Engines / APU Flashcards
Purpose of cold section module:
The cold section module is designed to clean, direct, and then compress the air.
4 Engine modules:
Cold section module
Hot section module
PT module
Accessory section module
3 sections of the Cold section module:
Inlet section
Compressor section
Diffuser section
Purpose of the ATS:
The ATS rotates the compressor, through the the accessory section module, until the engine reaches an Ng that permits it to be self sustaining.
Purpose of the radial driveshaft:
To drive the accessory section module.
Ng overspeed protection kicks in at:
110 +/- 2
How does Np overspeed protection work?
The ODV receives an electrical signal from the DECU when Np reaches 119.6 +/- 1. This opens the overspeed solenoid valve, which stops fuel flow to the injectors causing flameout.
The OPS prevents destructive turbine overspeed. The system receives Np signals from the torque and overspeed sensors located in the exhaust frame. If the Np meets or exceeds 119.6 ±1 percent, two frequency sensing circuits (CKT A and B) output a signal to the Overspeed System, which causes the ODV to shut off fuel flow to the engine.
What protects the engine lubrication system from excessive pressure during initial starts?
Cold oil relief valve
What functions does the DECU have that the ECU didn’t?
1) Can be fully powered by either the alternator or airframe 115 Vac, 400 Hz power.
2) MTRA, reduces the risk of exceeding the dual engine torque limit during uncompensated maneuvers (12% per second).
3) Hot start protection (900 C)
4) Torque spike suppression that locks out TQ signals below 35%Np. Prevent torque spike indications during startup/shutdown.
5) Fault codes (signal validation) above flight idle.
What engine parameters utilize the countdown timer feature?
Torque, TGT, and Ng
Which driveshafts couple the transmission to the IGB?
3, 4, and 5
What stops driveshaft sections from being thrown from the drive train?
Anti-flail assemblies
Purpose of the hot section:
The hot section module provides the necessary area for the mixing of fuel and air for combustion.
Purpose of the Power Turbine module:
The PT module extracts energy from hot expanding gases and converts it into mechanical energy (SHP).
Purpose of accessory section module:
The accessory section module provides mounting for engine-driven accessories and provides for engine starting.
The accessory section module is driven by _____________ and drives the _______.
the radial driveshaft
IPA
What does the collective droop potentiometer do?
The collective engine droop potentiometer provides a collective stick position input to the No. 1 and No. 2 engine DECUs or for droop (a decrease in engine rpm when power is applied) compensation.
It’s mounted to the canted bulkhead at the base of the collective control stick assembly in the pilot crewstation.
It generates an electrical signal proportional to the amount of stick movement, and aids in maintaining 101% Np during power demands.
What causes ETF degradation?
As an engine operates, it ingests FOD, reducing the engine efficiency by coating internal surfaces with dirt and grime or by eroding and damaging compressor blades. As the engine efficiency degrades, it must run hotter to produce the same torque.
If the aircraft HIT TGT exceeds the published HIT TGT limits, it is an indication that the engine performance has degraded to a point where cleaning and/or mechanical repairs must be performed.
How much can anti-ice reduce available torque by?
- 4% for 30 min
19. 2% for 10 min
What sits the moveable door in the bottom forward portion of each engine nacelle?
Fifth stage engine bleed air
When should the engine anti ice system be manually activated.
When the aircraft is flown in visible moisture in temps less than 5 degrees Celsius.
What heats the swirl vanes, nose splitter, and I let guide vanes?
Fifth stage bleed air
When is contingency power enabled?
When the input signal from the opposite engine to the DECU is 51% torque or below
What causes the +/- 12 deg variance factor on the TGT limiters?
The limiting function has an inherent +/- 4 deg. The resistance in the cabling and circuitry between the DECU and the SP, DP, and MPD account for +/- 8 deg.
3 windings contained in the alternator:
AC power for ignition
Power to the DECU for its control function
Ng speed signal
Engine emergency oil system provides oil mist lubrication to the engine bearings for how long?
30 seconds at 75% Ng
What are the users of IPAS air?
Ice detector probe Engine inlet anti ice Canopy defog Engine firewall / cooling louvers Environmental control system Air turbine starter Nitrogen inerting unit Hydraulic reservoirs Utility receptacle Fuel boost / transfer pump / external fuel tanks
At what APU speed is the APU ON advisory displayed on the EUFD?
95%
At what APU speed will the PTO clutch engage?
60% APU speed if the main transmission temp is above 0 deg F
95% APU speed if main transmission temp is below 0 deg F
What does the APU ECU monitor for automatic APU shutdown?
Over temp Over speed Over current Loss of thermocouple Loss of rpm (Ng) Low oil pressure
What happens if an engine is shutdown from above idle without letting it cool for 2 minutes?
Restart the engine within 5 minutes or engine must be allowed to cool for at least 4 hours
