E175 Engines Flashcards
Engine Type
General Electric CF34-8E5. It’s a high bypass, dual-rotor turbofan engine. It has a 10-stage compressor with variable geometry, a 2-stage high-pressure turbine, a 1-stage fan, and a 4-stage low-pressure turbine.
Takeoff thrust time limit
10 minutes or POSTMOD SB 170-73-0002
Maximum Engine Start Temperature
815C
EICAS
Engine Indicating & Crew Alerting System
EICAS Markings
- Red: Max & Min Limitations
- Yellow: Caution Range
- Green: Normal Operating Range
Flex Takeoff
A takeoff with reduced thrust. Thrust setting is based off an assumed temperature (telling the FADEC that it is warmer than it actually is so it will reduce the thrust)
Flex Takeoff Limitations
25% maximum reduction in thrust. Flex is Prohibited on contaminated runways.
ATTCS
Automatic Takeoff Thrust Control System. Must be on for all takeoffs and landings.
Engine Starter Duty Cycle
- Attempts 1 & 2: 90* seconds on, 10 seconds off
- Attempts 3-5: 90* seconds on, 5 minutes off
- 120 seconds in flight
Dry Motoring Duty Cycle Limits
- Attempt 1: 90 seconds on, 5 minutes off
- Attempts 2-5: 30 seconds on, 5 minutes off
- After 5 attempts, you can repeat the cycle after a 15 minute cool down.
Maximum Thrust
14,200lbs
What are the different ways the engine can be started?
APU air start, Crossbleed air start (engine assist), External air source start (air cart or huffer cart), or a windmilling start (airborne only).
Starting and ignition system components
ATS (air turbine starter), 2 igniters per engine, and starter control valve
How is the engine start sequence controlled?
By the dual-channel FADEC (full authority digital engine control). For air starts the FADEC ignores the “off” position selected on the ignition.
Normal start sequence
- ) Select engine start
- ) N2 rotation begins
- ) at 7% N2 ingition begins
- ) at 20% N2 fuel flow is introduced (light-off within 5 seconds)
- ) N2 rises and oil pressure stays within limits
- ) at 50% N2 ignition turns off and the starter cuts off
- ) Engine accelerates and reaches normal operating temperature
Thrust reverser system
- Hydraulically actuated
- FADEC provides interlock protection against inadvertent deployment
- Idle thrust is commanded if opened in flight
- For ground use only
- Idle thrust is commanded while cowls are not totally deployed
Engine FADEC
- ESS (essential electical bus) powered below 50% N2
- PMA (permanent magnet alternator) powered above 50% N2
- 1 installed per engine
- Each FADEC has 2 channels (active and standby)
ATTCS (automatic takeoff thrust control system)
- Controlled by the FADEC
- Automatically commands maximum thrust reserve (RSV) whenever it’s armed, thrust levers are set to TO/GA, and one of the following occurs
- DIfference between N1 values greater than 15%
- One engine failure during takeoff
- One engine failure during a go-around
- Windshear detection - Automatically armed for normal GA (go-around) mode
N1
-LP/fan rotation speed as a percentage of the maximum nominal speed
- Target (cyan tick): max N1 for selected engine thrust mode
- Rating (green tick): max N1 allowed for current thrust rating and current operating conditions
- Request (moving arc): value requested based on TLA (thrust lever angle)