ONTARIO, OR, USA
N3762A
Piper PA-22-135
During the climb-out from takeoff at about 200 feet above ground level, the left wing just outboard of the lift strut wing attach points folded upward. The aircraft then went into a vertical descent with the wing section trailing and still attached by what one witness thought were the control cables. The aircraft continued the vertical descent to ground collision. During the descent the forward left wing lift strut separated. Sections of the left side forward and aft lift strut attach fittings and fork assemblies were examined by an NTSB metallurgist. The metallurgist reported that all fracture features and deformation were typical of overstress fractures under bending load. Historical maintenance documentation revealed that the pilot, a non-mechanic, had been doing extensive structural maintenance on the aircraft since the late 1970's, and then having a certified mechanic sign-off his work.
HISTORY OF FLIGHT On November 17, 2000, at 1318 mountain standard time, a Piper PA-22-135, N3762A, registered to and operated by the commercial pilot as a 14 CFR Part 91 personal flight, experienced an in-flight breakup during the climb out shortly after takeoff from the Ontario airport, Ontario, Oregon. Visual meteorological conditions prevailed at the time and no flight plan was filed. A post-crash fire destroyed the aircraft. The commercial pilot, the sole occupant, was fatally injured. Witnesses located in the vicinity reported that they observed the aircraft takeoff from the airport and begin the climb. The witnesses estimated that the aircraft attained an altitude of about 200 feet above ground level when the left wing folded upward. The aircraft then went into a vertical descent with the wing section trailing and still attached by what one of the witnesses thought were the control cables. The aircraft continued the vertical descent to ground collision. After the collision, the aircraft was consumed by fire. PERSONNEL INFORMATION At the time of the accident, the pilot held a commercial and flight instructor certificates, and an instrument rating for single-engine land aircraft. The pilot's flight logbook 4, dated 10/13/84 to the last logged entry dated 7/13/00, was provided for review. The logbook indicated a total flight time in all aircraft of approximately 2,163 hours. Since the beginning of this logbook, the total flight time in the accident aircraft was 784 hours. The last logged biennial flight review was logged on May 2, 1985. Federal Aviation Administration medical records indicate that the pilot's last medical examination for the class three medical certificate was accomplished on March 29, 1990. At that time, the certificate did not list any waivers or limitations. AIRCRAFT INFORMATION Aircraft maintenance records and historical documentation indicated that the pilot purchased this aircraft in 1978. In a statement prepared by the pilot at an unknown time and found among the maintenance records, indicated that after the aircraft was purchased, it needed extensive repairs. The pilot indicated that every few days, an authorization inspection (AI) mechanic would check out the work that he (a non-certificated mechanic) was doing on the aircraft. The work included converting the fuselage to conventional landing gear, overhauling the engine and recovering the wings and fuselage. This work was completed in 1979. The pilot also indicated that the aircraft was involved in an accident on June 29, 1981, in which structural damage occurred to the right wing spar and three ribs. The pilot again reported that he disassembled the "right wing and replaced the rear spar and three ribs" under the supervision of a certificated mechanic. The major repair and alteration FAA Form 337, dated August 14, 1982, however, indicates that the "left wing rear spar" and "three ribs" were replaced at the aileron area of the wing. A drawing of the "left wing" indicates the area damaged (See attachment). The maintenance logbooks that were provided for review began in July 1985, at an annual inspection signoff. Annual inspections were noted in 1986, 1988, and 1989. In June 1989, the annual inspection sign-off noted "inspected control cables pulley's and bellcranks, wing attach points..." There were no further maintenance sign-offs until an annual inspection on April 15, 1999. The aircraft total times and entries in the pilot's flight logbook, indicate that approximately 150 hours had been accumulated on the aircraft from 1990 to 1995. About two-and-a-half hours of flight time were accumulated in 1995. No flight time was accumulated in 1996, 1997, or 1998. The first annual inspection accomplished after June 1989, was signed off on April 15, 1999, the sign-off noted, "Rigged and checked aircraft cable tension and routing, lubed hinges, pulleys and controls." Airworthiness Directive 99-01-05 was complied with in accordance with Service Bulletin 528D, to prevent in-flight separation of the wing from the airplane caused by corroded wing lift struts or cracked wing lift strut forks. The lift strut forks were sent to Precision Propeller, Boise, Idaho, and magnaflux inspected. No cracks were found. The most recent annual inspection prior to the accident was signed-off on June 14, 2000. During this inspection, the mechanic "Visually inspected controls and cables." The investigative team noted that the entry had not been signed off by the mechanic to indicate that the aircraft had been inspected in accordance with an annual inspection and was determined to be airworthy. The mechanic who performed the inspection reported that he did not know why the entry was not signed off and stated that the aircraft was in an airworthy condition at that time. WRECKAGE AND IMPACT INFORMATION The wreckage was located about 700 feet northeast of the departure end of runway 32. The terrain descended about 50 feet below the airport elevation at the end of the runway. The terrain was level with open agricultural fields and sparsely populated with trees. Small pieces of the aircraft such as two inspection cover plates, pieces of plexiglass, and fragments of fabric and paint chips were found in the field between the runway and the accident site. The largest piece found in the field was the entire section of the forward left wing lift strut that was located about 140 feet from the main wreckage. The main wreckage was positioned laying on its side and nearly inverted. A post-crash fire had consumed the entire fuselage and wings. The dry grass surrounding the wreckage was burned. The right wing was positioned parallel to the fuselage and laying inverted. Both the aileron and flap remained in place. Control continuity was established to the cockpit area. The right side wing fore and aft lift struts remained in place. The left wing was positioned nearly perpendicular to the fuselage. The wing was found "folded" about four inches outboard of the lift strut attach points. The entire section of the aft strut also separated and was found within 10 feet of the main wreckage. Control cables were noted among the left wing debris; however, due to the deformation of the wing continuity could not be established. The empennage was positioned nearly inverted and remained intact. Control continuity from the empennage to the cabin area was established. The engine was laying on its right side and remained in position with the fuselage. The propeller remained attached to the crankshaft. The spinner was crushed rearward. MEDICAL AND PATHOLOGICAL INFORMATION The Oregon State Medical Examiner's Report indicated the pilot's cause of death as high velocity impact trauma. Toxicological samples were sent to the Federal Aviation Administration Civil Aeromedical Institute, Oklahoma City, Oklahoma, for analysis. The results of the analysis were negative TESTS AND RESEARCH Sections of the left wing front and aft spar with the lift strut attachments on the wing; the front and rear lift strut assembly on the fuselage side; the front and rear lift strut assembly on the wing side; the front and rear fork assemblies, and two sections of control cable were all sent to the National Transportation Safety Board Material Laboratory in Washington DC, for inspection. The Senior Metallurgist reported, "Fracture features and deformation on all of the lift strut pieces were typical of overstress fractures under bending loads." The metallurgist reported, "...the fractured ends of the individual cables revealed elongated ends, typical of overstress fractures." (See attached report) ADDITIONAL INFORMATION The wreckage was released to the owner's representative on December 4, 2000. At the time of the release, the wreckage was being stored at the representative's facility in Payette, Idaho.
Overstress loading to the left wing lift strut resulting in the left wing folding upward during the initial climb.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
