Chapter 2: 2.1 & 2.2 Engines & Rotors

Question 1

-Name the parts of the engine

Answer 1

Inlet, Compressor, Combustion, Turbine, Exhaust
“Suck, Squeeze, Bang, Power, Blow”

Question 2

Inlet Section Description

Answer 2

-Inlet Cowling: air first passes. Heated by inlet anti-ice
-Swirl Frame / Swirl Vane: Imparts rotation for FOD removal. Heated by Anti-Ice
-Inertial Particle Separator: collects FOD and removes it from the engine
-Deswirl Frame: removes rotation and passes clean, smooth air to the compressor

Question 3

Compressor components

Answer 3

5 stage, single axial centrifugal rotor/stator assembly

Question 4

Combustion components

Answer 4

12 injectors, 2 igniters, flow through annular combustion chamber

Question 5

Describe the Turbines
Ng
Np
Where is TGT sensed

Answer 5

-Ng Turbine: gas-generator. Drives the compressor and AGB
-Np Turbine: connects to the input module.
-TGT is sensed between the Ng and Np turbines

Question 6

Exhaust percentages

Answer 6

70% for cooling, 30% for pressurization, T2 and P3

Question 7

AGB components

Answer 7

Front: Alternator and Engine Driven Fuel Boost Pump
Back: HMU, ODV, Engine Starters, IPS

Question 8

PCL positions

Answer 8

PCL OFF: power available spindle is mechanically off
PCL IDLE: starter sequence is commenced. HMU controls the start sequence until self-sustaining combustion
PCL FLY: max power that could be supplied, if demanded (FAIL-HIGH)
PCL Lockout: manually control Np and Ng. TGT, Np governing, Ng governing and load sharing are deactivated but Np overspeed protection is retained.

Question 9

Function of the Engine-Driven Fuel Boost Pump

Answer 9

(1) provide reliable suction feed to fuel tank/minimize vulnerability if damaged lines
(2) provide minimum pressure for HMU/high pressure pump

Question 10

HMU Provides? (RANFAN)

Answer 10

Rapid engine transient response through collective compensation
Automatic Fuel Scheduling
Ng governing: receives inputs from T2, P3, Ng to adjust metering valve flow
Flameout and Compressor Stall protection via the variable geometry vanes and anti-ice start/bleed valve
Acceleration Limiting
Ng overspeed protection: 110+/- 2%

Question 11

ODV Controls

Answer 11

Prevents coking by purging fuel overboard
Provides fuel to the 12 injectors
Traps fuel upstream so priming is NOT required
Returns fuel back to the HMU if Np overspeed is energized or if hot start preventer is activated

Question 12

EDECU Functions 4N 3CHEF TASTED
4N

Answer 12

1. Ng decay relight feature: if Ng drops below 62%, auto-ignition will attempt to re-ignite for 5 seconds
   2 .Np governing: based on actual vs reference Np
2. Np Overspeed Protection: 120%, sends signal to ODV to divert fuel back to HMU and cause flameout
3. Np Overspeed Test: re-references protection from 120% to 96%. When depressing A, system is testing B

Question 13

EDECU Functions 4N 3CHEF TASTED
3C

Answer 13

1. Manual Contingency Power: flipping the switch will increase the TGT limit to 891+/-10
2. Auto Contingency Power: enabled in OEI conditions. Torque less than 50%, opposite engine will auto reset TGT from 866+/-10% to 891+/-10%
3. Dual-Engine Auto Contingency Power: allows EDECU to limit at 891 +/- 10% but requires 1 of the following to occur:
   a. Np drops below 96%
   b. ≥3% droop between Np and reference Np
   c. ≥5%/second Np droop rate with Np ≤ reference Np

Question 14

EDECU Functions 4N 3CHEF TASTED
HEF

Answer 14

-Hot Start Prevention: TGT exceeds 900* C with Ng < 60% and Np < 50% and stops fuel flow by tripping ODV
-Engine Speed Trim: 96-101
-Fault Diagnostic System: EDECU Table

Question 15

EDECU Functions 4N 3CHEF TASTED
TASTED

Answer 15

-TGT Limiting: actual vs reference. When approaching 878* C
-Auto Ignition System: after an overspeed and flameout, auto ignition closes the overspeed valve and turns on the igniters for 5 seconds. Will continue to cycle until Np is under control
Signals: EDECU faults codes
-Transient Droop Improvement based on collective position
-EDECU Lockout

Question 16

Thermal Lockout of Engine Oil

Answer 16

below 38*C

Question 17

Engine Start System
-Starter dropout is when?
-Crossbleed start Ng requirements

Answer 17

-Starter dropout: 52-65%
-Crossbleed: Donor requires 90-94% and receiving engine requires 24% Ng.

Question 18

3 ways to Anti-Ice the Engines

Answer 18

1. Engine Anti-Ice/Start Bleed Valve to the swirl vane
2. Inlet Anti-Ice Valve to the Inlet Cowling
3. Continuously pumping engine oil through scroll vane

Question 19

Engine Anti Ice Malfunction Indications

Answer 19

1. ENG ANTI ICE when Ng is above 90% (94% with OAT > 15*C)
2. ENG ANTI ICE does NOT come on below 88% Ng
3. No illumination of ENG ANTI-ICE with switch ON
4. No rise in TGT when ENG ANTI-ICE on (30-100*C)

Question 20

If electrical power is removed to inlet anti-ice valve what happens

Answer 20

Valve is open regardless of ENG ANTI-ICE or DE-ICE position

Question 21

Freon Bellow positions based on temperature
What is the concern here

Answer 21

Less than 4C: INLET ANTI-ICE ON
4-13C: closing as temperature rises
>13C: closed
-If INLET ANTI-ICE is ON when OAT is greater than 13C, indicates a malfunction of INLET ANTI-ICE which could mean a loss of up to 49% max power

Question 22

How is TGT sensed

Answer 22

Thermocouple harness

Question 23

How is NG sensed

Answer 23

Alternator

Question 24

How long does it take for AVCS to analyze vibrations and provide a solution?

Answer 24

5 minutes

Question 25

Tail rotor is __ actuated but requires __ to operate

Answer 25

mechanically actuated but requires hydraulic px to operate the pitch change shaft to move the pitch change crossbeam to move the pitch change links to adjust the blade pitch angle

Question 26

Tail Rotor purpose
-Canted how much?
-Produces how much lift in a hover?
-Tail Rotor Index prevents what?
-1 cable fail vs 2 cable fail?

Answer 26

-provide anti-torque and directional control
-Canted 20* upward and accounts for 2.5% lift
-Tail Rotor Index prevents windmilling up to 60 kts
-Tail Rotor Quadrant: transmits tail rotor cable movement to tail rotor servo
2 Spring Cylinders: redundant system. 1 cable fails, operates normally. 2 cables fail: provide sufficient tension to maintain mid-position anti-torque (25 or 145 KIAS at 19,500lbs)