# Airbus Alert Operators Transmission A32P031-24 ## Copies (5) Copies the FAA filed in AD dockets on regulations.gov, newest revision first. A newer revision may exist. - Revision 04 ("AOT_A32P031-24_r04"), 9 pages: PDF https://openairdocs.org/files/sha256/18/8d/188d8a4d2d6c883c931d552015f2cc6a74e9463b36cc7ec5e4e190a298699c28; text https://openairdocs.org/service-documents/airbus/aot-a32p031-24/file/188d8a4d2d6c.md. Rights: © Airbus S.A.S. Filed by the FAA in regulations.gov docket FAA-2025-0912, the docket of AD 2025-22-01. Not covered by OpenAirDocs’ CC0 dedication. - Revision 04 ("Appendix 1 - AOT-A32P031-24-00"), 1 page: PDF https://openairdocs.org/files/sha256/96/b2/96b271bd0c9bf8fb02ed8ef039e8b0f4816311a61391f27d48a2a2858c892c9f; text https://openairdocs.org/service-documents/airbus/aot-a32p031-24/file/96b271bd0c9b.md. Rights: © Airbus S.A.S. Filed by the FAA in regulations.gov docket FAA-2025-0912, the docket of AD 2025-22-01. Not covered by OpenAirDocs’ CC0 dedication. - Revision 04 ("Appendix 2 - AOT-A32P031-24-00"), 1 page: PDF https://openairdocs.org/files/sha256/40/a5/40a513ffc5c511682b4adec0b89fb31005610bb6bb9eabe8ff328ac6bbcb0610; text https://openairdocs.org/service-documents/airbus/aot-a32p031-24/file/40a513ffc5c5.md. Rights: © Airbus S.A.S. Filed by the FAA in regulations.gov docket FAA-2025-0912, the docket of AD 2025-22-01. Not covered by OpenAirDocs’ CC0 dedication. - Revision 04 ("Appendix 3 - AOT-A32P031-24-00"), 1 page: PDF https://openairdocs.org/files/sha256/65/b9/65b9795bac7416b1407a4330e283e37d526df79d8f03f9a01b9577368f49582a; text https://openairdocs.org/service-documents/airbus/aot-a32p031-24/file/65b9795bac74.md. Rights: © Airbus S.A.S. Filed by the FAA in regulations.gov docket FAA-2025-0912, the docket of AD 2025-22-01. Not covered by OpenAirDocs’ CC0 dedication. - Revision 04 ("Appendix 4 - AOT-A32P031-24-01"), 19 pages: PDF https://openairdocs.org/files/sha256/8b/7f/8b7f0ee969151d769dd17c5d2bdfc937656d2b39d6e5b225d340865918bec8aa; text https://openairdocs.org/service-documents/airbus/aot-a32p031-24/file/8b7f0ee96915.md. Rights: © Airbus S.A.S. Filed by the FAA in regulations.gov docket FAA-2025-0912, the docket of AD 2025-22-01. Not covered by OpenAirDocs’ CC0 dedication. ## Details - Manufacturer: [Airbus](https://openairdocs.org/service-documents/airbus.md) - Type: Other document (Alert Operators Transmission) - Number: A32P031-24 - Latest revision known: A32P031-24, Revision 04, dated March 11, 2025 (OpenAirDocs) - Page: https://openairdocs.org/service-documents/airbus/aot-a32p031-24 ## ADs that cite it (1) (OpenAirDocs) Newest first, with the revision each names, as OpenAirDocs read it from the AD's text. - [AD 2025-22-01](https://openairdocs.org/ad/2025-22-01.md), effective Jan 2, 2026: Revision 04 ## Text (9 pages) Revision 04, the newest copy. Rights: © Airbus S.A.S. Filed by the FAA in regulations.gov docket FAA-2025-0912, the docket of AD 2025-22-01. Not covered by OpenAirDocs’ CC0 dedication. Some pages are OCR from a scan. OCR can misread letters and numbers. Each page's text from the PDF; open the PDF at a page with #page=N. ### Page 1 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: A32P031-24 Rev 04 Page 1 of 9 Date: 11-MAR-2025 C80_AOT_FM1104649_v8.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT SUBJECT: ATA 32 – A350 NLG Secondary seal activation to reduce lower bearing friction AIRCRAFT TYPE: A350 OUR REF.: A32P031-24 Rev 04 dated 11-MAR-2025 OUR PREVIOUS REF: A32P031-24 Rev 03 dated 26-SEP-2024 A32P031-24 Rev 02 dated 28-AUG-2024 A32P031-24 Rev 01 dated 29-JUL-2024 A32P031-24 Rev 00 dated 18-APR-2024 EFFECTIVITY DATE: 12-MAR-2025 0. REASON FOR REVISION This AOT is revised in order to: - Inform that Post MOD 120537 Sliding piston Assemblies are not affected by this AOT. - Clarify that when a new NLG is installed on aircraft with secondary seal activated, only paragraphs 5.6 steps f to j have to be accomplished. - Update the PN applicability of this AOT to the NLG Sliding Piston Assembly. - Include aircraft equipped with NLG Shock Strut Complete PN 6406Bxxxx. The revised paragraphs of this AOT are indicated between ***BEG REV*** and ***END REV***. 1. AIRCRAFT AFFECTED All A350 Aircraft. 2. REFERENCED DOCUMENTATION 2.1 APPENDIX Appendix 1: List of Aircraft MSN operated under RDAF Appendix 2: List of Aircraft MSN inspected as per RDAF Appendix 3: Reporting proforma Appendix 4: NLG Main Fitting Inspection and Repair procedure 2.2 REFERENCES - Reference 1: MP Task A350-A-32-51-XX-00001-340A-A “Functional Test of the Nose Wheel Steering (NWS) with the Hand Wheels (Snapshot)” - Reference 2: MP Task A350-A-32-51-XX-01001-340A-A “Functional Test of the NWS with the Hand Wheels (ACMS)” - Reference 3: MP Task A350-A-32-21-73-02001-132A-A “Closing of the NLG Seal Changeover- Valve to Reduce Lower Bearing Friction” - Reference 4: MP Task A350-A-32-21-73-01001-133A-A “Opening of the NLG Seal Changeover -Valve” - Reference 5: MP Task A350-A-07-11-XX-01001-171A-A “Lifting of the Aircraft at the Forward Jacking Point, with MLG Wheels on the Ground” - Reference 6: MP Task A350-A-07-11-XX-00001-171A-A “Lifting of the Aircraft for Maintenance Operations”. - Reference 7: MP Task A350-A-07-11-XX-00001-176A-A “Lowering of the Aircraft for Maintenance Operations” ### Page 2 ALERT OPERATORS TRANSMISSION - AOT AOT ref: A32P031-24 Rev 04 Page 2 of 9 Date: 11-MAR-2025 C80_AOT_FM1104649_v8.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT - Reference 8: MP Task A350-A-07-11-XX-01001-176A-A “Lowering of the Aircraft at the Forward Jacking Point, with MLG Wheels on the Ground” - Reference 9: TFU 32.21.00090: NLG friction noise during shock absorber rotation - Reference 10: MP Task A350-A-32-51-XX-02001-270A-A “Put the Nose Wheels on the Greased Plates and Remove them” 3. REASON The purpose of this AOT is to recommend performing a steering check and activating of the NLG Shock Absorber secondary seal on all A350 fleet to reduce the lower bearing friction. 3.1 FACTS Airbus informs operators that an increased friction effect on the NLG Shock Absorber Lower Bearing Carrier can potentially lead to wear damage on the NLG Main Fitting. This component is a Principal Structure Element (PSE) and as such is listed in the Airworthiness Limitations Section (ALS Part 1). 3.2 HISTORY/BACKGROUND Several operators have reported mechanical noise coming from the NLG Shock Absorber during steering (during Aircraft push-back or taxi). This noise is caused by the increased friction between the Lower Bearing Carrier and the Sliding Tube. A mitigation was developed which consists in activating the NLG Shock Absorber Secondary Seal with the NLG weight-off-wheels. This eliminates the friction effect by reducing the bearing pressure. 3.3 ROOT CAUSE The increased friction between the Lower Bearing Carrier and the NLG Sliding Tube may lead to a deformation of the anti-rotation tabs located on the Lower Bearing Carrier. As a consequence, relative movement can be present between the Lower Bearing Carrier and the Main Fitting. The relative movement of the Lower Bearing Carrier following anti-rotation tabs damage may allow wear to the corrosion protection coating on the Main Fitting due to subsequent movement of a retainer ring located between the two parts. 3.4 INVESTIGATION The investigation confirmed that, once relative movement is present during NLG rotation, the NLG Main Fitting corrosion protection may rapidly be worn through. 3.5 CONSEQUENCES Damage to the corrosion protection coating of the NLG Main Fitting could progressively lead to corrosion of NLG Main Fitting and, if no corrective action is performed, this could potentially lead to a NLG collapse. 4. OBJECTIVES OF THIS AOT This AOT recommends: - Performing a Steering Check to assess the presence of relative movement between the Lower Bearing Carrier and the Main Fitting, and report back the value to Airbus. - Activating the NLG Shock Absorber Secondary Seal on all A350 to eliminate the friction effect. - Performing a repetitive steering check to ensure the absence of relative movement. - If relative movement above 1mm is noticed during a steering check with NLG primary seal activated, perform an inspection/repair of the Main Fitting within 6 months. ### Page 3 ALERT OPERATORS TRANSMISSION - AOT AOT ref: A32P031-24 Rev 04 Page 3 of 9 Date: 11-MAR-2025 C80_AOT_FM1104649_v8.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT 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) ***BEG REV*** For Aircraft equipped with NLG Sliding Piston Assembly (5006GN) PN 6407A2000-01, 6407A2000-02 or 6407A2000-03 (Common NLG standard): Airbus recommended applying the procedure given in paragraph 5.6 within 5 months or 250FC (whichever occurs later) from the effectivity date of AOT A32P031-24 Rev 00 dated 18-APR-2024. This included a repetitive inspection before or at every 250FC. For Aircraft equipped with NLG Sliding Piston Assembly (5006GN) PN 5035A3200-01 or 5035A3200- 02 (EIS NLG Standard): Airbus recommended applying the procedure given in paragraph 5.6 within 20 months or 1000FC (whichever occurs later) from the effectivity date of AOT A32P031-24 Rev 00 dated 18-APR-2024. This included a repetitive inspection before or at every 1000FC. If during the steering test, movement above 1mm was found, then an inspection/repair of the NLG Main Fitting as per Appendix 4 of this AOT must be performed within 6 months (from the date of the test). Notes: - This AOT is not applicable to Aircraft in production. - Aircraft delivered after the effectivity date of AOT A32P031-24 Rev 00 dated 18-APR-2024 only have to apply the procedure (paragraph 5.6) before or at every 250FC from aircraft first flight. - If one of the previous revisions of AOT A32P031-24 (Rev 00, 01, 02 or 03) has been applied on the airplane (check of movement with primary and secondary seal activated and inspection/repair procedure detailed in Appendix 4 if required) only the repetitive tests (as per paragraph 5.6 steps i and j) must be performed. - For aircraft currently equipped with NLG Shock strut complete PN 6406B0000-xx with sliding piston assemblies 6407A2000-03 or earlier, if none of the previous revision of AOT A32P031- 24 (Rev 00, 01, 02 or 03) were accomplished, then this new AOT revision should be accomplished within one of the following thresholds, whichever occurs later: oWithin 50FC from the effective date of this AOT or oWithin 250FC from the date of NLG installation Aircraft equipped with post MOD 120537 Nose Landing Gears are no longer affected by this AOT. These are the aircraft equipped with Sliding Piston Assembly P/N 6407A2000-04 or later. ***END REV*** ### Page 4 ALERT OPERATORS TRANSMISSION - AOT AOT ref: A32P031-24 Rev 04 Page 4 of 9 Date: 11-MAR-2025 C80_AOT_FM1104649_v8.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT 5.2 MANPOWER The estimated time for the initial inspection is 4 Man-Hours. The estimated time for the repetitive inspection is 2 Man-Hours. In case of movement recorded during a steering test, the estimated time for the inspection/repair of the NLG Main Fitting is 10.5 Man-Hours. 5.3 ACCESS For the Job Set-up and Close-up, refer to References 1 to 8 (paragraph 2.2). 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 RELATED DOORS -THE CARGO DOORS -THE ENGINES -OTHER COMPONENTS THAT MOVE. MOVEMENT OF COMPONENTS CAN KILL OR CAUSE INJURY TO PERSONS AND/OR DAMAGE TO EQUIPMENT. WARNING: MAKE SURE THAT THE GROUND SAFETY-LOCKS ARE IN POSITION ON THE LANDING GEAR. THIS WILL PREVENT UNWANTED MOVEMENT OF THE LANDING GEAR, AND THUS POSSIBLE INJURY TO PERSONS AND DAMAGE TO THE AIRCRAFT AND/OR EQUIPMENT. WARNING: MAKE SURE THAT THE WHEEL CHOCKS ARE IN POSITION. MOVEMENTS OF THE AIRCRAFT CAN BE DANGEROUS. WARNING: BE CAREFUL WHEN YOU USE CONSUMABLE MATERIALS. OBEY THE MATERIAL MANUFACTURER INSTRUCTIONS AND YOUR LOCAL REGULATIONS. WARNING: USE PROTECTIVE GOGGLES AND GLOVES EACH TIME YOU CUT LOCKWIRE. DISCARD LOOSE OR USED LOCKWIRE IMMEDIATELY. LOOSE OR USED LOCKWIRE CAN CUT YOU OR MAKE YOU BLIND. CAUTION: WHEN YOU PUT THE NOSE WHEELS ON THE TOP PLATE, MAKE SURE THAT THE EDGES OF THE TOP PLATE DO NOT TOUCH THE TIRES. IF THE TOP PLATE TOUCHES THE TIRES, IT CAN CAUSE DAMAGE TO THE TIRES. 5.4 INSPECTION – (RC) Refer to Paragraph 5.6 5.5 FINDINGS – (RC) Refer to Paragraph 5.6 ### Page 5 (OCR) AIRBUS ALERT OPERATORS TRANSMISSION - AOT 5.6 INSTRUCTIONS - (RC) ***BEG REV*** Flowchart 1 Procedure entry point On this aircraft, was the NLG -Yes secondary seal activated before installation? (1) Is the aircraft currently flying under one of the RDAF listed in Appendix 1? (2) Apply the inspection Is the aircraft covered by one procedure as per *Yes of the RDAF listed in the applicable RDAF (3) Appendix 2 of this AOT? NO Is the aircraft NG currently Was the NG secondary seal operated on Primary No activated due to a leakage of Dynamic Seal the primary seal? Apply the procedure in paragraph 5.6 from Step f to j (4) Within the compliance time of this AOT, Replace the NLG Yes Shock Absorber dynamic seals as per MP Task A350-A-32-21-73- 00001-921A-A Apply the procedure in paragraph 5.6 from Step a to j (5)* ***END REV*** AOT ref: А32P031-24 Rev 04 Page 5 of 9 Date: 11-MAR-2025 C80_AOT_FM1104649_V8.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT ### Page 6 ALERT OPERATORS TRANSMISSION - AOT AOT ref: A32P031-24 Rev 04 Page 6 of 9 Date: 11-MAR-2025 C80_AOT_FM1104649_v8.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT Notes from Flowchart 1: ***BEG REV*** (1): This includes any new NLG installed on an Aircraft with the secondary seal activated. The list of Aircraft delivered with NLG secondary seal activated from Airbus production can be found in TFU 32.21.00090 ***END REV*** (2): The RDAF listed in the appendix 1 are superseded and replaced by this AOT. (3): The limitation stated by the RDAF listed in the appendix 2 remain applicable after application of this AOT. (4): If the relative movement on secondary seal as part of step f. is above 1mm, repeat the procedure from step a. and perform inspection/repair as per Appendix 4 if required within 6 months from the date of the test. (5): If the relative movement on primary seal as part of step b. is above 1mm, perform inspection/repair as per Appendix 4 within 6 months from the date of the test. If MP Task A350-A-32-21-73-02001-132A-A “Closing of the NLG Seal Changeover-Valve to Reduce Lower Bearing Friction” was applied, you still have to apply the procedure in paragraph 5.6 step a to k PROCEDURE: a. Make sure the NLG primary seal is active (no red indication on the seal changeover valve). If not, open the NLG Seal Changeover-Valve as per MP Task A350-A-32-21-73-01001-133A-A. General Note: During all steering checks called up in this procedure, the checks must be performed with the NLG on grease plates (no torque link disconnection) and the steering command is to be applied slowly to achieve approximately 5 degrees rotation per second. FIGURE 1 ### Page 7 ALERT OPERATORS TRANSMISSION - AOT AOT ref: A32P031-24 Rev 04 Page 7 of 9 Date: 11-MAR-2025 C80_AOT_FM1104649_v8.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT FIGURE 2 – example of movement recorded b. With the primary seal activated and the aircraft on greased plates (refer to Reference 10 in paragraph 2.2), determine if there is relative movement between the bearing carrier retainer ring and the main fitting (refer to Figure 1) by marking a line on both parts and performing a steering functional test (Refer to References 1 or 2 in paragraph 2.2), ensuring the steering is operated in both directions. Once steering has been operated in both directions, measure the total relative movement value between the maximum steering to the left side and the maximum steering to the right side (example on figure 2). Record the value and report back to Airbus using the reporting proforma in Appendix 3. If the relative movement value recorded is above 1mm, then the inspection/repair procedure detailed in Appendix 4 has to be accomplished within 6 months (from the date of steering functional test as per step b). Note: Airbus recommends operators to quickly contact the NLG OEM (Liebherr Aerospace) in order to organize a Working Party: technical-hotline-aog@liebherr.com. Once the inspection and repair procedure is applied (as per Appendix 4), the aircraft can return to service with NLG Secondary Seal activated for a temporary period of operation of 9000FC. Note: Before reaching 9000FC, one of the following options must be applied: 1. Re-application of the temporary repair procedure as per Appendix 4 to reset the 9000FC limitation. This may be reapplied multiple times, as required, 2. Full restoration of the NLG Main Fitting Corrosion Protection as per applicable CMM, which removes the temporary repair limitation. Note: When the inspection and repair procedure is applied (as per Appendix 4), the repetitive tests (as per paragraph 5.6 steps j and k) remain applicable. c. Jack the Aircraft so that the NLG shock absorber is fully extended (Refer to MP Task A350-A- 07-11-XX-01001-171A-A or MP TASK A350-A-07-11-XX-00001-171A-A). d. Activate the secondary seal in accordance with MP TASK A350-A-32-21-73-02001-132A-A “Closing of the NLG Seal Changeover-Valve to Reduce Lower Bearing Friction” to release the fluid pressure at the primary seal location. e. Lower the Aircraft (Refer to MP Task A350-A-07-11-XX-00001-176A-A or MP Task A350-A-07- 11-XX-01001-176A-A). ### Page 8 ALERT OPERATORS TRANSMISSION - AOT AOT ref: A32P031-24 Rev 04 Page 8 of 9 Date: 11-MAR-2025 C80_AOT_FM1104649_v8.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT f. With the secondary seal activated and the aircraft on greased plates (refer to Reference 10 in paragraph 2.2), determine if there is relative movement between the bearing carrier retainer ring and the main fitting (refer to Figure 1) by marking a line on both parts and performing a steering functional test (Refer to References 1 or 2 in paragraph 2.2), ensuring the steering is operated in both directions. Once steering has been operated in both directions, measure the total relative movement value between the maximum steering to the left side and the maximum steering to the right side (example on figure 2). Record the value and report back to Airbus using the reporting proforma in Appendix 3. g. With the secondary seal activated, if the value of relative movement measured at step f is above 1mm, repeat the procedure from step a. If the value of relative movement is above 1mm whilst on secondary seal following repetition of step f, secondary seal activation is not confirmed. Contact Airbus for further troubleshooting action to be taken before next flight. h. With the secondary seal activated, if the value of relative movement measured at step f is equal or less than 1mm, the Aircraft can be released to service with secondary seal activated. ***BEG REV*** The repetitive tests (as per steps i and j) must be performed regardless of the result of the last steering check. i. If the Aircraft is equipped with NLG Sliding Piston Assembly PN 6407A2000-01, 6407A2000- 02, 6407A2000-03 (Common NLG standard): Before or at every 250FC, repeat this procedure from step f. j. If the Aircraft is equipped with NLG Sliding Piston Assembly PN 5035A3200-01, 5035A3200- 02 (EIS NLG Standard): Before or at every 1000FC, repeat this procedure from step f. ***END REV*** 5.7 SPARES AND TOOLING Refer to References 1 to 10 (Paragraph 2.2). 6. ADDITIONAL INFORMATION 6.1 FOLLOW-UP PLAN ***BEG REV*** It is expected that this AOT will be revised with the in-service retrofit solution. ***END REV*** 6.2 IMPACTED DOCUMENTATION This AOT has no impact on the published documentation. ### Page 9 ALERT OPERATORS TRANSMISSION - AOT AOT ref: A32P031-24 Rev 04 Page 9 of 9 Date: 11-MAR-2025 C80_AOT_FM1104649_v8.0 © AIRBUS S.A.S. 2025. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT 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 inspection results (with or without findings) to Airbus Customer Services through the generic e-mail address monitored.retrofit@airbus.com and inspection.results@airbus.com, including the proforma in Appendix 3. Refer to the latest reporting policy (Ref in the OIT 999.0018/16). Give the AOT reference in the mail title, as follows: AOT A32P031-24 Inspection Result 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 32-21. Best Regards, WOLFGANG WOHLERS SENIOR VICE PRESIDENT ENGINEERING & MAINTENANCE CUSTOMER SERVICES MATHIEU DUMAS HEAD OF WIDE BODY PROGRAMME SUPPORT 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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