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 pipes, drain pipes,
    fuel lines and electrical feeders) of the systems connected to the engine.
** ON A/C NOT FOR ALL
2. Description
F Pylon ** ON A/C NOT FOR ALL
F Pylon Ribs ** ON A/C NOT FOR ALL
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
The aft pylon fairing 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
The rear pylon fairing 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 ** ON A/C NOT FOR ALL
(2) Hydraulic System
F Hydraulic System ** ON A/C NOT FOR ALL
(REF. DO 29-10-00-00)
(3) Engine Fire Detection and Extinguishing
F Engine Fire Detection and Extinguishing ** ON A/C NOT FOR ALL
(REF. DO 26-12-00-00U)
(REF. DO 26-21-00-00U)
(4) Engine Bleed-Air System
F Engine Bleed-Air System ** ON A/C NOT FOR ALL
(REF. DO 36-11-00-00U)
(5) Fuel System
F Fuel System ** ON A/C NOT FOR ALL
(REF. DO 28-16-00-00)
(REF. DO 28-20-00-00)
(6) Drainage System
F Drainage System ** ON A/C NOT FOR ALL
C. Pylon Zones
F Pylon Zones ** ON A/C NOT FOR ALL
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 nine 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 RIB07L.
This zone contains hydraulic lines.
This zone drains through two drain holes:
  • One is in the left front web between RIB03 and RIB04
  • A different one is between RIB07R and RIB07L.
The drain hole between RIB07R and RIB07L connects to the zone A drain line.
There is one bulkhead between the two holes which is not sealed.
This bulkhead lets the fluid from the top of zone A go down to the hole which is connects to the drain line.
(2) Zone B1:
This zone is in the pylon secondary structure between RIB06 and RIB07.
This zone contains the precooler.
This zone is not sealed and drained.
(3) Zone B2:
This zone is in the right front part of the pylon secondary structure, between RIB01 and RIB07R.
This zone contains the electrical system components.
There is a gap between zone B2 and zone F which lets fluids go into zone F.
This zone is not sealed.
(4) Zone C:
This zone is in the pylon primary structure.
This zone contains:
  • The fuel lines
  • The hydraulic lines
  • The engine fire-extinguishing components
  • The zone A drain line
  • The zone F front drain line
  • The zone F rear drain line, made of a metal braiding to make it flexible
  • The zone F drain line
  • One drain hole which drains all the leakages in zone C to the drain mast connection.
The zone F front drain line and the zone F rear drain line connect together in zone C. This is to make sure that they become one zone F drain line.
(5) Zone C1:
This zone is the internal part of zone C in the pylon primary structure.
This zone contains the engine bleed-air system components.
This zone is not sealed and drained.
(6) Zone D:
This zone is in the rear part of the pylon, adjacent to the wing tank.
Through zone D, electrical harnesses and hydraulic lines connect between the engine and the wing.
This zone has:
  • One drain hole in RIB10
  • Two drain holes in the bottom structure of the rear pylon fairing
  • The zone D drain pipe which lets fluids go out of the pylon.
(7) Zone F:
This zone is in the top area of the pylon between RIB07L and RIB8.
The components that follow go through this zone between the wing and the engine:
  • The engine bleed-air system components
  • The electrical system components
  • The hydraulic system components
  • The fuel system components.
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.
(8) Zone G:
This zone is between the pylon secondary structure and the pylon primary structure.
This zone contains the zone A drain line and the engine bleed-air system components.
This zone is not sealed.
If there is a leakage, it will go directly on the cowls.
(9) Zone APF:
This zone is in the aft pylon fairing.
This zone is not sealed and drained.
D. Pylon Seals
F Pylon Seals ** ON A/C NOT FOR ALL
(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 is between the engine core and zone G.
It is an elastomeric fire seal.
It gives a fire barrier between the engine core and zone G.
(4) Vapor Barrier Seal:
This seal is between the fan zone and zone G.
It is an elastomeric seal.
It gives an air sealing between the fan zone and zone G.
(5) Rear Mount Fairing (RMF) Finger Seal:
This seal is installed on the pylon.
It is made of titanium.
It has two types of seals:
  • RMF Aerodynamic Finger-Seal:
    It makes sure that there is sealing between the engine core and the secondary air flow.
  • RMF Fire Finger-Seal:
    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 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) Blade 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 01:58:51 UTC
"Aviabrain" 2025