DOC AIRBUS | AMM A320FENVIRONMENT PROTECTION - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The environment protection system is divided into:
The environment protection system is divided into:
- The protection of the wing leading edge
- The protection of the pylon
- The protection of the nacelles.
A. Protection of the Wing Leading Edge, the Pylon and the Nacelles
(1) Protection of the Wing Leading Edge, the Pylon and the Nacelles
The protection systems of the wing leading edge, the pylon and the nacelles keep the pressure in these areas to a limit. The protection systems operate if a pneumatic duct or a wing anti-ice duct bursts or has a large leak. This prevents damage to the structure and the systems installed.
The protection systems of the wing leading edge, the pylon and the nacelles keep the pressure in these areas to a limit. The protection systems operate if a pneumatic duct or a wing anti-ice duct bursts or has a large leak. This prevents damage to the structure and the systems installed.
2. Component Location
A. Protection of Wing Leading Edge
Component Location - Fixed Leading Edge of Underwing| ------------------------------------------------------------------------------- |
| FIN I FUNCTIONAL DESIGNATION I PANELIZONEIACCESS I ATA |
| I I I I DOOR I REF. |
| ------------------------------------------------------------------------------- |
| PANEL - ACCESS, NO. 1, LH 521 521AB 57-41-22 |
| PANEL - ACCESS, NO. 1, RH 621 621AB 57-41-22 |
| PANEL - ACCESS, NO. 2, LH 521 521CB 57-41-22 |
| PANEL - ACCESS, NO. 2, RH 621 621CB 57-41-22 |
| PANEL - ACCESS, NO. 3, LH 521 521EB 57-41-22 |
| PANEL - ACCESS, NO. 3, RH 621 621EB 57-41-22 |
| PANEL - ACCESS, NO. 4, LH 522 522AB 57-41-22 |
| PANEL - ACCESS, NO. 4, RH 622 622AB 57-41-22 |
| PANEL - ACCESS, NO. 5, LH 522 522CB 57-41-22 |
| PANEL - ACCESS, NO. 5, RH 622 622CB 57-41-22 |
B. Protection of the Pylons
| ------------------------------------------------------------------------------- |
| FIN I FUNCTIONAL DESIGNATION I PANELIZONEIACCESS I ATA |
| I I I I DOOR I REF. |
| ------------------------------------------------------------------------------- |
| DOOR-PRESSURE RELIEF, LH 410 413BL 54-52-11 |
| DOOR-PRESSURE RELIEF, LH 410 414BR 54-52-11 |
| DOOR-PRESSURE RELIEF, RH 420 423BL 54-52-11 |
| DOOR-PRESSURE RELIEF, RH 420 424BR 54-52-11 |
| DOOR-PRESSURE RELIEF, LH 471 471BL 54-53-11 |
| DOOR-PRESSURE RELIEF, RH 482 482BR 54-53-11 |
C. Component Location
| ------------------------------------------------------------------------------- |
| FIN I FUNCTIONAL DESIGNATION I PANELIZONEIACCESS I ATA |
| I I I I DOOR I REF. |
| ------------------------------------------------------------------------------- |
| DOOR-PRESSURE RELIEF, LH 438 438BR 71-13-00 |
| DOOR-PRESSURE RELIEF, RH 448 448BR 71-13-00 |
| REVERSER-THRUST, LH 451 451AL 71-00-00 |
| REVERSER/THRUST, RH 452 452AR 71-00-00 |
| REVERSER-THRUST, LH 461 461AL 71-00-00 |
| REVERSER-THRUST, RH 462 462AR 71-00-00 |
3. System Description
A. Protection of the Wing Leading Edge
This system has a protection function of the wing leading edge. It operates when a duct of the pneumatic or anti-icing system bursts or shows major leaks.
It keeps the pressure to a limit when it is too high. This prevents damage to the structure of the wing leading edge and the systems installed.
This system has a protection function of the wing leading edge. It operates when a duct of the pneumatic or anti-icing system bursts or shows major leaks.
It keeps the pressure to a limit when it is too high. This prevents damage to the structure of the wing leading edge and the systems installed.
(1) The access panels prevent an excessive pressure increase. They are located at:
- The applicable bay(s) of the fixed leading edges of the wing
- The leading edge of the fuselage fairing.
(a) The access panels in the fixed leading edge of the wing are also pressure relief panels of the 'blow down' type. There are five panels on each underwing between the fuselage and the anti-icing telescopic duct. Panels 1, 2 and 3 are inboard of the engine pylon. They are a protection against overpressure caused by leaks in the pneumatic duct. Panels 4 and 5 are outboard of the pylon. They are a protection against too much overpressure caused by leaks in the anti-icing duct.
(b) For inboarding leading edge/wing root fairing overpressure relief, a pressure relief valve, with an opening area of 300 cm2 (46.6 in.2) on each side, is installed in the belly fairing. The valve opens at a pressure of 0.15 bar (2.17 psi) (relative) and the pressure is discharged into the main landing gear bay.
B. Protection of the Pylon
This system is for the protection of the pylon. It operates if a duct of the pneumatic system breaks open or shows large leaks so that this cannot endanger safe flight and landing of the aircraft.
The system keeps the pressure to a limit. This prevents damage to the pylon structure and the components installed in the pylon.
This system is for the protection of the pylon. It operates if a duct of the pneumatic system breaks open or shows large leaks so that this cannot endanger safe flight and landing of the aircraft.
The system keeps the pressure to a limit. This prevents damage to the pylon structure and the components installed in the pylon.
(1) The pressure relief doors prevent an uncontrolled increase of the pressure. They are installed in the leading edge of the pylon fairing and in the pylon/wing interface.
(2) The leading edge of the pylon fairing and the pylon/wing interface have each one pressure relief door. The overpressure in this area is limited to 0.2 bar (2.90 psi) by the pressure relief doors.
C. Protection of the Nacelles
This system is made to protect the nacelle. It operates if a pneumatic duct breaks open or has a large leak, so that this cannot endanger the safe flight and landing of the aircraft. The system keeps the pressure to a limit. This prevents damage to the nacelle structure and the components installed in the nacelle.
This system is made to protect the nacelle. It operates if a pneumatic duct breaks open or has a large leak, so that this cannot endanger the safe flight and landing of the aircraft. The system keeps the pressure to a limit. This prevents damage to the nacelle structure and the components installed in the nacelle.
- Core Compartment
An overpressure in the core compartment cannot cause any damage to the thrust reverser. If an IP or HP bleed duct breaks open or has a large leak, the pressure increases in the core compartment. The maximum overpressure is 2.90 psi (0.2 bar).
The overpressure moves the thrust reverser. This movement increases the normal pressure relief area. - Fan Compartment
A pressure relief door is installed in the fan cowl. This door will stay open to give a visual indication of the past abnormal internal pressure (differential pressure of 2.90 psi (0.2 bar)).
4. Component Description
A. Protection of the Wing Leading Edge
(1) Pressure Relief Access Panels
The pressure relief panels are made of 3.5 mm (0.1378 in.) carbon fibre. Sections of nomex honeycomb or aluminum alloy angles reinforce the panels. The panels are attached to the wing structure at the leading and trailing edges. A 1.0 mm (0.0394 in.) aluminum alloy angle which is attached to the rear face of the sub spar holds the panels. When the pressure is too high the panel 'blows down' and thus bends the angle. The angle also contains the anchor nuts to attach the forward screws.
The trailing edge of the panel is attached to a landing. It is attached to the forward edge of the lower skin of the torsion box. The landing is made of two back-to-back aluminum alloy angles.
2.4 mm (0.0945 in.) shear rivets, spacers and special washers hold this unit together. Smooth interfaces permit the landing angles to slide freely. The angle installed on the panel has a slotted hole for the rivet and the spacer. This permits the angle to move when the wing flexes and prevents that the rivet shears at an unwanted time. Also, the angle is castellated between the rivets to give a larger space for the air to flow through.
When all rivets of the panels 2, 3, 4 and 5 shear, a 75 mm (2.9528 in.) dia. steel restraining lanyard connects the two angles of the landing. On access panel 1 is no restraining lanyard as the largest possible area is required to let the air out.
The trailing edge of the panel and the landing are wet-assembled with sealant. This seals the trailing edge against air leakage.
The pressure relief panels are made of 3.5 mm (0.1378 in.) carbon fibre. Sections of nomex honeycomb or aluminum alloy angles reinforce the panels. The panels are attached to the wing structure at the leading and trailing edges. A 1.0 mm (0.0394 in.) aluminum alloy angle which is attached to the rear face of the sub spar holds the panels. When the pressure is too high the panel 'blows down' and thus bends the angle. The angle also contains the anchor nuts to attach the forward screws.
The trailing edge of the panel is attached to a landing. It is attached to the forward edge of the lower skin of the torsion box. The landing is made of two back-to-back aluminum alloy angles.
2.4 mm (0.0945 in.) shear rivets, spacers and special washers hold this unit together. Smooth interfaces permit the landing angles to slide freely. The angle installed on the panel has a slotted hole for the rivet and the spacer. This permits the angle to move when the wing flexes and prevents that the rivet shears at an unwanted time. Also, the angle is castellated between the rivets to give a larger space for the air to flow through.
When all rivets of the panels 2, 3, 4 and 5 shear, a 75 mm (2.9528 in.) dia. steel restraining lanyard connects the two angles of the landing. On access panel 1 is no restraining lanyard as the largest possible area is required to let the air out.
The trailing edge of the panel and the landing are wet-assembled with sealant. This seals the trailing edge against air leakage.
B. Protection of the Pylon
Two types of pressure relief doors are installed:
Two types of pressure relief doors are installed:
- The one in the leading edge of the pylon (413BL,423BL) is spring loaded and made from titanium
- The one in the pylon/wing interface (471BL,482BR) is installed with shear rivets, a latch and a piano hinge. It is made of carbon honeycomb core in sandwich construction.
C. Protection of the Nacelles
A pressure relief door made of aluminum honeycomb is installed in the right fan cowl of the left and right engine. It protects the core compartment against a differential overpressure of 0.90 psi (0.06 bar). Two annealed lanyards limit the door travel and keep the door on the fan cowl if it opens. The door is manually latched. When the door opens during flight after an overpressure occurs, it does not latch again automatically if the overpressure decreases. You can see on the ground that the door is open.
A pressure relief door made of aluminum honeycomb is installed in the right fan cowl of the left and right engine. It protects the core compartment against a differential overpressure of 0.90 psi (0.06 bar). Two annealed lanyards limit the door travel and keep the door on the fan cowl if it opens. The door is manually latched. When the door opens during flight after an overpressure occurs, it does not latch again automatically if the overpressure decreases. You can see on the ground that the door is open.
5. Operation/Control and Indicating
A. Protection of the Wing Leading Edge
When a pneumatic or anti-icing duct leak occurs, the pressure in the wing fixed leading edge bay(s) of the wing(s) increases. This continues until the rivets which attach the two angles of the landing shear. Then the trailing edge of the access panel moves and the air flows overboard.
The pressure at which the rivets shear depend on:
If, after the access panel has 'blow down', a close inspection shows no damage, the panel and the landing can be used again. To install the access panel replace the attachment angle of the leading edge and the shear rivets.
When a pneumatic or anti-icing duct leak occurs, the pressure in the wing fixed leading edge bay(s) of the wing(s) increases. This continues until the rivets which attach the two angles of the landing shear. Then the trailing edge of the access panel moves and the air flows overboard.
The pressure at which the rivets shear depend on:
- The shape and the size of the access panel
- The number of rivets which hold the panel
- The rivet shear strength.
If, after the access panel has 'blow down', a close inspection shows no damage, the panel and the landing can be used again. To install the access panel replace the attachment angle of the leading edge and the shear rivets.
B. Protection of the Pylons
When a pneumatic duct in any area of the pylon breaks open or leaks, the pressure increases in this area. It continues up to a differential pressure of 0.20 bar (2.90 psi).
This causes:
The doors open and stay open to allow the overpressure to flow overboard.
When a pneumatic duct in any area of the pylon breaks open or leaks, the pressure increases in this area. It continues up to a differential pressure of 0.20 bar (2.90 psi).
This causes:
- The pressure to overcome the force of the spring on the doors 413BL and 432BL
- The rivets to shear on the doors 471BL and 482BR.
The doors open and stay open to allow the overpressure to flow overboard.
C. Protection of the Nacelles
When a pneumatic duct breaks open or has a large leak, the pressure in the nacelle zone increases. At a maximum differential overpressure of 2.90 psi (0.20 bar) the door opens automatically and the overpressure decreases.
When a pneumatic duct breaks open or has a large leak, the pressure in the nacelle zone increases. At a maximum differential overpressure of 2.90 psi (0.20 bar) the door opens automatically and the overpressure decreases.