W DOC AIRBUS | AMM A320F

PYLONS - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL
1. General
The function of the engine pylon installed below each wing is:
  • To hold the engine
  • To transmit the engine thrust to the aircraft
  • To contain the components (bleed air ducts, hydraulic lines, drain lines,
    fuel lines and electrical feeders) of the systems connected to the engine.
** ON A/C NOT FOR ALL
2. Description
F Pylon
F Pylon Ribs
A. Pylon Structure
(1) Pylon Box
The pylon box is the primary structure which holds the engine at two points and is attached to the wing at three points (Ref. AMM D/O 54-51-00-00).
(2) Forward Fairing
The forward fairing is the secondary structure which makes an aerodynamic joint between the pylon and the engine nacelle (Ref. AMM D/O 54-52-00-00).
(3) Pylon-to-Wing Center Fillets
The pylon-to-wing center fillets are access skin panels and doors which make the junction between the wing bottom surface and the pylon box (Ref. AMM D/O 54-53-00-00).
(4) Aft Pylon Fairing (APF)
The APF is a structure that you can remove which is installed between the pylon box and the engine nozzle (Ref. AMM D/O 54-56-00-00).
(5) Rear Pylon Fairing (RPF)
The RPF is a structure that you can remove which closes the rear pylon (Ref. AMM D/O 54-54-00-00).
(6) Rear Mount Fairing (RMF)
The RMF is a structure that you can remove. It gives access to the bolts of the aft engine mounts. It makes an aerodynamic joint between the pylon box and the aft pylon fairing (Ref. AMM D/O 54-57-00-00).
(7) Pylon-to-Nacelle Junction
The pylon-to-nacelle junction is the interface between the forward fairing, the engine nacelle and the pylon box (Ref. AMM D/O 54-57-00-00).
B. Systems
(1) Electrical System
F Electrical System
(2) Hydraulic System
F Hydraulic System
(REF. DO 29-10-00-00 )
(3) Engine Fire Detection and Extinguishing
F Engine Fire Detection and Extinguishing
(Ref. AMM D/O 26-12-00-00)
(REF. DO 26-21-00-00C)
(4) Engine Bleed-Air System
F Engine Bleed-Air System
(Ref. AMM D/O 36-11-00-00)
(5) Fuel System
F Fuel System
(REF. DO 28-16-00-00 )
(REF. DO 28-20-00-00 )
(6) Drainage System
F Drainage System
C. Pylon Zones
F Pylon Zones
There are components of these systems in the pylon zones:
  • The drainage system
  • The engine fire extinguishing
  • The fuel system
  • The hydraulic system
  • The engine bleed-air system
  • The electrical system.
For safety, the engine pylon is divided into seven zones.
Each zone contains installations related to the above systems.
(1) Zone A:
This zone is in the left front part of the pylon secondary structure, between RIB01 and RIB06.
This zone contains hydraulic and fuel lines.
You can drain this zone through a drain hole in the bottom area, between RIB05 and RIB06. This drain hole connects to the zone A drain line.
This zone has three stiffener holes between RIB02 and RIB04. These stiffener holes let fluid leakage flow along the forward secondary structure to the drain hole.
(2) Zone B1:
This zone is in the pylon secondary structure between RIB02 and RIB06.
This zone contains:
  • The precooler
  • The overpressure valve
  • The bleed duct
  • The starter bleed duct
  • The overheat-detection system loop.
This zone is a dry zone without a drain hole.
(3) Zone B2:
This zone is in the right front part of the pylon secondary structure, between RIB02 and RIB06.
This zone contains:
  • The electrical routing
  • The differential pressure sensor
  • The sense lines.
There is a hole at RIB06, between zone B2 and zone F which lets the condensation water flow out of zone B2.
This zone is a dry zone without a drain hole.
(4) Zone C:
This zone is in the pylon primary structure.
This zone contains:
  • The hydraulic lines
  • The engine fire-extinguishing components
  • The fan-air valve actuator
  • The bleed pressure sensor
  • The bleed monitoring pressure-sensor
  • The sense lines
  • The ventilation scoop. It is on the access doors (the access doors which give access to the fire-extinguishing bottles). This ventilation scoop lets the temperature in zone C decrease. This is to make sure that the temperature will not cause the auto fire-extinguishing bottle-percussion to operate.
  • The zone A drain line
  • The zone F front drain line
  • The zone F rear drain line
  • The zone F drain line
  • One drain hole in the bottom area between RIB1 and RIB2. This drain hole drains all the leakage from zone C to the drain mast.
(5) Zone D:
This zone is in the rear part of the pylon, adjacent to the wing tank.
This zone contains:
  • The electrical harnesses connected between the wing and the pylon
  • The hydraulic lines connected between the wing and the engine
  • One drain hole at RIB10
  • The zone A drain line
  • The outlet of the zone F drain line
  • The zone D drain line which lets fluids go out of the pylon.
(6) Zone F:
This zone is behind the forward fairing and above the primary structure (between RIB06 of the forward fairing and RIB8 of the pylon box).
The components that follow go through this zone between the wing and the engine:
  • The engine bleed-air duct
  • The electrical routing
  • The hydraulic lines
  • The fuel lines.
This zone contains the air dam seal between RIB7 and RIB8.
This zone has:
  • Two drain holes in the front which have a collector that connects to the zone F front drain line
  • Two drain holes in the rear which have a collector that connects to the zone F rear drain line.
All these drain holes collect fluids from leakages of hydraulic and/or fuel lines and/or water.
(7) Zone G:
This zone is between zone A and zone C.
This zone contains:
  • The fan air valve
  • The engine bleed duct
  • The electrical harness
  • The zone A drain line
  • The engine fire-extinguishing lines.
This zone is not sealed. If there is a leakage, the fluids will flow through the nacelle drains.
D. Pylon Seals
F Pylon Seals
(1) Karman Fairing Fire-Seal:
This seal is on the pylon-to-wing center fillets and the rear pylon fairing. It touches the wing bottom skin and the wing leading edge.
It is an elastomeric fire seal made of nine parts.
It prevents the movement of flames from the nacelle to the pylon if there is an engine fire in the nacelle.
(2) Air Dam Seal:
This seal is between zone F and zone D, it touches the wing bottom skin.
It is an elastomeric seal.
It gives air sealing between zone F and zone D if a bleed duct breaks.
(3) Nose Fire Seal:
This seal gives a fire barrier between the fan compartment and the pylon.
It is made of corrosion resistant steel.
(4) Engine Splitter Seal:
This seal is between the fan and zone G.
It is an elastomeric seal.
It gives a fire barrier between the fan and zone G.
(5) Rear Mount Fairing (RMF) Finger Seal:
This seal is installed on the pylon.
It is made of corrosion resistant steel.
It gives sealing between the engine core and the secondary air flow.
It gives a fire barrier if there is an engine core fire.
(6) RMF Block Fire-Seal:
This seal is between the thrust-reverser cowl doors and the pylon.
It is an elastomeric fire seal.
It gives a fire barrier if there is an engine core fire.
(7) Aft Pylon Fairing (APF) Finger Fire-Seal:
This seal is between the pylon box and the APF.
It gives a fire barrier between the pylon box and the APF.
(8) Thermal Blanket:
The thermal blanket gives protection to the lower spar of the pylon box against thermal radiation that comes from the engine core.
It is made of a heat insulator with inconel on it.
[Rev.10 from 2021] 2026.04.01 01:58:52 UTC
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