Severe excursions of airliners beyond their MMO
Several airliners have exceeded their MMO, the China Airliner sustained more than +5 vertical Gs, even Airbuses, but with light excursions beyond their MMO (Mach 0.86-0.87). These ones recovered after a few thousands feet altitude loss.
I have read in an Airbus flight testing manual that the high speed stability could be tested, by inducing a voluntary/controlled overspeeding phase, waiting for the protection law to activate. It was indicated in any cases "DO NOT EXCEED MACH 0.90". I don't know about any Airbuses or Boeings having closed or exceeded Mach 0.90 in a single piece and survived. One Boeing has probably largely exceeded this limit largely during a high dive at medium altitude (and has gone supersonic ?) but it broke into pieces before the surface impact. It the middle of a mesocluster of tropical thunderstorms, nearing the highest top Cb cell tower, I really wonder whether you need to operate a large excursion beyond the MMO to loose your flight stability margins and really be vulnerable to turbulence. I also wonder about the detrimental impact of the spoilers during a significant excursion beyond the MMO (there was a problem in the overspeed procedures of the Learjet about this aspect, the one of the manufacturer and the one of the pilot being different, but I also know that the wing/airframe geometry of a Learjet and of an Airbus are not the same)
Jeff
Last edited by Hyperveloce; 11th Aug 2009 at 15:41.