Subject - Oxygen – Flight Crew Oxygen Mask Regulator – Identification / Operational Procedure / Replacement
Applicability - Flight crew oxygen mask regulators, having Part Number (P/N) MC10, MF10 and MF20 series, with serial numbers (s/n) as listed in Appendix 1 of this AD.
The affected flight crew oxygen masks regulators are known to be installed on, but not limited to, aeroplanes manufactured by Airbus, ATR, Boeing, Bombardier (formerly Canadair, De Havilland Canada), Cessna, Gulfstream and McDonnell Douglas.
Reason In a repair station, improper maintenance on oxygen mask regulators was reported to Intertechnique: during an inspection of the oxygen test bench by its manufacturer, incorrect settings were noticed. This test bench setting discrepancy on the oxygen mask regulator could cause an improper mask dilution schedule.
This condition, if not detected and corrected, could lead, in case of a diversion above 10 000 feet after a depressurization event, to the inhalation of air with improper content of oxygen, due to the bad dilution settings, thereby providing inadequate protection to the affected flight crew member against hypoxia, which can start from a headache and drowsiness and lead eventually to unconsciousness with severe consequence in term of aeroplane controllability.
For the reasons described above, this AD requires the identification and replacement of all potentially affected units.
This AD also requires installation of a placard and implementation of an operational procedure pending replacement of the affected units.This AD is revised to allow accomplishment of the actions as required by paragraph (2) of this AD within 30 days after the effective date of the original issue of this AD.
EASA AD 2012 0254R1
SB MXH 35-240
Qualty,Safety and Training