# Airbus All Operators Transmission A35P010-17 ## Copies (5) Copies the FAA filed in AD dockets on regulations.gov, newest revision first. A newer revision may exist. - Revision 01 ("A35P010-17 Rev 01"), 6 pages: PDF https://openairdocs.org/files/sha256/17/1c/171c4169ca1bdedc37e8e1cd4eb86e909f6bc87bbb89f82562cfcfc76e9412a1; text https://openairdocs.org/service-documents/airbus/aot-a35p010-17/file/171c4169ca1b.md. Rights: © Airbus S.A.S. Filed by the FAA in regulations.gov docket FAA-2025-0343, the docket of AD 2025-11-12. Not covered by OpenAirDocs’ CC0 dedication. - Revision 01 ("AOT A35P010-17"), 6 pages: PDF https://openairdocs.org/files/sha256/db/5a/db5ae77a062b7e461b233d927f094505c6f945e10ab97c090656dde1c72b61be; text https://openairdocs.org/service-documents/airbus/aot-a35p010-17/file/db5ae77a062b.md. Rights: © Airbus S.A.S. Filed by the FAA in regulations.gov docket FAA-2019-0016, the docket of AD 2020-03-14. Not covered by OpenAirDocs’ CC0 dedication. - Revision 01 ("AOT A35P010-17 R1"), 6 pages: PDF https://openairdocs.org/files/sha256/ae/8d/ae8dd979442ed5d0741a9c327eaa6fdbd7f4c8db1dc2911d4301c4de1de677e5; text https://openairdocs.org/service-documents/airbus/aot-a35p010-17/file/ae8dd979442e.md. Rights: © Airbus S.A.S. Filed by the FAA in regulations.gov docket FAA-2019-0016, the docket of AD 2020-03-14. Not covered by OpenAirDocs’ CC0 dedication. - A35P010-17 Rev 00 ("A35P010-17 Rev 00"), 6 pages: PDF https://openairdocs.org/files/sha256/60/9d/609d2590b743773823b2e8b84a84880e3d2b08706aee1ef97ffbde0fc4e3e26d; text https://openairdocs.org/service-documents/airbus/aot-a35p010-17/file/609d2590b743.md. Rights: © Airbus S.A.S. Filed by the FAA in regulations.gov docket FAA-2025-0343, the docket of AD 2025-11-12. Not covered by OpenAirDocs’ CC0 dedication. - A35P010-17 Rev 02 ("A35P010-17 Rev 02"), 7 pages: PDF https://openairdocs.org/files/sha256/e2/51/e2515c3da477e92cda1a1e4ded0a634a692ad5c1ced58615610ca91024942fc7; text https://openairdocs.org/service-documents/airbus/aot-a35p010-17/file/e2515c3da477.md. Rights: © Airbus S.A.S. Filed by the FAA in regulations.gov docket FAA-2025-0343, the docket of AD 2025-11-12. Not covered by OpenAirDocs’ CC0 dedication. ## Details - Manufacturer: [Airbus](https://openairdocs.org/service-documents/airbus.md) - Type: Other document (All Operators Transmission) - Number: A35P010-17 - Latest revision known: A35P010-17, Revision 01, dated April 11, 2019 (OpenAirDocs) - Page: https://openairdocs.org/service-documents/airbus/aot-a35p010-17 Also cited in [1 proposed AD](https://openairdocs.org/service-documents/airbus/aot-a35p010-17/proposed.md). ## Text (6 pages) Revision 01, the newest copy. Rights: © Airbus S.A.S. Filed by the FAA in regulations.gov docket FAA-2025-0343, the docket of AD 2025-11-12. Not covered by OpenAirDocs’ CC0 dedication. Each page's text from the PDF; open the PDF at a page with #page=N. ### Page 1 CUSTOMER SERVICES DIRECTORATE 1 ROND POINT MAURICE BELLONTE 31707 BLAGNAC CEDEX FRANCE TELEPHONE + 33 (0)5 61 93 33 33 ALERT OPERATORS TRANSMISSION - AOT AOT ref: A35P010-17 Rev 01 Page 1 of 6 Date: 11-APR-2019 © AIRBUS S.A.S. 2019. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT SUBJECT: ATA 35 – Crew Oxygen Cylinder Regulator Assembly loose Filter Retainer AIRCRAFT TYPE: A350 OUR REF.: A35P010-17 Rev 01 dated 11-APR-2019 OUR PREVIOUS REF: A35P010-17 Rev 00 dated 20-Dec-2017 0. REASON FOR REVISION The purpose of this revision is to add the oxygen cylinder assembly PN 4441227-058-001 to the inspection scope of the AOT. The revised paragraphs are indicated between **BEG. REV** and **END REV**. 1. AIRCRAFT AFFECTED All A350 A/C. 2. REFERENCED DOCUMENTATION 2.1 APPENDIX None 2.2 REFERENCES Ref 1: AOT A35P010-17 Rev 00 dated 20-DEC-2017 Ref 2: Rockwell Collins VSB 4441227-35-003 – Oxygen – Cylinder-Regulator Assembly – Inspection Ref 3: MP Task A350-A-35-11-56-00001-520A-A – Removal of the Oxygen Reducer Cylinder-Assembly Ref 4: MP Task A350-A-35-11-56-00001-720A-A – Installation of the Oxygen Reducer Cylinder- Assembly Ref 5: MP Task A350-A-35-1X-XX-00001-398A-A – Special Precautions during Work on a Gaseous Oxygen System **BEG. REV** Ref 6: Collins VSB 4441227-35-004 – Oxygen – Cylinder-Regulator Assembly – Inspection Ref 7: EASA AD 2018-0245R1 issued 5.Dec.2018 - ATA 35 – Oxygen – Crew Oxygen Cylinder Regulator – Operational Check / Replacement **END REV**. ### Page 2 ALERT OPERATORS TRANSMISSION - AOT AOT ref: A35P010-17 Rev 01 Page 2 of 6 Date: 11-APR-2019 © AIRBUS S.A.S. 2019. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT 3. REASON The purpose of this AOT is to advise A350 operators about findings on Crew Oxygen Cylinder Regulator Assemblies and request inspection of Oxygen Cylinders after each removal and prior to each installation of an Oxygen Cylinder on A/C. This inspection is also applicable to spare units. 3.1 FACTS The Crew Oxygen Cylinder assembly consists of a composite oxygen cylinder which mates to the Regulator assembly. Fig 1: A350 Cylinder/Regulator Assembly P/N 4441227-058-00X The Regulator neck is threaded internally and externally, as follows: - The Filter Retainer assembly threads into the inner thread of the regulator neck - Fig 2. Item (1). - The outer thread of the Regulator neck threads into the Oxygen Cylinder - Fig 2. Item (2). Fig 2: A350 Regulator and Filter Retainer (1) Inner thread (2) Outer thread ### Page 3 ALERT OPERATORS TRANSMISSION - AOT AOT ref: A35P010-17 Rev 01 Page 3 of 6 Date: 11-APR-2019 © AIRBUS S.A.S. 2019. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT The upper portion of the Filter Retainer contacts the Regulator body, placing the Filter Retainer body in compression and providing filtration for the oxygen passing through the Filter Retainer and into the Regulator. Fig3: Schematics of the Regulator with Retainer Assembly During testing of assemblies in 2016, Supplier Rockwell Collins (former B/E Aerospace) identified several cases where the Filter Retainer assembly became detached from the Regulator and fell inside the Oxygen Cylinder. Following the first finding in 2016, AOT A35P009-16 was released which required reworking of all PN 4441227-058-000 for SN from 41227-058-00001 to 41227-058-00212. All these units have been reworked with a modified assembly technique to prevent the retainer from becoming loose and falling inside the Oxygen Cylinder. This modified installation was also implemented on production units from serial number -00213 and above. **BEG REV** Then, the A350 Crew Oxygen Cylinder PN 4441227-058-001 was introduced in early 2017 as a final fix to the recurring loss of the regulator inlet filter retainer seen on the initially delivered P/N 4441227-058- 000, as it was highlighted through the previous revision of this AOT. All Oxygen Cylinder PN 4441227- 058-000 were required to be returned for rework as per Ref 7. However, upon the in-shop testing of some returned oxygen cylinders assemblies from the current PN 4441227-058-001, Supplier Collins (former B/E Aerospace) identified three cases where the Filter Retainer assembly became detached from the Regulator and fell inside the Oxygen Cylinder. The Oxygen Cylinder PN 4441227-058-001 design was qualified with a lower regulator to cylinder installation torque of 30 ±3 ft-lb which was shown not to lead to loosening of the retainer. However, the supplier’ investigations showed that when the regulator assemblies were installed on the Oxygen Cylinders in production, significantly higher torque values were apparently applied, which could lead to Retainer detachment as seen previously with the original PN. **END REV** 3.2 CONSEQUENCES ### Page 4 ALERT OPERATORS TRANSMISSION - AOT AOT ref: A35P010-17 Rev 01 Page 4 of 6 Date: 11-APR-2019 © AIRBUS S.A.S. 2019. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT Testing has confirmed that a loose Filter Retainer will not create damage to or ignition within an Oxygen Cylinder subject to aircraft flight environment or normal handling. There is no consequence for Oxygen Cylinder Assemblies currently installed and not removed from A/C. Normal operation of the equipment while on the aircraft, including on Aircraft refilling of the Oxygen Cylinder, is also not affected by the described condition. For A/C equipped with the optional refilling port, it is still possible to refill Oxygen Cylinders on-wing. The following consequence could exist when a Cylinder/Regulator assembly with a detached Filter Retainer is installed on aircraft. Particles are generally present to some extent in all pressurized Cylinders. In the worst case, if an Oxygen Cylinder Assembly with a loose Filter Retainer assembly were to be inverted (i.e. put upside down), particles normally within the Cylinder could fall into the Regulator Assembly and be retained in the regulation mechanism. If particles are introduced into the Regulator Assembly, particles could be carried in the Oxygen gas stream when the Regulator is activated, and an ignition within the Oxygen System could occur. This could happen during the initial ground test which is performed after each Oxygen Cylinder Installation. To summarize, ignition can only occur if: a) The Regulator filtration function is lost due to detached Filter Retainer, b) The Cylinder with detached Filter Retainer is inverted during handling and particles are introduced into and stay within the Regulator, c) The Regulator is operated at high flow for the first time. This could only occur during the first testing of the Oxygen System, following cylinder reinstallation, which is performed on ground. As noted previously, there is no consequence from the loose Filter Retainer condition on the Crew Oxygen System function during flight. 3.3 AIM **BEG REV** The aim of this AOT is to inspect each Oxygen Cylinder PN 4441227-058-000 and PN 4441227-058- 001, as per Collins VSB’s 4441227-35-003 and 4441227-35-004 respectively: - after removal of the Cylinder from A/C as per Ref 3 MP Task A350-A-35-11-56-00001-520A-A for removal of Oxygen Cylinder Assembly - just before installation of the Cylinder on A/C as per Ref 4 MP Task A350-A-35-11-56-00001- 720A-A for Installation of Oxygen Cylinder Assembly - and in spare stock In case of finding, the affected Oxygen Cylinder has to be sent back to Collins, who will provide a replacement Oxygen Cylinder PN 4441227-058-001. **END REV** 4. SHORT TERM ACTION 4.1 PLANNING AND MANPOWER ### Page 5 ALERT OPERATORS TRANSMISSION - AOT AOT ref: A35P010-17 Rev 01 Page 5 of 6 Date: 11-APR-2019 © AIRBUS S.A.S. 2019. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT 4.1.1 ACCOMPLISHMENT TIMESCALE **BEG REV** After reception of this AOT, the inspection has to be performed: - After each removal of Oxygen Cylinder PN 4441227-058-000 or PN 4441227-058-001 as per REF 3. - Before each installation of Oxygen Cylinder PN 4441227-058-000 or PN 4441227-058-001 as per REF 4. - On Oxygen Cylinder PN 4441227-058-000 and PN 4441227-058-001 in stock **END REV** 4.1.2 MANPOWER **BEG REV** The estimated time to perform the inspection as per in Ref 2 VSB 4441227-35-003 or Ref 6 VSB 4441227-35-004 on a Cylinder Assembly PN 4441227-058-000 or PN 4441227-058-001 is 5 minutes. **END REV** 4.2 DESCRIPTION 4.2.1 ACCESS No particular Access is required. Before starting any task on the Crew Oxygen system, Ref 5 MP Task A350-A-35-1X-XX-00001-398A-A – Special Precautions during Work on a Gaseous Oxygen System shall be followed. 4.2.2 INSPECTION REQUIREMENTS **BEG REV** Operators are recommended to perform the inspection of Oxygen Cylinders PN 4441227-058-000 and 4441227-058-001 spares as per Ref 2 VSB 4441227-35-003 or Ref 6 VSB 4441227-35-004. Any unit found affected after the inspection shall be returned to Collins (former B/E Aerospace) for exchange with PN 4441227-058-001. Perform the inspection as per VSB 4441227-35-003 or VSB 4441227-35-004: - At removal of Oxygen Cylinder PN 4441227-058-000 or PN 4441227-058-001 as per Ref 3 MP Task A350-A-35-11-56-00001-520A-A for removal of Oxygen Cylinder Assembly - and just before installation of Oxygen Cylinder PN 4441227-058-000 or PN 4441227-058-001 as per Ref 4 MP Task A350-A-35-11-56-00001-720A-A for Installation of Oxygen Cylinder Assembly Any Oxygen Cylinder Assembly that does not pass the Ref 2 VSB 4441227-35-003 or Ref 6 VSB 4441227-35-004 inspection shall not be installed on A/C. **END REV** 4.2.3 FINDINGS **BEG REV** Oxygen Cylinder Assembly PN 4441227-058-000 or PN 4441227-058-001 inspection leading to identification of sound during agitation as per Ref 2 VSB 4441227-35-003 or Ref 6 VSB 4441227-35- 004 shall be returned to Collins Repair Centre for exchange. Oxygen Cylinder Assembly PN 4441227-058-001 shall be preferred for replacement. ### Page 6 ALERT OPERATORS TRANSMISSION - AOT AOT ref: A35P010-17 Rev 01 Page 6 of 6 Date: 11-APR-2019 © AIRBUS S.A.S. 2019. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT **END REV** 4.3 SPARES AND TOOLING **BEG REV** No specific tooling is required to perform the inspection of the Crew Oxygen Cylinder as per Ref 2 VSB 4441227-35-003 or Ref 6 VSB 4441227-35-004. **END REV** 5. FURTHER INFORMATION 5.1 FOLLOW-UP PLAN **BEG REV** New Crew Oxygen Cylinder PN 4441227-058-002 is in development by the supplier as a long term corrective action to the loose Retainer assembly issue. **END REV** 6. AOT APPROVAL The technical content of this document is approved under the authority of DOA nr. EASA.21J.031. 7. REPORTING Questions about this AOT are to be addressed to Airbus Customer Services through TechRequest on Airbus World, selecting Engineering Domain and ATA 35-10. As per latest reporting policy (Ref to OIT 999.0018/16), inspection results (with or without findings) are to be addressed to Airbus Customer Services through the generic e-mail address: inspection.results@airbus.com. Best Regards, Jean-Luc MOUYSSET VICE PRESIDENT ENGINEERING SUPPORT CUSTOMER SERVICES Stéphane GOSSELIN VICE PRESIDENT A350 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. Source documents are U.S. government works in the public domain, except the copies of manufacturers’ service documents, which belong to their rights holders.