Aircraft Accident Brief Ntsb/aab-02/01 (Pb2002-910401): Egypt Air Flight 990, Boeing 767-366er, Su-Gap - National Transportation Safety Board Page 26
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160 20
METEOROLOGICAL INFORMATION
The Safety Board’s review of data from the National Climatic Data Center
National Radar Mosaic (from about 0100 through 0230 on October 31, 1999) and other
meteorological data revealed no record of significant meteorological conditions in the area
at the time of the accident. No pilot reports indicating any significant meteorological event
were transmitted in the accident area between about 2300 EDT on October 30 and 0700 on
October 31, 1999.
FLIGHT RECORDERS
The FDR and CVR were recovered from the Atlantic Ocean by U.S. Navy
remote-operated vehicles on November 9 and November 14, 1999, respectively. Upon
recovery, they were immediately packed in water to prevent/delay the onset of corrosion
and shipped to the Safety Board’s laboratory in Washington, D.C., for readout.
Cockpit Voice Recorder
The CVR installed on the accident airplane was a Fairchild model A-100,
S/N 3193. Although the CVR unit exhibited external and internal structural damage and
the recording medium (magnetic tape) was wet, the tape was otherwise in good condition.
The CVR recording consisted of four channels of audio information, the following three
of which recorded usable audio information: the cockpit area microphone (CAM) and the
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hot microphones at the captain’s and first officer’s positions.
The quality of the audio
information recorded by the CAM was good, whereas the quality of the audio information
recorded by the hot microphone at the first officer’s position was excellent until 0141:11,
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after which time it was poor.
The audio information recorded by the hot microphone at
the captain’s position was difficult or impossible to decipher throughout most of the
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recording.
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This anomalous condition was discovered when a drooping elevator surface was observed during a
preflight inspection; there were no reports of in-flight anomalies before this discovery. The air carrier’s
maintenance personnel found sheared rivets in the bellcranks, which they repaired. The system was
functionally checked after the repair, and the airplane was returned to service. The air carrier reported the
anomalous condition and repair to Boeing and has reported no further anomalies. FDR data were not
available.
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For the purposes of this report, the compressible links are described as “bottomed out” when they
have been deflected to the full extent of their travel in either direction.
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The single hydraulic system maintenance check tests the operation of each PCA individually by
powering each of the airplane’s three hydraulic systems, one at a time. An inoperative elevator PCA will not
operate the elevator when powered by its hydraulic system. A PCA with a failed bellcrank shear rivet will
not operate the elevator properly.
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Indications of an improperly rigged PCA can occur as a result of yielded or failed shear rivets in a
bellcrank assembly.
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The fourth channel of audio information recorded by the CVR is usually recorded through audio
equipment at a cockpit jumpseat position. The FAA does not require a fourth channel to be installed/used on
airplanes equipped with CVRs.
NTSB/AAB-02/01
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