1. The General Electric T-700/T-701C
CW2 Rauch
References:
-10
T700 Engine manual
Student Handouts
UH-60L Qualification book

2. Develop pilots understanding of the T700 and T701C engines.
OBJECTIVE
Develop pilots understanding of the T700 and T701C engines.

3. Topics Engine characteristics History
Electrical control unit (ECU/DEC)
Hydromechanical unit (HMU)
Pressure and overspeed unit (POU/ODV)
NP overspeed protection
Engine Alternator

4. ENGINE CHARACTERISTICS
Output power: 1,543 A/1,662 L SHP (sea level standard day)
Type of compressor: 5 axial stages, 1 centrifugal
Variable geometry: IGV+ stage 1&2 stator vanes
Engine weight: 415 A/ 456 L LBS
Time between overhaul: none(on condition)

5. HISTORY&DEVELOPMENT
The T700 engine design was directed to minimizing required maintenance, T701C was derived from T700 w/85% common parts w/improvements to increase of 20% of Max power
Both maintenance tasks have been simplified
Corrective maintenance is on a “on condition” basis
Modular design allows sub-system replacement

6. HISTORY CONTINUED: Lock wire elimination Tool requirements reduced
LRU’s
External lines reduced
HMU no Rigging
Dual sided sight glass and “impending” bypass indicators

7. ENGINE MODULES Cold section Hot section Power turbine module
Accessory module

9. COLD SECTION

10. COLD SECTION
Includes the inlet comprised of , swirl frame, main frame, front frame, and scroll case. These together with the inlet duct and blower make up the Inlet.
Compressor section, diffuser and midframe.
Hot air and oil provide anti-icing
Scroll vanes act as air/oil cooler supplementing the fuel/oil cooler

12. BASIC OPERATION

13. HOT SECTION
Consists of combustion liner, #1 stage nozzle assembly, and the gas generator turbines.
Gas generator turbines rotor drives the compressor
12 fuel injectors, 2 primer nozzles, and 2 igniters

17. POWER TURBINE MODULE
Comprised of the power turbine rotors, power turbine driveshaft, power turbine case, the #3 and #4 nozzles, and the exhaust frame.
Expanding exhaust gases exiting drives the free power turbine at 20,900 RPM=100%NP
Casing support the 7 TGT Thermocouples and the NP/torque sensors

21. ACCESSORY MODULE
Mounts to the cold section module and is driven off the compressor section by a PTO via a radial driveshaft.
Provides drive and mounts (pads) for engine components

23. ECU/DEC

24. ECU/DEC….. WHAT’S IT DO?
Trims the HMU NG governor through the tq motor within acceptable engine limits to maintain isochronous NP governing. This can be overridden ONLY by TGT limiting.
Exchanges tq signals to provide automatic load sharing for multi-engine use.
Provides signal to the POU/ODV for NP overspeed protection %
Provides cockpit signals, NP, TGT, TQ

25. ECU FUNCTIONS, OR CHECK RIDE ANSWERS ?
Np reference from cockpit
Overspeed signal to POU (redundant power,TQ SIGNAL)
TGT limiting,
Signals to cockpit, TQ, TGT, Np
History recorder signal
Isochronous NP governing(will maintain ref.)
Torque load sharing

27. HYDOMECHANICAL UNIT

28. HMU DESCRIPTION Mounted on the aft center of the AGB
Receives filtered fuel through cored passages in the AGB
High pressure vane type pump. Max 832 PSI

29. HMU FUNCTIONS Pumps Fuel Meters Fuel
Collective pitch compensation (LDS)
Acceleration/deceleration flow limiting
Ng limiting (Governing & shutdown)
Variable geometry positioning
ECU/DEC Lockout/PAS override (lockout)
Torque motor to trim NG governor
Open Vapor vent (priming)

30. POU/ODV

31. POU/ODV DESCRIPTION
The Pressurizing overspeed unit and Overspeed drain valve is mounted on the rear of the accessory section of the engine
3 outlets. Start fuel manifold, main fuel manifold, and overboard drain or overspeed solenoid valve for T701C (+bypass during overspeed)

32. POU/ODV FUNCTIONS Sequences fuel to start fuel manifold (2)
No start fuel manifold or primer on T701C
Sequences fuel to main fuel manifold (12)
Purges start fuel manifold and nozzles after start, and main fuel manifold and nozzles during shutdown
Provides NP overspeed protection when activated from the ECU overspeed circuit
- Hot start preventer-recycles all fuel back to the HMU inlet, shutting off fuel flow to the engine

33. ENGINE ALTERNATOR

34. ALTERNATOR DESCRIPTION
Mounted on the right hand forward side of the Accessory gear box
Provides power to all essential engine functions
output consists of 3 individual signals (windings)
May fail independently or as a unit

35. ALTERNATOR FUNCTIONS (BY WINDING)
Provides power to the ignition exciter
Provides power to the ECU/DEC
Provides power to history recorder/counter
Provides NG signal to the cockpit

36. NICE TO KNOW STUFF BLUE=OVERSPEED GREEN=COCKPIT SIGNALS
BLACK=ENGINE IGNITION
YELLOW=ENGINE ELECTRICAL FUNCTIONS

37. ENGINE EP’S

39. Increasing % RPM R
1. ENG POWER CONT lever - Retard high power/TGT engine, maintain TRQ approximately 10% below other engine.
2. LAND AS SOON AS PRACTICABLE.
If the affected engine does not respond to ENG POWER lever movement in the range between FLY and IDLE, the HMU may be malfunctioning internally.

40. Continued If this occurs: 3. Establish single engine airspeed.
4. Perform EMER ENG SHUTDOWN (affected engine).
5. Refer to single engine failure emergency procedure.

41. FLUCUATIONS/OSCILLATIONS

42. %RPM Increasing/Decreasing (Oscillation).
1. Slowly retard the ENG POWER CONT lever on the suspected engine.
If the oscillation stops:
2. Place the engine in LOCKOUT and manually control the power.
3. LAND AS SOON AS PRACTICABLE.
If the oscillation continues:
4. Place the ENG POWER CONT lever back to FLY and retard the ENG POWER CONT lever of the other engine.

43. Continued When the oscillation stops:
5. Place engine in LOCKOUT, manually control the power.
6. LAND AS SOON AS PRACTICABLE.

44. 615
794

45. Engine Alternator Failure (Is not in Emergency Procedures)
(Rotor Stable) - Power control level on high TGT Engine, Retard to control TGT.

47. Single-Engine Failure
1. Collective-Adjust to maintain RPM R.
2._External cargo/stores - Jettison (if required).
If continued flight is not possible:
3. LAND AS SOON AS POSSIBLE
If continued flight is possible:
4. Establish single-engine airspeed.
5. LAND AS SOON AS PRACTICABLE
MOST RELIABLE INDICATION OF ENGINE POWER TGT

49. LOCKOUT OPNS -----ENGINE RESPONSE IS FASTER, TGT LIMITING INOP
Decreasing % RPMR
1. Collective-Adjust to control RPM R.
2. ENG POWER CONT lever-LOCKOUT low power/TGT engine. Maintain TRQ approximately 10% below other engine.
3. LAND AS SOON AS PRACTICABLE.
LOCKOUT OPNS -----ENGINE RESPONSE IS FASTER, TGT LIMITING INOP

51. Torque Split Between Engines 1 and 2
1. If TGT of one engine exceeds the limiter, retard ENG POWER CONT lever on that engine to reduce TGT. Retard the ENG POWER CONT lever to maintain torque of the manually controlled engine at approximately 10% below the other engine.

52. Continued
2. If TGT limit on either engine is not exceeded, slowly retard ENG POWER CONT lever on high % TRQ engine and observe % TRQ of low power engine.
3. If % TRQ of low power engine increases, ENG POWER CONT lever on high power engine -Retard to maintain % TRQ approximately 10% below other engine (The high power engine has been identified as a high side failure).

53. CONTINUED
4. If % TRQ of low power engine does not increase, or % RPM R decreases, ENG POWER CONT lever - Return high power engine to FLY (The low power engine has been identified as a low side failure).
5. If additional power is required, low power ENG POWER CONT lever, momentarily move to LOCKOUT and adjust to set % TRQ approximately 10% below the other engine.
6. LAND AS SOON AS PRACTICABLE.

54. NOTICEABLE BANGS , POPPING, POSSIBLE YAW
(Fluctuations)

55. Engine Compressor Stall
1. Collective - reduce.
If condition persists:
2. ENG POWER CONT lever (affected engine) - Retard (TGT should decrease).
3. ENG POWER CONT lever (affected engine) - FLY.
If stall condition recurs:
4. EMER ENG SHUTDOWN (affected engine).
5. Refer to single-engine failure emergency procedure.

57. Engine High-Speed Shaft Failure
1. Collective - Adjust.
2. EMER ENG SHUTDOWN (affected engine). Do not attempt to restart.
3. Refer to single-engine failure emergency procedure.

58. LIMITS A
OIL TEMP
OIL PRESS NG NP
TGT /
20-100/35-100
0-99/99-102/
91-95/95-101/ /
0-775/ /

59. LIMITS L OIL PRESS 22min/22-26/26-100/100-120 5min/120 TGT
0-810/ /851 start abort/ / /

60. SUMMARY
The T700 and T701C is closely integrated with helicopter components to provide proper power output for each flight condition
The system functions automatically, with no pilot action required after starting
Engine control is functionally split between the HMU and ECU/DEC. The HMU provides functions for safe operation, and the ECU/DEC performs a fine trim to reduce pilot workload
The system is self contained and engine powered

61. QUESTIONS ?