New details of a depressurisation incident on the world's highest time Boeing 737-200 now revealed by investigators tell how the captain and senior flight attendant spent several minutes unconscious when a crack that had gone undetected for 17 years let cabin air escape.
The aircraft, of UK charter operator Peach Air, was flying from Dubrovnik, Croatia to London Gatwick on 13 August last year when the cabin pressure dropped to an equivalent altitude of 20,000ft with the aircraft still at FL350.
The first officer managed to don his oxygen mask but the captain's mask became entangled with his spectacles and he collapsed from hypoxia as he tried to fit it.
Soon afterwards the senior flight attendant also collapsed when she tried to assist the captain without putting on a portable oxygen set.
The UK Air Accidents Investigation Board's (AAIB) report reveals how the situation was exacerbated by a blocked radio transmission which stopped the first officer's initial Mayday call from being received, followed by difficulties in finding a clear area for the aircraft to descend rapidly in the congested airspace of the Maastricht flight information region.
Both affected crewmembers recovered when the aircraft descended and investigations on the ground showed that when the aircraft was pressurised "the lower aft corner of the aft cargo door was seen to gape open by about half an inch (12mm)", preventing successful pressurisation.
Further investigation revealed cracks initially caused by fatigue and later through "fast tearing" starting at rivet holes. By relating the cracks to evidence of earlier repair work, the AAIB was able to say: "It was evident that the cracks in the door-beam members had existed for some 17 years without having been detected."
That, it says, was despite the door being modified in accordance with airworthiness directives in 1981 and being inspected in November 1997.
The AAIB says there had been similar instances of such cracking but that this one was unusual in that the previous aircraft affected had gradually suffered pressurisation difficulties rather than the sudden failure exhibited on the Peach Air aircraft.
Source: Flight Daily News
