DOC AIRBUS | AMM A320FCheck of the Internal Leakage of the Power Transfer Unit (PTU)
TASK 29-00-00-280-004-A
Check of the Internal Leakage of the Power Transfer Unit (PTU)
To make sure that the internal leakage of the PTU is in limits.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment
B. Work Zones and Access Panels
C. Referenced Information
3. Job Set-up
Subtask 29-00-00-010-054-A Subtask 29-00-00-865-057-A
Subtask 29-00-00-280-065-B
Subtask 29-00-00-860-059-A
[Rev.10 from 2021]
2026.04.01 07:54:02 UTC
Check of the Internal Leakage of the Power Transfer Unit (PTU)
WARNING:
MAKE SURE THAT THE TRAVEL RANGES OF THE FLIGHT CONTROLS SURFACES ARE CLEAR. MOVEMENT OF FLIGHT CONTROLS CAN CAUSE INJURY TO PERSONS AND/OR DAMAGE TO EQUIPMENT.
1. Reason for the JobTo make sure that the internal leakage of the PTU is in limits.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment
| REFERENCE | QTY | DESIGNATION |
|---|---|---|
| No specific | 2 | FLOWMETER 20.00 L.MN (5.2833 US GAL.MN) |
| ZONE/ACCESS | ZONE DESCRIPTION |
|---|---|
| 197CB, 198CB |
| REFERENCE | DESIGNATION |
|---|---|
| TASK 24-41-00-861-002-A | Energize the Aircraft Electrical Circuits from the External Power |
| TASK 24-41-00-861-002-A-01 | Energize the Aircraft Electrical Circuits from the APU |
| TASK 24-41-00-861-002-A-02 | Energize the Aircraft Electrical Circuits from Engine 1(2) |
| TASK 24-41-00-862-002-A | De-energize the Aircraft Electrical Circuits Supplied from the External Power |
| TASK 24-41-00-862-002-A-01 | De-energize the Aircraft Electrical Circuits Supplied from the APU |
| TASK 24-41-00-862-002-A-02 | De-energize the Aircraft Electrical Circuits Supplied from the Engine 1(2) |
| TASK 29-10-00-863-001-A | Pressurize the Green Hydraulic System with a Hydraulic Ground Power-Cart |
| TASK 29-10-00-863-002-A | Pressurize the Yellow Hydraulic System with a Hydraulic Ground Power-Cart |
| TASK 29-10-00-864-001-A | Depressurize the Green Hydraulic System |
| TASK 29-10-00-864-002-A | Depressurize the Yellow Hydraulic System |
| TASK 29-23-41-000-001-A | Removal of the Green/Yellow Power Transfer Unit |
| TASK 29-23-41-400-001-A | Installation of the Green/Yellow Power Transfer Unit |
Subtask 29-00-00-010-054-A Subtask 29-00-00-865-057-A
B. Make sure that this(these) circuit breaker(s) is(are) closed:
Subtask 29-00-00-860-058-A | PANEL | DESIGNATION | FIN | LOCATION |
|---|---|---|---|
| ** ON A/C ALL | |||
| 121VU | HYDRAULIC/SOL VALVES/G/Y/B/LEAK/TST | 1881GP | N35 |
| 121VU | HYDRAULIC/SOL VALVES/G/Y/PTU | 1801GL | N34 |
C. Aircraft Maintenance Configuration
(1) Connect a ground service cart with a FLOWMETER 20.00 L.MN (5.2833 US GAL.MN), calibrated to +/- 1.5% over full range to the ground test connections of the Green and Yellow hydraulic systems.
(2) Energize the aircraft electrical circuits (Ref. AMM TASK 24-41-00-861-002).
(3) On the overhead panel 50VU, lift the guard and set the HYD/LEAK MEASUREMENT VALVES/G and HYD/LEAK MEASUREMENT VALVES/Y pushbutton switches (P/BSW) to off ( the OFF lights come on).
(4) On the overhead panel 40VU, set the PTU P/BSW to off (the OFF light comes on).
(5) Pressurize the Green and Yellow hydraulic systems (Ref. AMM TASK 29-10-00-863-001) (Ref. AMM TASK 29-10-00-863-002).
4. Procedure(1) Connect a ground service cart with a FLOWMETER 20.00 L.MN (5.2833 US GAL.MN), calibrated to +/- 1.5% over full range to the ground test connections of the Green and Yellow hydraulic systems.
(2) Energize the aircraft electrical circuits (Ref. AMM TASK 24-41-00-861-002).
(3) On the overhead panel 50VU, lift the guard and set the HYD/LEAK MEASUREMENT VALVES/G and HYD/LEAK MEASUREMENT VALVES/Y pushbutton switches (P/BSW) to off ( the OFF lights come on).
(4) On the overhead panel 40VU, set the PTU P/BSW to off (the OFF light comes on).
(5) Pressurize the Green and Yellow hydraulic systems (Ref. AMM TASK 29-10-00-863-001) (Ref. AMM TASK 29-10-00-863-002).
NOTE: The two systems should have the same pressure, or not more than 300 psi difference, and the PTU must not operate.
Subtask 29-00-00-280-065-B
A. Measurement of the Internal Leakage of the PTU
(1) Wait for the pressure and flow in the two systems to become stable.
(2) Monitor and write down the flow (called Q1) of the Green system and of the Yellow system.
(3) On the overhead panel 40VU, set the PTU P/BSW to on (the OFF light goes out).
(4) Monitor and write down the flow (called Q2) of the Green system and of the Yellow system.
(5) Subtract the value Q1 from the value Q2 for the two systems. The result must not be more than 3.5 l.min (0.92 USgal.mn) for the Yellow system and 0.9 l.min (0.24 USgal.mn) for the Green system.
(6) Example:
(7) If the internal leakage in the Green and/or Yellow side of the PTU is higher than the given limit, replace the PTU (Ref. AMM TASK 29-23-41-000-001) (Ref. AMM TASK 29-23-41-400-001).
5. Close-up(1) Wait for the pressure and flow in the two systems to become stable.
(2) Monitor and write down the flow (called Q1) of the Green system and of the Yellow system.
(3) On the overhead panel 40VU, set the PTU P/BSW to on (the OFF light goes out).
(4) Monitor and write down the flow (called Q2) of the Green system and of the Yellow system.
(5) Subtract the value Q1 from the value Q2 for the two systems. The result must not be more than 3.5 l.min (0.92 USgal.mn) for the Yellow system and 0.9 l.min (0.24 USgal.mn) for the Green system.
(6) Example:
| ------------------------------------------------------------------------------- |
| ! Yellow system Q1 (PTU OFF) = 2.7 l/min. ! |
| ! Yellow system Q2 (PTU ON ) = 6.0 l/min. ! |
| !-----------------------------------------------------------------------------! |
| ! Q2 - Q1 = 6.0 - 2.7 = 3.3 l/min (< 3.5 l/min) ! |
| !-----------------------------------------------------------------------------! |
| ! - PTU internal leakage (Yellow "side") in limits ! |
| ------------------------------------------------------------------------------- |
(7) If the internal leakage in the Green and/or Yellow side of the PTU is higher than the given limit, replace the PTU (Ref. AMM TASK 29-23-41-000-001) (Ref. AMM TASK 29-23-41-400-001).
Subtask 29-00-00-860-059-A
A. Put the aircraft back to the serviceable condition.
(1) Depressurize the Green and Yellow hydraulic systems (Ref. AMM TASK 29-10-00-864-001) (Ref. AMM TASK 29-10-00-864-002).
(2) On the overhead panel 50VU, lift the guard and set the HYD/LEAK MEASUREMENT VALVES/G and HYD/LEAK MEASUREMENT VALVES/Y P/BSW to on (the OFF lights go out).
(3) De-energize the aircraft electrical circuits (Ref. AMM TASK 24-41-00-862-002).
(4) Disconnect the ground hydraulic supply from the aircraft ground test connections.
(5) Install the blanking caps on the ground test connections.
Subtask 29-00-00-410-057-A (1) Depressurize the Green and Yellow hydraulic systems (Ref. AMM TASK 29-10-00-864-001) (Ref. AMM TASK 29-10-00-864-002).
(2) On the overhead panel 50VU, lift the guard and set the HYD/LEAK MEASUREMENT VALVES/G and HYD/LEAK MEASUREMENT VALVES/Y P/BSW to on (the OFF lights go out).
(3) De-energize the aircraft electrical circuits (Ref. AMM TASK 24-41-00-862-002).
(4) Disconnect the ground hydraulic supply from the aircraft ground test connections.
(5) Install the blanking caps on the ground test connections.