Did an unfinished FAA/Boeing Air Safety Directive or AD doom MH370? Reinforcement to the fuselage mounting bracket for certain radio antennae on B777 aircraft may have been required by a recent FAA AD. However completion was allowed for an extended period. Metal fatigue and other cracking failure modes common on aluminum cyclically pressurized fuselages could lead to pressure vessel failure in the uncorrected configuration. In the event of a pressure vessel failure through metal rupture, normal pressurization differential by engine bleed air could then exacerbate the rupture further, as could high dynamic pressure from the high speed descent initiated by flight crew members in response to a rapid depressurization. If an antenna was connected to the ships ACARS or the transponder system, loss of the antenna would render the unit nonfunctional in terms of how the ground stations were reading that data.
A second B777 AD relating to emergency oxygen plumbing, if it had gone unfinished by maintenance could have rendered some oxygen backup systems ineffective. The work completion was not immediate and could have been deferred.
Combining this B777 AD information with the disappearance of MH370 may give investigators and others interested in the fate of this flight something to consider. A loss of comm, a rapid decompression, a divert and emergency descent all seem to fit what we know so far. The transponder and the ACARS might not have been “switched off.” Instead, if either or both of their antennae were rendered inoperative by a metallurgical fatigue or other similar material failure, to the outside observer, these various electrical devices would appear inoperative. Why? Because it is the exchange of their radio signals that we use to determine their operation from the ground. In a like manner, a small fire in baggage area from a stowage of lithium batteries or even a small explosive of a criminal nature might again cause a similar system failure.