1. The General Electric T-700Or
What makes that “Rotor Thing” turn?
CW3 SMART
References:
-10
T700 Engine manual
Student Handouts

2. OBJECTIVE
Develop student instructor pilots understanding of the GE T-700 engine.

3. Topics History and development IAW FTG Schedule
Electrical control unit (ECU)
Hydromechanical unit (HMU)
Pressure and overspeed unit (POU)
NP overspeed protection
Engine Alternator

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

5. HISTORY&DEVELOPMENT
The T700 engine design is directed at minimizing required maintenance
Maintenance tasks have been simplified
Corrective maintenance is on 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
100% NG=44,700 RPM

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

22. 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

24. ECU

25. ECU….. 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 for NP overspeed protection %
Provides cockpit signals, NP, TGT, TQ

26. 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

28. HYDOMECHANICAL UNIT

29. 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

30. HMU FUNCTIONS Collective pitch compensation (LDS)
Acceleration/deceleration flow limiting
Ng limiting (Governing & shutdown)
Torque motor to trim NG governor
PAS override (lockout)
Fuel pumping
Fuel metering
Variable geometry positioning
Vapor vent (priming)

31. POU

32. POU DESCRIPTION
The Pressurizing and overspeed unit is mounted on the aft, left hand side of the AGB
3 outlets. Start fuel manifold, main fuel manifold, and overboard drain (+bypass during overspeed)
3 inlets. Fuel through AGB core, P3 air, overspeed signal

33. POU FUNCTIONS Sequences fuel to start fuel manifold (2)
Sequences fuel to main fuel manifold (12)
Purges start fuel manifold and nozzles during start, and main fuel manifold and nozzles during shutdown
Provides NP overspeed protection when activated from the ECU overspeed circuit

34. ENGINE ALTERNATOR

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

36. ALTERNATOR FUNCTIONS (BY WINDING)
Provides power to the ignition exciter
Provides power to the ECU
Provides NG signal to the cockpit

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

38. ENGINE EP’S FAILURE LAUNDRY LIST COMPRESSOR SHAFT
INCREASE/DECREASE/TQ SPLIT

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

41. SUMMARY
The T700 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. The HMU provides functions for safe operation, and the ECU performs a fine trim to reduce pilot workload
The system is self contained and engine powered