Hydraulic Monitoring and Control Applications - HMCA S6

Reference: 29.00.00240 Issue date: 11-APR-2025 Last check date: 11-APR-2025 Status: Open
A/C type/serie: A350 ATA: 29-00
Engine manufacturer: Supplier:
Purpose / Reason for revision: ELEC PUMP START DM added and new CD filter chart
Engineering Support Status: Open

Applicability:

A350 -900 and -1000

References:

/Ref 1/: ISI 29.00.00224 - Hydraulic Monitoring and Control Applications (HMCA) STD5
/Ref 2/: TFU 29.10.00.057 - EDP overheat detection issue
Green Hydraulic System
/Ref 3/: AFI A350-A-29-31-XX-04002-421A-A - Clogged HP-Filter of the Green Engine Pump
/Ref 4/: AFI A350-A-29-31-XX-06001-421A-A - Clogged Case-Drain Filter of the Green Engine Pump
/Ref 5/: AFI A350-A-29-31-XX-0B001-421A-A - Clogged HP-Filter of the Green Electric Pump
/Ref 6/: AFI A350-A-29-31-XX-08001-421A-A - Clogged Filter of the Green Reservoir Return-Manifold
/Ref 7/: A350-A-29-11-XX-00001-560A-A - Deactivation of the Green Engine Pump (Engine Pump Disengagement)
Yellow Hydraulic System
/Ref 3/: AFI A350-A-29-31-XX-05002-421A-A - Clogged HP-Filter of the Yellow Engine Pump
/Ref 4/: AFI A350-A-29-31-XX-07001-421A-A - Clogged Case-Drain Filter of the Green Engine Pump
/Ref 5/: AFI A350-A-29-31-XX-0C001-421A-A - Clogged HP-Filter of the Yellow Electric Pump
/Ref 6/: AFI A350-A-29-31-XX-09001-421A-A - Clogged Filter of the Yellow Reservoir Return-Manifold
/Ref 7/: A350-A-29-13-XX-00001-560A-A - Deactivation of the Yellow Engine Pump (Engine Pump Disengagement)
/Ref 8/: TFU 24.70.00.005 - Inability to operate cargo doors linked to EPDC LRU failures
/Ref 9/: TFU 29.00.00.073 - Temperature Control valve spurious message
/Ref 10/: TFU 29.10.00068 - HMCA S6 DM CD Filter Clogging spurious message
Background:

The HMCA (Hydraulic Monitoring & Control Application) perform main control and monitoring functions, generate most interface
signals to other systems, and perform the system BITE.

 Following monitoring functions are available with HMCA:

 EDP HP (High Pressure) pressure monitoring

 EDP CD (Case Drain) pressure monitoring
 EDP CD temperature monitoring
 EDP clutch position monitoring
 EMP status monitoring
 EMP HP pressure monitoring
 Reservoir pressure monitoring
 Reservoir level monitoring
 Reservoir temperature monitoring
 Filters clogging monitoring (EDP HP, EDP CD, EMP HP and Return filter)
 Fire Shut-Off Valves (FSOV) position monitoring
 Temperature Control Valve (TCV) Monitoring
 Monitoring of Push Button (Cockpit, GSP)
 BITE

 Following control functions are available within HMCA:

 EDP depress control (manual and automatic, testing)

 EMP control & monitoring
  FSOV control (manual and automatic, testing)
 UERF Detection & protection Logic
 Manifold Isolation Valve control
 RSVR auto bleed control
 Tests and functions as part of the interactive BITE
 Cockpit P/B's illumination control

Description of improvements made with HMCA S6:

 Case Drain Temperature Sensors architecture compatibility

HMCA S6 allows compatibility to the Single Channel Temperature Transducer (Figure 1) and Dual Channel Temperature Transducer
(Figure 2) architectures which differ in terms of fitted equipment and wiring.
There are four CD temperature transducers installed on the aircraft, equipped on corresponding CD manifold on both Green
Hydraulic System (FIN 7JG1 and 7JG2) and Yellow Hydraulic System (FIN 7JY1 and 7JY2).

CD Manifold Temperature Sensor Configuration HMCA S4.2 HMCA S5 HMCA S6

Single Channel Sensor
X X
(PN 945193-61) installed on CD manifold P/N 945193-3
Dual Channel Sensor
X X
(PN 945193-80) installed on CD manifold P/N 945193-4

With HMCA S6 installation, all additional EDP case drain overheat protections fitted with HMCA S5 (Dual Channel architecture
only) will be available for both case drain temperature sensor architecture. Please refer to /Ref 1/ for improvements introduced
with HMCA S5.

The change from HMCA S4.2 to S6 will not require any hardware modification (except pin programming) as S6 will support single
channel temp sensor PN 945193-61. This improvement will be achieved through duplication of logics and modification of HW and
SW CPIOM PIN programming.

This new logic will support EDP CD temperature monitoring reliability. Thus, the CMR tasks introduced mandated via EASA AD
2018-0004 (/Ref 2/ for more information) will no longer be required.
 Figure 1 - Schematic of CD filter manifold with Single Channel Temperature Sensors Architecture Figure 2 - Schematic of CD filter manifold with Dual Channel Temperature Sensor Architecture

NOTE: (1) CD Pressure transducers / (2) Hydraulic Filter / (3) CD temperature transducer / (4) Hydraulic Heat Exchanger (HHX)
Bypass Valve (BPV) / (5) Check-Valves on outlet ports

 Filter Clogging Monitoring Improvement

HMCA S6 will improve the robustness of the filter clogging monitoring for all locations: EDP HP (High Pressure), EDP CD (Case
Drain), EMP HP (High Pressure) but also Return filter (LP – Low Pressure) elements.

The new filter clogging logics will take into account fluid viscosity changes due to temperature. The logics will integrate this new
parameter in order to adapt pressure drop monitoring (indicating potential restriction of the filter element, i.e. clogging) based
on the temperature of the fluid measured at the closest vicinity of the filter.

This improvement targets to reduce known spurious activation of #HYD FILTER CLOGGED# DM (Dispatch Messages) and avoid
operational impact.

In addition, the AFI (Aircraft Fault Isolation) related to filter clogging (/Ref 3/ to /Ref 6/ Rev. July 2022) have been improved in
order to allow re-installation of EDP HP, EDP CD, EMP HP and Return (LP) filter elements, if no metal particles found or damage.
Indeed, if a new filter element is not available, the procedure will require to remove and inspect the filter element:
 In case of damage or metal particles, the operator has to replace the filter and continue the procedure,
 If no finding, the filter can be reinstalled as is.
 Introduction of new Filter Clogging Alerting

In addition to the improvement of Hydraulic Filter Clogging monitoring logic, the introduction of new FWS S7/2.1 (Flight Warning
System) will alleviate ATA29 MMEL item linked to filter clogging (MMEL Item 29-09-02).
FWS S7/2.1 is introduced via SB 42-P017 and SB 42-P018 embodiment for the in-service fleet.

Dispatch Messages will be as follows with FWS S7/2.1 (refer to Figure 3):
 Existing DM #HYD FILTER CLOGGED# will now cover only EDP HP and EMP HP filter elements,
 New DM #HYD G(Y) ENG 1(2) CASE DRAIN FILTER CLOGGED# will be dedicated to the EDP Case-Drain filter elements,
 Existing DM #HYD G(Y) SYS RETURN FILTER# will remain unchanged and will still cover the return filter on the LP line.
 HMCA S4.2, S5 & S6 HMCA S5 & S6 with FWS
HMCA S4.2
with FWS S7/2.1 S7/2.1 since JAN 2025

EDP CD EDP CD EDP CD

HYD G(Y) ENG 1(2) CASE HYD G(Y) ENG 1(2) CASE
HYD FILTER CLOGGED DM
DRAIN FILTER DM DRAIN FILTER DM

MMEL NO GO MMEL GO IF MMEL GO

Figure 3 - New Dispatch Messages for CD filter clogging introduced with FWS S7/2.1 and MMEL update

Therefore, with these new Dispatch Messages, the MMEL Item will also be adapted:
 Existing DM #HYD G(Y) SYS RETURN FILTER# will remain unchanged and associated to MMEL Item 29-09-01
 Existing DM #HYD FILTER CLOGGED# will be associated to MMEL Item 29-09-02
 New DM #HYD G(Y) ENG 1(2) CASE DRAIN FILTER CLOGGED# will be associated to dedicated MMEL Item 29-09-03, linked
with the condition of associated EDP deactivation as per /Ref 7/.
 Engine Driven Pump (EDP) overpressure monitoring

With HMCA S6 a new monitoring will be put in place to raise a cockpit alert (via ECAM alert HYD ENG 1(2) G(Y) PMP FAULT
DUE TO PMP PRESS HI) in case of EDP outlet pressure too high.
The associated FCOM procedure request the crew to depressurize the pump on the overhead panel in order to mitigate the risk
of EDP malfunction or failure.

 System Low Temperature monitoring

This temperature monitoring will be active on aircraft equipped with HMCA S6 and FWS S7/2.1 and future standards.

This alert provides crew awareness that the G(Y) hydraulic system temperature is too low for aircraft dispatch due to a
performance impact. Insufficient hydraulic system fluid temperature could lead to degraded hydraulic performances during Take
Off and Climb flight phases, potentially impacting flight controls.

The alert will be indicated on the ECAM page (HYD G(Y) SYS TEMP LO) and will also be visible on the Cockpit Display System
(CDS) as shown on Figure 4 below.
 Figure 4 - Hydraulic System Low Temperature alert on the HYD SD page

Solutions and Improvements related to in-service issues with previous HMCA standards:

 Electric Motor Pump (EMP) Control Robustness Improvement

Issue summary

The Motor Control and Protection Unit (MCPU) provides control and protection of the connected EMP (one EMP per hydraulic
system). The MCPU detects all conditions and failure modes of the EMP causing unsafe operation, then triggers the inhibition of
the EMP operation in consequence and indicates faults to the HMCA.

With HMCA S4.2 and S5, in case of suspected failure or abnormal behavior by the MCPU, it prevents the usage of the EMP for
cargo doors automatic operation on ground.
Indeed, in case of failure of Electrical Power Distribution Center (EPDC) units, the input parameters of the MCPU status are set to
“Non Computed Data” (NCD). As a result, the MCPU prevents the EMP from starting when the crew attempts to operate the cargo
doors electrically. Please refer to /Ref 8/ for additional information.
A second scenario for EMP inhibition by the MCPU happens in case of input current with out of range frequency. EMP is supplied
with constant frequency current (400Hz) from APU or external Ground power Unit (GPU). In case the MCPU detects that the input
Alternating Current (AC) frequency is out of the valid range, then the MCPU shuts down the EMP, preventing to operate
automatically the cargo doors.
When switching ATA24 source between APU and GPU in ground, it creates a subsequent transient power loss which can lead to a
transient frequency fault detected by the MCPU. While this fault detection is self-resettable at MCPU level if current frequency is
back to its normal range, however the EMP fault is latched at HMCA level, independently of its root cause.
The associated maintenance message is FC 2900FF09 - RCCB-Y ELEC PUMP(1002JJ) / CTL UNIT ELEC PUMP,YELLOW(2JJ).

Solution

HMCA S6 will introduce new dispatch message to distinguish ATA29 internal and external failure (such as ATA24) that leads to an
inoperative EMP in order to improve operator awareness and create more accurate troubleshooting procedure.

Dispatch Messages for EMP issue will be as follows with HMCA S6:
 Existing DM #HYD G(Y) ELEC PMP# will remain unchanged in case of failed EMP.
 New DM #HYD G(Y) ELEC PMP START# will indicate an EMP inhibited by the MCPU due to external sources (e.g. ATA24) but
not declared as faulty.

Therefore, with these new Dispatch Messages, the MMEL Item will also be adapted:
 Existing DM #HYD G(Y) ELEC PMP# will remain unchanged and associated to MMEL Item 29-20-01 for Green EMP and 29-
20-02 for Yellow EMP (GO IF for 10 consecutive calendar days),
 New DM #HYD G(Y) ELEC PMP START# will be associated to dedicated MMEL Item, which will be GO (10 consecutive
calendar days).

To prevent EMP fault due to single EPDC failure, HMCA S6 will improve the logic to take into account EPDC LRU redundancy
parameters.

In addition, the MCPU frequency fault will be removed from the EMP fault detection HMCA logic to ensure that ATA24 source
switching between APU and GPU does not lead to a latched EMP fault, leading to inoperative EMP.
 Temperature Control Valve (TCV) spurious messages

Issue summary

Prior to the first engine start, spurious Maintenance Messages (MM) related to Temperature Control Valve (TCV – also known as
Heater Valves) have been found in the CMS data and when achieving a BITE scanning at the Onboard Maintenance Terminal
(OMT).

These messages are generated when the TCVs are open for heating the hydraulic circuit with EMP operation. Indeed the closure
detection of the TCV switch when the EMP is switched OFF is slower compared to the low pressure detection of the hydraulic
circuit, which triggers an alert due to disagreement between the two sources.

However, there is no operational impact to the above MM as there is no cockpit effect associated to these messages nor
required crew action. In addition, there is also no immediate maintenance or dispatch action associated to these messages.
Please refer to /Ref 9/ for more information.

Solution

With HMCA S6, the monitoring window for TCV failure will be reduced to engine start and engine spooldown phases in order to
avoid spurious triggering of these fault messages.
In addition, the monitoring logics will take into account additional parameters to increase the robustness of the logic.

 DM HYD G(Y) SYS MONITORING FAULT during engine spooldown

Issue summary

Some cases of spurious HYD G(Y) SYS MONITORING FAULT Dispatch Messages have been experienced during Engine
spooldown. It has been established that this phenomenon does not affect the integrity of the hydraulic system.

HMCA S5 introduced a safety test for FSOVs and EDPs depressurization which are executed at engine spool down to verify their
correct behavior. It had been noted that if the two HMCAs (per Green or Yellow) are not well synchronized when they start the
test, then the internal set up of logics could indicate a test failure and the above mentioned fault codes are triggered.
 For further information, please refer to /Ref 1/.

Mitigation

There is currently no direct mitigation possible to avoid HYD G(Y) SYS MONITORING FAULT. However, please find below few
good practices to reduce its risk such as:
– Do not restart the engines during Flight Phase 13 (i.e. in the 5 minutes following engine shutdown),
– Avoid to switch electrical power supply during the daily hydraulic tests, performed during Flight Phase 13.

These two situations could cause a potential desynchronization of HMCA Sides 1 & 2, leading to SYS MONITORING fault if this
disagreement lasts too long.

Solution

With HMCA S6 equipped, the daily FSOV and EDP tests will not consider HMCA disagreement as a failure cause of the test
anymore. The daily test will only be performed by the HMCA designated as master by the aircraft system for this flight. The
master/slave HMCA definition will swap at each flight cycle to be tested in alternating mode.
In addition, HMCA synchronizations issue due to incorrect data inputs sent by FADEC and other engines parameters will be
solved.

 SPURIOUS DM HYD ENG 1(2) G PMP at engine start

Issue summary

This DM can be triggered at engines start sequence in an aircraft where the TO CONFIG Pushbutton was pushed during the
aircraft flight until the phases 11 (Taxi-in) on the previous aircraft flight.

HMCA features an UERF (Uncontained Engine Rotor Failure) hydraulic protection logic which ensures operability of a hydraulic
system even if it is impacted by an UERF fragment from one engine by closing the FSOV for the EDP on the affected engine.
This protection is inhibited on ground in accordance with Flight Phases.
 If the TO CONFIG Pushbutton is pushed inadvertently (or jammed) before FP 11, FWS (Flight Warning System) resets the
current flight phase to flight phase 2, preventing the inhibition of the HMCA UERF logic for ground operation.
Thus, as soon as the first engine is shutdown (and thus associated EDP does not pressurize anymore the hydraulic system), the
low pressure signal observed on the aircraft will trigger the UERF logic and close the FSOV for the EDP on the affected engine.

This phenomenon is observed only on the Green System since UERF logic has not the same triggering condition on Green and
Yellow Hydraulic systems. Indeed, Yellow Hydraulic System Logic includes loss of specific electrical wires detected by ATA27
PFCS (Primary Flight Control System via PRIM 1, 2 and 3 computers) additionally to the EDP pressure drop.

In case of TO CONFIG P/B inadvertently pushed or jammed activated:

 There is no immediate cockpit effect at engine shutdown;
 Due to still active UERF hydraulic protection FSOV ENG G will be closed on engine that is shut down first;
 FSOV amber closed is displayed in the ATA29 HYD System Display;
 ISOL pushbutton illuminated on the overhead panel;
 CMS Dump will show Maintenance Message (MM) 2900F7X4, 2900F4CN (FMC 958) related to G ENG1 FSOV closure or
2900F4CP, 2900F7X5 (FMC 959) related to G ENG2 FSOV closure;
 Alert or Dispatch Message will appear only at next engine start.

For further information, please refer to /Ref 1/.

Solution

HMCA S6 will eliminate all dependencies of HMCA on the flight phase information coming from FWS (Flight Warning System) to
avoid spurious triggering of alerts.

In addition, the UERF activation conditions will be updated to use additional parameters from the engines and other ground status
parameters rather than the flight phase to ensure a more robust activation and deactivation logic and avoid known issues from
in-service experience.

 MM EDP LOW PRESS AFTER ENGINE RESTARTED

Issue summary

Few operators have reported that they were not able to pressurize the EDPs after engine shutdown and subsequent restart
following long taxi phase:
 There is no immediate cockpit effect at engine shutdown;
 Alert or Dispatch Message appear only at engine restart;
 HYD G+Y SYS PRESS LO alert appeared on the ECAM;
 All 4 EDPs were shown in amber as commanded OFF on the ATA 29 HYD System Display,
 EDPs depress pushbuttons illuminated on the overhead panel (Figure 5).

Figure 5 - All Green and Yellow EDPs pushbuttons with FAULT illuminated following EDP depressurization after engine restart

Indeed, in case of the engines being restarted during flight phase 13 (within 5 minutes after last engine shutdown), the flight
phase from FWS will change from 13 to 2 and skip the flight phase 1.
As a consequence, the depress command from the daily EDP depress test that had been performed at engine spool down will not
be reset within HMCA, leading to the EDP depress command remaining active and therefore, the hydraulic engine pumps cannot
be restarted.

Note: The daily EDP depress command will be triggered at engine shutdown, which is only allowed when flight phase is equal or
higher 11 (taxi in). Therefore, there is no risk of these symptoms during engine relight in flight.

Solution

HMCA S6 will eliminate all dependencies of HMCA on the flight phase information coming from FWS (Flight Warning System) to
avoid spurious triggering of alerts.
 WORDING OF EXPECTED P/B STATE IN I-BITE PRECONDITION SCREEN

Summary

HYD I-BITE may request certain preconditions to be fulfilled in order to start a test.

This includes the required state of certain pushbuttons on the ICP, eg ELEC PMP OFF P/B
The wording was changed and is now different to HMCA S5 and different to other systems.

Figure 7a: Wording of expected P/B state in I-BITE precondition screen

 Figure 7b: Wording of expected P/B state in I-BITE precondition screen

Further information:

The required P/B state of all HYD P/B is given in three redundant manners.

Example:
Make sure that the GND HYD/GREEN ELEC PMP pushbutton switch is not pushed (OFF legend off).

 State wording: ‘‘Pushed’’ / ‘’Released’’ � Not consistent to other systems.

 Additional information: “OFF legend off” / “OFF legend on” is correct.
 Color: Green/red indicating if the condition is fulfilled is correct.

Only the following I-BITE tests are affected

 Electric motor pump system test (EMP P/B)

  Engine 1(2) pump depressurization test (EDP P/B)
 System isolation valve test (EMP P/B)

The engine depressurization test also asks for certain P/B states of PRIM, FADEC and ENG MAN START.
These P/Bs are not monitored by HMCA (green/red indication) and the wording is “correct” (corresponding to other systems).

HMCA S6 availability

The certification of HMCA S6 is completed.

Flight Warning System Batch 7B (SB 42-P019 and SB 42-P020) will be a pre-requisite to HMCA S6 embodiment on aircraft.

The introduction of HMCA S6 on the A350 fleet will be the following:

 For production aircraft:

o Airbus has delivered the first A350 aircraft equipped with HMCA S6 in March 2024.

 For In-service aircraft:

o SB 29-P051 Mod 120342 will be dedicated for aircraft equipped with HMCA S4.2
o SB 29-P052 Mod 120343 will be dedicated for aircraft equipped with HMCA S5
o Both SB’s will be mandated by an EASA Airworthiness Directive with dedicated timeline for application.
 6 months timeline allowance after AD publication for SB 29-P051.
 12 months timeline allowance after AD publication for SB 29-P052.

EASA AD 2025-035 has been issued on the 12th Feb 2025 with an effective date set on the 26th February 2025.

SBs mentioned above were issued in October 2024. RIL V29M24001267 R1 has been issued to cover monitoring and industrial
support condition of the previously mentioned SBs.

Airbus recommends operators to anticipate installation of Flight Warning System Batch 7B in priority for aircraft installed with
HMCA S4.2.
 Spurious CD filter clogging has been reported in flight while there is no EDP misbehavior. TFU 29.10.00068 has been released in
that respect.

A wire PN mismatch has been identified in SB 29-P051 kit, SBIT 24-0065 has been issued to provide details on this issue.

Issues Identified with HMCA S6 embodiment

 Isolation valve stucked in open position

During production line it has been identified few cases of isolation valve found sucked in open position. This issue can be
reproduced with the following condition:
 EMPs manual start by pushing EMP P/B (panel 222VM), this action also commands the isolation valve in open position
 ACCU REINFLATE P/B is pushed on panel 115VM, this action would also start the EMP but not the isolation valve
 Attempt to manually stop the EMPs by releasing the P/B before the end of the 2 minutes timer of accumulator reinflation
 FC 2900F4E0 or 2900FF1E is trigged and latched

Above mentioned fault code can be cleared with relevant isolation valve BITE test.

 Return filter clogging DM HYD G(Y) SYS RETURN FILTER

Some report of Green return filter MM 2900F7W9 & 2900F4BT (DM HYD G SYS RETURN FILTER 2931H020) has been received further
to HMCA S6 embodiment via SB 29-P051/052. It is confirmed that a new logic has been implemented with HMCA S6, the clogging
rate is now dependent to hydraulic fluid temperature. As per customer experience, a one-time filter cartridge replacement fix the
issue. We recommend operator to have some return filter spare part once the above mentioned SBs are embodied.

 HYD G(Y) RSVR AIR BLEED DM

Multiple "HYD G RSVR AIR BLEED" and/or "HYD Y RSVR AIR BLEED" Dispatch Messages were reported on A/C fitted with HMCA S6.
Both Dispatch Messages may trigger on both Reservoir simultaneously. These Dispatch Messages may be associated to the following
fault codes: 2900F4DW, 2900F7YC, 2900FBGU and 2900FF1A. These fault codes may accuse the fact that the RSVR Auto Bleed
Valve did not detect the presence of Air for too many flight cycles. In-service return of experience showed that these fault codes
may trigger around 200 Flight Cycles which is very too early. Investigations are in progress and a discrepancy with the incrementation
of the counter is suspected.

As part of mitigations, Airbus recommend to perform the BITE Function of the Auto Bleed Valve (Reset of the Failure Counter) as
per MP Task A350-A-29-33-XX-01001-345A-A.
AFI Tasks associated to the previous fault codes is under revision.

 HYD ENG 1(2) G(Y) PMP DM with RELAY-ENG1(2) PUMP DEPRESS, GREEN (YELLOW) MM
Further to HMCA S6 via SB 29-P051 (from HMCA S4.2) some instance of HYD ENG 1(2) G(Y) PMP DM with one of the following fault
codes has been reported:
2900F4EW
2900F7ZC
2900FBHU
2900FF2A
2900F4EX
2900F7ZD
2900FBHV
2900FF2B

Analysis indicates a potential clogging of the Minimum flow orifice (MFO) check valve FIN 6120JM11, 6120JM12, 6120JM21 or
6120JM22.
Hence it is recommended to follow relevant AFI procedure (A350-A-29-11-XX-28ZZZ-421Z-A as example) and to only perform BITE
of the corresponding EDP depressurization function and to NOT replace the EDP (unless the previously mentioned BITE test failed).
The MFO shall be replaced or cleaned as per CMM 29-13-39 instead of replacing the corresponding EDP in order to avoid repetitive
fault code occurrence. AFI updated is attached to this ISI and is introducing MFO as a potential cause.

 HYD G(Y) ELEC PUMP START DM

Few instances of HYD G(Y) ELEC PMP START DM (2920H090 & 2920H110) has been reported during ENG start

This DM is reported only when the corresponding ELEC PMP is ON prior to ENG start.
This EMP start might be requested in the frame of MMEL 29-10-04A for HYD Y RSVR PRESS

DM triggered because of incorrect interface definition between HMCA and FWS

MMEL update is on-going to disregard HYD G(Y) ELEC PMP START DM when EMP is ON prior to engine start when in the frame of
MMEL 29-10-04A for HYD G(Y) RSVR PRESS. MMEL update is expected for April 2025 revision.

Survey for the Engineering Support section

Retrofits Monitoring Status: Open Retrofit Information Letter: YES

This modification is subject to an AIRBUS Monitored Retrofit.

Airbus Retrofit Information Letter is available.

It details retrofit process and material ordering.

For a complete list of monitored retrofits applicable to your fleet, please contact monitored.retrofit@airbus.com.

Survey for the Retrofits Monitoring section

 Annex

General Information
Potential impact: Operational Reliability
Key information:
Solution benefit:
First issue date: 11-AUG-2022 Issue date: 11-APR-2025 Last check date: 11-APR-2025

Technical parameters
ATA: 29-00
A/C type/serie: A350
Engine:
Engine manufacturer:
HYD > HYD G ELEC PMP START, HYD > HYD Y ELEC PMP START, PUMP-ENG 1,YELLOW(2JY1) / RELAY-ENG1 PUMP
DEPRESS,YELLOW(10JY1) / FIRE SOV-ENG 1,YELLOW(3JY1), PUMP-ENG 1,YELLOW(2JY1) / RELAY-ENG1 PUMP
DEPRESS,YELLOW(10JY1) / FIRE SOV-ENG 1,YELLOW(3JY1), PUMP-ENG1,GREEN(2JG1) / RELAY-ENG1 PUMP
Fault code/ECAM DEPRESS,GREEN(10JG1), PUMP-ENG1,GREEN(2JG1) / RELAY-ENG1 PUMP DEPRESS,GREEN(10JG1), PUMP-ENG2,GREEN(2JG2) /
warning: RELAY-ENG2 PUMP DEPRESS,GREEN(10JG2), PUMP-ENG2,GREEN(2JG2) / RELAY-ENG2 PUMP DEPRESS,GREEN(10JG2), PUMP-
ENG2,YELLOW(2JY2) / RELAY-ENG2 PUMP DEPRESS ,YELLOW(10JY2), PUMP-ENG2,YELLOW(2JY2) / RELAY-ENG2 PUMP
DEPRESS ,YELLOW(10JY2) / FIRE SOV-ENG 2,YELLOW(3JY2), VALVE-RSVR AUTO BLEED,GREEN(7JR1), VALVE-RSVR AUTO
BLEED,GREEN(7JR1), VALVE-RSVR AUTO BLEED,YELLOW(7JR2), VALVE-RSVR AUTO BLEED,YELLOW(7JR2)
FIN: 1JG1SW1, 1JG2SW1, 1JY1SW1, 1JY2SW1
Part Number:
Supplier:

Attachments
Engineering Support:
- ADVC_DME-FAPE3-ENV-A350-A-29-11-XX-28002-421A-A_001-01_SX-US.pdf
- ADVC_DME-FAPE3-ENV-A350-A-29-11-XX-28002-421A-A_001-01_SX-US.pdf
- ADVC_DME-FAPE3-ENV-A350-A-29-11-XX-29002-421A-A_001-01_SX-US.pdf
 - ADVC_DME-FAPE3-ENV-A350-A-29-13-XX-2D002-421A-A_001-01_SX-US.pdf
Retrofits Monitoring:
- RIL V29M24001267 R01.pdf
- RIL V29M24001267 R01 Appendix.xlsx

Links
Other articles (ISI/TFU):
- 24.70.00.005, 29.00.00249, 29.10.00068

© Airbus SAS, 2025. All rights reserved. Confidential and proprietary document.The technical information provided in this article is for convenience and information purposes only. It
shall in no case replace the official Airbus technical or Flight Operations data which shall remain the sole basis for aircraft maintenance and operation. These recommendations and
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