HSC-3 FRS > Engine Control & Engine Oil System > Flashcards

Engine Control & Engine Oil System Flashcards

(40 cards)

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1
Q

What is the engine control system?

A

All the components that are necessary for proper and complete control of the engine to maintain a constant Np/Nr

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2
Q

What are the major components of the engine control system?

A
  1. HMU - Hydromechanical control unit
  2. ODV - Overspeed and drain valve
  3. EDECU - Enhanced digital electronic control system
  4. Engine drive-train alternator
  5. Series of fuel flow control valves
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3
Q

The basic system control is governed through the interaction between what two components?

A

HMU and EDECU

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4
Q

What inputs does the HMU recieve?

A
  • Two mechanical inputs from the cockpit:
    • Collective position via the LDS (Load Demand Spindle)
    • PCL position via the PAS (Power Available Spindle)
  • One electrical signal from the EDECU:
    • Activates TRQ motor servo to precisely trim Ng speed
  • T2
  • P3
  • Ng
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5
Q

What does the HMU provide scheduled fuel for?

A
  • Minimum fuel
  • Maximum fuel
  • Variable stator vane control
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6
Q

What functions does the HMU provide?

RANFAN

A
  1. R - Rapid engine transient response through collective compensation (via the 3-D cam)
  2. A - Automatic fuel scheduling for engine start (via the 3-D cam)
  3. N - Ng overspeed protection (with a mechanical fly-weight ball)
  4. F - Flameout and compressor stall protection (unused fuel is then used has hydraulic pressure to move the variable inlet guide vanes)
  5. A- Acceleration limiting (this is done via the 3-D cam)
  6. N- Ng governing
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7
Q

What does the Overspeed and Drain Valve provide? (TRPP)

A
  1. Provides main fuel flow to 12 fuel injectors
  2. Purges main fuel manifold overboard after engine shutdown via shutoff and drain valves
  3. Traps fuel upstream to keep the fuel-oil heat exchanger full so the system doesn’t need to be primed prior to the next start
  4. Returns fuel back to the HMU if the Np Overspeed is energized or the EDECU Hot Start Preventer is activated
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8
Q

What does the EDECU do?

A

Trims the HMU within acceptable engine limits to maintain Np governing while automatically limiting TGT

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9
Q

Where is the EDECU located?

A

Mounted below the compressor casing on the engine

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10
Q

What are the control parameters of the EDECU?

A
  1. Np sensing
  2. Np overspeed and torque sensing
  3. TGT monitoring
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11
Q

What inputs does the EDECU receive?

A

Three inputs from the cockpit:
1. ENG SPD TRIM switch
2. CONTGCY PWR switch
3. ENG OVERSPEED TEST A and B buttons

Four inputs from the helicopter:
1. Torque from the other EDECU
2. Np demand
3. 400-Hz back up power
4. HMU (LVDT)

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12
Q

What signals does the EDECU send to the cockpit?

A
  1. TRQ
  2. Np
  3. TGT
  4. Contigency power
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13
Q

What functions does the EDECU provide?

4N MADE CHEF EATT

A
  1. N - Np Governing
  2. N - Np Overspeed Protection
  3. N - Np Overspeed Test
  4. N - Ng Decay Rate Relight
  5. M - Manual Contingency Power (TGT limit is now 903°C)
  6. A - Auto Contingency Power (TGT limit from 866±10°C - 891±10°C)
  7. D - Dual Engine Contingency Power (TGT limit is now 891°C with the conditions met)
  8. E - Engine Load Sharing
  9. C - Cockpit Signals
  10. H - Hot Start Prevention
  11. E - Engine Speed Trim
  12. F - Fault Diagnostic System
  13. E - EDECU Lockout
  14. A - Auto-Ignition System
  15. T - Transient Droop Inprovement
  16. T - TGT Limiting
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14
Q

What does the engine alternator do?

A

Powers all of the essential engine electrical functions (igniter assembly and EDECU)

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15
Q

When does Np Overspeed protection activate?

A

At 120% Np

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16
Q

When does the Ng Overspeed Valve trip?

A

At 110 ± 2% Ng

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17
Q

When is the hot-start prevention activated?

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A

When TGT exceeds 900°C when Ng is below 60% and Np is below 50%

18
Q

Which overspeed protection system can you test? How?

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A

You can test the Np overspeed protection system via the TEST A/B buttons for each engine.

19
Q

When is the ENG OUT warning triggered?

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A

When the Ng tape is below 55% with aircraft weight off wheels

20
Q

Do you have Ng overspeed protection or compressor stall protection after LOCKOUT?

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A

Yes; those functions are internal to the HMU and not affected by LOCKOUT.

21
Q

For EDECU LOCKOUT mode, what capabilities are lost?

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A
  1. Np governing
  2. TGT limiting
  3. ENG load sharing
22
Q

What is P3? What is it used for?

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A

P3 is compressor discharge pressure. It is a direct input to the HMU metering valve.

Direct relationship: the higher the P3, the higher the fuel flow.

23
Q

What is T2? What is it used for?

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A

T2 is engine intake temperature. It is an indirect input to the HMU metering valve via the torque motor servo, Ng, LDS, and PAS.

Inverse relationship: the higher the T2, the lower the fuel flow.

24
Q

What type of system is the engine oil system?

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A

A self-contained, pressurized, recirculating dry-sump system

25
What is the oil capacity in the engine?
There is 7 quarts in the tank and 7.3 quarts in total
26
How is engine oil cooled?
* Fuel/oil cooler (heat-exchanger) * Air/oil cooler (scroll vanes)
27
What does the torque motor servo valve do?
Converts EDECU electrical signals into mechanical signals for the HMU
28
What does the linear variable displacement transducer do?
Converts HMU mechanical signals into electrical signals for the EDECU
29
What are the conditions for activating the Dual-ENG Automatic Contingency PWR?
TGT within 11°C of the MRP (866±10) limiters, plus one of the followers: * Np drops below 96% * Greater than 3% droop between actual Np and Np reference set point * Greater than 5% per sec Np droop rate between actual Np and Np reference set point
30
When is fuel flow restored to the engine after a hot start prevention?
When TGT either decreases to 300°C or after 25 seconds **(whichever occurs first)**
31
What are the two possible malfunctions that can occur in the LDS (Load Demand System)?
1. LDS roll-pin failure 2. LDS cable malfunction
32
What would happen with a LDS roll-pin failure?
Will result in the max LDS input to the HMU regardless of collective position
33
What would happen with a LDS cable malfunction?
A jammed or stuck cable may result in the minimum LDS input to the HMU regardless of the collective position thus restricting max power available from the affected engine
34
What are the symptoms of an LDS malfunction with **the PCLs in IDLE.**
Ng of the malfunctioning engine is 3-4% higher than the good engine
35
What are the symptoms of an LDS malfunction **during rotor engagement.**
The engine with the failed LDS will indicate a higher torque as the PCLs are advanced to the FLY position
36
What are the symptoms of an LDS malfunction during **the inital collective increase during takeoff.**
Torque split: **TRQ of the engine with the failed LDS will be lower than good engine**
37
What are the symptoms of an LDS malfunction during **a collective increase when its below 75% of its full up position.**
Torque split: **TRQ of the engine with the failed LDS will be lower than good engine**
38
What are the symptoms of an LDS malfunction during **a collective increase when its above 75% of its full up position.**
Torque split: **TRQ of the engine with the failed LDS will be lower than good engine**
39
What are the symptoms of an LDS malfunction during **a collective decrease when its below 75% of its full up position.**
Torque split: **TRQ of the engine with the failed LDS will be above the other engine**
40
What are the symptoms of an LDS malfunction during **an autorotation.**
Rapid Np/Nr rise May show a residual torque of ~12% with the collective full down
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