Arlington, AZ, USA
N101LX
Burton Fly Baby
The pilot departed the airport for a local personal flight in the amateur built experimental-category airplane. About 25 minutes after takeoff, the airplane was observed flying in an easterly direction at an undetermined altitude. The witness reported hearing the engine slow down and then speed up. Seconds later, the witness heard "what sounded like an explosion" followed by the airplane falling to the ground in multiple pieces. The witness was located approximately 1 mile from where the wreckage came to rest. Post accident examination of the wreckage revealed that the right wing's forward and aft solid flying wires, turnbuckles and respective wire anchor attachment brackets remained intact, however the attachment brackets were separated from the forward and aft spar assemblies. The four through bolts (AN3 3/16-inch-diameter) associated with the forward brackets were fractured along the bolt shank near the bolt head. The bolts were necked down and were bent near the fracture points; the fracture surfaces were angular. Only two of the four through bolts associated with the aft bracket were recovered and similar findings were noted; the bolts were necked down and the fracture surfaces were angular. The builder's instruction manual for the airplane recommends AN3 (3/16-inch-diameter) anchor attach bracket bolts for standard operations and AN4 (1/4-inch-diameter) anchor attach bracket bolts if aerobatics are intended to be performed in the airplane. The specified anchor attachment bracket bolts (both AN3 and AN4) range in length from 5-1/2-inches to 6-3/4-inches. A personal friend of the pilot reported that about 2 weeks before the accident, the pilot completed a flight in the accident airplane. Upon returning from the flight, the pilot stated that he had completed a "slow roll." The pilot stated the airplane performed well during the flight.
HISTORY OF FLIGHT On April 4, 2007, about 1038 mountain standard time, an experimental Burton Fly Baby airplane, N101LX, was substantially damaged upon impact with terrain following an in-flight break up approximately 1.1 miles southeast of Arlington, Arizona. The commercial pilot/registered owner of the airplane was killed in the accident. The airplane was operated by the pilot as a visual flight rules (VFR) personal flight under the provisions of Title 14, Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed. The flight originated from Buckeye, Arizona, approximately 25 minutes prior to the accident. According to an inspector from the Federal Aviation Administration (FAA), and a witness, the airplane was observed flying in an easterly direction at an undetermined altitude. The witness reported hearing the engine slow down and then speed up. Seconds later, the witness heard "what sounded like an explosion" followed by the airplane falling to the ground in multiple pieces. The witness was located approximately 1 mile from where the wreckage came to rest. A personal friend of the pilot reported that on March 21, 2007, the pilot completed a flight in the accident airplane. Upon returning from the flight, the pilot stated that he had flown to an area near Arlington and completed a "slow roll." The pilot stated the airplane performed well during the flight. PERSONNEL INFORMATION The certified pilot, age 57, held a commercial certificate with airplane single engine land, multi engine land, instrument, glider aerial tow and helicopter ratings. The pilot's most recent Federal Aviation Administration (FAA) second-class airman medical certificate was issued on August 7, 2006. Federal Aviation Administration records indicated that the pilot's total flying experience was 3,114 hours, with approximately 60 hours in make and model. The pilot accumulated approximately 8 hours of flight time in the 90-day period preceding the accident. AIRCRAFT INFORMATION The single-seat open cockpit experimental airplane, serial number LBX101, was powered by a Continental 85 series carbureted engine. The airplane was issued a special airworthiness certificate, experimental amateur built, in 1986. WRECKAGE AND IMPACT INFORMATION The wreckage was examined at the accident site on April 4, 2007. The FAA inspector reported that the airplane wreckage was located in a drainage area covered by heavy vegetation and trees. The wreckage debris field was approximately 3/8-mile in length, with the airplane's engine located at the furthest point of the debris field. Both wings separated from the fuselage and were located along the debris path. The left wing sustained less damage than the right. The right wing was severely fragmented with numerous pieces of the wing located near the beginning of the debris field. The inspector reported that the right wing through bolts, that attach the solid wire anchor attach brackets to the wing spar (forward and aft) exhibited tension overload signatures. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed on the pilot on July 2, 2007, under the direction of the Maricopa County Medical Examiner's Office. According to the autopsy report, the manner of death was accidental and the cause of death was "Severe blunt impact injuries..." The FAA's Civil Aerospace Medical Institute, Oklahoma City, Oklahoma, performed forensic toxicology tests on specimens from the pilot and no drugs of abuse were detected. An unspecified amount of Amlodipine was detected in the pilot's system. ADDITIONAL INFORMATION / TESTS AND RESEARCH After the airplane was recovered it was examined further. The right wing forward and aft solid flying wires, turnbuckles and respective anchor attachment brackets remained connected to one another, however, the attachment brackets were separated from the forward and aft spar assemblies. The four through bolts (AN3 3/16-inch-diameter) associated with the forward bracket were fractured along the bolt shank near the bolt head. The bolts necked down and were bent near the fracture points; the fracture surfaces were angular. Only two of the four through bolts associated with the aft bracket were recovered and similar findings were noted; the bolts necked down and the fracture surfaces were angular. The builder's instructions manual for the airplane recommends AN3 (3/16-inch-diameter) anchor attach bracket bolts for standard operations and AN4 (1/4-inch-diameter) anchor attach bracket bolts if aerobatics are intended to be performed in the airplane. The specified anchor attachment bracket bolts (both AN3 and AN4) range in length from 5-1/2-inches to 6-3/4-inches.
The pilot exceeding the design stress limits of the aircraft while maneuvering in intentional aerobatics.
Source: NTSB Aviation Accident Database
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