HUBBARD, OR, USA
N719JX
LUSCOMBE 8A
WITNESSES OBSERVED THE LEFT WING OF THE AIRPLANE SEPARATE AS THE PILOT WAS MANEUVERING APPROXIMATELY 1,000 FEET ABOVE THE GROUND. EXAMINATION OF THE WRECKAGE REVEALED THAT THE LOWER LIFT STRUT ATTACHMENT BOLT HAD SLIPPED OUT OF THE ATTACHMENT LUG, DEFORMED, AND SEPARATED IN POSITIVE BENDING OVERLOAD. THE ATTACHMENT NUT HAD EITHER BACKED OFF THE BOLT OR HAD NEVER BEEN INSTALLED. IT WAS NOT FOUND DURING AN EXTENSIVE SEARCH OF THE WRECKAGE AND THE ACCIDENT SITE. THE BOLT AND NUT FROM THE OPPOSITE WING WERE EXAMINED AND REVEALED THAT THE SELF-LOCKING NUT WAS NOT PROPERLY ENGAGED IN THE BOLT. ENTRIES IN THE MAINTENANCE LOGS INDICATED THAT THE AIRPLANE HAD BEEN REBUILT, AND THE LIFT STRUTS RE-ATTACHED, BY A MECHANIC WHO HAD INSPECTION AUTHORIZATION. THE REBUILD OCCURRED 2 YEARS AND 70 FLIGHT HOURS PRIOR TO THE ACCIDENT. THE AIRPLANE HAD SUBSEQUENTLY RECEIVED AN ANNUAL INSPECTION APPROXIMATELY 6 FLIGHT HOURS PRIOR TO THE ACCIDENT BY ANOTHER MECHANIC WHO HAD INSPECTION AUTHORIZATION, AND NO DISCREPANCIES WERE NOTED.
HISTORY OF FLIGHT On June 24, 1995, about 2110 hours Pacific daylight time, N719JX, a Luscombe 8A airplane, operated by the owner/pilot, broke apart while maneuvering in flight and was destroyed in Hubbard, Oregon. The private pilot and his passenger were fatally injured. Visual meteorological conditions prevailed and no flight plan had been filed. The local flight was conducted under 14 CFR 91 for personal reasons. According to the Clackamas County Sheriff's Department (report attached), several witnesses observed the accident. One witness stated that the pilot, the pilot's wife, the pilot's daughter, and the daughter's acquaintance, had just landed at the Lenhardt Airpark in Hubbard in a Cessna 182 after returning from dinner. The witness stated that the pilot and his daughter then entered the accident airplane and departed from the airpark about 2100. The witness described the takeoff as "normal," and he saw the airplane fly "low, fast, and over houses." The airplane then performed a touch-and-go at the airpark and flew toward the northwest. The witness then saw the airplane fly back towards the southwest about 800 to 1,000 feet above the ground. He observed the airplane begin to "dive down," and then pull up. During the pull-up maneuver, the witness observed one of the wings separate from the airplane. Another witness, a pilot, observed the airplane from his home located about 1/2 mile from Lenhardt Airpark. The witness stated that the pilot "... was going to do a loop," because he saw the airplane begin a dive and then pull up. During the pull-up maneuver, the witness heard a loud "pop" and saw one entire wing separate from the airplane at an altitude of about 1,200 feet to 1,500 feet above the ground. The airplane was then observed to fall "straight down." Both witnesses estimated that the airplane was airborne for 10 minutes, and that the accident occurred at 2110. The accident occurred during the hours of dusk. The impact site coordinates of the main wreckage were 45 degrees, 10.68 minutes North; and 122 degrees, 44.06 minutes West. PERSONNEL INFORMATION According to FAA records, the pilot, age 61, was issued an FAA private pilot certificate with a rating for single engine land airplanes on May 3, 1955. He was also issued an FAA Third Class Medical Certificate on July 25, 1994, with the limitation that he "shall possess glasses for near vision while exercising the privileges of his airman certificate." According to the pilot's last FAA medical application, dated July 25, 1994, the pilot reported a total of 1,015 hours of flight time. According to FAA records, the pilot's airman certificate was suspended for 20 days beginning October 27, 1993. The stated reason for the suspension was for operation of an aircraft "... over two private homes and within 500 feet of persons and structures...." on March 20, 1993. AIRCRAFT INFORMATION The accident airplane was manufactured in 1946 by the Luscombe Airplane Corporation. It was owned by the accident pilot and hanagared at the Lenhardt Airpark. It was designed as a two-seat, high-wing, single-engine airplane. The airplane's maintenance records were recovered and examined. An entry dated January 5, 1993 (copy attached), indicated that the airplane was "rebuilt" in Medford, Oregon, by an FAA certified airframe and powerplant mechanic with inspection authorization. The entry also stated: "Airframe reassembled with new hardware and wing struts" and was "... determined airworthy." The recorded tachometer time next to this entry was 190.7 hours. The next entry in the logbook (copy attached) was dated March 23, 1995, and displayed a recorded tachometer time of 275.5. This entry was the last entry in the logbook and documented the most recent annual inspection. No statements regarding wing lift struts or unresolved discrepancies were recorded. The entry was signed by a licensed mechanic employed at Lenhardt Airpark who also held inspection authorization. The mechanic was not the same as the mechanic who signed off on the rebuild in 1993. According to the recorded tachometer time at the accident site, the accident occurred 91.12 flight hours after the rebuild work in 1993, and 6.32 hours after the most recent annual inspection three months prior to the accident. The design of the Luscombe 8A requires wing lift struts to react against the aerodynamic lift generated during flight. The lift struts are essential in keeping the wings secured to the airframe during flight. Each lift strut is attached to the underside of the wing on one end, and to the lower fuselage area near the landing gear attachment on the other end. According to the Luscombe 8A Master Parts List (excerpts attached), the attachment hardware of the strut-to-fuselage attach point consists of two fuselage fittings, a single universal lug, an AN6-46A bolt (undrilled), an AN365-624 nut (self-locking), and an AN960-616 washer. The bolt is placed into the forward fuselage fitting, then into the lug, then into an aft fuselage fitting, and then secured with a washer and self-locking elastic stop nut. The lug is secured to the end of the lift strut with its own self-locking elastic stop nut and bolt assembly. WRECKAGE AND IMPACT INFORMATION The airplane wreckage was examined at the accident site on June 25, 1995. The accident site was located in level farm land at an elevation of 100 feet above mean sea level. The entire left wing, including the attached lift strut and fuselage attach lug, was found 0.25 nautical miles from the remainder of the wreckage. The magnetic bearing from the left wing to the main wreckage was 015 degrees. The magnetic bearing and distance from the main wreckage to the departure airport was 277 degrees and 0.36 nautical miles respectively. All primary and secondary flight control surfaces were accounted for at the accident site. The right wing and empennage remained attached to the airframe. No evidence was found to indicate a flight control deficiency. Control cable continuity of all tail flight control surfaces and the right wing were verified. Control cables for the left wing were stretched and separated. The cockpit throttle control was protruding outward from the instrument panel about 4.5 inches and bent downward. The tachometer read 1,850 revolutions per minute. The "G-meter" read a negative 1/2 g. The altimeter read 350 feet and was set to 30.13 inches of mercury. No other indications from the cockpit could be read. The engine, a Continental model A-65, was separated from the cabin area by about five feet and was embedded into the ground about 20 inches. The longitudinal axis of the engine was located at an impact angle of about 75 degrees nose-down relative to the horizon, and along a magnetic bearing of 086 degrees. No evidence of preimpact mechanical deficiencies was found. The two-blade metal propeller remained attached to the engine. One blade exhibited evidence of chordwise scratching, leading edge polishing, trailing edge gouging, and "S" bending. About three inches of the blade tip was twisted forward. The other propeller blade did not exhibit "S" bending as was bent aft. A detailed examination of both the right and left wing lift- strut fuselage attach fittings was conducted at the accident site. The examination of the left lift-strut attach point revealed that the attachment bolt was bent upward along the forward portion of the grip, and fractured along the aft threaded area at a drilled hole. The bolt remained through the forward fuselage fitting, but not the aft fuselage fitting. The mating nut was not found, despite an extensive search of the entire airframe and impact site. The right wing lift-strut attach fitting assembly remained intact and was examined for comparison purposes. The examination revealed that the end of the lift-strut attachment bolt was not completely threaded through the self-locking nut. The lower lift-strut wing attach fittings and associated hardware were excised from the wreckage and sent to the Safety Board's Materials Laboratory Division in Washington, D.C. for analysis. According to the Metallurgist's Factual Report dated September 26, 1995 (attached): Visual examination of the fuselage attachment fitting assembly... for the lift strut of the left wing revealed that [the] bolt... fractured at the threaded end. The fracture intersected a through-hole for a cotter pin and the threaded end exhibited bending deformation.... The crowns of the threads... exhibited compression deformation but were not stripped. Stereo microscope examination of the separated end after it was ultrasonically cleaned with soap and water revealed only fracture features consistent with a ductile overstress separation in bending.... A thread remnant from the fractured end [of the bolt] was found embedded in the through-hole of this lug.... The mouth of the through-hole on one end of this lug exhibited severe elongation damage... with circumferencial thread impression marks.... This damage was consistent with the threaded end of [the bolt] bending within the mouth of the lug through-hole. The mouth of the through-hole on the opposite end of the lug contained no deformation.... However, metal flow... and gouge marks were noted [in this area]. Stereo microscope examination of the bolt remnant after it was removed from the through-hole of the lug revealed crown damage consistent with the threaded end of the bolt bending within the lug through-hole The bolt remnant measured approximately 0.2 inch long and contained the manufactured threaded end of the bolt. Examination of the threads revealed no evidence of thread stripping.... Examination of the fractured end of [the bolt] and remaining fractures revealed no preexisting cracks. All fractures appeared typical of overstress separations. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed on the pilot by Dr. Larry V. Newman, M.D., of the Oregon State Police, Medical Examiner Division, Portland, Oregon, on June 26, 1995. A toxicological analysis (report attached) was performed on specimens taken from the pilot by the FAA Civil Aeromedical Institute, Oklahoma City, Oklahoma. ADDITIONAL INFORMATION The entire aircraft wreckage, except the lower lift-strut attach fittings and the maintenance records, was released to Mr. Jack Lenhardt, Hubbard, Oregon, on June 25, 1995. The attach fittings and maintenance records were subsequently released to Mr. Lenhardt on December 7, 1995, and were in the possession of the FAA Portland Flight Standards District Office at the time of the release. Mr. Lenhardt was representing the registered owner of the airplane.
THE FAILURE OF THE MAINTENANCE PERSONNEL WHO REBUILT THE AIRCRAFT TO PROPERLY INSTALL THE WING LOWER LIFT STRUT ATTACHMENT BOLTS. CONTRIBUTING TO THE ACCIDENT WAS THE FAILURE OF ANOTHER MAINTENANCE PERSON TO ADEQUATELY INSPECT THE AIRCRAFT FOR PROPERLY SECURED BOLTS.
Source: NTSB Aviation Accident Database
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