Summary
We propose to adopt a new airworthiness directive (AD) that applies to certain Intertechnique Aircraft Systems oxygen mask regulators. This proposed AD was prompted by a report of a malfunctioning mask having an inflatable harness with a high premature rupture rate due to defective silicon. This proposed AD would require inspecting and replacing defective harnesses with new or modified serviceable units. We are proposing this AD to detect and correct defective harnesses which could lead, in case of a sudden depressurization event, to a harness rupture, thereby providing inadequate protection against hypoxia and possibly resulting in unconsciousness of the affected flightcrew member and consequent reduced control of the airplane.