# Airbus All Operators Transmission A27P021-25 Copy: Revision 1 ("AOT_A27P021_25_r01"), 14 pages: PDF https://openairdocs.org/files/sha256/b9/88/b988eb7a8e358dc6f1ab9e80ce0420c3f9e306f6082d0c282e19bff0112b5aff; text https://openairdocs.org/service-documents/airbus/aot-a27p021-25/file/b988eb7a8e35.md. Rights: © Airbus S.A.S. Filed by the FAA in regulations.gov docket FAA-2025-5390, the docket of AD 2025-25-12. Not covered by OpenAirDocs’ CC0 dedication. ## Details - Manufacturer: [Airbus](https://openairdocs.org/service-documents/airbus.md) - Type: Other document (All Operators Transmission) - Number: A27P021-25 - Latest revision known: A27P021-25, Revision 1, dated June 4, 2025 (OpenAirDocs) - Page: https://openairdocs.org/service-documents/airbus/aot-a27p021-25 ## Text (14 pages) Rights: © Airbus S.A.S. Filed by the FAA in regulations.gov docket FAA-2025-5390, the docket of AD 2025-25-12. Not covered by OpenAirDocs’ CC0 dedication. Each page's text from the PDF; open the PDF at a page with #page=N. ### Page 1 Airbus Amber CUSTOMER SERVICES DIRECTORATE 2 ROND POINT EMILE DEWOITINE 31700 BLAGNAC FRANCE TELEPHONE + 33 (0)5 61 93 33 33 ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27P021-25 Rev 01 Page 1 of 14 Date: 04-JUN-2025 C80_AOT_FM1104649_v9.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT SUBJECT: ATA 27 – FCRM Contamination due to Hydraulic fluid ingress AIRCRAFT TYPE: A350 OUR REF.: A27P021-25 Rev 01 dated 04 JUN 2025 OUR PREV REF.: A27P021-25 Rev 00 dated 30 APR 2025 EFFECTIVITY DATE: 06-Jun-2025 Export Control: Not technical 0. REASON FOR REVISION The reasons for this AOT revision are to: Request removals of 22 FCRMs which were exposed to hydraulic leak prior to A/C delivery. Clarify way forward in case of servocontrol leakage from dynamic seal (including weep hole) within limits of the MP Task for “Check of the Hydraulic Components for External Leakage” from AOT Rev 00 effective date. Include the inspection §5.4 as Required for Compliance (RC) Add MP Task for swapping of the FCRM of the Spoiler ServoControl (SC) and the Outboard Aileron SC as Ref. 11. Add ATA 29 MP Task procedure for Check of the Hydraulic Components for External Leakage as Ref. 12. Update the impact on documentation in §6.2: oTemporary remove from AirnavX publication of Ref. 5 MP task for swapping of FCRM of the Elevator SC and the Inboard Aileron SC oTemporary remove from AirnavX publication of Ref. 6 MP task for swapping of FCRM of the Elevator SC and the Outboard Aileron SC oTemporary deletion in Ref.7 of swapping of the FCRM of: the Elevator SC and the Spoiler 1 SC and the Rudder SC and the Spoiler 1 SC oTemporary revision of Ref 12. to be in accordance with the AOT. The revised paragraphs are indicated between ***BEG REV*** and ***END REV***. The Appendixes 01 and 02 are not modified. The Appendix 03 is modified to: - correct the Reporting Sheet (only removed component information are requested) - to add reporting of FCRM removals in case of leakages prior A/C delivery. The Appendixes 04, 05 and 06 are added to include flowcharts in cases of leakages from Servocontrol from AOT issuance date respectively for the upper rudder SC FIN 1CY, mid rudder SC FIN 2CY and both elevator SC FIN 1CTx. A note has been added to clarify that flowcharts are only for information. The Appendix 07 is added to provide the list of the 22 FCRMs exposed to hydraulic fluid prior to A/C delivery. ### Page 2 Airbus Amber ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27P021-25 Rev 01 Page 2 of 14 Date: 04-JUN-2025 C80_AOT_FM1104649_v9.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT 1. AIRCRAFT AFFECTED A/C type Serie A350 A350-900 A350 A350-1000 2. REFERENCED DOCUMENTATION Reference 1: MP Task A350-A-27-24-53-A1ZZZ-520Z-A Removal of the Flight Control Remote Module (FCRM) of the Rudder Servocontrol Reference 2: MP Task A350-A-27-24-53-A1ZZZ-720Z-A Installation of the Flight Control Remote Module (FCRM) of the Rudder Servocontrol Reference 3: MP Task A350-A-27-34-53-A1ZZZ-520Z-A Removal of the Flight Control Remote Module (FCRM) of the Elevator Servocontrol Reference 4: MP task A350-A-27-34-53-A1ZZZ-720Z-A Installation of the Flight Control Remote Module (FCRM) of the Elevator Servocontrol Reference 5: MP Task A350-A-27-XX-XX-A4ZZZ-921A-A Swapping of the Flight Control Remote Modules (FCRM) of the Elevator Servo Control(s) and the Inboard Aileron Servo-Control(s) Reference 6: MP Task A350-A-27-XX-XX-A2ZZZ-921A-A Swapping of the Flight Control Remote Modules (FCRM) of the Elevator Servo Control(s) and the Outboard Aileron Servo-Control(s) Reference 7: MP Task A350-A-27-XX-XX-A0ZZZ-921A-A Swapping of the Flight Control Remote Modules (FCRM) of the Aileron, the Rudder and the Elevator Servocontrols Reference 8: MP Task A350-A-27-XX-XX-A3ZZZ-921A-A Swapping of the Flight Control Remote Modules (FCRM) of the Spoiler Servo Control(s) and the Inboard Aileron Servo-Control(s) Reference 9: SB 42-P020 INTEGRATED MODULAR AVIONICS - BATCH 7B - PART 2. Reference 10: TFU 27.00.00129 FCRM Contamination due to Hydraulic fluid ingress ***BEG REV*** Reference 11: MP Task A350-A-27-XX-XX-A1ZZZ-921A-A - Swapping of the Flight Control Remote Modules (FCRM) of the Spoiler Servo Control(s) and the Outboard Aileron Servo-Control(s) Reference 12: MP Task A350-A-29-XX-XX-ZZZZZ-360A-A - Check of the Hydraulic Components for External Leakage ***END REV*** 2.1 APPENDIX: Appendix-01: Rev00-FC1-A27P021-25 Rudder Flowchart Inspection and Replacement Appendix-02: Rev00-FC2-A27P021-25 Elevator Flowchart Inspection and Replacement ***BEG REV*** Appendix-03: Rev01-RS1-A27P021-25 Rudder and Elevator Reporting Sheet Appendix-04: Rev00-FC3-A27P021-25 Rudder 1CY FlowChart Inspection and replacement from AOT Rev01 effective date Appendix-05: Rev00-FC4-A27P021-25 Rudder 2CY FlowChart Inspection and replacement from AOT Rev01 effective date Appendix-06: Rev00-FC5-A27P021-25 Elevator 1CTx FlowChart Inspection and replacement from AOT Rev01 effective date Appendix-07: Rev00-SL-A27P021-25 List of SC exposed prior to A/C Delivery ***END REV*** ### Page 3 Airbus Amber ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27P021-25 Rev 01 Page 3 of 14 Date: 04-JUN-2025 C80_AOT_FM1104649_v9.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT 3. REASON ***BEG REV*** The reason of this AOT is: to provide instructions in case of current installed Rudder and Elevator FCRM exposed to a hydraulic leak (before to AOT Rev00 issuance and from AOT Rev00 effective date) To forbid the FCRM swapping operations between Elevator or Rudder and another positions (spoiler or aileron) from AOT Rev00 effective date. ***END REV*** 3.1 FACTS Airbus informs the operator that, further to the loss of control of an outboard aileron surface, one FCRM (Flight Control Remote Module) has been removed and found contaminated by a hydraulic fluid ingress during shop investigation. 3.2 HISTORY/BACKGROUND This event is related to an in-service occurrence that led to the loss of control of an outboard aileron surface in flight and for which a specific investigation has been done by the supplier. 3.3 ROOT CAUSE The most probable root cause of the FCRM hydraulic fluid contamination is a prolonged contact of hydraulic fluid with the FCRM seal leading to a functional degradation of the seal (loss of tightness). The difference of pressure experienced during the flight cycles accumulation would then allow hydraulic fluid ingress inside the cover, leading to hydraulic fluid coming into contact with the FCRM electronic card. The presence of hydraulic fluid at this location around the seal of the FCRM connector could be attributed to a hydraulic leakage coming from this servocontrol at the level of its accumulator probe but could also come from older hydraulic leakages in the vicinity. 3.4 INVESTIGATION Investigations of this unit at supplier level have shown that the electronic card of the FCRM was contaminated by hydraulic fluid. Analysis of in-service shop findings reports identified that some other servocontrol types, fitted on other surfaces, experienced similar hydraulic ingress contaminating the FCRM electronic card. However, among the other contaminated FCRM, no systematic failures were observed (as some FCRMs were still operational, other faulty but with no link with the contamination) Airbus analysis shows that two sources of hydraulic contamination could lead to such ingestion: either a hydraulic leakage coming from the servocontrol; or a leakage of the hydraulic circuit close to the servocontrol. 3.5 CONSEQUENCES The contamination of the FCRM circuitry can generate functional failures of the FCRM leading to the loss of the affected servocontrol (transition to damping mode). In some very specific cases this could also lead to the undue switching to active mode and to potential runaway of the affected surface. ### Page 4 Airbus Amber ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27P021-25 Rev 01 Page 4 of 14 Date: 04-JUN-2025 C80_AOT_FM1104649_v9.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT The consequence at aircraft level depends on the affected surface: For Aileron and Spoiler: control of the aircraft can be maintained through the use of other control surfaces For Elevator and Rudder: control of the aircraft may be significantly degraded and there is the risk of structural damages 4. OBJECTIVES OF THIS AOT The objective of this AOT is to provide instructions as follows: To Inspect Maintenance records of current rudder and elevator FCRM to look for previous hydraulic leakages and to replace potential contaminated FCRMs not yet removed post hydraulic leaks. ***BEG REV*** To provide instructions in case of hydraulic leakage affecting Elevator or Rudder FCRM from AOT Rev01 effective date: oHydraulic leakage from hydraulic circuit oHydraulic leakage from servocontrol and within Normal Operation Limit oHydraulic leakage from servocontrol and above Normal Operation Limit but within Dispatch Limit oHydraulic leakage from servocontrol and above Dispatch Limit To forbid the FCRM swapping operations between Elevator or Rudder and another positions (spoiler or aileron) from AOT Rev00 effective date. To replace FCRMs that were exposed to hydraulic leakages prior to A/C delivery. ***END REV*** 5. MAINTENANCE PROCEDURE NOTE: This AOT is classified mandatory or expected to be classified mandatory by an Airworthiness Directive (AD). If the instructions of this AOT are marked as Required for Compliance (RC), the operator must follow the instructions as indicated. These instructions are introduced by “in accordance with”. NOTE: The instructions of this AOT include procedures given in other documents or in other sections of the AOT. If the instructions of this AOT are NOT marked as Required for Compliance (RC), the operator can use an alternative procedure accepted by his/her local authority. These instructions are introduced by “refer to”. NOTE: When this AOT gives the access or close-up instructions with no return to service tests, the operator can adapt these instructions to add flexibility to the maintenance operations. The technical intent of this AOT must comply with the set parameters. 5.1 PLANNING – (RC) Affected units are detailed on section 5.4: ***BEG REV*** FCRM exposed to hydraulic fluid after MSN delivery (Section 5.4.1) and before AOT Rev00 effective date must be removed from aircraft no later than 31 May 2025 FCRM with missing history since last shop visit (Section 5.4.3) must be removed from aircraft no later than 31 May 2025 FCRM exposed to hydraulic fluid from AOT Rev00 effective date (Section 5.4.2) must be removed from aircraft before next flight ***END REV*** ### Page 5 Airbus Amber ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27P021-25 Rev 01 Page 5 of 14 Date: 04-JUN-2025 C80_AOT_FM1104649_v9.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT ***BEG REV*** FCRM exposed to hydraulic fluid prior to A/C delivery (Section 5.4.4) must be removed from aircraft no later than 30 June 2025 ***END REV*** 5.2 MANPOWER The estimated time to perform complete FCRM replacement is: access opening/closing: 2 hours elapsed time FCRM replacement: 1 hour elapsed time 5.3 ACCESS For affected units to be removed, get access to this FCRM, refer to “job setup” paragraph per Ref. 1, 2, 3 or 4 MP task as required. ***BEG REV*** 5.4 INSPECTION - (RC) ***END REV*** An affected unit is: 5.4.1 - An elevator or rudder FCRM (PN CA71323-0ZZ) currently fitted on A/C that was exposed, on that aircraft, to hydraulic fluid since A/C delivery: either due to a hydraulic fluid leak from the hydraulic circuit (flexible or rigid pipes or any other spillage occurred during maintenance activities) close to the FCRM/Servocontrol. or for FCRM of the rudder green, due to a hydraulic leak coming from the rudder yellow servocontrol To perform the mapping of the affecting units, maintenance records have to be used. ***BEG REV*** 5.4.2 - An elevator or rudder FCRM (PN CA71323-0ZZ) exposed to a hydraulic fluid from the AOT Rev00 effective date: either due to a hydraulic fluid leak from the hydraulic circuit (flexible or rigid pipes or any other spillage occurred during maintenance activities) close to the FCRM/Servocontrol. or for FCRM of the rudder green, due to a hydraulic leak coming from the Rudder Yellow servocontrol ***END REV*** 5.4.3 - An elevator or rudder FCRM (PN CA71323-0ZZ) currently fitted on A/C and for which its history since last shop visit cannot be reconstructed (eg. further to swap, etc…) ***BEG REV*** 5.4.4 - An elevator or rudder FCRM (PN CA71323-0ZZ) initially installed on a servocontrol listed on Appendix 07 from delivery. ***END REV*** 5.5 FINDINGS ***BEG REV*** The flowcharts available on Appendix 01, 02, 04, 05 and 06 supplement the information given in this section and are not the primary source for the instruction or the compliance times given in this AOT. ***END REV*** ### Page 6 Airbus Amber ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27P021-25 Rev 01 Page 6 of 14 Date: 04-JUN-2025 C80_AOT_FM1104649_v9.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT ***BEG REV*** For Rudder FCRM exposed to Hydraulic leak prior to AOT Rev00 issuance (Appendix 01): ***END REV*** In case of hydraulic leak recorded close to Servocontrol FIN 1CY: If current installed FCRM FIN 201CY has not been replaced since the observation of the leak, then the FCRM FIN 201CY has to be replaced. If current FCRM FIN 202CY has not been replaced since the observation of the leak, then the FCRM FIN 202CY has to be replaced. In case of hydraulic leak recorded close to Servocontrol FIN 2CY: If current installed FCRM FIN 202CY has not been replaced since the observation of the leak, then the FCRM FIN 202CY has to be replaced. In case of hydraulic leak recorded coming from the Servocontrol FIN 1CY: If current installed FCRM FIN 202CY has not been replaced since the observation of the leak, then the FCRM FIN 202CY has to be replaced. As per Airbus maintenance standard practices, Servocontrol FIN 1CY (including FCRM FIN 201CY) needs to be replaced to fix the leak. If not previously removed, complete Servocontrol FIN 1CY has to be replaced. In case of hydraulic leak recorded coming from the servocontrol FIN 2CY: As per Airbus maintenance standard practices, Servocontrol FIN 2CY (including FCRM FIN 202CY) needs to be replaced to fix the leak. If not previously removed, complete Servocontrol FIN 2CY has to be replaced. In case of current rudder FCRM previously installed on other positions since last shop visit: If current installed FCRM FIN 201CY (resp. FIN 202CY) was exposed to hydraulic leak on a previous position and swapped with the rudder after the recorded leak, then the FCRM FIN 201CY (resp. FIN 202CY) has to be replaced. If current installed FCRM FIN 201CY (resp. FIN 202CY) history cannot be reconstructed since last shop visit, then FCRM FIN 201CY (resp. FIN 202CY) has to be replaced. Rudder Inspection results and FCRM replacement information (with or without findings) have to be reported to Airbus using Reporting Sheet available on Appendix 03 ***BEG REV*** For Elevator FCRM exposed to Hydraulic leak prior to AOT Rev00 issuance (Appendix 02) ***END REV*** In case of hydraulic leak recorded close to Servocontrol FIN 1CT1: if current installed FCRM FIN 201CT1 has not been replaced since the observation of the leak, then the FCRM FIN 201CT1 has to be replaced. In case of hydraulic leak recorded close to Servocontrol FIN 1CT2: if current installed FCRM FIN 201CT2 has not been replaced since the observation of the leak, then the FCRM FIN 201CT2 has to be replaced. In case of hydraulic leak recorded coming from the servocontrol FIN 1CT1: As per Airbus maintenance standard practices, Servocontrol FIN 1CT1 (including FCRM 201CT1) need to be replaced to fix the leak. If not previously removed, complete Servocontrol FIN 1CT1 has to be replaced. ### Page 7 Airbus Amber ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27P021-25 Rev 01 Page 7 of 14 Date: 04-JUN-2025 C80_AOT_FM1104649_v9.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT In case of hydraulic leak recorded coming from the servocontrol FIN 1CT2: As per Airbus maintenance standard practices, Servocontrol FIN 1CT2 (including FCRM 201CT2) need to be replaced to fix the leak. If not previously removed, complete Servocontrol FIN 1CT2 has to be replaced. In case of current elevator FCRM previously installed on other positions since last shop visit: If current installed FCRM FIN 201CT1 (resp. FIN 201CT2) was exposed to hydraulic leak on a previous position and swapped with the elevator after the recorded leak, then the FCRM FIN 201CT1 (resp. FIN 201CT2) has to be replaced If current installed FCRM FIN 201CT1 (resp. FIN 201CT2) history cannot be reconstructed since last shop visit, then FCRM FIN 201CT1 (resp. FIN 201CT2) has to be replaced Elevator Inspection results and FCRM replacement information (with or without findings) have to be reported to Airbus using Reporting Sheet available on Appendix 03 ***BEG REV*** For Rudder or Elevator FCRM exposed to hydraulic from AOT Rev01 effective date (Appendix 04, 05 and 06) Leak close to Servocontrol In case of hydraulic leak close to Servocontrol FIN 1CY: on top of the maintenance actions to fix the leak from hydraulic circuit, FCRM FIN 201CY and 202CY have to be replaced before next flight In case of hydraulic leak close to Servocontrol FIN 2CY: on top of the maintenance actions to fix the leak from hydraulic circuit, FCRM FIN 202CY has to be replaced before next flight In case of hydraulic leak close to Servocontrol FIN 1CT1: on top of the maintenance actions to fix the leak from hydraulic circuit, FCRM FIN 201CT1 has to be replaced before next flight In case of hydraulic leak close to Servocontrol FIN 1CT2: on top of the maintenance actions to fix the leak from hydraulic circuit, FCRM FIN 201CT2 has to be replaced before next flight Leak coming from Servocontrol within Ref. 12 normal operation limit In case of hydraulic leak coming from Servocontrol FIN 1CY below Ref. 12 normal operation limit (Refer to Appendix 04): if FCRMs does not show evidences of hydraulic contamination: oBefore next flight: FCRM FIN 201CY and 202CY have to be replaced and Servocontrol FIN 1CY has to be cleaned FCRM FIN 201CY and 202CY have to be inspected after 500FH and no later than 700FH from FCRMs replacement: If no trace of hydraulic is observed, there is no further action to be done If trace of hydraulic fluid is observed and SC PN CA67007-ZZZ spare is available, replace SC FIN 1CY and FCRM FIN 202CY before next flight If trace of hydraulic fluid is observed and SC PN CA67007-ZZZ spare is not available, replace FCRM FIN 201CY and 202CY and clean SC FIN 1CY before next flight and then repeat the inspection of the FCRMs at intervals between 500FH and 700FH ### Page 8 Airbus Amber ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27P021-25 Rev 01 Page 8 of 14 Date: 04-JUN-2025 C80_AOT_FM1104649_v9.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT if FCRM shows evidences of hydraulic contamination: oif SC PN CA67007-ZZZ spare is available, replace SC FIN 1CY and FCRM FIN 202CY before next flight oif SC PN CA67007-ZZZ spare is not available: Before next flight: FCRM FIN 201CY and 202CY have to be replaced and Servocontrol FIN 1CY has to be cleaned: FCRM FIN 201CY and 202CY have to be inspected after 500FH and no later than 700FH from FCRMs replacement: If no trace of hydraulic is observed, there is no further action to be done If trace of hydraulic fluid is observed and SC PN CA67007- ZZZ spare is available, replace SC FIN 1CY and FCRM FIN 202CY before next flight If trace of hydraulic fluid is observed and SC PN CA67007- ZZZ spare is not available, replace FCRM FIN 201CY and 202CY and clean SC FIN 1CY before next flight and then repeat the inspection of the FCRMs at intervals between 500FH and 700FH In case of hydraulic leak coming from Servocontrol FIN 2CY below Ref. 12 Normal Operation limit (Refer to Appendix 05): if FCRM does not show evidences of hydraulic contamination: oBefore next flight: FCRM FIN 202CY has to be replaced and Servocontrol FIN 2CY has to be cleaned FCRM FIN 202CY has to be inspected after 500FH and no later than 700FH from FCRM replacement: If no trace of hydraulic is observed, there is no further action to be done If trace of hydraulic fluid is observed and SC PN CA67007-ZZZ spare is available, replace SC FIN 2CY before next flight If trace of hydraulic fluid is observed and SC PN CA67007-ZZZ spare is not available, replace FCRM FIN 202CY and clean SC FIN 2CY before next flight and then repeat the inspection of the FCRM at intervals between 500FH and 700FH if FCRM shows evidences of hydraulic contamination: oif SC PN CA67007-ZZZ spare is available, replace SC FIN 2CY before next flight oif SC PN CA67007-ZZZ spare is not available: Before next flight: FCRM FIN 202CY have to be replaced and Servocontrol FIN 2CY has to be cleaned: FCRM FIN 202CY has to be inspected after 500FH and no later than 700FH from FCRM replacement: If no trace of hydraulic is observed, there is no further action to be done If trace of hydraulic fluid is observed and SC PN CA67007- ZZZ spare is available, replace SC FIN 2CY before next flight If trace of hydraulic fluid is observed and SC PN CA67007- ZZZ spare is not available, replace FCRM FIN 202CY and clean SC FIN 2CY before next flight and then repeat the inspection of the FCRM at intervals between 500FH and 700FH ### Page 9 Airbus Amber ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27P021-25 Rev 01 Page 9 of 14 Date: 04-JUN-2025 C80_AOT_FM1104649_v9.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT In case of hydraulic leak coming from Servocontrol FIN 1CTx within Ref. 12 Normal operation limit (Refer to Appendix 06): if FCRM does not show evidences of hydraulic contamination: oBefore next flight: FCRM FIN 201CTx has to be replaced and Servocontrol FIN 1CTx has to be cleaned FCRM FIN 201CTx has to be inspected after 500FH and no later than 700FH from FCRM replacement: If no trace of hydraulic is observed, there is no further action to be done If trace of hydraulic fluid is observed and SC PN CA67005-ZZZ spare is available, replace SC FIN 1CTx before next flight If trace of hydraulic fluid is observed and SC PN CA67005-ZZZ spare is not available, replace FCRM FIN 201CTx and clean SC FIN 1CTx before next flight and then repeat the inspection of the FCRM at intervals between 500FH and 700FH if FCRM shows evidences of hydraulic contamination: oif SC PN CA67005-ZZZ spare is available, replace SC FIN 1CTx before next flight oif SC PN CA67005-ZZZ spare is not available: Before next flight: FCRM FIN 201CTx have to be replaced and Servocontrol FIN 1CTx has to be cleaned: FCRM FIN 201CTx has to be inspected after 500FH and no later than 700FH from FCRM replacement: If no trace of hydraulic is observed, there is no further action to be done If trace of hydraulic fluid is observed and SC PN CA67005- ZZZ spare is available, replace SC FIN 1CTx before next flight If trace of hydraulic fluid is observed and SC PN CA67005- ZZZ spare is not available, replace FCRM FIN 201CTx and clean SC FIN 1CTx before next flight and then repeat the inspection of the FCRM at intervals between 500FH and 700FH Leak coming from Servocontrol above Ref. 12 normal operation limit and Ref. 12 within dispatch limit In case of hydraulic leak coming from Servocontrol FIN 1CY above Ref. 12 normal operation limit and within Ref. 12 dispatch limit (Refer to Appendix 04): if FCRMs does not show evidences of hydraulic contamination: oBefore next flight: FCRM FIN 201CY and 202CY have to be replaced and Servocontrol FIN 1CY has to be cleaned FCRM FIN 201CY and 202CY have to be inspected after 500FH and no later than 700FH from FCRMs replacement: If no trace of hydraulic is observed there is no further action to be done If trace of hydraulic fluid is observed and SC PN CA67007-ZZZ spare is available, replace SC FIN 1CY and FCRM FIN 202CY before next flight If trace of hydraulic fluid is observed and SC PN CA67007-ZZZ spare is not available, replace FCRM FIN 201CY and 202CY and clean SC FIN 1CY before next flight and then repeat the inspection of the FCRMs at intervals between 500FH and 700FH. If the subject servocontrol FIN 1CY is replaced between 2 successive checks, FCRM 202CY must also be replaced before next flight. if FCRM shows evidences of hydraulic contamination: oif SC PN CA67007-ZZZ spare is available, replace SC FIN 1CY and FCRM FIN 202CY before next flight ### Page 10 Airbus Amber ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27P021-25 Rev 01 Page 10 of 14 Date: 04-JUN-2025 C80_AOT_FM1104649_v9.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT oif SC PN CA67007-ZZZ spare is not available: Before next flight: FCRM FIN 201CY and 202CY have to be replaced and Servocontrol FIN 1CY has to be cleaned: FCRM FIN 201CY and 202CY have to be inspected after 500FH and no later than 700FH from FCRMs replacement: If no trace of hydraulic is observed, there is no further action to be done If trace of hydraulic fluid is observed and SC PN CA67007- ZZZ spare is available, replace SC FIN 1CY and FCRM FIN 202CY before next flight If trace of hydraulic fluid is observed and SC PN CA67007- ZZZ spare is not available, replace FCRM FIN 201CY and 202CY and clean SC FIN 1CY before next flight and then repeat the inspection of the FCRMs at intervals between 500FH and 700FH If the subject servocontrol FIN 1CY is replaced between 2 successive checks, FCRM 202CY must also be replaced before next flight. In case of hydraulic leak coming from Servocontrol FIN 2CY above Ref. 12 normal operation limit and within Ref. 12 dispatch limit (Refer to Appendix 05): if FCRM does not show evidences of hydraulic contamination: oBefore next flight: FCRM FIN 202CY has to be replaced and Servocontrol FIN 2CY has to be cleaned FCRM FIN 202CY has to be inspected after 500FH and no later than 700FH from FCRM replacement: If no trace of hydraulic is observed, there is no further action to be done If trace of hydraulic fluid is observed and SC PN CA67007-ZZZ spare is available, replace SC FIN 2CY before next flight If trace of hydraulic fluid is observed and SC PN CA67007-ZZZ spare is not available, replace FCRM FIN 202CY and clean SC FIN 2CY before next flight and then repeat the inspection of the FCRM at intervals between 500FH and 700FH If the subject servocontrol FIN 2CY is replaced between 2 successive checks, there is no further action to be done. if FCRM shows evidences of hydraulic contamination: oif SC PN CA67007-ZZZ spare is available, replace SC FIN 2CY before next flight oif SC PN CA67007-ZZZ spare is not available: Before next flight: FCRM FIN 202CY have to be replaced and Servocontrol FIN 2CY has to be cleaned: FCRM FIN 202CY has to be inspected after 500FH and no later than 700FH from FCRM replacement: If no trace of hydraulic is observed, there is no further action to be done If trace of hydraulic fluid is observed and SC PN CA67007- ZZZ spare is available, replace SC FIN 2CY before next flight If trace of hydraulic fluid is observed and SC PN CA67007- ZZZ spare is not available, replace FCRM FIN 202CY and clean SC FIN 2CY before next flight and then repeat the inspection of the FCRM at intervals between 500FH and 700FH If the subject servocontrol FIN 2CY is replaced between 2 successive checks, there is no further action to be done. ### Page 11 Airbus Amber ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27P021-25 Rev 01 Page 11 of 14 Date: 04-JUN-2025 C80_AOT_FM1104649_v9.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT In case of hydraulic leak coming from Servocontrol FIN 1CTx above Ref. 12 normal operation limit and within Ref. 12 dispatch limit (Refer to Appendix 06): if FCRM does not show evidences of hydraulic contamination: oBefore next flight: FCRM FIN 201CTx has to be replaced and Servocontrol FIN 1CTx has to be cleaned FCRM FIN 201CTx has to be inspected after 500FH and no later than 700FH from FCRM replacement: If no trace of hydraulic is observed, there is no further action to be done If trace of hydraulic fluid is observed and SC PN CA67005-ZZZ spare is available, replace SC FIN 1CTx before next flight If trace of hydraulic fluid is observed and SC PN CA67005-ZZZ spare is not available, replace FCRM FIN 201CTx and clean SC FIN 1CTx before next flight and then repeat the inspection of the FCRM at intervals between 500FH and 700FH If the subject servocontrol FIN 1CTx is replaced between 2 successive checks, there is no further action to be done. if FCRM shows evidences of hydraulic contamination: oif SC PN CA67005-ZZZ spare is available, replace SC FIN 1CTx before next flight oif SC PN CA67005-ZZZ spare is not available: Before next flight: FCRM FIN 201CTx have to be replaced and Servocontrol FIN 1CTx has to be cleaned: FCRM FIN 201CTx has to be inspected after 500FH and no later than 700FH from FCRM replacement: If no trace of hydraulic is observed, there is no further action to be done If trace of hydraulic fluid is observed and SC PN CA67005- ZZZ spare is available, replace SC FIN 1CTx before next flight If trace of hydraulic fluid is observed and SC PN CA67005- ZZZ spare is not available, replace FCRM FIN 201CTx and clean SC FIN 1CTx before next flight and then repeat the inspection of the FCRM at intervals between 500FH and 700FH If the subject servocontrol FIN 1CTx is replaced between 2 successive checks, there is no further action to be done. Note: As per Ref. 12, leakage rate check has to be performed before each flight. During this check, if the leakage rate remains above normal operation and within the dispatch limit, FCRM(s) do(es) not need to be replaced again before each flight but only after repetitive check depending on FCRM contamination Leak coming from Servocontrol above Ref. 12 Dispatch limit In case of hydraulic leak coming from Servocontrol FIN 1CY above Ref. 12 dispatch limit: SC FIN 1CY and FCRM 202CY have to be replaced before next flight In case of hydraulic leak coming from Servocontrol FIN 2CY above Ref. 12 dispatch limit: SC FIN 2CY has to be replaced before next flight In case of hydraulic leak coming from Servocontrol FIN 1CT1 above Ref. 12 dispatch limit: SC FIN 1CT1 has to be replaced before next flight In case of hydraulic leak coming from Servocontrol FIN 1CT2 above Ref. 12 dispatch limit: SC FIN 1CT2 has to be replaced before next flight Rudder and Elevator Inspection results and replaced FCRM information (only in case of findings) have to be reported to Airbus using the Reporting Sheet available on Appendix 03 Page 2,3, 4 and 5. ### Page 12 Airbus Amber ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27P021-25 Rev 01 Page 12 of 14 Date: 04-JUN-2025 C80_AOT_FM1104649_v9.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT For Rudder or Elevator FCRM exposed to hydraulic prior to A/C Delivery For each servocontrol mentioned in Appendix 07: -If the complete servocontrol (ie. including its FCRM) or the FCRM alone has been replaced since delivery and sent to shop, no action is required. -if the currently installed FCRM has not been replaced since A/C delivery, subject FCRM has to be replaced. -If no history regarding installed FCRM is available, current installed FCRM has to be replaced Rudder and Elevator Inspection results and replaced FCRM information for FCRM exposed to hydraulic leak before A/C delivery have to be reported to Airbus using the Reporting Sheet available on Appendix 03 Page 6. ***END REV*** 5.6 INSTRUCTIONS – (RC) WARNING: MAKE SURE THAT THE SAFETY DEVICES AND THE WARNING NOTICES ARE IN POSITION BEFORE YOU START A TASK ON OR NEAR: - THE FLIGHT CONTROLS - THE FLIGHT CONTROL SURFACES - THE LANDING GEAR AND THE RELATED DOORS - COMPONENTS THAT MOVE. MOVEMENT OF COMPONENTS CAN KILL OR CAUSE INJURY TO PERSONS AND/OR DAMAGE TO EQUIPMENT. WARNING: MAKE SURE THAT THE TRAVEL RANGES OF THE FLIGHT CONTROL SURFACES ARE CLEAR. MOVEMENT OF THE FLIGHT CONTROL SURFACES CAN CAUSE INJURY TO PERSONS AND DAMAGE TO THE AIRCRAFT OR EQUIPMENT. CAUTION: MAKE SURE THAT YOU DO NOT CAUSE DAMAGE TO THE SURFACES. THESE COMPONENTS ARE MADE OF CARBON FIBER REINFORCED PLASTIC. CAUTION: AIRBUS RECOMMEND NOT WORKING ON BOTH HYDRAULIC SYSTEMS DURING THE SAME MAINTENANCE INPUT WITH THE SAME MAINTENANCE PERSONNEL. THIS IS TO MAKE SURE THAT A POSSIBLE MAINTENANCE ERROR ON ONE SYSTEM IS NOT REPEATED ON A DIFFERENT SYSTEM. A MAINTENANCE ERROR ON MORE THAN ONE HYDRAULIC SYSTEM CAN CAUSE SYSTEM FAILURE ON MULTIPLE SYSTEMS. IF MAINTENANCE IS NECESSARY ON MORE THAN ONE SYSTEM AT THE SAME TIME AND INVOLVES LINES / COMPONENTS DISCONNECTION, DIFFERENT MAINTENANCE PERSONNEL MUST BE USED FOR EACH SYSTEM. IF MAINTENANCE NEEDS TO BE PERFORMED ON BOTH HYDRAULIC SYSTEMS AT THE SAME TIME A SPECIAL CHECK BY A THIRD PERSON SHALL BE PERFORMED TO VERIFY PROPER BLEEDING, TORQUES AND LOCKING ### Page 13 Airbus Amber ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27P021-25 Rev 01 Page 13 of 14 Date: 04-JUN-2025 C80_AOT_FM1104649_v9.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT OF BOLTS AND NUTS HAVE BEEN APPLIED, THIS IS IN ADDITION TO THE LEAK CHECK OF THE PRESSURIZED SYSTEM. REGARDING HYDRAULIC SYSTEM BLEEDING, THIS COULD BE CARRIED OUT BY MEANS OF A HYDRAULIC GROUND CART. ENGINE RUN IS REQUESTED IF MAINTENANCE ACTION HAS BEEN DONE ON THE HYDRAULIC SYSTEM LOCATED ON THE ENGINE AREA. In case an affected unit is installed on aircraft, apply the following corrective action within compliance time listed in paragraph 5.1: For Rudder FCRM (PN CA71323-0ZZ, as applicable: FIN 201CY, 202CY): Remove the Rudder FCRM refer to Ref. 1. Install new Rudder FCRM refer to Ref. 2. For Elevator FCRM (PN CA71323-0ZZ, as applicable: FIN 201CT1, 201CT2): Remove the Elevator FCRM refer to Ref. 3. Install new Elevator FCRM refer to Ref. 4. Send the removed FCRM to Moog shop mentioning the Reason for removal: Replaced further to AOT- A27P021-25-00. This FCRM will be scrapped or repaired depending on the findings observed during the shop activities 5.7 SPARES AND TOOLING No specific tooling or component except those listed in procedures Ref. 1, 2, 3 and 4 are required to perform these AOT instructions. Units removed are to be sent to Moog shop at the following address: Moog Aircraft Group (CAGE code: 94697) Plant 24, 6860 Seneca Street, Elma, NY 14059, USA Email: CASC@moog.com 6. ADDITIONAL INFORMATION 6.1 FOLLOW-UP PLAN As a terminating action, to avoid reproducing such experience in-service event, a new software of Flight Control Computer (PRIM/SEC) is under definition. This new software will be proposed via a dedicated Airbus Maintenance Documentation planned to be issued in August 2025 and will necessitate as prerequisite the Avionic Batch 7B - part 2 (Ref. 9). Follow-up of this AOT will be provided through TFU Ref. 10. 6.2 IMPACTED DOCUMENTATION ***BEG REV*** FCRM Swap are limited between Spoiler and Aileron positions from AOT Rev00 effective date. ### Page 14 Airbus Amber ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27P021-25 Rev 01 Page 14 of 14 Date: 04-JUN-2025 C80_AOT_FM1104649_v9.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT As a consequence: FCRM swapping between Elevator and Inboard Aileron (Ref. 5) is forbidden from the AOT Rev00 effective date ●Related MP Task (Ref. 5) has been temporarily deleted from AirnavX since 16 MAY 2025. FCRM swapping between Elevator and Outboard Aileron (Ref. 6) is forbidden from the AOT Rev00 effective date ●Related MP Task (Ref. 6) has been temporarily deleted from AirnavX since 16 MAY 2025. FCRM swapping between Aileron, Elevator or Rudder and Spoiler is partially forbidden from the AOT Rev00 effective date: oOnly is authorized swapping from Aileron to Spoiler from the AOT Rev00 effective date oFCRM swapping between Rudder or Elevator and Spoiler is forbidden. oRelated MP Task (Ref. 7) will be temporarily updated from AirnavX Jun 2025 Rev. MP Task allowing FCRM swapping between Spoiler and Aileron (Ref. 8 and Ref. 11) are still authorized from the AOT Rev00 effective date. ***END REV*** ***BEG REV*** Moreover, ATA29 MP Task “Check of the Hydraulic Components for External Leakage” (Ref. 12) has being modified to be in accordance with the AOT. This revised task is available on AirnavX since 22 MAY 2025. ***END REV*** 7. AOT APPROVAL The technical content of this document is approved under the authority of the DOA ref.EASA.21J.031. 8. REPORTING Address your acknowledgment and inspection results (Appendix 3) (with or without findings) to Airbus Customer Services through the In-Service Alerts and Information Cockpit tile on Airbus World by using the referenced AOT page. You can address your questions about this AOT to Airbus Customer Services through TechRequest on Airbus World, selecting Maintenance & Engineering Domain, Engineering Support section and ATA 27/Topic AOT A27P021-25 Rev 01. Best Regards, Ahmed CHABBOUH SENIOR DIRECTOR IN-SERVICE ENGINEERING CUSTOMER CARE CENTER Mathieu DUMAS VICE PRESIDENT WIDEBODY PROGRAMME CUSTOMER SERVICES --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. 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