited for removing or installing the rudder on theHercules aircraft. When attached to the rudder, the slingcables are not long enough to allow the hoist plate toclear the top of the rudder; in addition, the center ofgravity of the rudder is offset from the lifting attachpoints. The rudder therefore tends to pivot from the ver-tical position during removal or installation. This makesit rather tricky to remove or install a rudder withoutcausing damage to the vertical stabilizer, the rudder, orboth.

A modification to the 3400961-l sling assembly hasbeen developed in the form of a balance weight plusextension cables which completely eliminates this prob-lem. The modification consists of removing two fittingsand two links and adding two new attach fittings, twoextension cables, two weight-attach cables, and a balanceweight. Modification of an existing sling to the new con-figuration for use on the rudder is simple and requireslittle time and effort. The modified sling can just asquickly be returned to the original configuration for useon another flight control or stabilizer.

To modify a 3400961-l sling assembly, first obtain thenecessary parts from the Lockheed-Georgia Company.The modification kit, P/N 3403147-1, contains one P/N3403147-3 weight assembly, two P/N 3403147-s wire ropeassemblies, two P/N 3403147-7 wire rope assemblies, twoP/N 3403147-11 fittings, two G-209 l/2-ton shackles, twoG-210 l/2-ton shackles, and modification instructions.

Modification Procedure

To modify the 3400961-l sling assembly, begin bymaking sure that the sling is configured for rudder

removal or installation in accordance with the appro-priate flight control systems maintenance manual. Nowtake off the 348701-l fitting and 403577-l link assemblyfrom the lower end of each 3400961-3 cable assemblyby removing the MS21042-5 nut, AN960-516 washer,

Figure 1. First disconnect fitting and linkassembly from P/N 3400961-3 cable assembly.

346912 HOIST PLATE

MS21042-5 NUTAN960-516 WASHERNAS1005.13A BOLT346362-g SPACER

403577.1LINK ASSY

346701-lFITTING

Lockheed SERVICE NEWS Vl 1 N2 13

Figure 2. Next attach the new fitting and wirerope assemblies to the -3 cable assembly.

NAS1005-13A bolt, and 348362-9 spacer (Figure 1).Store all of these parts with the other parts of the3400961-l sling assembly that are not used for rudderremoval or installation.

Next attach a 3403147-7 wire rope assembly to the freeend of each 3400961-3 cable assembly, using a G-209l/2-ton shackle (Figure 2). To the free end of each3403147-7 wire rope assembly, connect a 3403147-11 fit-ting, using the G-210 l/2-ton shackle. Finally, connectthe 3403147-5 wire rope assemblies to the -11 fittings andthe 3403147-3 balance weight, using the hardware fur-nished with the -5 wire rope assemblies. The sling assem-bly is now ready for removing or installing a Herculesaircraft rudder.

To install the modified sling for use, suspend it fromwhatever hoisting device will be used and mate each -11fitting to the sling attach point on each side of the rud-der with the fitting’s captive “T” handle pin (Figure 3).The 3403147-3 balance weight fits over the trailing edgeof the rudder. Make sure that control is maintained overthe balance weight when connecting the fittings ordamage could occur to the rudder.

Figure 3. Then connect the modified sling to therudder.

With the modified sling attached to the rudder, therudder can now be removed or installed, safely andeasily, using the standard procedures outlined in the

flight control systems maintenance manuals.

For technical information on the 3403147-l modifica-tion kit, contact:

Lockheed-Georgia CompanySupport Equipment Design Dept.Department 72-68, Zone 450Marietta, Georgia 30063Telephone (404) 424-5468TELEX 542642

For quotations or purchase of the 3403147-l modifica-tion kit or the 3400961-I General Purpose SlingAssembly incorporating the modification, contact:

Lockheed-Georgia CompanySupply Sales and Contracts Dept.Department 65-11, Zone 451Marietta, Georgia 30063Telephone (404) 424-3842TELEX 542642

14 Lockheed SERVICE NEWS Vl 1 N2

Japan became the 55th nation to own and operatethe Hercules aircraft when two advanced C-130Hswere delivered to the Japan Air Self Defense Force inDecember of 1983. The second of these versatileairlifters had the additional distinction of being the1700th C-130 to be delivered by the Lockheed-GeorgiaCompany. The occasion was marked by appropriateceremonies at the Lockheed production facility inMarietta, Georgia (see picture at right).

The Air Staff Office of the JASDF selected theC130H to serve their heavy airlift mission require-ments after several years of thorough study anddetailed analysis. Among the important factors that ledto the selection of the Hercules aircraft was its opera-tional flexibility. This remarkable airplane can serveeffectively in many roles, from meeting nationaldefense airlift commitments to bringing emergencysupplies, rescue personnel, and construction equip-ment to regions laid waste by natural disasters.

Other considerations that placed the Hercules air-craft in the forefront of the selection process were itslegendary durability and proven design. Operationalefficiency in such matters as fuel requirements andmaintenance costs also weighed heavily in the C-130’sfavor, as did its respect for the environment withregard to airport community noise levels.

In addition to the two aircraft received in December,Japan has two more C-130Hs on order, with deliveriesscheduled for the second half of 1984. We want toextend our best wishes to the Japan Air Self DefenseForce for many years of successful operations with thec-130.

Lockheed SERVICE NEWS Vl 1 N2 15