AAIB investigation to DHC-8-402 Dash 8, G-ECOC
Unavailability of crew oxygen due to blocked regulator, from Aberdeen to Birmingham, 13 December 2018.
Summary:
During the climb to cruising altitude the flight crew took the precautionary action of using the fixed oxygen system following a pressurisation event. The aircraft pressurisation system was reset and functioned normally, however the oxygen system failed to provide the pilots with oxygen. The oxygen cylinder regulator was later disassembled, and the crew oxygen supply port was found blocked with a piece of debris. It is suspected that the debris was the tip of a screw extraction tool, but no evidence could be found to explain how it came to be in the regulator. The operator has changed the ‘first flight’ checks to ensure the flight deck emergency oxygen system is functioning correctly.
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