Engine Types
GE CF34-10E high bypass ratio dual rotor turbofan
Igniter Knob in Off position
- deactivates ignition on the ground
- FADEC disregards Off position in flight
How does fuel flow from the fuel tank to the fuel injectors?
- Fuel exited tank via ejector pumps —> Low Pressure Fuel Pump —>
A) High Pressure Fuel Pump —> Fuel tank return
B) Heat Exchanger —> Hight Pressure Fuel Pump —> Fuel Filter —> FMU —> fuel injectors
When does the FADEC energize both ingniters
- engine air start
- engine flame out
- missed light off
- cold soak condition on the ground
- high alt airport ground start
- selector OVRD
When should an auto-relight be considered unsuccessful
- engine relight does not occurs within 30 secs
- N2 falls below 7.2%
Components of Engine Control System
- FADEC
- Thrust Levers
- T2 sensors
- N1 sensors
What do T2 and N1 sensors provide?
- T2 sensors monitor engine inlet temp for use by FADEC
- N1 sensors provide Fan Speed data for FADEC and airplane vibration monitoring
Function of the FADEC
- 2 channels (in-control channel switch after each engine start)
– Engine protection;
– Control of the requested and max N1;
– Control of the ATTCS
What powers the FADEC
- PMA above 50% N2
- Airplane electrical system below 50% N2 and as backup
ATTCS activation logic
RSV automatically commanded when TL as TOGA and:
– Difference between both engine N1 values is greater than 15%; or
– One engine failure during takeoff; or
– One engine failure during go-around; or
– Windshear detection
*auto armed for go-around
Min Flex takeoff thrust
- 75% maximum rated takeoff thrust; or
- CLB-2 + 1% N1
(Whichever is higher)
When is GA mode activated
- inflight
- landing gear down
- flaps down
- thrust mode other than takeoff
- TL set to TOGA
Approach Idle activation
- allows rapid acceleration to GA thrust
– In flight;
– Altitude less than 15000 ft; and
– Flaps 1 or greater or landing gear down
Final Approach thrust activation
– Altitude lower than 1200 ft AGL;
– Landing flaps;
– Landing gear down
Engine Protections
FADEC Start Protections:
- Hung Start
- Hot Start
- No Light Off
Overspeed Protection
- at 102% N2 FADEC commands engine shutdown
Overtemp Protection
- FADEC controls ITT limits throughout start and engine operation
Min Oil level for takeoff
Oil level must be in the green range
When does FADEC alternate exciters
After each start
Engine indication during start
- ignition at approx 7% N2
- fuel flow at approx 20% to 25% N2
- light off
- starter cutout at 50% N2
How are the thrust reversers controlled
- Electrically controlled via the FADEC
- Hydraulically actuated
- independently operated
