Aircraft Accident Brief Ntsb/aab-02/01 (Pb2002-910401): Egypt Air Flight 990, Boeing 767-366er, Su-Gap - National Transportation Safety Board Page 42
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160 36
Examination of the left engine (which was recovered relatively intact) revealed
evidence of little, if any, rotation at the time of impact. The right engine was severely
broken up, and only about 80 percent of it was recovered. Examination of the recovered
portions of the right engine showed evidence of little, if any, rotation at the time of impact.
The observed deformations on the right engine were consistent with a steep impact angle,
whereas observed deformations on the left engine were consistent with an inverted,
slightly aft-end-down impact angle. Although the recovery location of and damage to the
left engine were consistent with it separating from the airplane before impact, no evidence
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of any preimpact catastrophic damage or fire was observed on either engine.
TESTS AND RESEARCH
Review of Radar Data
Five radar sites detected primary and/or secondary returns from EgyptAir
flight 990. These sites are located at North Truro, Massachusetts; Riverhead, New York;
Gibbsboro, New Jersey; Oceana, Virginia; and Nantucket, Massachusetts. The Safety
Board’s examination of the available radar data revealed that four of the five radar sites
recorded no sequence of primary or secondary radar returns that intersected EgyptAir
flight 990’s position at any time nor did they reveal any radar returns consistent with a
projectile or other object traveling toward the accident airplane. Although the Riverhead
radar site recorded numerous radar returns near the flightpath of EgyptAir flight 990
within 5 minutes of the accident, none of the radar sites with areas of coverage that
overlapped this area of Riverhead’s coverage recorded similar radar returns. Consultation
with the USAF Radar Evaluation Squadron revealed that the primary returns in question
from the Riverhead radar site were caused by radio frequency interference from the Bucks
Harbor, Maine, long-range radar site.
No secondary radar returns were received from EgyptAir flight 990 after 0150:36
(about the time the CVR and FDR stopped recording); however, after this time, several
radar sites recorded primary radar returns that continued along the accident airplane’s
extended flightpath from its last recorded radar position. As previously discussed, these
primary radar data (with extrapolated FDR data and simulation results) indicated that after
the airplane’s FDR and CVR stopped recording, the airplane descended to an altitude of
about 16,000 feet msl, then climbed to about 25,000 feet msl and changed heading from
80º to 140º before it began its second descent, which continued until it impacted the
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ocean.
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For additional information, see Powerplants Group Chairman’s Factual Report.
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For additional information, see the Aircraft Performance Group Chairman’s Aircraft Performance
Study.
NTSB/AAB-02/01
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