15.19 Powerplant Installation

Question 1

What is referred to as a power plant?

Answer 1

The engine and its accessories, including the gearbox, fuel control, intake cowling, exhaust, thrust reverser assembly, fire protection equipment, sensors, generators, ducting, wiring, cowling, mounts, control cables and rods, drains and firewalls

Question 2

What is the most common power plant installation?

Answer 2

Wing mounted

Question 3

What is a firewall?

Answer 3

A firewall is a partition between the engine powerplant installation and the aircraft

Question 4

What is the function of a firewall?

Answer 4

Its function is to isolate the powerplant from the airframe structure in case of fire and the heat created during normal engine operation

Question 5

What are firewalls made out of?

Answer 5

Sheet metal shields made from stainless steel or some other high heat resistant metal

Question 6

The engines, struts and pylons have zones what could these zones be?

Answer 6

fire zone, flammable fluid leakage zone, or dry bay zone, according to the potential for the presence of flammable fluids and ignition sources

Question 7

Fire zones are classified based on what?

Answer 7

compartments that contain ignition sources and the potential for flammable fluid leakage are classified as fire zones

Question 8

How are fire zones isolated?

Answer 8

Firewalls

Question 9

What are some examples of fire zones?

Answer 9

Examples are the engine case around the compressor, combustor, and turbine sections of the engine

Question 10

Why do helicopters use firewalls?

Answer 10

Helicopters utilise the firewalls to ensure the engine is separated from the adjacent engine or the main gearbox section

Question 11

Why are there cowls on the engine?

Answer 11

To protect the engine and its accessories from the operating environment and to provide a streamlined, aerodynamic surface

Question 12

What are the cowlings also for?

Answer 12

Also designed to route cooling air effectively around the engine and its components

Question 13

When designing cowlings what is kept in mind?

Answer 13

Ease of access for maintenance

Question 14

What are the thrust reversers cowls commonly referred to as?

Answer 14

C duct cowls

Question 15

How must the engine be mounted?

Answer 15

In a way that the weight of the engine and thrust developed is transmitted to the aircraft structure and the mountings

Question 16

With the temperature ranges what do the mounts need to allow?

Answer 16

For expansion in both radial and axial directions

Question 17

On side-mounted engines, the front and rear saddle-type beams connect the engine through fillets to the airframe how are they connected to the engine?

Answer 17

The beams are connected to the engine mounting points by swinging links and thrust trunnions, with a thrust strut connected to the airframe

Question 18

How are pylon mounted engines mounted to the pylon?

Answer 18

Connected with front and rear brackets attached to links at the top front and rear of the engine

Question 19

Where are the mounting points on the engine?

Answer 19

The actual mounting points on the engine are usually located at the front, on the compressor casing and at the rear on the exhaust/turbine casing

Question 20

What loads forward engine mounts carry?

Answer 20

Vertical, side and axial (thrust) loads and allow engine growth due to thermal expansion

Question 21

What loads do aft mounts carry?

Answer 21

Vertical and side loads only

Question 22

What do the main mounting bolt/trunnion assemblies have?

Answer 22

They often have spherical bearings to allow for expansion and torque, some engines use a form of rubber bushing to absorb vibration, such as the Auxiliary Power Unit (APU) and turboshaft engines

Question 23

What do you have to ensure when replacing or repairing a fuel line?

Answer 23

That all fittings are compatible with their mating parts

Question 24

What is it essential fuel lines don’t chafe against?

Answer 24

Control cables, airframe structure or meet electrical wiring

Question 25

Where you can’t separate fuel lines and electrical wiring what should you do?

Answer 25

Ensure the fuel line is below the wiring and clamp it securely to the airframe structure

Question 26

What do you always need to ensure for hydraulic lines?

Answer 26

There is no leaks, scratches, kinks, cracks, burrs

Question 27

What do you need to ensure with hydraulic lines and hoses?

Answer 27

That they do not chafe against one another and are correctly secured and clamped

Question 28

What do you need ti do when replacing flexible lines?

Answer 28

Use the same type, size, part number and length of hose

Question 29

What do you need to avoid in flexible lines because they cause failure!

Answer 29

Tight bend

Question 30

Where must wire bundles be routed?

Answer 30

Wire bundles must be routed in accessible areas that are protected from damage and maintenance activity

Question 31

Where must wire bundles not be routed?

Answer 31

They must not be routed in areas where they are likely to be used as handholds or as support for personal equipment or where they are likely to become damaged during the removal of aircraft equipment

Question 32

Why must wiring be clamped?

Answer 32

Must be clamped so that contact with equipment and structure is avoided

Question 33

What must you do if you want clamp the wires?

Answer 33

Where this cannot be accomplished, extra protection, in the form of grommets and chafe strips must be provided

Question 34

What can you do to prolong deterioration of insulation?

Answer 34

Wiring must be routed away from high-temperature equipment and lines

Question 35

What must happen to wiring routed across hinged panels?

Answer 35

They must be routed and clamped so that the bundle will twist, rather than bend, when the panel is moved

Question 36

What is the minimum radii for bends?

Answer 36

Bends in wire groups or bundles must not be less than 10 times the outside diameter of their largest wire

Question 37

Where would control cable and rods be used on powerplants?

Answer 37

Used on many power plant installations to activate accessories such as the fuel control unit

Question 38

How should you lift an engine?

Answer 38

Only via the dedicated lifting points and are used to raise and lower the engine into position

Question 39

Why can you find drains in the power plant?

Answer 39

To drain various fluids from the power plant, some are for malfunction and some are designed for normal operation if the engine

Question 40

Why do you need to inspect the drains?

Answer 40

Ensure they are open and clear of debris

Question 41

What are the man in components of the drain system?

Answer 41

The drain lines which collect the fluids Module assembly where all the drain lines end

Question 42

Where are the drains located?

Answer 42

Lower part of the module and consists of the drain mast

Question 43

What do the drain lines do?

Answer 43

Collect fluids and vapour from any point where lines and components may leak, or where fluid can accumulate in cavities

Question 44

What are some typical areas drain lines are used?

Answer 44

The pylon The area of fuel-operated components such as the variable bleed valve and variable stator vane actuators and servo valves The oil tank scupper The bearing sump seal drains The fuel-oil heat exchanger Many components on the accessory gearbox