Japan Air Lines Cargo Flight 46E

Japan Air Lines Cargo Flight 46E was a scheduled cargo flight on 31 March 1993, operated by a Boeing 747-100 for Evergreen International Airlines, on behalf of Japan Air Lines, from Anchorage International Airport, in Anchorage, Alaska, to O'Hare International Airport, in Chicago. After departure, while climbing through 2,000 feet, the pylon for engine two detached, causing the whole engine to fall off the wing. The pilots managed to land the 747 back at Anchorage without further incident.

The NTSB concluded that the lateral separation of the No. 2 engine pylon was possibly 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.

Flight

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 airplanes. As Flight 46E taxied onto the runway to await takeoff clearance, the local controller informed "the flight crew that the pilot of another Evergreen Boeing 747 reported severe turbulence at 2500 ft while climbing out from runway 06R." After takeoff, at an altitude of about 2000 ft, the airplane experienced an uncommanded left bank of approximately 50 degrees.

While the desired airspeed was 183 knot, the airspeed fluctuated about 75 knot from a high of 245 knot to a low of 170 knot. Shortly thereafter, the flight crew 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 flight crew 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. At about 12:45, Flight 46E advised the tower that they were on the runway.