Low Pressure of the Power Transfer Unit (PTU) (Yellow to Green)

TASK 29-23-00-810-812-A
Low Pressure of the Power Transfer Unit (PTU) (Yellow to Green)

1. Possible Causes

PTU [1088GM]
MANIFOLD,PTU [1113GM]
MANIFOLD,PTU [3015GM]
CHECK VALVE-ENG 1 PUMP DELIVERY, G [1050GM]
CHECK VALVE-ENG 2 PUMP DELIVERY, Y [3050GM]
RELIEF VALVE G SYS [1063GM]
MANIFOLD,HP [1111GM]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 29-00-00-280-004	Check of the Internal Leakage of the Power Transfer Unit (PTU)
AMM 29-10-00-220-001	Functional Check to Monitor Internal Leak Rate of Yellow and Green Hydraulic Systems
AMM 29-11-14-000-001	Removal of the HP Manifold of the Green Hydraulic System
AMM 29-11-15-000-001	Removal of the Power Transfer Unit (PTU) Manifold of the Green Hydraulic System
AMM 29-11-15-400-001	Installation of the Power Transfer Unit (PTU) Manifold of the Green Hydraulic System
AMM 29-11-32-000-001	Removal of the Pressure Relief Valve of the Green Hydraulic System
AMM 29-11-36-000-001	Removal of the Engine 1 Green Hydraulic Pump Delivery Check Valve
AMM 29-11-36-400-001	Installation of the Engine 1 Green Hydraulic Pump Delivery Check Valve
AMM 29-13-15-000-001	Removal of the Power Transfer Unit (PTU) Manifold of the Yellow Hydraulic System
AMM 29-13-15-400-001	Installation of the Power Transfer Unit (PTU) Manifold of the Yellow Hydraulic System
AMM 29-13-36-000-001	Removal of the Engine 2 Yellow Hydraulic Pump Delivery Check Valve
AMM 29-13-36-400-001	Installation of the Engine 2 Yellow Hydraulic Pump Delivery Check Valve
AMM 29-23-00-710-003	Functional Check of the Power Transfer Unit (PTU) Yellow to Green
AMM 29-23-41-000-001	Removal of the Green/Yellow Power Transfer Unit
AMM 29-23-41-400-001	Installation of the Green/Yellow Power Transfer Unit

3. Fault Confirmation
Subtask 29-23-00-710-071-A

A. Do these tests:
(1) Do a check of the internal leakage of the Power Transfer Unit (PTU) AMM 29-00-00-280-004.
(2) If the internal leakage of the PTU is in the permitted limits:

do a functional check to monitor the internal leak rate of the Yellow and Green hydraulic systems AMM 29-10-00-220-001.

(3) If the internal leak rate of the Yellow and Green hydraulic systems is in the permitted limits:

do the operational test of the PTU AMM 29-23-00-710-003.
look for external leakage of the Yellow hydraulic system.

4. Fault Isolation
Subtask 29-23-00-810-064-B

A. If there is no external leakage and the pressure in the Green hydraulic system was less than 2100 psi during the operational test of the PTU:
- replace the PTU [1088GM] AMM 29-23-41-000-001 and AMM 29-23-41-400-001.
(1) If the fault continues:

replace the MANIFOLD,PTU [1113GM] AMM 29-11-15-000-001 and AMM 29-11-15-400-001.

(2) If the fault continues:

replace the MANIFOLD,PTU [3015GM] AMM 29-13-15-000-001 and AMM 29-13-15-400-001.

(3) If the fault continues:
(a) replace the CHECK VALVE-ENG 1 PUMP DELIVERY, G [1050GM] AMM 29-11-36-000-001 and AMM 29-11-36-400-001.
(b) Do the test in the Para. Fault Confirmation.
(4) If the fault continues:
(a) replace the CHECK VALVE-ENG 2 PUMP DELIVERY, Y [3050GM] AMM 29-13-36-000-001 and AMM 29-13-36-400-001.
(b) Do the test in the Para. Fault Confirmation.
(5) If the fault continues:
(a) Replace the RELIEF VALVE G SYS [1063GM] , AMM 29-11-32-000-001 and AMM 29-11-32-000-001
(b) Do the test in the Para. Fault Confirmation.
(6) If the fault continues:
(a) Replace the MANIFOLD,HP [1111GM] , AMM 29-11-14-000-001 and AMM 29-11-14-000-001

Subtask 29-23-00-710-072-A

B. Do the test as given in para. 3. to make sure that the operation is correct.

[Rev.8 from Aug 2018] 2026.04.04 04:29:29 UTC