Aircraft Accident Brief Ntsb/aab-02/01 (Pb2002-910401): Egypt Air Flight 990, Boeing 767-366er, Su-Gap - National Transportation Safety Board Page 53

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[Left and right] elevator deflection as a result of right elevator dual PCA jam is
consistent with the FDR data where Boeing data is valid.
In the area beyond the airplane normal design envelope where the data is not
valid, all the flight control behavior is uncertain, control surfaces are subject to
flutter.
The right elevator middle and outboard bellcrank rivets shear direction is
consistent with a jammed PCA reacting against pilot input to move the elevator
up.
Analysis revealed that there are a lot of [radar] returns forming continuous
paths crossing the flightpath of [EgyptAir flight 990], which may reflect
deliberate [evasive] action by one of the pilots.
EgyptAir’s August 11, 2000, Submission
In its August 11, 2000, submission, EgyptAir asserted that ground tests and
simulations conducted during the investigation were flawed because simulations were
conducted using Boeing’s published 767 data and “did not reflect the actual operation of
the airplane”; steady-state values were used to calculate the control column forces in
various dynamic flight conditions, thus invalidating conclusions; and extrapolation of data
for calculated airplane speeds in excess of those for which test data existed (Mach 0.91)
“cannot produce accurate results.”
EgyptAir also argued in its submission that the relief first officer did not
deliberately cause the accident. According to the submission, “the deliberate act theory
was based, in large part, on the initial inaccurate translation of an expression repeated
several times by the [relief] first officer…[which] has been eliminated not only by credible
evidence and analysis but also by accurate translation of the CVR.” EgyptAir further
stated that (1) the relief first officer had no motive to kill himself or others aboard
EgyptAir flight 990; (2) the relief first officer did not use his seniority to insist that he be
allowed to fly the airplane; (3) the relief first officer may not have been alone in the
cockpit at the onset of the dive; and (4) the captain returned to the cockpit almost
immediately after the dive started, and there was no indication of a struggle or
disagreement between the two flight crewmembers. EgyptAir further stated that “the
cockpit conversations showed an effort at teamwork rather than a crew working at cross
purposes.” Further, EgyptAir indicated that several of the relief first officer’s actions were
not consistent with a deliberate attempt to crash the airplane. For example, it stated that
the cockpit door was not closed and locked; the throttle levers were moved to idle,
whereas engine power would have accelerated the descent; and more radical flight control
inputs were available (more nose-down elevator deflection or aileron and rudder with
elevator deflections) but not used.
EgyptAir also contended in its submission that at least three flight crewmembers
were in the cockpit during the descent, as evidenced “by the fact that if either the captain
or [relief] first officer had let go of their control columns to shut the engines or to deploy
NTSB/AAB-02/01

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