DOC AIRBUS | AMM A320FFREE FALL EXTENSION - 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
** ON A/C NOT FOR ALL
1. General
A mechanical free-fall system extends the L/G if the normal extension and retraction system (Ref. AMM D/O 32-31-00-00) is not servicable.
The free-fall system releases the door and L/G uplocks. A mechanically operated valve isolates the hydraulic supply. Other mechanically operated valves let fluid move in the hydraulic components of the normal extension and retraction system. This prevents cavitation and hydraulic locks.
The L/G doors are opened by the L/G weight and aerodynamic force. Gravity extends the L/G, which is held and locked in the extended position. When the L/G is extended by the free-fall system, the L/G doors stay open.
When the control handle of the free-fall system is reset, the Green hydraulic system is pressurized. The L/G control lever can then be set to the DOWN position to close the L/G doors and set the L/G.
** ON A/C NOT FOR ALL A mechanical free-fall system extends the L/G if the normal extension and retraction system (Ref. AMM D/O 32-31-00-00) is not servicable.
The free-fall system releases the door and L/G uplocks. A mechanically operated valve isolates the hydraulic supply. Other mechanically operated valves let fluid move in the hydraulic components of the normal extension and retraction system. This prevents cavitation and hydraulic locks.
The L/G doors are opened by the L/G weight and aerodynamic force. Gravity extends the L/G, which is held and locked in the extended position. When the L/G is extended by the free-fall system, the L/G doors stay open.
When the control handle of the free-fall system is reset, the Green hydraulic system is pressurized. The L/G control lever can then be set to the DOWN position to close the L/G doors and set the L/G.
2. Component Location
** ON A/C NOT FOR ALL 
Free-Fall Extension| FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C NOT FOR ALL | |||||
| 2532GM | VENT VALVE-NLG | 124 | 32-33-14 | ||
| ** ON A/C ALL | |||||
| 2515GM | CUT OUT VALVE-L/G FREE FALL | 140 | 32-33-12 | ||
| 2516GM | VENT VALVE-MLG | 140 | 32-33-13 | ||
| ** ON A/C NOT FOR ALL | |||||
| 2532GM | VENT VALVE-NLG | 120 | 32-33-14 | ||
3. System Description
The free-fall extension-handle is at the rear of the cockpit center pedestal. A system of rods, cables and bellcranks connect the free-fall extension-handle to:
When the free-fall extension-handle is turned it operates the L/G components in the sequence that follows:
Shear devices protect the L/G system if either the L/G door or release mechanism jam when the free-fall system is operated.
The free-fall extension system has:
The free-fall extension-handle is at the rear of the cockpit center pedestal. A system of rods, cables and bellcranks connect the free-fall extension-handle to:
- the L/G door uplocks
- the L/G uplocks
- the vent valves and a cut-out valve.
When the free-fall extension-handle is turned it operates the L/G components in the sequence that follows:
- the cut-out valve closes to isolate the pressure supply and connect it to return
- the vent valves operate to bypass the normal L/G extension system
- the L/G and the L/G door uplocks release.
Shear devices protect the L/G system if either the L/G door or release mechanism jam when the free-fall system is operated.
The free-fall extension system has:
- a mechanical system in the MLG and NLG bays
- hydraulic components which have an interface with the Green hydraulic system.
A. Mechanical System
(1) MLG
In the RH MLG bay, the mechanical linkage connects to:
In the LH MLG bay, the mechanical linkage connects to:
In the RH MLG bay, the mechanical linkage connects to:
- the cut-out valve (2515GM)
- the MLG uplock (2510GM)
- the MLG door uplock (2520GM).
In the LH MLG bay, the mechanical linkage connects to:
- the MLG vent valve (2516GM)
- the MLG uplock (2509GM)
- the MLG door uplock (2521GM).
(2) NLG
In the NLG bay, the mechanical linkage connects to:
In the NLG bay, the mechanical linkage connects to:
- the vent valve (2532GM)
- the NLG uplock (2530GM)
- the NLG door uplock (2534GM).
(3) Uplocks
Refer to (Ref. AMM D/O 32-31-00-00) for the description and operation of these components:
Refer to (Ref. AMM D/O 32-31-00-00) for the description and operation of these components:
- the MLG uplock 2509GM (2510GM)
- the MLG door uplock 2521GM (2520GM)
- the NLG uplock 2530GM
- the NLG door uplock 2534GM.
B. Hydraulic Components
The hydraulic components in the free-fall extension system are:
The hydraulic components in the free-fall extension system are:
- a cut-out valve 2515GM
- a MLG vent valve 2516GM
- a NLG vent valve 2532GM.
(1) Cut-out Valve
The cut-out valve isolates the L/G hydraulic system from the Green hydraulic system supply and connects the L/G selector manifold to the hydraulic reservoir return.
The cut-out valve isolates the L/G hydraulic system from the Green hydraulic system supply and connects the L/G selector manifold to the hydraulic reservoir return.
(2) Vent Valve
Two ports on the vent valve connect to these components (Ref. AMM D/O 32-31-00-00):
The vent valve lets the hydraulic fluid move between the extension and retraction lines on some components, to prevent cavitation. It also lets any unwanted fluid go back to the reservoir through the third port on the vent valve.
The third port on the vent valve connects to the Green hydraulic system return.
Two ports on the vent valve connect to these components (Ref. AMM D/O 32-31-00-00):
- the L/G downlocks
- the L/G actuating cylinders
- the L/G door actuators
- the L/G uplocks.
The vent valve lets the hydraulic fluid move between the extension and retraction lines on some components, to prevent cavitation. It also lets any unwanted fluid go back to the reservoir through the third port on the vent valve.
The third port on the vent valve connects to the Green hydraulic system return.
4. Power Supply
A. Hydraulic Power Supply
The operation of the free-fall extension system isolates the Green hydraulic power system from the extension and retraction system.
The operation of the free-fall extension system isolates the Green hydraulic power system from the extension and retraction system.
B. Electrical Power Supply
The only electrical power used is for indication functions.
The only electrical power used is for indication functions.
** ON A/C NOT FOR ALL
6. Component Description
(1) Description
The L/G free-fall extension-handle assembly is at the rear of the cockpit center-pedestal. During the normal extension and retraction operations, the free-fall extension-handle is folded for storage.
The L/G free-fall extension-handle assembly is at the rear of the cockpit center-pedestal. During the normal extension and retraction operations, the free-fall extension-handle is folded for storage.
(2) Operation
When the free-fall extension-handle is rotated for three revolutions in a clockwise direction, it:
When the free-fall extension-handle is rotated for three revolutions in a clockwise direction, it:
- stops the high-pressure hydraulic supply and connects the L/G system to the reservoir return
- connects the L/G hydraulic-actuator 'retraction' chamber and the L/G door hydraulic-actuator 'close' chamber to the reservoir return
- releases the L/G door uplocks
- releases the L/G uplocks.
B. L/G Free-Fall Cut-out Valve FIN: 2515-GM
(1) Description
The mechanically operated cut-out valve is in the RH MLG bay, immediately upstream of the electro-hydraulic selector manifold.
There is a rigging hole for locking the input handle, to permit system rigging.
The valve has three hydraulic-port connections identified A, B and C:
The mechanically operated cut-out valve is in the RH MLG bay, immediately upstream of the electro-hydraulic selector manifold.
There is a rigging hole for locking the input handle, to permit system rigging.
The valve has three hydraulic-port connections identified A, B and C:
- port A is the hydraulic-pressure supply inlet
- port B is the hydraulic-pressure supply to the L/G selector manifold
- port C is the hydraulic-reservoir return connection.
(2) Operation
During a L/G normal extension and retraction operation, the cut-out valve port A is open to port B so that hydraulic power is supplied to the L/G selector manifold.
During a L/G free-fall extension, the cut-out valve closes port A, before it opens port B to port C and connects the L/G selector manifold to the hydraulic reservoir.
During a L/G normal extension and retraction operation, the cut-out valve port A is open to port B so that hydraulic power is supplied to the L/G selector manifold.
During a L/G free-fall extension, the cut-out valve closes port A, before it opens port B to port C and connects the L/G selector manifold to the hydraulic reservoir.
C. Vent Valve FIN: 2516-GM FIN: 2532-GM
(1) Description
There are two mechanically-operated vent valves (of the same type) in the L/G free-fall extension system, one for the MLG and one for the NLG. The MLG vent valve is in the LH MLG bay. The NLG vent valve is in the NLG bay, to the left and forward of the NLG uplock.
There is a rigging hole for locking the input handle in the closed position, to permit system rigging.
Each vent valve has three hydraulic-port connections identified A, B and C:
There are two mechanically-operated vent valves (of the same type) in the L/G free-fall extension system, one for the MLG and one for the NLG. The MLG vent valve is in the LH MLG bay. The NLG vent valve is in the NLG bay, to the left and forward of the NLG uplock.
There is a rigging hole for locking the input handle in the closed position, to permit system rigging.
Each vent valve has three hydraulic-port connections identified A, B and C:
- port A is the L/G door close line
- port B is the L/G lift line
- port C is the hydraulic-reservoir return line.
(2) Operation
During a L/G normal extension and retraction operation, ports A and B are closed. The internal leakage vents to return through port C.
During a L/G free-fall extension, the operation of the vent valve opens ports A and B to port C so that hydraulic fluid returns to the reservoir.
During a L/G normal extension and retraction operation, ports A and B are closed. The internal leakage vents to return through port C.
During a L/G free-fall extension, the operation of the vent valve opens ports A and B to port C so that hydraulic fluid returns to the reservoir.
7. Operation/Control and Indicating
A. Operation/Control
A handle assembly on the cockpit center-pedestal controls the L/G free-fall extension. When operated, it starts (through a system of cables and mechanical links) the sequence that follows:
After landing with free-fall extension, it is necessary to make the L/G and the L/G doors safe (Ref. AMM D/O 32-00-00-00).
With the aircraft in flight, the L/G system can be put back to its normal extension and retraction mode from a free-fall extension test. The L/G control handle must be set to DOWN and the L/G free-fall extension-handle put to its stowed position. The cut-out valve connects the green hydraulic supply to the landing gear selection manifold and the vent valves close ports A and B. Hydraulic power is therefore supplied for normal operation.
A handle assembly on the cockpit center-pedestal controls the L/G free-fall extension. When operated, it starts (through a system of cables and mechanical links) the sequence that follows:
| CONDITION ACTION |
| 1. The cut-out valve operates - the pressure supply line closes |
| - the L/G hydraulic-supply system |
| is connected to return. |
| 2. The NLG and MLG vent valves - the hydraulic fluid from the door |
| open actuator 'close' chamber and |
| the L/G actuator 'retraction' |
| chamber goes to the reservoir. |
| 3. The L/G door uplocks release - the L/G doors open. |
| 4. The NLG and MLG uplocks - the NLG and MLG extends. |
| release |
| 5. The check valve operates - the supply of hydraulic fluid to |
| the L/G actuator 'extension' |
| chambers is increased, to prevent |
| cavitation. |
After landing with free-fall extension, it is necessary to make the L/G and the L/G doors safe (Ref. AMM D/O 32-00-00-00).
With the aircraft in flight, the L/G system can be put back to its normal extension and retraction mode from a free-fall extension test. The L/G control handle must be set to DOWN and the L/G free-fall extension-handle put to its stowed position. The cut-out valve connects the green hydraulic supply to the landing gear selection manifold and the vent valves close ports A and B. Hydraulic power is therefore supplied for normal operation.
B. Indicating
There is no special indication for the position of the L/G in the free-fall extension mode. The L/G doors will show OPEN when the free-fall extension system is used. The other indications in the cockpit are the same as those for the normal extension and retraction system. These are:
There is no special indication for the position of the L/G in the free-fall extension mode. The L/G doors will show OPEN when the free-fall extension system is used. The other indications in the cockpit are the same as those for the normal extension and retraction system. These are:
- the WHEEL page on the System Display (SD)
- the L/G downlock indicator on panel 402VU
- the light on the L/G control lever 6GA comes on (Ref. AMM D/O 32-61-00-00).
- L/G DOOR NOT CLOSED
- MAX SPEED 250 kt.
8. BITE Test
Not applicable
Not applicable