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MH60S > ENGINES > Flashcards

ENGINES Flashcards

1
Q

5 Engine Sections

A

Inlet
Compressor
Combustor
Turbine
Exhaust

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2
Q

Inlet cowling heated by…

A

fifth stage bleed air via the anti-ice valve as well via the perforated slits

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3
Q

Combustion section consits of…

A

flow-through, annular combustion chamber
2 igniters
12 fuel injectors (ODV fed)

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4
Q

What does the Ng turbine drive?

A

Compressor
Accessory Gearbox (AGB)

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5
Q

What does the Np turbine drive?

A

Power turbine drive shaft (turns inside Ng turbine coaxially)
High speed shaft (connects to input module)

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6
Q

Where is TGT sensed?

A

between Ng and Np turbine

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7
Q

30% of airflow through the engine is used for what?

A

Combustion process

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8
Q

70% of airflow through the engine is used for what?

A
  1. Compressor inlet temperature (T2) air.
  2. Compressor discharge pressure (P3) air.
  3. Combustor and turbine cooling.
  4. Engine oil seal pressurization.
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9
Q

The AGB is driven by what?

A

rotor via a radial drive shaft from the Ng turbine drive shaft

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10
Q

The rear face provides drive pads for the…

A
  1. engine starter
  2. HMU
  3. IPS blower
  4. Overspeed and Drain Valve (ODV)
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11
Q

Engine Control System Purpose

A
  1. maintain constant Np/Nr
  2. Basic system operation is governed through the interaction of the EDECU and HMU
  3. HMU provides gas generator control
  4. EDECU trims the HMU to
    satisfy the requirements of the power turbine load and reduce pilot workload
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12
Q

Engine Control System Components

A

HMU
ODV
EDECU
engine-driven alternator
fuel flow control valves

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13
Q

If the PCL is momentarily advanced to LOCKOUT
and then retarded, the PCL is used to manually control…

A

Np and Ng.

TGT limiting, Np governing, and load sharing functions are deactivated and must be manually controlled. The Np overspeed protection system is retained when in
LOCKOUT via a direct link between the EDECU

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14
Q

The engine-driven fuel boost pump mounted on the forward side of the AGB is designed to:

A
  1. Provide reliable suction feed from the aircraft fuel tank to the engine, minimizing vulnerability and fire hazard in the event of damaged fuel lines.
  2. Provide discharge pressure to satisfy the minimum inlet pressure requirement of the HMU or high-pressure fuel pump.
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15
Q

Hydromechanical Control Unit Components

A
  1. high-pressure fuel pump
  2. Ng governor
  3. metering valve
  4. Linear Variable Displacement Transducer (LVDT)
  5. torque motor servo
  6. variable geometry vane servo
  7. vapor vent
  8. shutoff valve
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16
Q

Some fuel is tapped off to operate various servos
in the HMU for the following:

A
  1. Positioning a metering valve to ensure proper fuel flow to the engine.
  2. Positioning a servo piston that actuates the variable geometry vane servo and start bleed valve.
  3. Amplifying various signals (T2, P3, Ng) that influence fuel flow and variable geometry servo position.
17
Q

The HMU responds to two mechanical linkages from the cockpit and one electrical signal. What are they?

A

LDS
PAS
electrical signal from the EDECU (actuates the torque motor servo)

18
Q

The HMU receives cockpit inputs from the collective via the LDS and the PCL via the PAS. The HMU responds to the PCL for:

A
  1. Fuel shutoff.
  2. Setting engine start fuel flow with automatic acceleration to ground idle.
  3. Setting permissible Ng up to maximum.
  4. Fuel priming.
  5. EDECU override capability (LOCKOUT).

*The HMU also responds to T2, P3, and Ng. These inputs aid the HMU in controlling variable stator vanes and anti-ice/start bleed valve position during engine start and normal operation, reducing the chance of compressor stall.

19
Q

The HMU provides:

A
  1. Rapid engine transient response through collective compensation.
  2. Automatic fuel scheduling for engine start.
  3. Ng overspeed protection. The HMU mechanically limits Ng to 110 ±2 percent. If the Ng servo, within the
    Ng governor, reaches a position corresponding to an overspeed, a centrifugal valve secures fuel flow to the engine. Once the overspeed condition has passed, the valve reopens, allowing normal operation to resume.
  4. Ng governing. The HMU receives T2, P3, and Ng inputs from their respective sensors, which are used to schedule fuel for minimum flow, maximum flow, and variable geometry vane control.
  5. Acceleration limiting. The Ng governor ensures any PCL motion will result in safe engine operation and will not cause engine damage. Except for intentional shutoff of the PCL, an inadvertent shutdown will not
    occur during PCL motion.
  6. Flameout and compressor stall protection. The HMU adjusts variable geometry vane position and opens
    the anti-ice/start bleed valve to prevent compressor instability.
20
Q

The ODV has four main functions:

A
  1. Provides main fuel flow to the 12 fuel injectors during engine start and operation.
  2. Purges the main fuel manifold overboard, after engine shutdown, through a shutoff and drain valve to prevent
    coking of the fuel injectors.
  3. Traps fuel upstream, which keeps the fuel/oil heat exchanger full, so that system priming is not required prior to the next start.
  4. Returns fuel back to the HMU if the Np overspeed is energized or if the EDECU hot start preventer is activated.
21
Q

Alternator provides AC power to the following:

A
  1. ignitor assembly
  2. EDECU
  3. Ng signal to the vertical instruments
22
Q

The control parameters of the EDECU are:

A
  1. Np sensing (governing).
  2. Np overspeed and torque sensing (load sharing, cockpit torque indication, and Np overspeed protection).
  3. TGT monitoring (temperature limiting circuit).
23
Q

The EDECU receives the following inputs from the cockpit:

A
  1. ENG SPD TRIM switch.
  2. CONTGCY PWR switch.
  3. ENG OVERSPEED TEST A and B buttons.
24
Q

The EDECU receives the following input signals from the helicopter:

A
  1. Torque from the other EDECU.
  2. Np demand.
  3. 400-Hz backup power.
  4. HMU (LVDT).
25
Q

The EDECU sends the following signals to the cockpit:

A
  1. Torque.
  2. Np.
  3. TGT.
  4. Contingency power.
26
Q

During normal operations, the EDECU performs the following functions:

(2.1.4.3)

A
  1. Np governing.
  2. Np overspeed protection.
  3. Np overspeed test (120% to 96%)
  4. Engine load sharing.
  5. Engine speed trim (96 and 101% Np)
  6. Manual contingency power.
  7. Auto-contingency power (one eng below 50% sets other from 866 ±10 to 891 ±10)
  8. Dual-engine auto-contingency power (bypass
    the 10-min TGT limit of 866 ±10 up to 891 ±10)
    a. Np drops below 96%.
    b. Greater than 3% droop
    between reference
    power turbine speed (Np) and actual Np reference set point.
    c. Greater than 5% per second Np droop rate exists with Np less than or equal to Np reference set point.
    *logic resets when within 0.5% of reference Np and TGT is below 866 °C
  9. TGT limiting (878/ 866±10)
  10. EDECU LOCKOUT
  11. Cockpit signals (Provides Np, TGT, and torque signals to DTC)
  12. Hot start prevention (TGT exceeds 900 °C with Ng below 60% and Np below 50%)
  13. Transient droop improvement (TDI)
  14. Auto-ignition system (Np ovspd results in 5 second auto ignition sequence)
  15. Ng decay rate relight feature (disabled below 62% Ng)
  16. Fault diagnostic system
27
Q

Engine Oil System Components

A
  1. Oil tank.
  2. Oil supply and scavenge system.
  3. Oil filter and condition monitoring system.
  4. Air/oil cooler (scroll vanes).
  5. Fuel/oil cooler.
  6. Chip detector.
  7. Pressure and temperature indicators.
28
Q

Eng oil filter thermal lockout

A

PDI has a thermal lockout below 38 °C

29
Q

Starter dropout

A

52 to 65 percent Ng

30
Q

Engine inlet anti ice system components

A
  1. engine anti-ice start/bleed valve, mounted to the bottom of the compressor section
  2. inlet anti-ice valve
  3. inlet thermal switch, contained in the engine inlet cowling
31
Q

There are three ways to anti-ice the engine:

A
  1. Vent bleed air into the engine swirl vanes and engine Inlet Guide Vanes (IGVs) by the engine anti-ice/start bleed valve.
  2. Vent bleed air into the airframe engine inlet by the engine inlet anti-ice valve.
  3. Continuously pump engine oil through the scroll vanes.
32
Q

Engine Anti-Ice/Start Bleed Valve operation

A

engine anti-ice/start bleed valve provides fifth stage bleed air

The valve remains open below 80.5% Ng during starts

Above 96.5% Ng, the anti-ice/start bleed valve closes

33
Q

A malfunctioning anti-ice/start bleed valve is indicated by any of the following:

A
  1. Appearance or disappearance of the ENG ANTI-ICE ON advisory when outside of the range specified in
  2. No appearance of the ENG ANTI-ICE ON advisory when the ENG ANTI-ICE switch is selected ON.
  3. No rise in TGT when ENG ANTI-ICE switch is selected ON.
34
Q

1/#2 INLET ANTI-ICE ON advisory will illuminate when:

A

bleed air heats the engine inlet to approximately
93 °C; however, full inlet anti-ice capability may not be available above 4 °C and will not be available above 13 °C.

35
Q

Inlet anti ice valve bellows operation

A
  1. Less than 4 °C, the valve is open and the INLET ANTI-ICE ON advisories appear when inlet temperature reaches 93 °C.
  2. Between 4 and 13 °C, the valve is controlled by a temperature-compensating Freon-filled bellows. The bellows begins closing the valve when the OAT reaches 4 °C and should be completely closed by 13 °C.
  3. Above 13 °C, the valve is closed and the INLET ANTI-ICE ON advisories will extinguish when inlet cowling temperature drops below 93 °C.
36
Q

Np sensors location

A

top of the exhaust frame

left sensor provides
an Np signal to the EDECU

right sensor feeds the torque computation circuit and the Np overspeed protection system

37
Q

The alternator supplies an Ng signal to the:

A

vertical instruments in the cockpit

38
Q

The thermocouple harness consists of:

A

seven thermocouples for measuring TGT. The thermocouples are joined in parallel and provide an average output that is provided to the EDECU. The TGT signal is biased -71 °C by the EDECU, then relayed to the TGT vertical instruments from the EDECU.

MH60S (11 decks)

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