Plane Crash Essays - Boeing 747, Boeing 747-8, Fatigue, Stall

Plane Crash Essays - Boeing 747, Boeing 747-8, Fatigue, Stall Plane Crash Instructor: Greg Alston Abstract This paper examines the in-flight separation of the number two pylon and engine from a Boeing 747-121 shortly after takeoff from the Anchorage International Airport on March 31, 1993. The safety issues discussed focus on the inspection of Boeing 747 engine pylons, meteorological hazards to aircraft, the lateral load-carrying capability of engine pylon structures, and aircraft departure routes at Anchorage International Airport during turbulent weather conditions. Shortly after noon on March 31, 1993 the number two engine and pylon separated from Japan Airlines Inc. flight 46E shortly after departure from the Anchorage International Airport. The aircraft, a Boeing 747-121, had been leased from Evergreen International Airlines Inc. The flight was a scheduled cargo flight from Anchorage to Chicago-O'Hare International Airport. On board the airplane was the flight crew and two nonrevenue company employees. The airplane was substantialy damaged during the separation of the engine but no one on board the airplane or on the ground was injured. Flight 46E departed Anchorage about 1224 local time. The flight release and weather package provided to the pilots by Evergreen operations contained a forecast for severe turbulence. As fight 46E taxied onto the runway to await its takeoff clearance, the local controller informed the flight crew that the pilot of another Evergreen aircraft reported severe turbulence at 2,500 feet while climbing out from runway 6R. After takeoff, at an altitude of about 2,000 feet, the airplane experienced an uncommanded left bank of approximately fifty degrees. Although the desired air speed was 183 knots, the air speed fluctuated from a high of 245 knots to a low of 170 knots. Shortly thereafter the flight crew reported the number two throttle slammed to its aft stop, the number two thrust reverse indication showed thrust reverser deployment, and the number two 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 6R. The number one engine was maintained at maximum power. While on the downwind portion of the landing pattern bank angles momentarily exceeded forty degrees alternating with wings level. About twenty minutes after takeoff flight 46E advised the tower they were on the runway. The aircraft was substantially damaged as a result of the separation of the number two engine. Estimated repair costs exceeded twelve million dollars. In addition, several private dwellings, automobiles, and landscaping were damaged by the impact of the number two engine and various parts of the engine pylon and the wing leading edge devices. The National Transportation Safety Board (NTSB) determined the probable cause of this accident was the lateral separation of the number two engine pylon due to an encounter with severe or possibly extreme turbulence. This resulted in dynamic lateral loadings coming from many directions that exceeded the lateral load-carrying capability of the pylon. It was later discovered that the load-carrying capability of the pylon was already reduced by the presence of the fatigue crack near the forward end of the pylon's forward firewall web. As a result of this investigation the NTSB made seven recommendations to the Federal Aviation Administration (FAA), including the inspection of Boeing 747 engine pylons, the potential meteorological hazards to aircraft, an increase in the lateral load capability of engine pylon structures, and the modification of the aircraft departure routes at Anchorage International Airport during periods of moderate or severe turbulence. The NTSB also recommended that the National Weather Service (NWS) use the WSR-88D Doppler weather radar system to document mountain-generated wind fields in the Anchorage area and to develop detailed low altitude turbulence forecasts. In the course of the investigation the NTSB explored virtually every contributing factor contributing to the aircraft accident. These included weather, mechanical failure, design deficiencies, and human factors. The flight crew was properly trained and qualified for this fight. None of the crew members' Federal Aviation Administration (FAA) records contained any history of accidents, incidents, or violations. The flight crew and the mechanics who had worked on the airplane before the flight volunteered to be tested for the presence of alcohol and both lawful and illegal drugs. All of the test results were negative. The investigation revealed that the flight crew was in good health. The airplane, registration N473EV, was a Boeing model