Low Pressure Flexible Oxygen Hose Cracking - Civil Aviation Safety Alert (CASA) No. 2021-12


Owners, Operators and Maintainers of Aircraft Equipped with Flexible Oxygen Hoses Manufactured by O2 Corporation

File Classification No.: Z 5000-35
RDIMS No.: 17256991
Document No.: CASA 2021-12
Issue No.: 01
Effective Date: 2021-08-24


The purpose of this Civil Aviation Safety Alert (CASA) is to raise awareness of airworthiness concerns regarding the failure of certain low pressure flexible oxygen hoses manufactured by O2 Corporation.


Previously, the Federal Aviation Administration (FAA) released Special Airworthiness Information Bulletin (SAIB) NM-13-34 (link to SAIB) to advise owners and operators of an airworthiness concern regarding the failure of oxygen hoses manufactured by O2 Corporation. Recently, failures of oxygen hoses have been observed during scheduled maintenance on Bombardier Global Express and Challenger aeroplanes. Therefore, Transport Canada (TC) issued Airworthiness Directive (AD) CF-2021-17R1, dated 19 July 2021 (link to AD), to correct the issue on Global Express aeroplanes and an AD on the Challenger will be issued in the near future. Since these hoses may be installed on other aircraft, this CASA is being issued to reinforce the recommendations contained within the FAA SAIB.

An Investigation of the in-service oxygen hose failures revealed that the low pressure hoses were becoming rigid or brittle and failing in-service due to cracking and breaking. The service life of these hoses can be dependent on the type of installation and the operating environment. Temperature extremes, humidity and moisture, liquid agents, standing pressure, and mechanical stress are examples of conditions that could affect hose life. Without adequate inspection and/or replacement action, this condition may result in an undetected failure of the oxygen system to deliver oxygen to the passenger and crew masks when needed. These hoses may have been installed on a wide range of aircraft as part of the original design, through supplemental type certificates or other approvals. TC determined that the condition was unsafe on the Bombardier Global Express and Challenger aeroplanes, leading to the issuance of ADs.

The O2 Corporation has issued Service Letter 02-SL-001 to provide operators with guidelines to inspect hoses having base part numbers (P/Ns) O2C20T1, O2C20T3, O2C20T5, O2C20T13, O2C20T14, O2C20T15, and O2C20T16, for proper installation and routing, and for any discrepancies identified in the above-mentioned service letter. These are the base P/Ns; the actual hose P/Ns will include a code to identify the end fitting and length. Additionally, for some installations, the hoses may be part of a higher subassembly such as a passenger service unit, and therefore O2 Corporation P/Ns may not appear in an aircraft parts manual.

Recommended action:

TC recommends that all owners and operators of the subject aircraft comply with the guidelines outlined in O2 Corporation Service Letter 02-SL-001. TC also recommends that all operators of aircraft with installed oxygen systems, pay particular attention in their inspection and maintenance programs, to flexible hoses installed in the oxygen system.

Contact office:

For more information concerning this issue, contact a Transport Canada Centre; or contact Christopher Banken, Continuing Airworthiness in Ottawa, by telephone at 1-888-663-3639, by facsimile at 613-996-9178 or by e-mail at TC.CAWWEBFEEDBACK-retroactionWebMDLN.TC@tc.gc.ca

Original signed by

Rémy Knoerr
Chief, Continuing Airworthiness
National Aircraft Certification


The Transport Canada Civil Aviation Safety Alert (CASA) is used to convey important safety information and contains recommended action items. The CASA strives to assist the aviation industry's efforts to provide a service with the highest possible degree of safety. The information contained herein is often critical and must be conveyed to the appropriate office in a timely manner. The CASA may be changed or amended should new information become available.