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Helicopters > Ch 8 Powerplants > Flashcards

Ch 8 Powerplants Flashcards

1
Q

Define flat rate

A

Means that a given horsepower may be reached at a given temperature, such as 80 degrees

(An engine having a HP rating at higher than standard day temperatures)

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2
Q

Define torque limited

A

Used in regards to power engine may deliver to transmission- which is torque limited or capable of withstanding only so much of the engines potential power output

(A limitation placed on the drive train in regards to power output of the engine)

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3
Q

Purpose of engine alignment

A

Ensures driveshaft alignment between engine output and transmission input

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4
Q

To measure rpm on a shaft turbine, what is used?

A

Tachometer

There’s

  • Dual Tach
  • Tripple Tach (2 engines & 1 M/R)
  • married needles (if needles in line= all good)
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5
Q

N1 or Ng

A

Compressor or gas producer

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6
Q

N2 or Nf

A

Power turbine

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7
Q

What does the N2 tachometer indicate and what type is it?

A
  • dual tachometer

- indicates engine and main rotor output

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8
Q

Define droop

A

If the N2 rpm can’t maintain or lags behind as collective is increased

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9
Q

What are causes of droop?

A

Overloaded Helicopter
Worn engine
Incorrect adjustment

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10
Q

What do these acronyms stand for?

EGT, ITT, TIT, TOT

A

EGT- Exhaust Gas Temp.
ITT- Inner Turbine Temp.
TIT- Turbine Inlet Temp.
TOT- Turbine Outlet Temp.

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11
Q

Particle Separators purpose

A

Device used to remove foreign material from the air entering the engine
(By means of centrifugal force)

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12
Q

What was modified on fixed wing engines to be put on helicopters?

A
  • Lubrication System (oil sump relocated and modification to/ Intro of oil scavenge system)
  • increased Power Requirements (added fan/oil pump= work harder and its constant speed, blade pitch change= more drag= more power to over come)
  • Cooling System (not cooled from prop/ram airflow so fan added to produce required cooling airflow)
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13
Q

Other than the modifications to the lubrication/cooling systems as well as increase in power requirements, what other modifications were made to the engines?

A
  • Method of controlling power (need constant rpm)
  • increased idle rpm
  • shortened life (result of modifications and higher power settings needed)
  • carburetor heat, superchargers, fuel injection, transient rpm ranges, shortened life TBO 1200-2000 (R22)
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14
Q

How do cracks form on cooling fan? And what do you do with a cracked fan?

A
  • have to replace

- caused by out of balance/vibrations and centrifugal force

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15
Q

Maintenance problems?

A
  • location of accessories (L/H side of engine on R/H side of helicopter)
  • unable to easily rotate crankshaft (special tooling to allow to turn engine)
  • removal and install of engine a lot harder on helicopter than fixed wing
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16
Q

Correlation System on what type of engine?

A

Reciprocating only

17
Q

Before Rigging Correlation System, what must be rigged first?

A

Collective

Throttle rigging should never be attempted unless collective has been properly rigged

18
Q

Turbine engines for weight and power, what 2 things are helicopters referred to?

A
  • Flat rated (given HP may be reached at a given temp.)

- Torque limited (amount of power that engine may deliver to transmission-always watch torque gauge)

19
Q

What is droop compensation? Purpose and prevents?

A
  • a linkage between the collective pitch control and turbine speed governor
  • adjusts for increased load. The rotor places on engine as collective pitch is increased
  • prevents rotor speed decreasing as load applied
20
Q

Main difference between droop compensation and correlation System?

A

Correlation is directly linked to Fuel Control whereas the Droop Compensator isn’t connected to Fuel System at all (connected to governor which tells FCU more fuel-it’s predictive)

21
Q

If adjust beep switch too low? Too high?

A

Too low- lose alt.
Too high- overspeed= blade stall

(Rig governor position with beep switch and collective position- ICC beep switch /secondary&primary control, twist grip is primary)

22
Q

Functions of twist grip are:

A

-mechanical control of internal shut-off valve of FCU (N1)

23
Q

Purpose of droop comp. linkage?

A

To change governor position mechanically to anticipate required action as the collective is moved

24
Q

Beep switch purpose?

A

Trims N2 rpm which trims rotor speed

25
Q

Interstate bleed System purpose and location

A
  • Bleed band located 5th stage axial compressor

- purpose is to unload compressor during acceleration

26
Q

Power lever

A
  • another way to control FCU, usually in centre of roof
  • common on 2 engine a/c
  • positions are; off, idle (flight and ground), may have start and emergency positions
27
Q

Engine Ice Protection (typically anti-ice System) purpose

A
  • Protect engine from ice congestion
  • Anti-ice uses Pc (Compressor discharge air)

/diffuser has most pressure/

28
Q

What indication would there be if anti-ice was selected?

A

Slight temp increase (from taking cooling air) shown on EGT, TOT,/ITT instrument

29
Q

Indicates power output of engine

A

Torquemeter

  • Magnetic Pickup
  • Wet lines
  • Transmitters
30
Q

Oil is critical b/c it cools & lubricates components. What gauges will you have for the oil system?

A

Oil pressure and oil temp. Gauges

Temp. measured after cooler

31
Q

Causes of a Hot start

A
  • low battery (doesn’t spoil up fast enough)
  • faulty Fuel Control
  • pilot error
32
Q

What is a Hung start and how do you fix?

A
  • engine fails to reach idle rpm

- adjust Fuel Control

33
Q

Compressor inlet Guide vanes, inspect for…

A
  • F.O. Damage
  • Dirt (changes shape of airfoil/ reduces efficiency)
  • Erosion (caused by sand, salt, pollution. Which removes material from airfoils which results in power loss)
34
Q

Compressor wash. What do you do?

A
  • disconnect lines and cap so don’t get water in them (bleed valves/ bleed bands must be held closed by mechanical means)
  • injection of cleaning compound into compressor while engine being motored by Starter generator (speed and volume matter so don’t bend blades)
35
Q

An inlet barrier filter is another type of ____________ and is ______

A
  • particle accelerator

- cleanable

36
Q

Blockage of particle accelerators & reverse scoops result in…

A
  • Limits airflow
  • may result in stall or flameout
  • some causes include ice, weeds, leaves, engine covers
37
Q

What can a pilot do on ground or in flight to ensure the clutches, freewheeling units, overrunning clutches are functioning on the free turbine engine?

A

Pilot will roll of throttle and see a split in the dual tachometer. If needles don’t split then slowly decrease, engine is dragging down the rotor

Helicopters (7 decks)

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