Airworthiness Notice - B072, Edition 1 - 21 November 2005

Incompatible Oxygen Fittings


This notice is issued to inform aircraft owners, operators, and maintainers that some portable oxygen equipment carried aboard aircraft may have fittings installed on their regulators and masks, which are not compatible with other types of portable oxygen equipment.


While at cruise altitude, during a routine flight of a commercial airliner, the aircraft suddenly experienced a loss of cabin pressure, which automatically deployed the passenger oxygen masks. During the descent, one of the flight attendants observed a mother having difficulty placing an oxygen mask on her infant. The flight attendant obtained a portable oxygen bottle, donned the mask attached to it, and went to assist the mother and infant.

It was decided to use another portable oxygen mask for the infant. A spare mask was retrieved from another station to be attached to the second outlet of the flight attendant’s oxygen bottle. Unfortunately, the spare mask was equipped with a different style of connector, which was incompatible with the portable oxygen bottle carried by the flight attendant. Once the problem was discovered, the flight attendant then retrieved a second portable bottle and mask for the infant.

Portable oxygen equipment manufacturers do not necessarily use the same type of fittings on their regulators and masks. When more than one type of portable oxygen equipment is carried aboard the same aircraft, or used within the same operator, there is a possibility that this equipment may be incompatible.

Recommended Practice

Oxygen bottles, regulators, and masks should be verified to ensure that each different model carried aboard is in fact compatible with the others. Also, any changes to the coupling and/or the oxygen bottle assemblies should not affect the flow of oxygen for both normal or emergency flight requirements.  Also, for consideration during the compatibility verification, some couplings provide either metered or full flow oxygen depending on part number configuration.

Operators can verify the compatibility of their portable oxygen equipment prior to the purchase or installation of this equipment. However, depending on the number and types of aircraft in an operator’s fleet, it may be more practical to add a separate maintenance task to the maintenance schedule to verify that any newly installed oxygen equipment is compatible with the equipment already aboard. This can normally be accomplished by adding a compatibility check as part of the installation procedure.

For the Minister of Transport

D.B. Sherritt
Director, Maintenance and Manufacturing

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