Engines / APU

Question 0

Purpose of cold section module:

Answer 0

The cold section module is designed to clean, direct, and then compress the air.

Question 1

4 Engine modules:

Answer 1

Cold section module
Hot section module
PT module
Accessory section module

Question 2

3 sections of the Cold section module:

Answer 2

Inlet section
Compressor section
Diffuser section

Question 3

Purpose of the ATS:

Answer 3

The ATS rotates the compressor, through the the accessory section module, until the engine reaches an Ng that permits it to be self sustaining.

Question 4

Purpose of the radial driveshaft:

Answer 4

To drive the accessory section module.

Question 5

Ng overspeed protection kicks in at:

Answer 5

110 +/- 2

Question 6

How does Np overspeed protection work?

Answer 6

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.

Question 7

What protects the engine lubrication system from excessive pressure during initial starts?

Answer 7

Cold oil relief valve

Question 8

What functions does the DECU have that the ECU didn’t?

Answer 8

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.

Question 9

What engine parameters utilize the countdown timer feature?

Answer 9

Torque, TGT, and Ng

Question 10

Which driveshafts couple the transmission to the IGB?

Answer 10

3, 4, and 5

Question 11

What stops driveshaft sections from being thrown from the drive train?

Answer 11

Anti-flail assemblies

Question 12

Purpose of the hot section:

Answer 12

The hot section module provides the necessary area for the mixing of fuel and air for combustion.

Question 13

Purpose of the Power Turbine module:

Answer 13

The PT module extracts energy from hot expanding gases and converts it into mechanical energy (SHP).

Question 14

Purpose of accessory section module:

Answer 14

The accessory section module provides mounting for engine-driven accessories and provides for engine starting.

Question 15

The accessory section module is driven by _____________ and drives the _______.

Answer 15

the radial driveshaft

IPA

Question 16

What does the collective droop potentiometer do?

Answer 16

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.

Question 17

What causes ETF degradation?

Answer 17

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.

Question 18

How much can anti-ice reduce available torque by?

Answer 18

20. 4% for 30 min

19. 2% for 10 min

Question 19

What sits the moveable door in the bottom forward portion of each engine nacelle?

Answer 19

Fifth stage engine bleed air

Question 20

When should the engine anti ice system be manually activated.

Answer 20

When the aircraft is flown in visible moisture in temps less than 5 degrees Celsius.

Question 21

What heats the swirl vanes, nose splitter, and I let guide vanes?

Answer 21

Fifth stage bleed air

Question 22

When is contingency power enabled?

Answer 22

When the input signal from the opposite engine to the DECU is 51% torque or below

Question 23

What causes the +/- 12 deg variance factor on the TGT limiters?

Answer 23

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.

Question 24

3 windings contained in the alternator:

Answer 24

AC power for ignition
Power to the DECU for its control function
Ng speed signal

Question 25

Engine emergency oil system provides oil mist lubrication to the engine bearings for how long?

Answer 25

30 seconds at 75% Ng

Question 26

What are the users of IPAS air?

Answer 26

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

Question 27

At what APU speed is the APU ON advisory displayed on the EUFD?

Answer 27

95%

Question 28

At what APU speed will the PTO clutch engage?

Answer 28

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

Question 29

What does the APU ECU monitor for automatic APU shutdown?

Answer 29

Over temp
Over speed
Over current 
Loss of thermocouple
Loss of rpm (Ng)
Low oil pressure

Question 30

What happens if an engine is shutdown from above idle without letting it cool for 2 minutes?

Answer 30

Restart the engine within 5 minutes or engine must be allowed to cool for at least 4 hours