15.19 Powerplant Installation Flashcards
What is referred to as a power plant?
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
What is the most common power plant installation?
Wing mounted
What is a firewall?
A firewall is a partition between the engine powerplant installation and the aircraft
What is the function of a firewall?
Its function is to isolate the powerplant from the airframe structure in case of fire and the heat created during normal engine operation
What are firewalls made out of?
Sheet metal shields made from stainless steel or some other high heat resistant metal
The engines, struts and pylons have zones what could these zones be?
fire zone, flammable fluid leakage zone, or dry bay zone, according to the potential for the presence of flammable fluids and ignition sources
Fire zones are classified based on what?
compartments that contain ignition sources and the potential for flammable fluid leakage are classified as fire zones
How are fire zones isolated?
Firewalls
What are some examples of fire zones?
Examples are the engine case around the compressor, combustor, and turbine sections of the engine
Why do helicopters use firewalls?
Helicopters utilise the firewalls to ensure the engine is separated from the adjacent engine or the main gearbox section
Why are there cowls on the engine?
To protect the engine and its accessories from the operating environment and to provide a streamlined, aerodynamic surface
What are the cowlings also for?
Also designed to route cooling air effectively around the engine and its components
When designing cowlings what is kept in mind?
Ease of access for maintenance
What are the thrust reversers cowls commonly referred to as?
C duct cowls
How must the engine be mounted?
In a way that the weight of the engine and thrust developed is transmitted to the aircraft structure and the mountings
With the temperature ranges what do the mounts need to allow?
For expansion in both radial and axial directions
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?
The beams are connected to the engine mounting points by swinging links and thrust trunnions, with a thrust strut connected to the airframe
How are pylon mounted engines mounted to the pylon?
Connected with front and rear brackets attached to links at the top front and rear of the engine
Where are the mounting points on the engine?
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
What loads forward engine mounts carry?
Vertical, side and axial (thrust) loads and allow engine growth due to thermal expansion
What loads do aft mounts carry?
Vertical and side loads only
What do the main mounting bolt/trunnion assemblies have?
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
What do you have to ensure when replacing or repairing a fuel line?
That all fittings are compatible with their mating parts
What is it essential fuel lines don’t chafe against?
Control cables, airframe structure or meet electrical wiring
Where you can’t separate fuel lines and electrical wiring what should you do?
Ensure the fuel line is below the wiring and clamp it securely to the airframe structure
What do you always need to ensure for hydraulic lines?
There is no leaks, scratches, kinks, cracks, burrs
What do you need to ensure with hydraulic lines and hoses?
That they do not chafe against one another and are correctly secured and clamped
What do you need ti do when replacing flexible lines?
Use the same type, size, part number and length of hose
What do you need to avoid in flexible lines because they cause failure!
Tight bend
Where must wire bundles be routed?
Wire bundles must be routed in accessible areas that are protected from damage and maintenance activity
Where must wire bundles not be routed?
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
Why must wiring be clamped?
Must be clamped so that contact with equipment and structure is avoided
What must you do if you want clamp the wires?
Where this cannot be accomplished, extra protection, in the form of grommets and chafe strips must be provided
What can you do to prolong deterioration of insulation?
Wiring must be routed away from high-temperature equipment and lines
What must happen to wiring routed across hinged panels?
They must be routed and clamped so that the bundle will twist, rather than bend, when the panel is moved
What is the minimum radii for bends?
Bends in wire groups or bundles must not be less than 10 times the outside diameter of their largest wire
Where would control cable and rods be used on powerplants?
Used on many power plant installations to activate accessories such as the fuel control unit
How should you lift an engine?
Only via the dedicated lifting points and are used to raise and lower the engine into position
Why can you find drains in the power plant?
To drain various fluids from the power plant, some are for malfunction and some are designed for normal operation if the engine
Why do you need to inspect the drains?
Ensure they are open and clear of debris
What are the man in components of the drain system?
The drain lines which collect the fluids
Module assembly where all the drain lines end
Where are the drains located?
Lower part of the module and consists of the drain mast
What do the drain lines do?
Collect fluids and vapour from any point where lines and components may leak, or where fluid can accumulate in cavities
What are some typical areas drain lines are used?
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
