Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 1

Alert Service Bulletin Appendix 2: 

M601 Reduction Gearbox and Supporting 

Cone Inspection procedure
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 2

1. Before disassembly 

Measure the engine vibration on the wing, Power Turbine and GGT section in 

accordance with appropriate engine model Maintenance Manual, chp. 72.01.01 2. 

2. Disassembly 

2.1. Disassemble the bonnet and propeller from the engine

2.2. Close the bleed valve and seal the intake screen to the engine and exhaust 

bends (on aircrafts with short exhausts) or disassemble the exhaust bends at 

the flanges (aircrafts with long exhausts). 

2.3. Release from the engine (from the accessory gearbox and reduction gearbox) 

oil to prepared container. To do so, disassemble from the engine the 

electromagnetic signaler of chips (can be left suspended on a cable) and to its 

place, install the preparation for release of oil from the reduction gearbox–

903.7. On the accessory gearbox, remove the magnetic plug -572.9 and 

assemble preparation -9020.7. After release of oil from accessory gearbox, put 

back the magnetic plug and secure it. 

Close the bleed valve.

Seal both exhausts bends. 

motoru

Seal the intake 

screen.

Release oil from the 

reduction gearbox using the 

-903.7 equipment.

Release oil from the 

accessory gearbox using 

-9020.7 equipment. After 

release, take out the 

preparation and reinstall 

here and secure with 

magnetic plug.

Flange for 

electromagnetic 

signaller of chips

Check tightness of the flange 

for magnetic plug before 

securing.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 3

2.4. Disassemble the extinguishing installation around the reduction gearbox 

including the holders (if assembled). Cover all pipes and openings. 

2.5. Disconnect the operating rod of the propeller governor from the propeller 

governor and disconnect it from the reduction gearbox flange including the 

holder (according to the version).

Disassemble the installation 

including the holder from the 

fire detector.

Disassemble the 

installation from the 

front bulkhead and the 

extinguishing pipe. 

Disassemble the installation from 

the flange of the reduction 

gearbox including the holders on 

both sides. 2x2 pieces of M6 nuts.

2. After disconnecting the 

rod from the governor, 

disassemble it together

with holder from the 

reduction gearbox flange. 

2 pieces of M6 nuts.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 4

2.6. Disassemble the pipe of the feathering pump (if assembled together with EHO, 

on the engine versions M601D the pipe is connected on the front bulkhead). 

Cover the pipe and openings.

Disconnect the 

electrical 

installation 

cable from the 

pipe.

Unlock and 

loosen cap nuts.

Disassemble the cap 

on the front bulkhead

Rear bulkhead

Front 

bulkhead
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 5

2.7. Disassemble the control device of the propeller governor. 

1.7.1 Unlock and loosen nut -7142.4, fixing the eye-bending shafts of kinetic 

link -703.9 to the double-lever, remove the eye from the double-lever pin (pin 

on the shorter arm of the double-lever). 

1.7.2 Disconnect the control pipe from the holder on the exhaust set. Loosen 

both nuts on the outlet flange and disconnect the control case M601-731.4 

from the flange. 

1.7.1

.

1.7.2

.

Pertinax 

insulation. Liner

Holder of the 

control bushing

Exhaust housing

holder is between 

the screw head 

and insulation.

Individual eyes of the rods 

with spherical bearings 

secure with wire to prevent 

their falling out and getting 

lost.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 6

2.8. Disassemble the pipe to EHA -864.9 (if assembled together with EHA) from the 

screwing of the propeller governor and electrohydraulic actuator and slide 

electrical installation cable with the propeller heating collector under it (if 

heating is assembled, otherwise do not unlock or loosen). Put the pipe back but 

do not secure it.

2.9. Disassemble all the electric installation from the reduction gearbox (i.e. from 

the propeller governor, electromagnetic chip signaler, electrohydraulic 

actuator (if assembled) speed transmitter, fire detector (if assembled) and ELM 

cable (if assembled) including holders to the cable installation. On electrical 

installation, disassembled electromagnetic chip signaler, collector for propeller 

heating (if assembled) and fire detector (if assembled) can be left. 

Unlock and loosen 

the hollow screw.

Unlock and loosen the 

cap nut on the 

propeller governor.

From the pipe -864.9 

disassemble the electrical 

installation cables. Leave 

holders where they are.

Note: Prior to the disassembly of the electric installation holder and 

the fire detector cable from the main flange of the reduction gearbox, 

mark the screws which the holders were assembled to. Thus, the 

subsequent assembly will be easier.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 7

2.10. Disassemble the front holder -848.6 of the electric installation on the top 

connection of the exhaust housing fixed with 3 screws. 

 

2.11. Disassemble the air sealing pipe -828.7 from the flange on the exhaust 

housing, the air sealing pipe of the PT labyrinth -861.9 from the bulkhead and 

from the air intake pipe -1408.7. Cover the pipes. 

Disassemble the front holder -848.6 

(electric installation). Disassemble three 

screws with self-locking nuts.

Disassemble the air 

sealing pipe -828.7 

from the flange on 

the exhaust housing

(2 screws with lock 

washers), from the 

bulkhead

(disassemble covers), 

from the air intake 

pipe and from the PT 

labyrinth air sealing

pipe (cap nut).
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 8

2.12. Remove the air sealing pipe -880.9 and its sealing from the exhaust housing 

flange. 

Remove the air 

sealing pipe -880.9 

including sealing 

from the exhaust 

housing flange.

Sealing

If the pipe cannot be removed using hands, an extreme 

solution is holding the flange over a cloth in pliers and 

carefully removing it. Under no circumstances the pipe 

can be levered under the flange.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 9

2.13. Disassemble the pressure oil pipe to GT 839.6 from the pressure oil pipe -826.6 

and pressure oil bushing -827.9. Cover screwing and the pipe. 

2.14. Disassemble the pressure oil pipe -826.6, cover the openings.

2.15. Disassemble the scavenge pipe from the reduction gearbox -827.6, cover the 

openings.

The pressure oil pipe -826.6 The scavenge pipe -827.6

Pull the pipes -826.6 

and -827.6 from the 

accessory gearbox.

Cover the openings.

Disassemble the holders 

from the divinding plane 

of the engine.

Disassemble the 

covers from the front 

bulkhead, dispose of 

the sealing and leave 

the rubber washer for 

subsequent 

disassembly.

1.13 

Disassemble 

the pressure 

oil pipe to 

GT -839.6.

For easier 

disassembly of 

the pipes squirt 

with lubricant.

Unlock the lock washers, 

loosen and disassemble the 

nuts on both pipes 4 pieces.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 10

2.16. Disassemble the pressure oil bushing by loosening cap nut -3006.9 from the oil 

intake pipe 343.9. Push the cap nut -3006.9 along the pipe -343.9 to the 

exhaust housing. 

2.17. Disconnect the torquemeter pipe -840.6 from the pipe -841.6. Remove the 

covers, the sealing and the rubber insert from the front bulkhead. The pipe 

could be left connected to the reduction gearbox and exhaust housing, but to 

make the following halving of the engine easier, it is recommended to 

disassemble the pipe. Cover the openings. 

Hold the bushing with 

wrench against the 

cap nut -3006.9 and 

loosen it.

The pipe can be left 

assembled to the reduction 

gearbox and exhaust 

housing.

Disassemble covers, 

rubber insert and 

sealing from the 

bulkhead.

After disassembly of 

the bushing, push the 

cap nut into the 

exhaust housing.

After disassembly, check 

that the sealing ring 

remained on the bushing, 

or take it out from the 

pipe -343.9 to prevent its 

falling in the engine.

Pipe -841.6

Disconnect the pipe -840.6 

from the pipe -841.6.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 11

2.18. If you decide to disassemble the pipe, unlock, loosen and screw out the screw 

of the holder on the exhaust case. Then unlock and screw out two screws 

connecting the pipe to the reduction gearbox flange. Then disassemble the 

pipe. Seal the pipes and openings. 

2.19. After disconnecting the torquemeter pipe from pipe -841.6 and sealing them, 

attach cover to the pipe -841.6 to prevent forgetting it during assembly. 

Disassemble the pipe 

from the engine, seal 

reduction gearbox and 

pipes -841.6 and -840.6.

Pipe -841.6

Fix the cover to pipe -841.6 to 

prevent forgetting it later.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 12

2.20. Disassemble the scavenge oil bushing -8030.9 by loosening the cap nut on the 

oil drain pipe -862.8 and the cap nut -3007.9 on the scavenge oil pipe -304.7. 

Push the cap nut -3007.9 into the exhaust housing.

2.21. Disassemble the screw of the drain pipe LN 6169 with sealing rings 10x14 CSN 

02 9310 connecting the drain pipe -806.7 to the flange on the exhaust 

housing.

Disassemble the screw of 

the drain pipe.

Cover the pipe after the 

screw removal.

Disassemble the drain oil bushing.

After bushing disassembly, 

cover the oil drain pipe and 

push the cap nut into the 

exhaust housing
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 13

2.22. Disassemble the thermocouple transmitters cables. Then disassemble the 

thermocouple set bus from the flange. Move the bus away from the engine 

similarly as in 1.9. 

2.23. Disassemble individual thermocouple transmitters. Mark the thermocouples or 

write down their correct location for assembly (M601E, M601F, M601T, GE Hseries). Verify the function of thermocouple transmitters using multimeter. 

Move the cables away from the 

engine in front of the front bulkhead.

Cover the flanges after thermocouples 

with adhesive plaster.

Carefully take the 

thermocouples out of the 

engine.

Disassemble 

cables from 

thermocouples.

Mark the 

thermocouples 

for the 

reassembly. Then 

store them safely 

away from the 

engine.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 14

2.24. Disassemble and remove screws and nuts connecting the flange of the 

exhaust housing with the flange of the centrifugal compressor housing that 

have various holders under nuts (all long screws). Leave the other screws. 

2.25. Remove self-locking nut with washer on the centring screw of the reduction 

gearbox and fourth screw with nut in the longitudinal parting flange of the 

exhaust system and insert the “reduction gearbox holder” (first part of 

preparation). 

Disassemble and take out 

screws and nuts from the 

exhaust housing flange and 

centrifugal compressor 

housing that have various 

holders under nuts (i.e. all 

long screws).

First part of engine 

halving 

preparation, 

“reduction gearbox

holder” fix under 

the self-locking nut 

and its washer on 

the centring screw 

and under fourth 

screw of the 

longitudinal 

parting flange.

“Reduction gearbox holder” (first part of 

preparation for engine halving.

Leave short screws 

with nuts.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 15

2.26. Remove the centring screw with nut and then three screws with nuts from 

longitudinal parting flange counted from the centrifugal compressor flange (on 

top and bottom part at cross dividing plane) and assemble part of the exhaust 

system holder with centring needles (the other part of the engine halving 

preparation). According to the picture.

Slide centering needle of 

the other part of the 

preparation to the 

opening in cross parting 

flange and then assemble 

the preparation to the 

longitudinal parting 

flange.

Assemble the other part of the 

engine halving preparation 

using two technological screws 

and nuts that are part of it. 

Tighten the screws and nuts.

Between the preparation 

and flange, insert spacer 

that is part of the 

preparation

In the bottom, fix the 

preparation with 

centring needle the 

same as the top part. 

Do not tighten the 

screws and nuts here.

Top part

Bottom part
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 16

2.27. From the assembled mount, take one by one pins and replace them with 

technological pins that are part of the preparation. Before disassembly, cover 

the air inlet screen to the compressor (if haven’t done at the beginning of the 

disassembly) to prevent foreign objects falling in 

the compressor. 

Unlock cotter pin, 

disassemble and 

replace pins of the 

engine mount with 

technological pins 

of the preparation.

Third part of 

the preparation.

Easily tighten 

technological pins of the 

preparation so that the 

pin could be still moved.

Final look of the assembled 

third part of the preparation.

At other types of engine mount, assemble flanges 

that are part of the preparation and fix the third part 

of the engine halving preparation to them.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 17

2.28. Assemble to the engine the supporting part of the engine halving preparation, 

and place it on the top hinge of the engine and to achieve the right 

preparation position, insert centring ring on it. Then insert big spacer on the 

supporting part.

Big spacer

Centring ring

Supporting part of 

the preparation

Insert centring ring over the 

cutout to the opening on the 

preparation and turn it so 

that it locks on the 

preparation.

Insert regulation washer 

to the preparation.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 18

2.29. On the assembled supporting part of the preparation, assemble the bearing 

part. Then insert pin with spacer and secure with cotter pin.

After assembling the 

bearing part, insert pin 

with small spacer so that 

the openings for cotter 

pin were aligned.

Bearing part of the 

engine halving 

preparation

Secure the 

bearing part of 

the preparation 

with cotter pin.

Slide the bearing 

part of the 

preparation to the 

supporting one.

Pin

Small spacer
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 19

2.30. Connect the third part of the preparation with the assembled bearing and 

supporting parts using screw with washer. After tightening the screw, set the 

bearing part of the preparation so that the bottom part of the preparation is 

vertically away from the place on the reductiojn gearbox as in the picture 345 

mm. Execute petting with two adjusting screws on the third part of engine 

halving preparation. 

Connect the third part of the 

preparation with assembler 

supporting and bearing part 

using screw with washer.

345mm

.

Using adjusting 

screws, set the 

bearing part so 

that the bottom 

part is 345 mm 

away from the 

marked place on 

the reduction

gearbox.

Place for 

measuring 

vertical 

distance to the 

preparation.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 20

2.31. From the case of the halving preparation, take out the other part, “slider” and 

assemble it to operational state. Then slide it on the bearing part of the 

preparation and fix it to the first and second part of the preparation. Then set it 

so both holders are perpendicular to the longitudinal axis of the engine. 

“Rider” part of the preparation.

Assemble the “slider” to 

operational state and 

slide it on the bearing 

part of the engine 

halving preparation.

Set the preparation so 

that both holders are 

perpendicular to the 

longitudinal axis of the 

engine.

Fix the “slider” to the reduction gearbox holder 

and to the other part with centring needle of the 

engine halving preparation, connect to the 

reduction gearbox holder by second or third eye.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 21

2.32. After assembling the preparation pre-tighten the system using screw No. 1 by 

15 mm (which means 330 mm) and set so that the back holder is free without 

extra tension. This holder is meant to catch the back part of the exhaust 

system all the way to putting out the whole exhaust system outside centring 

needles.

Place on the reduction gearbox

from which the distance of the pretightening is measured.

Back holder set 

so it is free 

without extra 

tension. This 

holder is meant

to catch the 

back part of the 

exhaust system

all the way to 

putting out the 

whole system.

Pre-tighten the system using 

screw No. 1 so that the bottom 

part of the bearing is 330 mm 

away from the place marked on 

the reduction gearbox.

Screw No. 2 Screw No. 1

Pre-tighten 

by 15 mm to 

330 mm.

330mm

In the front part, secure the 

preparation with stopper 

(screw) to prevent falling of 

the „slider“.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 22

2.33. Screw out the nuts on the remaining screws of the exhaust housing flange and 

centrifugal compressor housing flange by approx. 4 mm. To the openings, 

insert crosswise 6 leading needles. Check that there is no thermocouple or air 

sealing pipe -836.6 in the exhaust housing, check that the cap nut -3006.9 and 

3007.9 are on the oil intake pipes -343.9 and oil discharge pipe -304.7 inserted 

to the internal space of the exhaust housing not preventing pulling out. 

Execute complete check 

of the engine and make sure 

that no part will prevent 

pushing away of the exhaust

system from the centrifugal

compressor housing.

Around the 

perimeter insert 

leading pins to 

openings (6 pieces).

Check whether cap 

nuts are on oil pipes 

slided to the internal 

space of the exhaust

system.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 23

2.34. Loosen the exhaust system with 4 forcing-off screws M6 at connecting screws 

in the length of the loosened nuts. Keep checking alignment of flanges and 

mobility of the PT (danger of damage of the blades of the power (free) turbine!). 

Insert 

forcing-off 

screws M6 in 

six openings.

Conduct forcing off 

very slowly and 

carefully. The flanges 

must be aligned all 

the time. During 

forcing off keep 

checking mobility of 

the PT.

Check mobility of the Power

Turbine with hand inserted in 

the exhaust nozzle. If the 

turbine gets stuck, the exhaust

system must be returned to 

the original position where 

movement still occurred and 

then keep on forcing off.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 24

2.35. After loosening the exhaust system, screw out the nuts on the remaining 

screws and keep forcing off to the end of threading of the forced-off screws 

while checking PT freeness and discharge pipe -304.7 freeness.

2.36. With slight pull at exhaust bends, remove the exhaust system on the holder 

from the generator part before the stopper and stop. Disassemble forcing-of 

screws and leading pins.

Stopper on the bearing 

part of the exhaust 

system.

Disassemble forcing-off 

screws and leading pins

from the exhaust system.

Stop the “slider” 

with the exhaust

system of the 

engine at the end 

of the holder using 

screw on the front 

holder.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 25

2.37. Catch the preparation with a crane, tighten the crane wire, remove the stopper 

on the bearing part of the engine halving preparation, release the “slider” and 

carefully remove the exhaust system from the holder. Cover the exhaust 

systém and store it in a convenient place with convenient conditions.

2.38. Check that the power (free) turbine blades bandage is not damage. 

Fix the crane by the front holder. Remove the stopper from 

the holder and release the “slider”. Then, remove the whole 

exhaust system from the holder using the crane.

After removal of the engine exhaust 

system, check whether the power 

(free) turbine blading cover is not 

damaged or whether there are no 

cuts on the turbine.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 26

2.39. Remove the cotter pin from the bearing and supporting part of the engine 

halving preparation and move away the bearing part so it does not obstruct 

further assembly. 

2.40. Check that there is no spacer on the flange of the centrifugal compressor 

housing, that is inserted between the centrifugal compressor housing and the 

exhaust housing. 

2.41. Secure the GT guide vane ring flange with the centrifugal compressor housing 

flange using four screws M5x12 CSN 02103.14 (including nuts and washers). 

Remove the spacer from the 

flange. This spacer does not 

have to be on the engine.

Fix the washer to the exhaust

system with lashing wire so it 

will not be forgotten during 

engine reassembly.

Technologically connect the 

PT guide vane ring to the 

centrifugal compressor 

housing (at least 4 screws 

crosswise).
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 27

3. Disassembly of exhaust system 

3.1. Unlock the lock washers 6,2 ONL 3288.2 on the reduction gearbox and exhaust 

system flange. Loosen and remove 34 nuts M6 ONL 3248 and M6 ČSN 02 1402.44 

and washers -4063.4. Leave only 2 nuts on the sides of the reduction gearbox near 

the levelling marks. Remove all the brackets and holders. 

Tools: unlocking pin, wrenches 

3.2. Pose the exhaust system with the reduction gearbox on the top. 

M6 ONL 3248

-4063.4

M6 ČSN 02 1402.44

6,2 ONL 3288.2
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 28

3.3. Prevent power turbine from rotating with tools 300-475-2024 and 300-557-

0038.Loosen 8 nuts -3041.5 using socket wrench 300-313-3007 and remove lock 

washers -3058.9. Keep the nuts on the plate 300-745-7007 according to their 

numbers. Remove tool300-475-2024. Remove the power turbine using tools 100-

477-1004 and 100-477-1008. 

Tools: Tools to prevent PT from rotating 300-475-2024 and 300-557-0038, socket 

wrench 300-313-3007, plate for the nuts 300-745-7007, tools for power turbine 

removal 100-477-1004 a 100-477-1008

-3041.5

-3058.9

300-557-0038/02

300-475-2024
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 29

3.4. Unlock 12 lock washers 5,2 ONL 3288 and loosen 12 screws LN 5153 connecting 

bracket -4512.5 and labyrinth seal - 4016.5. Then use 3 of these screws as 

jackscrews to disassemble bracket -4512.5 from labyrinth seal - 4016.5. 

Tools: unlocking pin, socket wrench

-3041.5

300-745-7007

-4512.5

Disassembled 

screwsLN 5153 and 

lock washers 5,2 

ONL 3288.2

Holes for 

jackscrews
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 30

3.5. Loosen the last 2 nuts on the reduction gearbox and exhaust system flange. Remove 

exhaust system -4.5 from support ring -457.7 and reduction gearbox -6.6 using tools 

100-477-1004 and 100-475-2055. 

Tools: wrenches, tools for exhaust system removal 100-477-1004 and 100-475-2005 

100-477-1004

100-475-2055

-4.5

-6.6
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 31

3.6. Remove insert -659.9 and O-ring LN 5096 from PT shaft using tool 300-475-2037. 

Tools: tool for insert removal 300-475-2037

-659.9

LN 5096

300-475-2037
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 32

3.7. Remove bolt -6107.9 connecting PT shaft -4004.7 and quilt shaft -6172.5. Use tool 

300-475-2022 to prevent PT shaft from rotating. Then remove lock retaining ring -

6100.9 and ring -6014.9. 

Tools: special wrench 300-313-9009,tool for PT shaft holding 300-475-2022

300-475-2022 300-313-9009

-6170.9

-6100.9

-6014.9
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 33

3.8. Remove support cone with PT shaft -403.7 from countershaft casing -62.2 using 3 

jackscrews 300-475-2011. Force-off support cone carefully, equally around 

perimeter. When all the tubes are loose, remove the support cone. Pay attention to 

quilt shaft -6172.5. It may get stuck in the PT shaft and then fall down. Remove 

bearing ring with rollers from quilt shaft -6172.5. 

Tools: jackscrews 300-475-2011 

-6172.5

Bearing ring with 

rollers
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 34

4. Inspection 

4.1. Inspection of Quill shaft M601-6172.5, M601-6172.6 

4.1.1. The Maximum spline wear is 0,12mm based on the actual measurements. 

4.1.2. Tools: 

- Micrometer (resolution: Thousandth-meter) 

- 2 calibrated rollers of 3,2 mm diameter with length to fit the spline which 

will represents the maximum allowable spline wear 

4.1.3. Measurement: 

4.1.3.1. Prior to measurement sufficiently clean the quill shaft 

Note: Inspection area may be cleaned using a copper brush. 

4.1.3.2. Perform measurement for minimum of 4 diameters, Fig 4.1. 

Fig. 4.1 – quill shaft scheme with rollers 

4.1.4. Requirement: 

If one of the measured value is smaller than 28,6 mm the wear is more than 

the maximum allowed.

7 mm

Two identical rollers

>28.6 mm
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 35

4.2. Inspection of Power turbine shaft M601-4004.7 

4.2.1. Maximum spline wear is 0,12mm based on the actual measurements. 

4.2.2. Tools: 

- Bar calibrated to a size of 19,175 mm diameter to fit between the rollers 

- Two calibrated rollers of 2,8mm diameter which represents the maximum

allowed spline wear 

4.2.3. Measurement: 

4.2.3.1. Prior to measurement sufficiently clean the power turbine shaft 

Note: Inspection area may be cleaned using a copper brush. 

4.2.3.2. Perform measurements for a minimum of 4 diameters, Fig 4.2 

Fig. 4.2 – power turbine shaft scheme with rollers 

4.2.4. Requirement: 

If the calibrated bar with the rollers is possible to insert freely– the spline wear 

is more than maximum allowed.

Min. 7 mm

Two identical rollers

Calibrated to

19,175 mm
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 36

4.3. Inspection of Support cone M601-457.7 

4.3.1. Tools 

- Magnifying glass 10x 

- Suitable light 

- Fluorescent-Penetrant inspection (FPI) kit 

4.3.2. Measurement: 

4.3.2.1. Prior to measurement sufficiently clean the supporting cone 

4.3.2.2. Perform visual inspection using 10x lens on flange Ø67 mm. see fig 4.2., 

if no crack is visible, perform inspection using FPI kit on same area 

4.3.3. Requirement: 

Cracks are not allowable. If cracks are found, the part will be scrapped. 

Fig. 4.3 – supporting cone scheme with inspection area of flange Ø67 mm

Inspection area
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 37

5. Assembly of the exhaust system 

5.1. Put ring of the roller bearing on the quilt shaft -6172.5. For easier assembly it is 

possible to “stick“ rollers to the quilt shaft with Vaseline. Put the quilt shaft -6172.5 

into the countershaft casing -62.2. Marked teeth of the quilt shaft must fit to the 

marked teeth on countershaft gears. 

Tools: none 

-6172.5
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 38

-6172.5
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 39

-63.6

-62.2

-6172.5
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 40

5.2. Degrease contact surface of the support cone with PT shaft, complete -403.7 and 

contact surface of countershaft casing -62.2. Then apply Alhyl on those surfaces. 

Apply Vaseline on all the tubes and O-rings. 

Tools: Vaseline, Alhyl 

Degrease + apply 

Alhyl

vaseline

Degrease + apply 

Alhyl
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 41

5.3. Put support cone with PT shaft complete -403.7, on the reduction gearbox -6.6. Mark 

on PT shaft -4004.7 must fit between marked teeth of quilt shaft -6172.5. 

Marks on the PT 

shaft

Marks on the 

quilt shaft

-6172.5

-457.7

-4004.7

-6.6
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 42

5.4. Put ring -6014.9, retaining ring -6100.9 and bolt -6170.9 into the PT shaft. Teeth on 

the lower side of the retaining ring must be rotated with 90° to the cut on the quilt 

shaft. Apply Molycote on the bolt -6170.9. 

Tools: Molycote 

-6172.5

Cut on the 

quilt shaft

-6170.9

-6100.9

-6014.9
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 43

5.5. Put tool 300-475-2022 to bolt -6170.9. Cuts on the end of the tool must be rotated 

with 90° to the cuts on retaining ring -6100.9. Tighten the bolt. First tighten the bolt 

unless all the parts are moving. Then slightly release, rotate with the rotating part of 

the tool, meanwhile tighten and release until it is obvious that the teeth are in the 

cuts. Hold the PT shaft with the tool to prevent its rotation. Tightening torque is 25±2

Nm. Because it is not possible to see if the teeth are in the cuts, make sure, that these 

parts were assembled properly. In other case repeat this section. 

Tools: tool 300-475-2022, torque wrench 

-6170.9 -6100.9 Rotational part 300-475-2022

300-475-2022
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 44

5.6. Lock retaining ring -6100.9 with tool 300-476-0018. 

Tools: tool 300-476-0018/01, hammer 

D

D view

300-476-0018/01
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 45

5.7. Put O-ring LN 5096 on insert -659.9. Put insert -659.9 into PT shaft -4004.7. Apply 

Vaseline on the O-ring. Side with the O-ring goes first. Hit the insert with tool Z3-

01197-00 and hammer. Clean the contact surface of PT shaft. 

Tools: hammer, Vaseline, tool Z3-01197-00 

-659.9

LN 5096

Z3-01197-00
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 46

5.8. Check clearance V6/104 (0,25÷1,2) mm. Calculate it from the distance of the PT 

shaft contact surface and the surface of the insert. If the clearance is bigger, change 

the insert to meet proper values. 

Tools: depth gauge 

5.9. Put exhaust system -4.5 on support cone -457.7 and reduction gearbox -6.6. Place 

the exhaust system with the sign “xxx” to the levelling mark. Apply Konkor 101 on 

bolts -4053.4, -4065.4 and -4066.4. Tighten at least 4 nuts on the reduction gearbox 

-6.6 and exhaust system -4.5 flange. 

Nástroje: Konkor 101, stranový klíč
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 47

5.1. Clean and degrease all contact surfaces of PT disc with blades. Cool PT disc to -18°C 

for 30 min. Clean and degrease all contact surfaces of bracket -4512.5. 

5.2. Put bracket -4512.5 on labyrinth seal - 4016.5. Make sure that sign “xxx” is on the top 

of the engine. Apply Molycote into 12 holes of bracket -4512.5 and also on threads 

on 12 screws LN 5153. Assemble screws LN 5153 and lock washers 5,2 ONL 3288.2. 

Tightening torque is (4÷5) Nm. Then lock washers 5,2 ONL 3288.2. 

Tools: torque wrench, Molycote, locking pliers 300-312-2006

-4.5

-6.6

levelling mark

center screw
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 48

12x apply Molycote

5,2 ONL 3288.2

LN 5153

Sign of the top „xxx“

-4512.5
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 49

5.3. Warm up the center and the flange of PT shaft to the 80°C temperature using 

warming tool or warming pistol. Apply Molycote on the line between two diameters 

on the PT disc. Traces of Molycote are not allowed on contact surface. Press power 

turbine into the PT shaft using tool Z3-01197-00 and a hammer. The sign “xxx” must 

be on the top. 

Tools: Molycote, hammer, tool for turbine pressing,warming tool 

Warming tool

Z3-01197-00
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 50

5.4. Put nuts -3041.5 and lock washers -3058.9 on screws -3363.5. Firstly put the nut nr. 1 

which is placed on the top (sign “xxx”). Other nuts put counter-clockwise. Before 

assembly apply Molycote on threads and contact surfaces of the nuts. Tighten 

crosswise. Tightening torque is 8 Nm. Then let settle down temperature difference. 

Tools: Molycote ,torque wrench, plate for the nuts 300-745-7007 

-3058.9

-3041.5

300-745-7007

-3041.5

-3058.9
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 51

5.5. Install tool for measurement of elongation of the screws. Prevent the turbine against 

rotating using fixing tool. Put the tip of the indicator on the end of the screw and 

chceck elongation values. Tighten the nuts twice to the 0,105 ÷ 0,110 elongation of 

the screws. Check if the screws shrink back. Final elongation must be 0,075 ÷ 0,080. 

Tighten crosswise. Tightening torque must be within

(5 ÷ 15) Nm. 

Tools: tool 300-557-0038/02, screwdriver,socket wrench 300-313-7030,tool for 

turbine stabilizing 300-475-2024

300-557-0038/02

300-475-2024
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 52

 

5.6. After tightening the screws lock the washers with locking pliers. Then clean and 

degrease all the surfaces 

Tools: locking pliers 300-312-5005

300-557-0038/02

300-313-7030

300-312-5005
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 53

5.7. Attach all the brackets and holders you removed during the exhaust system 

disassembly.on the flange of the reduction gearbox and exhaust system. Tighten all 

the nuts M6 ONL 3248 with washers -4063.4 and nuts M6 ČSN 02 1402.44 with lock 

washers 6,2 ONL 3288.2. Tightening torque is 4+2 Nm. Then lock the washers. 

Tools: wrench, locking pliers 300-312-2006,torque wrench 

M6 ONL 3248

-4063.4

M6 ČSN 02 1402.44

6,2 ONL 3288.2
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 54

6. Assembly 

6.1. Bind lashing wire to cap nuts of the oil pressure pipes -342.9 and oil drain 

pipes -304.6, i.e. cap nuts -3006.9 and -3007.9 for following pulling the nuts 

from the exhaust housing so that it has at least 250 mm. At M601D also bind 

the lashing wire to the bushing from the thermocouples. 

6.2. Disassemble the sealing from the lateral flange and one exhaust nozzle. Clean 

the contact surfaces of the flanges from the exhaust system of the engine. 

Check placing of the piston ring (position of the lock is arbitrary) by pulling a 

piece of paper under the piston ring. The paper will show the clearance 

between the ring and its flange. Cut overlapping paper with a razorblade. 

Bind lashing wire to 

the cap nuts (or 

thermocouple 

bushing). Due to the 

wire, you will be able

to pull the nuts 

through the exhaust 

housing, after 

connecting the 

exhaust system to

the generator.

Correct placing of the piston ring is achieved 

by inserting the piece of paper under the 

piston ring. Subsequently cut the paper.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 55

6.3. Attach the front holder of the engine halving preparation connected to the 

exhaust systém to the crane and slide it carefully on the bearing part of the 

engine halving preparation fixed on the aircraft. After that, stop the “slider” and 

insert a stopper to the end of the bearing part of the preparation before 

loosening the crane. Then remove the crane hook. 

Stop the “slider” 

with the exhaust

system on the 

holder using screw.

Insert stopper on 

the bearing part 

of the exhaust

system.

Fix the crane 

using the front 

holder.

After mounting the 

exhaust system of the 

engine to the bearing part 

of the engine halving 

preparation, disconnect 

the crane and prepare 

leading needles (6 pieces 

around the perimeter).

Stopper
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 56

6.4. Disassemble technological screws from the GT guide vane ring flange and 

centrifugal compressor case flange and release the “rider” and move the 

outtake system so that it is possible to pull through lashing wires connected to 

cap nuts -3006.9 and -3007.9 through the exhaust case coat in the 

appropriate places (at M601D, pull the wire through from the thermocouple 

bushing). Then slide the outtake system to the position where the centring 

needles touch the front of the PT guide vane ring flange. In this position, check 

and adjust, if necessary, evenness of flanges, insert around the perimeter in 

the openings other six leading needles, then mount centring needles in the 

relevant openings in flanges of the PT guide vane ring and the centrifugal 

compressor case. Slide the outtake system even further so that the space 

between the flanges is 20 mm in maximum, in this position, check again 

alignment of flanges, if necessary, set with screw No. 1 on the preparation. 

Screw No. 2 must be free, during approximation keep checking with your hand 

the mobility of the power (free) turbine. After securing the correct position, 

lightly move the outtake system to the PT guide vane ring flange and secure it 

with at least 6 screws with applied Molyka. Cap nuts of oil pipes -3006.9 and -

3007.9 pull through the coat of the exhaust case. CAREFUL: do not forget to 

insert the washer between the exhaust case and flange of the PT guide vane 

ring if it was part of the engine. Check evenness even from the side (not only 

height-se), if necessary, press the coat of the outtake system to the relevant 

side. 

If washer was part of the engine, 

it must be reassembled. Check mobility of the 

PT turbine with your 

hand inserted in the 

exhaust. If the turbine 

gets stuck, the system 

must be returned to 

the position where it 

moved, and then 

continue in bearing 

on, or adjust the 

position.

Pull the cap nuts wires through 

the relevant openings.

Conduct bearing on 

very slowly and 

carefully. The flanges 

must be completely 

even all the time. Keep 

checking the mobility 

of the PT turbine.

Make sure 

the nut 

does not 

prevent 

sliding.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 57

6.5. Add number of other screws to the flange (in particular short ones, do not 

forget to rub them in Molyka) and disassemble the engine halving preparation 

from the engine. This includes the “rider”, the bearing and supporting part of 

the preparation and also the reduction gearbox holder, the other part with 

centering needles and the third part (while disassembling the third part, 

replace the pins of the preparation with pins of the engine bed progressively, 

the engine bed needles with crown secure with cotter pin.) Add screws and 

nuts to the longitudinal parting flange of the exhaust case at the openings 

from disassembled parts of the preparation. 

Disassemble all parts of the 

enging halving preparation and 

store them in the case.

Disassemble the second 

part of the preparation 

with centring needles 

from the top and bottom 

part.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 58

6.6. Connect the flanges of the centrifugal compressor case and the outtake 

system using 41 screws -3007.7, 19 screws -8019.7 (rub them in Molyka) and 

60 self-locking nuts -3009.4 (numbers of long and short screws may differ, long 

screws are where a holder is connected under the nut). In the 10th opening 

(counted from the top connection of the outtake system clockwise, “in the 

direction of the flight”) insert screw -8019.7 and under the screw Ø 5.3 also 

holder -8015.6 (slightly turned to the top of the engine). Insert holders of the 

front partition under the nut of 5th, 15th and 25th screw, also insert and use 

screws -8019.7. At positions 11 and 12, insert the holder of the fire detector 

under the nuts (if assembled). 

To openings 2, 8, 14, 20 and 26 (right half of the engine), also insert screws -

8019.7, connect the holders of the thermocouple collector under the nuts on 

these screws. 

To openings 3, 4, 6, 7, 8, 16, and 26 (counted from the bottom connection of 

the outtake system clockwise) insert -8019.7. Under the nuts of screws 3 and 

4, insert the top part of the holder -839.8, at screw 6 and 7, insert the top part 

of the holder -840.8 under the nut. Under the nut of screw 5, 15 and 25, insert 

the holders of the front firewall -8044.6. Under nuts 9, 16 and 26, connect the 

thermocouple collectors. On position 25 and 26, insert the holder of fire 

detector (if assembled). 

Tighten the nuts crosswise to 6 Nm. 

Screws with nuts under 

which the thermocouple 

collectors are connected.

Screws with nuts under 

which the holders of 

the front firewall are 

connected.

Screws with nuts under 

which the fire detector 

holder are connected.

Screws with nuts under 

which the top parts of 

the holders -839.8 and 

-840.8 are connected –

assemble by oil pipes.

Screw with nut under 

which the holder -

8015.6 is connected.

L P

2.

8.

.

14.

20.

26.

9.

.

16.

26.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 59

6.7. Measure individual thermocouples and check their state. (no clearance, nut 

must be tightened). 

6.8. To nine flanges on the exhaust case progressively insert 9 thermocouple 

transmitters (does not apply to M601D). Each thermocouple must go to the 

same place from which it was removed, their position is marked according to 

1.22. Before tightening check whether each transmitter sits well in the flange, 

then tighten it with 2 screws LN 5135 (rub the screw screwing in the mixture of 

molybdenum sulphide and oil), insert lock washers 5.2 ONL 3288.2 under the 

screw heads, secure the screws after tightening. After assembly, check each 

thermocouple transmitter for damage on the electrical circuit with 4.5V 

ohmmeter. Test the thermocouple transmitters with “A” pole towards the 

reduction gearbox. 

6.9. Connect to the exhaust case flange thermocouple transmitter bus. According 

to the sketch on sheet 63. Before the bus platform is fixed, according to the 

need, release its inconvenient distortion with hand so that individual wires to 

be tightened and connected to individual poles of the thermocouple 

transmitters are not under extreme pressure, distorted, crossed, slacking, etc. 

To the flanges on the exhaust 

case, insert 9 thermocouple 

transmitters. Before 

tightening, try to centre the 

thermocouple transmitters.

Thermocouple 

transmitters position 

with “A” pole facing the 

reduction gearbox. 

After tightening of the 

screws, secure the lock 

washers.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 60

6.10. Assemble cables to the thermocouple transmitters. Connect cables with read 

heads to „Ch“ pole and the ones with green heads to „A“ pole. To connect the 

green head, use the LN 5444 screw and LN 5168 self-locking nut. To connect 

the read head, use the LN 5084 screw and the LN 5167 self-locking nut. 

Position the cable heads to be almost horizontal with the exhaust case and to 

be oriented anti-clockwise (viewing from the direction of flight). The only 

exception is the connection of two thermocouple transmitters, where in one 

case, the cable heads are oriented to the front partition (at the thermocouple 

transmitter located next to the flange for intake of cooling air of the GT oil 

collector cover) and in the other thermocouple transmitter, the cables are 

oriented clockwise (the lowest thermocouple transmitter on the left side of the 

exhaust case). While connecting the wires to the thermocouple transmitter 

poles, make sure the wires are not torn, partially broken, crossed (i.e. damaged) 

and that the outlet thermocouple contacts are not damaged – bent – during 

assembly. During tightening, hold the screws, then secure them and place the 

wire eyes under the screw heads. After assembly, check insulation resistance 

of the whole thermocouple set with MEGMET 100 Vss device – the insulation 

resistance must amount to at least 5Ω. The rubber inserts of the holder can be 

put together from two parts, in certain strongly bandaged places of the 

platform, holder insert cannot be used. During assembly of the cable platform, 

maintain the distance of the cable outlets from the pipes (at least 5mm), at the 

platform, contact of braid and pipes is allowed. The screws are inserted to the 

thermocouple transmitters poles from the accessory gearbox, at the 

transmitter on the left side, they are inserted from top to bottom, and at the 

transmitter thermocouples (the bottom one on the left), they are inserted from 

the reduction gearbox. 

On the left side of the 

engine, there are two 

thermocouple transmitters 

– exceptionally positioned 

this way.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 61

6.11. At the exhaust case opening (pressure oil intake), take out the oil pipe cap nut 

using the lashing wire (or hook) through the sealing connection. Using the cap 

nut on the oil intake pipe, connect the pressure oil bushing -829.9, the bushing 

must be oriented for subsequent connection of the pressure oil pipe to GT. 

Insert sealing ring Js 4 -8056.9 to the ONL connections. Glue the ring to the 

bushing using vaseline, assemble the bushing and then remove it and check 

that the ring did not move. 

6.12. At the opening in the exhaust case (oil discharge), take out the oil pipe cap nut 

using lashing wire (or hook) through the sealing connection. Using cap nut, 

connect the pressure oil bushing -8030.9 to the oil discharge pipe. Using cap 

nut, assemble the bushing to the oil discharge pipe and secure the cap nut. 

Insert sealing ring Js 8 -8058.9 to ONL connections. 

Insert sealing rings to ONL connections. 

CAREFUL: you must be absolutely sure that the 

ring did not move and does not prevent oil flow 

or cause pipe leakage.

Connect bushing using 

cap nut.

Insert sealing rings to ONL 

connections. CAREFUL: you must be 

absolutely sure that the ring did not 

move and does not prevent oil flow or 

cause pipe leakage.

Connect the 

bushing using cap 

nut with discharge 

pipe and secure 

both.

Connect the bushing using cap nut.

Apply 

Molyka to 

the bushing 

threading.

Apply 

Molyka to 

the bushing 

threading.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 62

6.13. To the hollow screw of the drain pipe LN 6169, insert sealing ring (Cu) 10x14 

CSN 02 9310 and slide it through the discharge pipe -806.7, then mount 

another sealing ring on the screw and screw it to the flange threading on the 

bottom of the exhaust case. Secure the screw with lashing wire. Before 

assembly, apply Molyka to the hollow nut threading. 

6.14. Slide cover -8048.8 on the torqumeter pipe -840.9. Connect the torquemeter 

pipe to the pipe -841.6 using cap nut. Tighten the nut and secure with lashing 

wire. Then mount the sealing -8060.8 (2 pieces) and rubber insert -8061.8 to 

the pipe. Fix the sealing and rubber insert to the front firewall using covers -

8048.8, fix the covers to the firewall with 2 screws LN 5084, washers LN 5156 

and nuts LN 5167. 

Before assembly, place 

-8048.8 cover, -8060.8 

sealing and rubber 

insert -8061.8 on the 

pipe.

After connecting the pipe, 

tighten both covers on the 

front firewall.

Secure cap nut after 

tightening with 

lashing wire.

Insert hollow screw through 

the drain pipe and fix it to the 

exhaust case threading. On 

both sides of the pipe (on the 

screw), sealing rings (Cu) must 

be placed. After tightening, 

secure the screw with lashing 

wire.

Sealing rings (Cu) 10x14 CSN 02 9310
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 63

6.15. Check O rings LN 5161 (2ks) and LN 5162 (2ks), which are on pipes -826.6 a -

827.6, or replace if necessary. 

6.16. At the pressure oil pipe -826.6, clean the contact surfaces (on the side of the 

pipe to face the reduction gearbox) and apply a thin layer of Hylomar. Apply 

vaseline to the other end with the O ring. Then, insert the pipe to the cover -

8048.8 and put pipes through the opening in the fornt firewall and insert the 

second cover. Insert one end to the accessory gearbox and the other to 

reduction gearbox. Insert sealing -8052.8 on pipe -826.6, insert cover -8053.8, 

sealing -8052.8 and fix the covers to the partition with screws LN 5084, nuts LN 

5167 and washers LN 5165. 

6.17. To the reduction gearbox, fix a pipe with two M5 CSN 021401.44 nuts, insert 

lock washers 5.2 LMN 3290 under the nuts. 

6.18. Insert a washer on pipe -826.6 and fix the pipe to the flange of the exhaust 

case and centrifugal compressor case. Fix the bottom part of the holder -840.8 

to the pipe and both parts of the holder with inserted rubber washer connect 

with 2 screws LN 5178 and self-locking nuts LN 5168. 

6.19. Assemble the pressure oil pipe to GT -839.6 using cap nuts to the pipe -826.6 

and pressure oil bushings -827.9 and secure with lashing wire. On both ends, 

insert sealing rings Js 4 -8056.9 to ONL connections. 

6.20. To the pipe sucking oil from the reduction gearbox -827.6, insert a cover -

8054.6 and insert -8055.6 and covers connect similarly as in 4.41. Insert one 

end to the driver box and the other to the reducer box. Before assembly, coat 

on the side the contact surface of the pipe flange in Hylomar, and apply a thin 

layer of vaseline to the other end with O ring. Fix the pipe to the reduction 

gearbox with two nuts MS CSN 02 1401.44, insert lock washers 5.2 LMN 3290 

under the the nuts.

Apply a thin layer of vaseline 

on the end of pipes with the 

O ring and put them in the 

accessory gearbox.

Before pulling 

pipes through the front firewall, slide a cover on them, as well as 

after pulling, before storing the pipe in the accessory gearbox.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 64

6.21. Slide insert on the pipe -827.6 and fix the pipe to the holder on the flange of 

the exhaust case and to the centrifugal compressor case using the bottom 

part of the holder -839.8, screw LN 5190 and nut LN 5168 (a rubber washer is 

inserted in the holder). Put sealing -827.6 on the pipe. 

Tighten the covers -8048.8 

-8049.8 with sealings and 

inserts on the front firewall.

According to 5.44, 

assemble the pipe 

-839.6 and secure. 

On both ends, insert 

to ONL conections 

sealing rings Js 4-

8056.9

Clean contact surfaces 

and apply thin layer of 

Hylomar (only the cap 

part).

Fix pipes to the 

flange of the 

exhaust case and 

centrifugal 

compressor case

with holders.

Between covers, 

insert sealing -8052.8 

(for pipe -826.6) or 

8054.9 (for -827.9) 

and rubber washers -

8053.8 (for -826.6) or 

8055.6 on the front 

firewall.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 65

6.22. In the flange of the exhaust case, insert air intake pipe -880.8. Apply ALHYL 

paste on the flange on the exhaust case before assembling the air pipe for 

sealing. 

Apply ALHYL paste to the 

contact surfaces from both 

sides.

Insert the pipe in the opening 

on the exhaust case. Make sure 

the pipe is in the right position. 

“XXX” marking must face the 

reduction gearbox.

Apply ALHYL paste to the 

exhaust case flange.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 66

6.23. To the inflate pipe -828.7, slide cover -8048.8 from the side with O ring, slide 

the pipe through the opening in the front firewall and slide on the other cover -

8048.7. Apply thin layer of MOGUL LV 2-3 vaseline to the side of the pipe with 

the O ring LN 5295 (or other tested vaseline, e.g. vacuum one) and insert it to 

the connection of the air outtake pipe -108.7 and secure them. Connect the 

other end of the pipe to the exhaust case flange using screws ONL 3282.2 and 

secure them. Seal all contact surfaces of the flange and sealing with ALHYL 

paste. Then assemble the inflate pipe -828.7 with the labyrinth inflate pipe PT -

861.9 using cap nut, and secure the nut with lashing wire after tightening. 

Then, insert, between sealing covers -8005.7, rubber insert -8006.7 and sealing 

-8005.7 on the inflate pipe -828.7 and fix them in the opening in the front 

firewall with covers using LN 5084 nuts and LN 5167 nuts. Insert washers LN 

5165 under the nuts. 

Slide the end of the 

pipe with O ring to 

the air discharge 

pipe. Apply thin layer 

of vaseline to the 

ring.

Apply ALHYL 

paste to the pipe 

contact surface.

After tightening the screws, 

secure lock washers. Then 

connect the PT labyrinth inflate 

pipe using cap nut, and secure 

the nut with lashing wire.

Insert sealing 

covered in ALHYL 

paste between 

the inflate pipe 

and the air 

intake pipe.

Between covers in the front firewall,

insert rubber sealing washer and 

tighten the cover screws.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 67

6.24. On the top part of the exhaust case, mount to 3 -4055.4 screws the front 

holder (cable platform) -848.6 (screws to position 2, 11 20 from the reduction 

gearbox flange). 

Assemble the front holder -848.6 (cable platform) to three 

screws -4055.4 with relevant self-locking nuts -3009.4.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 68

6.25. Connect electrical installation and fire detector (if assembled) cables to the 

front holder -848.6 (to the cable platform). 

6.26. Loosen the pipe to EHO -846.9 (if assembled along with EHO) from the 

propeller governor and electrohydraulical actuator screwing and slide 

electrical installation cable with the propeller heating bus under it. Then 

reassemble the pipe, tighten and secure cap nut with lashing wire on the side 

of the propeller governor and hollow screw on the side of electrohydraulic 

actuator (at versions with propeller heating). 

Release the pipe to 

EHO, slide the propeller 

heating bus cable under 

it and reassemble the 

pipe. Tighten and 

secure with lashing 

wire the cap nut on the 

propeller governor side 

and the hollow screw 

on the electrohydraulic 

actuator side.

Connect cables to the front 

holder (cable platform) using 

three connectors.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 69

6.27. To the reduction gearbox flange, assemble, to position 3 and 4 to the left 

clockwise from the centering screw fire detector (if assembled) using two selflocking nuts M6 ONL 3248, and insert washers LN 5275 under them. Fix the 

cable with holder to the reduction gearbox flange to position 1. 

6.28. Lead the cable to the revolution indicator transmitter. At engines with EKO, 

lead it along it and fix it by holders and two longer screws (under two nuts M6 

CSN 02 1402.44 with lock washers 6.2 LMN 2390) of electrohydraulic actuator. 

At engines without EHO, fix the cable to the reduction gearbox flange on 

position 1 to the right next to the centring screw and to two screws (under nuts 

M6 CSN 02 1402.44 with lock washers 6.2 LMN 3290). Insert the plug to the 

revolution indicator transmitter, tighten and securing with lashing wire. Secure 

lock washers. 

Assemble fire detector including the holder to 

position 3 and 4 using two self-locking nuts M6 

and washers LN 5275.

Fix the detector cable to 

the reduction gearbox

flange to position 1.

Centring screw
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 70

6.29. If electrohydraulic actuator is part of the engine, insert to it the relevant 

connector (plug), tighten and secure with lashing wire. 

6.30. Lead the electrical installation cable to the propeller governor and 

electromagnetic signaller of chips (or to the ELM switch). If EHO is part of the 

engine, lead the cable along the pipe to EHO -864.9 (two holders). If EHO is not 

part of the engine, connect the cable to screw 9 on the reduction gearbox 

flange from the centring screw. Or assemble the cable according to the 

original assembly. 

Secure the connector with lashing 

wire from the drilled flange 

through cap nut to the connector 

screws.

Insert the connector to the 

electrohydraulic actuator.

Lead the cable along the pipe to 

EHO -864.9 to the propeller 

governor flange.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 71

6.31. Assemble the pipe of the feathering pump -818.6 (if it was assembled). On it, 

slide the cover sheet -8048.8, sealing -8058.8 and rubber insert -8059.8 and 

slide it through the front firewall. Then slide on the cover sheet from the other 

side and fix and tighten cap nuts on both sides of the pipe and secure with 

lashing wire. To make the subsequent assembly of electrical installation of the 

magnetic signaller and propeller governor easier, slide the relevant cables 

between the reduction gearbox case and the feathering pump pipe. 

Fix the feathering pump pipe -818.6 and secure with 

lashing wire. Before fixing the pipe, slide the 

electrical installation cable under it. Fix the cable to 

the pipe.

Slide cover sheet -8048.8, sealing and rubber 

insert on it and slide it through the front firewall, 

then insert cover sheet from the other side. After 

fixing the pipe tighten the covers.

 Front firewall

 Rear firewall

Sealing (-8058.8)

Rubber insert (-8059.8)
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 72

6.32. Connect the connector to the ELM switch and secure with lashing wire. If ELM 

is part of the engine. 

6.33. Assemble the control rod of the propeller governor to the reduction gearbox 

flange with holder and two nuts M6 CSN 02 1402.44 with lock washers 6.2 ONL 

3288.1. Secure the nuts (if such kind of control is assembled).

Connect the 

connector to the 

ELM switch. Secure 

the connector with 

lashing wire.

Fix the cable to the 

propeller governor.

Assemble the control rod 

to the reduction gearbox 

flange using 2 M6 nuts 

with lock washers. Secure 

the nuts.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 73

6.34. Electrical installation cable attach to the feathering pump pipe -818.6, or as it 

was attached originally. Then connect, tighten and secure the plug to the 

propeller governor. Or connect and tighten plug ELM (if it is part of the engine). 

6.35. Fix the remaining cable to the filter screw -615.4 according to the picture and 

then connect and secure the electromagnetic signaller of chips.

Attach the cable to the feathering 

pump pipe (according to the 

version, if not already done 

pursuant to 4.57).

Connect plug to the propeller 

governor and secure it with 

lashing wire against loosening.

Connect the cable to the 

filter screw -615.4 (can 

be connected to the 

other screw).

Connect and secure

the electromagnetic 

signaller of chips.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 74

5.1. Disassemble propeller regulator control device. 

5.62.1 Connect the control case -731.4 to the holder on the outtake set using 

to LN 5289 screws. Fix the case so that the holder of the outtake box is under 

the screw heads, then there is insulation -7114.4, then case holder, insulation -

7114.4 and -7036.7 liner. Tighten the screws using nuts M5 CSN 02 1401.44, 

insert lock washers 5.2 ONL 3288.2 under them (see scheme below). Apply thin 

layer of mixture of molybdenum sulphide and oil (Molyka) to the screw 

threading. Insert the holder from the torquemeter pipe under the bottom nut 

with lock washer (at M601E versions). 

5.62.2 Connect connecting eye-bending shafts of kinetic connection -703.9 to 

the double-lever (double-lever pin) using crown nut -7142.4 and cotter pin LN 

5009, and secure it. 

5.62.3 Connect control rod of the propeller regulator to the propeer regulator 

using pin, washer and cotter pin, and secure it. 

5.62.2.

5.62.1.

Between the 

screw head and 

insulation, 

exhaust case

holder is located.

Control case 

holder

Pertinax 

insulation

Liner

5.62.3.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 75

6.36. Assemble the water extinguishing platform, secure the cap nuts with lashing 

wire (if assembled). 

6.37. Check the completeness of the engine. 

6.38. Assemble propeller and bonnet. 

6.39. Add oil to the engine, discharge air from the oil system. Record the executed 

work in the engine log book. 

6.40. Verification of the engine function execute with engine test according to the 

“Manual for technical operation”, part 72.03.00 (apart from points 7 and 11) 

including test flight. 

Assemble the platform 

to the front firewall and 

the extinguishing pipe 

using cap nuts. Secure 

the nuts with lashing 

wire.

Assemble the 

platform to the 

holder of the fire 

detector.

Assemble the platform to the 

flange of the reduction gearbox

using the holders on both sides. 

2x2 pieces of M6 nuts and lock 

washers 6.2 ONL 3290.
Appendix 2: 

M601 Reduction Gearbox and Supporting Cone

Inspection procedure

No. M601D/44 R2

M601D-1/29 R2

M601D-11NZ/18 R2

M601E/59 R2

M601E-11/28 R2

M601E11A/15 R2

M601E-21/26 R2

M601F/26 R2

GE PROPRIETARY INFORMATION: Subject to the restrictions on the cover page P a g e | 76

7. Verification of the engine function 

 Execute verification of the engine function by the engine perfomance test and 

 measure the Power Turbine and Gas Generator Turbine engine vibration on the wing, 

 according to appropriate engine model Maintenance Manual, chp. 70.01.01 and 

 compare with measurement in pharagrph 1. 

 Record the maximum and minimum valies of spline wear for quill shaft and the PT 

 shaft into the engine log book.