Wednesday, March 1, 2006
Overstressing The Airframe
Exercise good preflight and in-flight judgment to keep your airplane intact
Beech Bonanza 36TC
On July 18, 2004, at 5:08 p.m., a Beech BE-36TC, operated by a private pilot, broke up in flight at approximately 10,000 feet MSL during a cruise flight near Sylvester, Ga. The flight was operated under Part 91. Instrument meteorological conditions prevailed and an IFR flight plan was filed. The pilot and three passengers received fatal injuries, and the airplane sustained substantial damage. The flight originated from Sarasota, Fla.
The pilot had received a weather briefing from an FAA Automated Flight Service Station at about 1:05. The briefer advised of convective activity from Sarasota, extending up to Georgia, moving east-northeast at 30 knots with tops to FL 450. The briefer also stated thunderstorms were east, west and south of Columbus, Ga., moving east at 25 to 35 knots. The pilot filed an IFR flight plan from Sarasota to Lawrenceville, Ill.
ATC broadcast several messages regarding SIGMETs for convective activity. The pilot had reported on frequency when the messages were broadcast. At about 4:49, the pilot advised the Jacksonville Center that he was level at 10,000 feet. At about 4:56, the controller asked the pilot if he had a Stormscope or weather radar on board, to which the pilot replied, “I have a Stormscope.”
The controller advised the pilot that there was a significant cell 10 miles in front of him extending 30 miles. The pilot advised that he was looking and asked, “What does the weather look like if we turned about heading 336 now?” The controller stated that the significant weather was solid, 20 miles wide with level 4 and 5 thunderstorms. The pilot asked if the controller could suggest a heading. The controller advised that there were no openings.
The pilot then asked how far the cell was, and the controller replied five miles and suggested, “If you wanted to go eastbound that’s the clearest route—due east about 45 miles then northbound—that’s the clearest route.”
The pilot replied, “We’ll try that.” There were no further transmissions from the pilot. At about 5:04, the controller attempted to contact the pilot, but there was no response. At 5:08, radar contact was lost. At 5:14, a local sheriff’s department received the first 911 call from a local resident reporting a plane crash. The airplane’s wreckage was located at 5:21.
The nearest weather reporting facility was Southwest Georgia Regional Airport, in Albany, Ga., located approximately 13 miles west of the accident site at a ground elevation of 197 feet. There were localized IFR conditions in thunderstorms and moderate rain at the time of the accident. The thunderstorms began at 5:05 and continued through 5:12, with a second round of thunderstorms moving back into the area between 5:24 and 5:46.
Examination of the accident site found the wreckage path to be about 5,900 feet in length on a heading of 360 degrees. A search of the area at the beginning of the wreckage path found cabin interior components, followed by heavier items consisting of cabin doors, an emergency escape side window and some airframe skin. The right wing, left wing and empennage were next, followed by the cockpit and cabin seats. The engine and instrument panel were located at the end of the wreckage path. All of the fractures examined found no indications of fatigue. Examination of the right wing front and rear spars found bending in the upward or positive direction with wrinkling of the upper skin at the fracture sites.
The NTSB determined that the probable cause of this accident was the pilot’s inadequate in-flight planning and decision making, which resulted in flight into thunderstorms and an in-flight breakup of the airframe.
Peter Katz is editor and publisher of NTSB Reporter, an independent monthly update on aircraft accident investigations and other news concerning the National Transportation Safety Board. To subscribe, write to: NTSB Reporter, Subscription Dept., P.O. Box 831, White Plains, NY 10602-0831.
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