Re: A brief commentary

From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
Date:         27 Jun 96 12:56:53 
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>What may appear statistically significant is probably not so. Consider the
>spate of DC-10 crashes in the late '70's, none of which was actually an
>inherent design fault. There was o'Hare, where improper maintenance (using a
>forklift to align the engine) resulted in stresses on the engine mounting
>bolt, which sheared on takeoff.

>From the NTSB report on that crash (AA 191, Chicago O'Hare, May 25, 1979):

    The safety board is also concerned that the designs of the flight
    control, hydraulic, and electrical systems in the DC-10 aircraft
    were such that all were affected by the pylon separation to the
    extent that the crew was unable to ascertain the measures needed
    to maintain control of the aircraft.


    ... The possibility of pylon failure, while remote, was not
    impossible.  Pylons had failed.  Therefore, fault analyses should
    have been conducted to consider the possible trajectories of the
    failed pylon, the possibilities of ddamage to aircraft structure,
    and the effects on the pilot's ability to maintain controlled
    flight.  Since the capability of continued flight was highly
    probable, the fault analysis might have indicated additional steps
    or methods which could have been taken to protect those systems
    essential to continued flight.

    Therefore, the Safety Board concludes that the design and
    interrelationship of the essential systems as they were affected
    by the structural loss of the pylon contributed to this accident.

While the improper maintenance caused the engine separation, that was
simply a triggering event, which need not have cost 273 lives.  The
NTSB clearly felt that the design was weak, if not outright faulty.

Before commenting further, please check your facts.  A good place to
start, besides the official reports on this and other crashes, is to
search the archives of this newsgroup, which can be found at

Karl Swartz	|Home
Moderator of sci.aeronautics.airliners -- Unix/network work pays the bills