04 - System: Engine Flashcards by Mikkel Dahlmann

Engine: How is the engine mounted to the helicopter?

Forward coupling to the gearbox
To the rear structure via two rubber anti-vibration mounts

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.2)

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Engine: What kind of compartment is the power plant mounted in?

In a fire-proof compartment

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.2)

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Engine: How is the engine bearing and gears lubricated?

By oil circulation under pressure

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.3.1)

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Engine: What is the purpose of the Thermostatic Valve?

Returns oil directly to the tank without passing through the cooling system.

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.3.3)

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Engine: At which temperatures are the Thermostatic Valve operated?

< 74°: The valve is wide open, and the oil therefore returns directly to the tank
≥ 86°: The valve is fully closed and all the oil flows through the oil cooler

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.3.3)

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Engine: Where is the oil cooler located?

Forward of the MGB.

Engine oil cooling: To the left when looking through the oil cooler air intake (larger portion of the oil cooler)
MGB oil cooling: To the right when looking through the oil cooler air intake (smaller portion of the oil cooler)

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.3.5)

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Engine: What provides the cooling effect of the engine oil in forward flight?

Ram air passing through the oil cooler

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.3.3)

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Engine: What provides the cooling effect of the engine oil in hover flight?

The cooling air flow is provided by the motor-driven fan

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.3.3)

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Engine: Where is the thermal switch operating the motor-driven fan located?

Within the oil tank

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.3.3)

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Engine: At which temperatures are the motor-driven fan operated?

> 77°: The fan motor starts
< 68°: The fan motor stops

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.3.3)

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Engine: What are the two functional parameters of a lubrication system, as for the engine?

Temperature and Pressure

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.3.4)

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Engine: Which components are used to monitor the engine oil system?

Temperature indicator located in the oil tank
Pressure indicator located after the pressure pumps and oil filter
A low pressure warning light (<ENG P>) which illuminates below 1.3 bar
A chip detector (<ENG CHIP>) fitted on the scavange pump

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.3.4)

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Engine: Which mechanical controls act on the engine?

Fuel flow control
- Twist grip - operated by the pilot
- Consider it as “Power available”
Engine governor
- Coupled with the collective pitch
- Consider it as “Power demand”

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.4.1.)

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Engine: What is the function of the governor?

Meters fuel quantity
Maintains constant NTL

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.4.1)

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Engine: What is static droop?

The small NR variations which occours when power demand is increased or decreased.

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.4.1)

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Engine: What causes static droop?

The flyweight inability to quickly react to sudden power changes - due to the centrifugal forces lack in response time.

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.4.1)

Engine: How is static droop compensated?

By the collective pitch/governor (anticipator) coupling, which changes the tension of the spring in the flyweight centrifugal governor.

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.4.1)

Engine: What does the collective pitch/governor (anticipator) prevent?

Compensates for static droop and thereby prevents:

Surging on sudden accelerations
Flame-out on sudden decelerations

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.4.1)

Engine: Which valves does the fuel flow control lever acts on?

Main valve
Emergency valve

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.4.1)

Engine: During starting, with the twist grip in starting range, how is fuel supplied to the engine?

Main valve partly open
- Fuel metering is determined by the position of the twist grip
Starting solenoid valve open (due to pilot pressing starter)
Bleed valve closed (controlled by fuel pressure)

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.4.2.1)

Engine: How is fuel flow controlled with the twist grip in flight position?

Main valve is fully open
NG governor
- meters fuel based on NTL
- controls accel/decel with anticipator
Starting solenoid is closed
Bleed valve open

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.4.2.1)

Engine: How is fuel supplied to the engine with the twist grip in emergency range?

Directly through the emergency valve - the pilot has to adjust the opening af the valve according to the collective pitch

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.4.2.1)

Engine: The thresholds for power limitations are set in order protect which components?

Engine protection
- T4
- Ng
MGB protection
- Torque

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.5.1)

Engine: Where is the Ng transmitter located?

In the accessory gearbox

(Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.5.2)

Engine: Where is T4 measured?

At the free turbine inlet (Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.5.3)

Engine: How is torque measured?

At the engine **reduction gear** The intermediate pinion is **displaced** as torque is increased, causing **oil flow** to increase, which in turn is converted to a **torque reading** (Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.5.4)

Engine: What is the difference between the \>Starter SwitchCrank

**Starter** switch * **Fuel** injection via the starting solenoid-valve * **Ignition** * Accelerates the starter/generator **(NG)** **Crank** * Accelerates the starter/generator **(NG)** * Cool and dry the gas stream * Evacuate potentially trapped fuel * _Does Not_ * Inject fuel * Engage igniters (Instruction Manual - Basic 1 - Main Systems, Chapter 14, Paragraph 14.6.2.)

Engine: What are the main modules of the engine?

(Turbomeca Training Notes, Arriel 1, page 3.5)

Engine: How is air compressed before entering the combustion chamber?

* Axial compressor (1st stage) * Centrifugal compressor (2nd stage) (Turbomeca Training Notes, Arriel 1, page 3.6 - 3.9)

Engine: How is the compressed air distributed in the combustion chamber?

* Primary air: * Mixed with the fuel for combustion * Secondary air: * Calibrated to obtain flame stability * Cooling of the gas * Distribution of temperature on the turbine (Turbomeca Training Notes, Arriel 1, page 3.10)

Engine: Which components are driven by the accesory gearbox?

**B-O-S 1-1-2-2** * **B**reather (seperates oil from air/oil mist and vents the system) * **O**il pump * **S**tarter-generator * N**1** tachometer generator * N**1** governor * N**2** tachometer generator * N**2** governor (Turbomeca Training Notes, Arriel 1, page 3.20)

Engine: Which oil pumps does the oil system contains?

* **One** pressure pump * **Three** scavange pumps (Turbomeca Training Notes, Arriel 1, page 4.4)

Engine: Does the input for ENG P light and Oil Pressure Indicator originate from the same transmitter?

No * ENG P: Low oil pressure switch * Oil Pressure Indicator: Pressure transmitter (Turbomeca Training Notes, Arriel 1, page 4.16)

Engine: What are the functions of the different air systems in the engine?

* P0 - Internal Air System - also called "secondary air system" (P-C-B) * **P**ressurises the labyrinth seals * **C**ools certain internal engine parts * **B**alances the forces on the rotating assemblies * P1 - Compressor Bleed Valve * Closes when Ng reaches **96%** * Opens when Ng decreases below **94%** * P2 - Air Tappings (S-H-A-G B) * **S**tart injector ventilation * **H**eater/Demister * **A**ir intake (Sandfilter) * **G**overnor (used during metering of fuel) * **B**leed valve operation (Turbomeca Training Notes, Arriel 1, page 5.2 - 5.6)

Engine: How many fire detector are mounted on the engine?

**6** * 3 in cold area (In front of combustion) * One at the axial compressor (200°C) * Two at the accessory gearbox (200°C) * 3 in hot area (Aft of combustion) * One at T4 (400°C) * One at exhaust (400°C) * One at the reduction gearbox (300°C) (Turbomeca Training Notes, Arriel 1, page 11.21) (Instruction Manual - Basic 1 - Main Systems, Chapter 13, Paragraph 13.4.1)

Engine: Principle sketch of how the governor meters fuel

(Turbomeca Training Notes, Arriel 1, page 3.5)