CRJ 700 Powerplant Flashcards
(44 cards)
What drives the accessory gear box?
The N2 compressor, which is derived by the high pressure turbine
What items are on the accessory gear box?
- Hydraulic pump
- Fuel pump (3 pumps interconnected on a common shaft)
- Oil pump (integral oil pump & reservoir)
- FADEC alternator
- Integrated drive generator
- Air turbine starter
There are three interconnected fuel pumps within the accessory gear box. What are they?
- Low pressure pump
- High pressure pump
- Motive flow pump
What are the rated thrust outputs of the engines?
Normal is 12,670 and APR is 13,790
What drives the N1 fan?
The low pressure turbine
How many stages is the low pressure turbine?
Four
What comprises and engine start?
A stage includes a set of stators and rotors. In the compressor section of the engine, rotor blades spin to simultaneously accelerate and compress air. The stator vanes remain fixed and direct air to the next set of rotor blades. In the turbine section of the engine (aft of the combustion chamber), escaping exhaust gas spins the turbine rotors. The turbine rotors are used to spin the compressor blades through an interconnected concentric shaft running through the center of the engine. Stator vanes are used in the turbine section to efficiently direct the flow of exhaust to the next set of turbine rotors.
How much of there engine’s overall thrust is provided by the N1 fan?
80%
What powers the Variable Geometry (VG) vanes?
Fuel pressure directed by the FADEC
What is the operability valve?
The operability valve works in conjunction with the VG vanes to remove the internal air pressure from the compressor section of the engine reducing the risk of a compressor stall
What power the operability valve?
Fuel pressure directed by the FADEC
How is fuel heated prior to combustion?
Through the use of a fuel / oil heat exchanger
How many channels does the FADEC have, and when do the channels change?
There are two channels, A and B. The channels change when the N2 rpm falls below 7% on every other engine shutdown
How many FADEC channels are in use at once?
One channel commands the engine while the other channel monitors the controlling channel and is in standby incase the commanding channel fails
Is there ever a time when both FADEC channels will command the engine simultaneously?
In an engine overspeed situation both FADEC channels will command the fuel valves to close to bring the speed into the normal range
What happens if both FADEC channels fail or the FADEC loses power?
The engine will fail
Cant he left engine’s FADEC control the right engine?
No
Do the left and right engine’s FADECs cross-talk with each other?
Yes. They compare engine speed and thrust reverser position information
While cross-talking, when will one engine’s FADEC assume the other engine has failed?
When there is a difference of at least 15% N1
When an engine fails, what will the operative engine’s FADEC automatically command?
APR in the TOGA defend, MCT in the climb detent, and a proportionate increase throughout the cruise range
What will the FADEC command if a thrust reverser deploys in flight?
It will reduce that engine’s thrust to idle
At what speed does the FADEC lock in the final N1 computation during takeoff?
65 KIAS
What powers the FADEC?
Aircraft electrical power with an N2 of less than 50%, and the FADEC alternator with an N2 of greater than 50%
If we wait for the FADEC to shut the engine down during a hot start are we guaranteed that the ITT limit will not be exceeded?
No
