TM 55-2840-241-23 Change 19          7-7 1213/1214 1. Gas producer tachometer- 4. Torquemeter spanner nut 9. Power takeoff generator 5. Power turbine fuel govenor 10. Gas producer fuel control 2. Power takeoff 6. Spare (not used) 3. Power turbine tachometer 7. Fuel pump generator generator 8. Starter-generator Figure  7-4.  Gearbox Accessory Pad Locations   c. If any gearbox-mounted accessory is removed, visually  inspect  the  gearbox  studs  for  security,  worn areas, and damaged threads. Replace loose, damaged, or worn studs. (Refer to paragraph 7-28.) d. Check for damaged paint surfaces. Repair dam- aged paint per paragraph 7-29. 7-15.   Thermocouple Assembly Inspection.   When erroneous indications are suspected, ensure that the indicating system is functioning properly. Per- form a TOT gage calibration check and a total TOT circuit resistance check. (Refer to TM 55-4920-244-14 and TM 55-1520-228-23.) If no discrepancies are noted, check the thermocouple system as follows. Do not remove the thermocouple assembly from the engine. a. Visually inspect the thermocouple assembly for broken leads, loose terminals, and other visible damage. b. Disconnect the leads from the terminal assembly mounted on the right-hand side of the exhaust collector. c. Check the internal resistance of the thermocou- ple harness at the terminal block on the right-hand side of the exhaust collector. Resistance shall be 0.55 to 0.65 ohms. d. Reconnect the leads to the terminal assembly. 7-16.   Exhaust Collector Support Inspection.   Visually  inspect  the  exhaust  collector  support  for cracks. Cracks are not repairable, replace the engine. If cracks in the exhaust collector are suspected, refer to TM 1-1520-254-23, Technical Manual Aviation Unit Mainte- nance (AVUM) and Aviation Intermediate Maintenance (AVIM) Manual Nondestructive Inspection Procedure for OH-58 Helicopter Series. 7-17.   Outer Combustion Case Inspection.   Visually inspect for cracks and dents in sheet metal surfaces and wear in the air tube bosses. Replace the outer combustion case if the repairable limits are exceed- ed. If cracks on sheet metal surface are suspected, refer to  TM  1-1520-254-23,  Technical  Manual  Aviation  Unit Maintenance (AVUM) and Aviation Intermediate Mainte- nance (AVIM) Manual Nondestructive Inspection Proce- dure for OH-58 Helicopter Series. a. Check for cracks in the outer shell. Replace the outer combustion case if nonrepairable cracks are found. (See  figure  7-5.)  Weld  all  repairable  cracks.  (Refer  to paragraph 7-30.) If cracks in outer shell are suspected, refer to TM 1-1520-254-23, Technical Manual Aviation Unit  Maintenance  (AVUM)  and  Aviation  Intermediate Maintenance (AVIM) Manual Nondestructive Inspection Procedure for OH-58 Helicopter Series. b. Check for cracks in the liner (inner basket). Weld repair cracks three inches or less in length and a mini- mum of one inch apart. (Refer to paragraph 7-30.) Re- place the outer combustion case if cracks are greater than three inches in length, cracks are less than one inch apart, or there are more than two cracks. c. Check for dents in the outer shell. Replace the outer  combustion  case  if  dents  are  more  than  1/8  in. deep. (See figure 7-6.) d. Check for wear in the air tube bosses. Replace the outer combustion case if wear is greater than 0.004 in. deep or out of round more than 0.004 in. (measure from adjacent unworn area.) (See figure 7-7.)