Narrative:
JAL Flight 46E departed Anchorage about 12:24 local time. The flight release/weather package provided to the pilots by Evergreen operations contained a forecast for severe turbulence and indicated that severe turbulence was reported by other large airplanes. As flight 46E taxied onto the runway to await its takeoff clearance, the local controller informed "the flightcrew that the pilot of another
Evergreen B-747 reported severe turbulence at 2,500 feet while climbing out from runway 06R.
After takeoff, at an altitude of about 2,000 feet, the airplane experienced an uncommanded left bank of approximately 50 degrees. While the desired air speed was 183 knots, the air speed fluctuated about 75 knots from a high of 245 knots to a low of 170 knots. Shortly thereafter, the flightcrew reported a "huge" yaw, the No. 2 throttle slammed to its aft stop, the No. 2 reverser indication showed thrust reverser deployment, and the No. 2 engine electrical bus failed. Several witnesses on the ground reported that the airplane experienced several severe pitch and roll oscillations before the engine separated. Shortly after the engine separated from the airplane, the flightcrew declared an emergency, and the captain initiated a large radius turn to the left to return and land on runway 06R. The No. 1 engine was maintained at
emergency/maximum power. While on the downwind portion of the landing pattern, bank angles momentarily exceeded 48 degrees, alternating with wings level. About 12:45, flight 46E advised the tower that they were on the runway.
PROBABLE CAUSE: "The lateral separation of the No. 2 engine pylon due to an encounter with severe or possibly extreme turbulence that resulted in dynamic multi-axis lateral loadings that exceeded the ultimate Iateral load-carrying capability of the pylon, which was already reduced by the presence of the fatigue crack near the forward end of the pylon's forward firewall web."
Engine separation
Forced landing on runway
» NTSB Safety Recommendations A-94-9 and -10
» NTSB/AAR-93/06
accident date: 31-03-1993
type: Boeing 747-121
registration: N473EV
accident date: 31-03-1993
type: Boeing 747-121
registration: N473EV
| Status: | Accident investigation report completed and information captured |
| Date: | Wednesday 31 March 1993 |
| Time: | 12:34 |
| Type: |  Boeing 747-121 |
| Operating for: | Japan Air Lines - JAL |
| Leased from: | Evergreen International Airlines |
| Registration: | N473EV |
| MSN: | 19657/37 |
| First flight: | 1970-04-15 (23 years) |
| Total airframe hrs: | 83906 |
| Cycles: | 18387 |
| Engines: | 4 Pratt & Whitney JT9D-7D |
| Crew: | Fatalities: 0 / Occupants: 3 |
| Passengers: | Fatalities: 0 / Occupants: 0 |
| Total: | Fatalities: 0 / Occupants: 3 |
| Aircraft damage: | Substantial |
| Aircraft fate: | Repaired |
| Location: | Anchorage International Airport, AK (ANC) ( United States of America)
|
| Phase: | Initial climb (ICL) |
| Nature: | Cargo |
| Departure airport: | Anchorage International Airport, AK (ANC/PANC), United States of America |
| Chicago-O'Hare International Airport, IL (ORD/KORD), United States of America | |
| Flightnumber: | JL46E |
JAL Flight 46E departed Anchorage about 12:24 local time. The flight release/weather package provided to the pilots by Evergreen operations contained a forecast for severe turbulence and indicated that severe turbulence was reported by other large airplanes. As flight 46E taxied onto the runway to await its takeoff clearance, the local controller informed "the flightcrew that the pilot of another
Evergreen B-747 reported severe turbulence at 2,500 feet while climbing out from runway 06R.
After takeoff, at an altitude of about 2,000 feet, the airplane experienced an uncommanded left bank of approximately 50 degrees. While the desired air speed was 183 knots, the air speed fluctuated about 75 knots from a high of 245 knots to a low of 170 knots. Shortly thereafter, the flightcrew reported a "huge" yaw, the No. 2 throttle slammed to its aft stop, the No. 2 reverser indication showed thrust reverser deployment, and the No. 2 engine electrical bus failed. Several witnesses on the ground reported that the airplane experienced several severe pitch and roll oscillations before the engine separated. Shortly after the engine separated from the airplane, the flightcrew declared an emergency, and the captain initiated a large radius turn to the left to return and land on runway 06R. The No. 1 engine was maintained at
emergency/maximum power. While on the downwind portion of the landing pattern, bank angles momentarily exceeded 48 degrees, alternating with wings level. About 12:45, flight 46E advised the tower that they were on the runway.
Probable Cause:
PROBABLE CAUSE: "The lateral separation of the No. 2 engine pylon due to an encounter with severe or possibly extreme turbulence that resulted in dynamic multi-axis lateral loadings that exceeded the ultimate Iateral load-carrying capability of the pylon, which was already reduced by the presence of the fatigue crack near the forward end of the pylon's forward firewall web."
Accident investigation:
 |
|
Classification:
TurbulenceEngine separation
Forced landing on runway
Sources:
» Air Safety Week 7:14 5 April 1993 (5)» NTSB Safety Recommendations A-94-9 and -10
» NTSB/AAR-93/06
Follow-up / safety actions
NTSB issued 10 Safety Recommendations
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Photos
accident date: 31-03-1993
type: Boeing 747-121
registration: N473EV
accident date: 31-03-1993
type: Boeing 747-121
registration: N473EV
Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Anchorage International Airport, AK to Chicago-O'Hare International Airport, IL as the crow flies is 4534 km (2834 miles).
Distance from Anchorage International Airport, AK to Chicago-O'Hare International Airport, IL as the crow flies is 4534 km (2834 miles).
This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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