Aircraft Accident Brief Ntsb/aab-02/01 (Pb2002-910401): Egypt Air Flight 990, Boeing 767-366er, Su-Gap - National Transportation Safety Board Page 142
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160 In particular, the NTSB’s assertion that there is no relevant FAA Service Difficulty
Reports (SDR) is incorrect. The following incidents involving the Boeing 767 elevator system
are included in the SDR's:
i.
On September 12, 1994, United Airlines reported that a B767-300 airplane (serial
number 27159) experienced a frozen elevator condition (while descending
through 11,000 feet), which took 30 pounds forward pressure to pop the elevator
free. A post-landing inspection revealed no discrepancies in the elevator control
system.
ii.
On June 20, 1996, the same airplane reported that it was “unable to hold altitude
at 10,000 feet on autopilot which was disconnected and the elevator was stiff.
After 5 to 10 minutes of using stabilizer trim, while pushing up and down on the
control column, something let go at 4,000 feet and the airplane flew normal
since.” A post-landing inspection, once more, revealed no discrepancies in the
elevator control system.
Finally, on March 27, 2001, American Airlines reported that one of its B767-300
airplanes experienced pitch control difficulties when descending through 6,000 feet on approach
to Paris, France. A post-incident evaluation of the FDR confirmed that one of the elevators was
frozen (believed to be the right elevator) in response to both autopilot and manual inputs. This
event was described in the NTSB letter to the ECAA dated April 19, 2001 as a binding of the
elevator aft quadrant. The pilots used the stabilizer trim to land the airplane. On the ground, the
crew applied a higher force on the control column to break the elevator free. The post-landing
inspection also revealed no discrepancies in the elevator system and the airplane was ferried back
to Dallas, Texas. The incident is still under investigation by the NTSB, FAA, and Boeing.
Not only are these incidents significant because they provide documented evidence of
malfunction in the Boeing 767 elevator system, they also conclusively demonstrate that such
malfunctions can occur without leaving any obvious physical evidence. The NTSB’s five-year
investigation of the USAir 427 accident was made all the more difficult and prolonged precisely
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