Lee Campbell Flight 811 Investigation

2560 Words Nov 21st, 2011 11 Pages
Lee Campbell Flight 811 Investigation
Anthony Vallido
Aviation Safety 409 Abstract United Airlines Flight 811 left Honolulu bound for Auckland, New Zealand on February 24, 1989. A few minutes in the flight the cargo doors blew out and because of the decompression, nine passengers were immediately sucked out of the plane. The debris from the cargo door damaged the planes Number 3 and 4 engines. Captain David Cronin prepared for an emergency landing. The parents of one of the fatalities, Lee Campbell, investigated the accident because they want to know what caused the cargo door to open in midair. Kevin and Susan Campbell were very persistent and relentless in their fight to prove that the cause of the cargo door opening is a malfunction
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From these documents they found information that was not released to the public. There were reports that there disturbing problems with the forward cargo door going right back to its original design. Instead of a plug door that gets jammed into its frame as the aircraft pressure rises, Boeing opted for an outward opening door which allows for more cargo space but the door is not failsafe like the plug design so Boeing built was they thought was a fool proof locking mechanism. Boeing built in multiple redundancies to make sure the door is properly latched and does not open. They built it to a point where it is extremely improbable for the door to open. The Campbell’s discovered that the problem lies with the locking mechanism. To lock the cargo door on the 747, electric motors rotate C-shaped latches around pins in the door frame. A handle then moves L-shaped arms known as locking sectors over the top of the C-shaped latches to prevent them opening. But as early as 1975, problems were found with the locking sectors. Kevin Campbell, an experienced engineer, built a model to show the weakness of the Boeing design. Initially the locking mechanisms were made of aluminum and in 1975 they did not realize that it was not strong enough. The weakness of the aluminum drastically increased the risk of the door accidentally opening. With the aluminum locking sectors, if the C locks tried to backwind open

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