This document provides inspection instructions for scheduled inspections at 50, 100, 600, and 1200 hour intervals of a BTH-47G3 helicopter. Key points include: - Inspections are to be performed in accordance with the maintenance manual chapter specified. - The 1200 hour inspection includes removing and inspecting lateral, collective, and cyclic control tubes for corrosion, nicks, or scratches. Acceptable tubes are cleaned and treated with primer and paint. - Control tube end fittings are removed and reinstalled after inspection. Sealant is applied before and after installation to prevent corrosion. - Rigging is checked after reinstalling control tubes and cotter pins are installed.

1. SCHEDULED INSPECTIONS BTH-47-CR&O
1200 hours inspections
Data 03/11/2015 Initial
Reference:BTH-47G3 mech other
Inspection task desription
Date: 03/11/2015
Facility:
HelicopterS/N:
Total time:
Ganeral
each listedinspectionitemor maintenance fuctionis to be
performedin accordance with the maintenance manual
chapter specified
Instruction
Chapter 53
PeriodicInspections- requiredat 50, 100, 600 and 1200
hour intervals.
Special Inspections- requiredbyunusual events,such as
hard landingor suddenstoppage of rotor.
Mandatory RetirementSchedule - listof parts which are
limitedto a definite maximumservice life.
Daily inspecion
The dailyinspectionisarigidvisual inspectiontoascertainif
the helicopterisairworthyandif anyitemhasbecome loose,
worn,or damagedduringflightthe previousdayorsince the
accomplishmentof anypreviousinspection.Performdaily
inspectionpriortothe firstflightof the day.

2. 50 hours
-rigidvisual inspection
1. Inspectinstrumentsforbroken,crackedorloose cover
glass,and conditionof range andlimitmarkings.
2. Inspectbatteryfor evidenceof spilledelectrolyte,security
of mountingandgeneral conditionCheckbattery.draintube
for unobstructeddrainage.
3. Inspectgeneral conditionof all wiring,insulatedtubing
and clips.Testoperationof all switchesandcircuitbreakers.
Checknavigationandlandinglightsandrotatingbeaconsfor
operationandsecurityof mounting.
4. Inspectgeneratorandstarter forsecurity.
5. Drain static andpitottubesat drainplugif water,in
system,issuspected.
20 nov-2015 rev 1

3. SCHEDULED INSPECTIONS BTH- BTH-47-CR&O
1200 hours inspections
Data:03/11/2015 Initial
Reference:BTH-47G3 mech other
Inspection task desription
Date:03/11/2015
Facility:
HelicopterS/n
Total time:
Ganeral
each listedinspectionitemor maintenance fuctionis to be performed
in accordance with the maintenance manual chapter specified
Instrucion
Chapter44
100 hours
Flightcontrol
1.Disconnectcontrol rodfrom control ringhorns andcleanhorns with
suitable cleaning solvent.Inspecthornswith10 powermagnifyingglass
to determine if acrack or cracks exist.If cracks are found,remove
swashplate andreplace immediately.
2. Inspecttaperbushingsandboltsinlateral jackshaftat transmission
for security.
3. CheckCSC870-5 dampersfor security,leaksandpropertiming.

4. 600 hours
Accomplishacomplete dailyinspection,50-hourinspection,100-hour
inspectionandthe inspection
1 Make thoroughvisual inspectionforcracksinall parts of cylinder
supportand bellcrankassemblies,including attachmentbrackets
2.Checkfor excessive radial playof cylindertrunnioninbushingsof
supportsandbellcranks.
3.Test systemoperatingpressure,adjustrelief valveasnecessary
ROTATINGAND FLIGHT CONTROLTUBES
1.Remove followingcontrol tubes
1200 hours
Note
The followingcontrol tubesare installedwithina30 degree angle of the
vertical axisof the helicopter.
b.Remove collectivepitchcontrol tube betweenpowercylinderand
idler.
c. Remove lateral cycliccontrol tube betweenpowercylinderand
torque tube assembly.Remove control tube betweentorque tube
assemblyandswashplate.
d. Remove fore andaftcyclic control tube betweenpowercylinderand
lever.Remove control tube between leverandswashplate.
2. Remove endfittingfromcontrol tubesasfollows:
a. Mark fittings andtube endstoensure fittingisassembledinoriginal
position.
b. Remove bothendfittingsbycarefullydrillingoff rivetheadsanddrive
out rivets.Donot enlarge rivetholes intube orfitting.
3. Inspecteach control tube forinternal corrosionusingalightand
borescope orequivalentinspectionmeans

5. Note
Control tubeswithdouble drilledrivetholes,sharpnicks,scratchesor
internal corrosionare consideredunserviceable.
4. Cleanand refinishacceptable control tubesasfollows:
a. Remove all paintandprimerfrominternal surface of control tubes,
usingsteel wire brushonsteel control tubesandbristle brushon
aluminumcontrol tubes,withMethyl-Ethyl-Ketone.
Note
a.Internal surface mustbe completelycleantoensure adhesionof
protective film.
b. Addthree partsof thinner(TolueneTT-T-548) to fourparts of zinc
chromate primer,byvolume,andmix thoroughly.
c. Applyprimertoinside of control tubes,coatentire internal surface
while rotatingcontrol tube.Allow excessprimertodrain.Wipe excess
fromfittingarea,leavingalightcoat.Allow six hoursminimumdrying
time priorto furtherfinishing.
Mixaluminumpaintasfollows:
The followingwill provide approximatelyone gallon.If asmall quantity
isrequired,reduce all quantitiesproportionally.
a. Dissolve sixteenouncesof aluminumpigment(TT-P-320A) paste
(Type 11 ClassA)orpowder(Type IClassA)ina small amountof thinner
(TT-T-266).
b. Addaluminumpigmenttoone gallonof clearcellulose nitratelacquer
(TT-L-32).
c. Addequal volume of thinnertolacquerandmix thoroughly.Strain
througha paint strainer.
6. Applyaluminumlacquertoinside of control tube,coatentire internal
surface while rotatingcontrol tube,Allow excesslacquertodrain.Wipe
excessfromfittingarea,leavingalightcoat.Allow 2 hoursbefore
installingendfittings.

6. Note
Rod ends,fittings,andcevisesmustbe platedortreated;andmust
notexhibitanycorrosion.Replace partsthathave inadequate finish.
7. Hollowendsmayrequire refilling.If adhesive fillerisdamagedwhen
the rivetswere drivenout,remove oldfillerandfill withhardepoxy
adhesive Metal SetA4or equivalent.Allow adhesivetocure 24 hours
before drillingholes
Note
Outside surface of control tube assemblymaybe primedpriorto
applyingsealant.Sealantwilladhere tochemicallytreatedmetal orfully
curedzinc chromate surface.
8. Applyproseal 890-B2 to I.D.of control tubesandO.D. of endfittings,
at fayingsurfaces,before assemblyInstall endfittings incontrol tube.
9. Dip MS20613-5P rivetsinproseal andinstall.MS20613-6P rivets
(oversize) maybe used.Replace anysteel
control tube that requiresrivetslargerthanMS20613-6P rivets.
a. On aluminumrotatingcontrol tubes,use MS20470-AD5 rivets. Use of
oversize rivetsisnotapprovedonaluminumrotatingcontrol tube
assemblies.
10. Seal eachendof control tube assemblyandaroundrivetswith
proseal 890-B2 sealant.Applysealantasshownonfigure 1-20control
tube sealing(typical).Cure sealant atroomtemperature for72 hours.
Note
Control tubesmaybe reinstalledwhensealantisnottacky
(approximately24hours).Do notuse heat to cure sealant.
11. Reinstall all control tubesandcheckrigging.Tightenjam-nutsand
install all cotterpins.

7. 20 nov-2015 rev