Although the exact connection to the APU electric supply is beyond my knowledge, I know that a group of Greek and Cypriot pilots and engineers also believe that a bleeds-off takeoff was done, with a ground-air sensor malfunction leading to the pressurization failure at a much later stage than the official explanation would admit. (By the way, I have an engineering discussion paper on this, which is circulating at the Athens airport … I’ll find it, type it up neatly, and post it later.)
Previously on Prune, both Kaptin M and Rockhound had suggested that the ground air sensor might have mistakenly been left in air mode after the pressurization tests the morning of the flight. If I misinterpreted your meaning, please correct me, Kaptin M and Rockhound. Also, please tell me if this would be picked up on the FDR.
If the sensor was left in air mode:
(1) How would that affect the T/O configuration and the pressurization settings during climbout?
(2) How would that affect the operation of the APU during a bleeds-off takeoff?
(3) When the captain spoke to Irwin and discussed the air conditioning problem, what CB was pulled at 29,000 feet? On the CB panel behind the captain’s seat, the T/O Aural Warning and T/O Configuration CBs are next to one another. Will this also be picked up on the FDR?
(4) For pulling CBs in flight, I excerpted the following from Chris Brady’s technical site. Emphasis added is my own: From the QRH CI.2.3 March 29, 2004 "Flight crew reset of a tripped circuit breaker is flight is not recommended. Unless specifically directed to do so in a non-normal checklist. However, a tripped circuit breaker may be reset once, after a short cooling period (approximately 2 minutes), if in the judgement of the Captain, the situation resulting from the circuit breaker trip has a significant adverse effect on safety. A ground reset of a tripped circuit breaker by the flight crew should only be accomplished after maintenance has determined it is safe to reset the circuit breaker. Flight crew cycling (pulling and resetting) of circuit breakers to clear non-normal conditions is not recommended."