Crew oxygen mask stowage cup non-radiused latch tabs preventing full face crew oxygen mask removal - Civil Aviation Safety Alert (CASA) No. 2020-07


Owners, operators and maintainers of De Havilland Aircraft of Canada Limited (formerly Bombardier Inc.) DHC-8 300/400 aeroplanes

File Classification No.: Z 5000-35
RDIMS No.: 16360437
Document No.: CASA 2020-07
Issue No.: 01
Effective Date: 2020-08-18


The purpose of this Civil Aviation Safety Alert (CASA) is to advise DHC-8 300/400 operators of the possibility that some B/E Aerospace crew oxygen masks may be difficult to remove from their cup assembly when required during an emergency.

The purpose of this CASA is also to advise operators that there is an available B/E Aerospace Service Bulletin (SB 119301-35-001 Rev 000) that provides the directions to rework the crew oxygen mask cup assembly to allow for easy mask removal.


DHC-8 400 production pilots reported that they were experiencing difficulties removing full face crew oxygen masks from stowage cup part number (P/N) 119301-90 (N669-8038, 8SC1028-1). All Nippon Airways (ANA) reported similar issues with this mask to De Havilland Aircraft of Canada Limited (formerly Bombardier Inc.). Investigation by B/E Aerospace, the manufacturer of the equipment, confirmed that the latch tabs on the two sides of the stowage cup lid had a sharp edge that should have been radiused according to the B/E Aerospace drawing. The full face crew oxygen mask is only used on DHC-8 300 and DHC-8 400 aircraft.

B/E Aerospace has developed a Service Bulletin (SB 119301-35-001 Rev 000) to rework the cup assembly latch tabs to remove the interference causing the impediment.

Recommended action:

It is recommended that all operators of DHC-8 300/400 aircraft complete the requirements of B/E Aerospace SB 119301-35-001 Rev 000 to effectively improve accessibility to the crew oxygen masks on the DHC-8 300/400 aircraft.

The figures below offer details and are excerpted from the B/E Aerospace SB.

Sweep on Fullface Stowage Cup - Open
Stowage Cup Lid Assembly - Lid Hook Before Sanding
Stowage Cup Lid Assembly - Lid Hook After Sanding

Contact office:

For more information concerning this issue, contact a Transport Canada Centre; or Philip Lynch, Continuing Airworthiness in Ottawa, by telephone at 1-888-663-3639, facsimile at 613-996-9178 or e-mail at

Original signed by

Daniel Gosselin
Acting 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.