Date:	Wednesday 31 March 1993
Time:	12:34
Type:	Boeing 747-121
Owner/operator:	Japan Air Lines - JAL
Registration:	N473EV
MSN:	19657/37
Year of manufacture:	1970
Total airframe hrs:	83906 hours
Cycles:	18387 flights
Engine model:	Pratt & Whitney JT9D-7D
Fatalities:	Fatalities: 0 / Occupants: 3
Aircraft damage:	Substantial, repaired
Category:	Accident
Location:	Anchorage International Airport, AK (ANC) -   United States of America
Phase:	Initial climb
Nature:	Cargo
Departure airport:	Anchorage International Airport, AK (ANC/PANC)
Destination airport:	Chicago-O'Hare International Airport, IL (ORD/KORD)
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

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."

Air Safety Week 7:14 5 April 1993 (5)
NTSB Safety Recommendations A-94-9 and -10
NTSB/AAR-93/06

photo (c) NTSB; Anchorage International Airport, AK (ANC); 31 March 1993; (publicdomain)

photo (c) NTSB; Anchorage International Airport, AK (ANC); 31 March 1993; (publicdomain)

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