11.3.5 - Nacelles/Pylons Flashcards
List the primary functions of a nacelle
The primary functions of the nacelle are to:
- Cause a smooth airflow both around and into the engine to decrease drag and give better engine performance
- Prevent damage to the external surface of the engine and its accessories
- Give additional strength to the engine structure so it is more resistant to the forces that can cause it to bend (cowl load sharing)
- Permit service door access to the engine and its components
List the primary functions of a nose cowl, and is it part of the engine?
It provides maximum airflow into the engine compressor.
It is bolted to the engine inlet case, however it is not part of the engine. It is part of the engine cowling system
What is the main difference between a composite hot section door and a cold section door?
Cold section door = fan case
hot section door = core engine and provides fire protection
What are stub wings?
The side pylons for rear fuselage mounting are sometimes called ‘‘stub wings’’
List the functions of an engine pylon? (4)
- To support the engine
- To transmit the engine thrust to the aircraft
- To enable the routing and attachment of all the systems connected with the engine (electrical wiring, hydraulic, bleed air and fuel lines)
- To serve as fire barrier between engine and aircraft structure
What part of the pylon is the primary load bearer?
(what material?)
made of titanium and steel alloy
Difference between pylon and nacelle?
What material is a firewall typically made from?
Titanium and steel
List the general functions of a fire seal (4)
- prevent entry of combustible matter into areas where auto-ignition may occur and avoids propagation of fire
- confines effects of pneumatic duct and turbine rupture or major leaks
- prevents air from the hot section of the engine core from circulating in the fan case area.
- facilitates the effective use of the fire detection system by containing the fire in one area
Write a brief note on the purpose of engine mounts?
The engine mount system serves as interface between the engine and the pylon. It is fail-safe damage tolerant design capable to transmit all the loads from the engine to the aircraft structure.
(typically 2 or 3)
Which engine mount generally takes the thrust loads?
Forward mount
What is all included in an engine nacelle and what is its function?
The nacelle includes the entire engine cowling system which is a nose cowl, hinged removable cowl panels, exhaust nacelle and thrust reverser
To provide smooth airlfow over the engine, protect them from damage, give additional strength to engine and allow access to engine.
Which zones of the nacelles are provided with fire walls?
The zones are divided by fireproof bulkheads, usually made of stainless steel, titanium or thermoplastics
What is the function of engine pylons?
- To support the engine
- To transmit the engine thrust to the aircraft
- To enable the routing and attachment of all the systems connected with the engine
- to serve as fire-barrier between engine and aircraft structure
How are the engine loads distributed on the engine mounts?
Aft mount - Vertical, side and torque loads
Forward mount - Thrust, Vertical and side loads
The nose cowl leading edge is normall supplied with …
Anti-icing air
