SEA96FA182

The pilot was practicing touch-and-go landings at his unlighted private dirt airstrip. Shortly after sunset, his family noted him missing. The aircraft wreckage was found at the bottom of a 300-foot-deep gully adjacent and parallel to the airstrip early the next morning. The pilot was found fatally injured 10 feet from the wreckage. Investigators found a set of tracks curving off the edge of the airstrip toward the gully, along with broken pieces of wingtip fairing; the track extended off the airstrip edge down slope for 400 feet and terminated. The aircraft wreckage was roughly aligned with these tracks although a second ground scar going the opposite direction was found running down the slope near the bottom, adjacent to the wreckage. Investigators did not find any evidence of preimpact malfunctions of the aircraft, but did find the aircraft's seat belt and shoulder harness unfastened with no evidence of damage to, or failure of, the seat belt or buckle. The pilot's son reported that the pilot had been taking 'Pondemun and Fastum' [sic] diet pills.

History of flight

Sometime between 2115 mountain daylight time on August 7, 1996 and 0347 on August 8, 1996, a Cessna 182P, N9136M, registered to M and B Enterprises of St. Anthony, Idaho, was noted missing by the pilot's family. According to the pilot's son, the recently certificated private pilot/aircraft owner had been practicing "touch-and-go" landings at his private airstrip east of St. Anthony. No flight plan had been filed for the local 14 CFR 91 flight. The substantially damaged aircraft wreckage was found by family members at the bottom of an approximately 300-foot-deep gully paralleling the airstrip on the morning of the 8th. The pilot, who had been the aircraft's only occupant, was found fatally injured approximately 10 feet from the aircraft wreckage. Idaho Falls, Idaho, approximately 38 nautical miles southwest of the accident site, reported visual meteorological conditions with light to calm winds during this time period.

The accident occurred at an undetermined time between sunset on August 7 and sunrise on August 8 (see Meteorological Information below), at approximately 43 degrees 56.1 minutes North and 111 degrees 29.2 minutes West.

Personnel information

The pilot received his private pilot certificate on March 18, 1996. According to his pilot logbook, which his son furnished to investigators after the accident, the majority of his flight time had been logged in the accident aircraft. The pilot had logged 3 total hours of night time (none as pilot-in-command and none within the last 90 days) and had not logged any flight time since June 5, 1996, but his logbook did indicate that he met the general recent flight experience requirements of 14 CFR 61.57(c).

The pilot did not hold an FAA medical certificate. He was found to be listed in two separate entries in the FAA's airman registry. One entry, updated July 25, 1996, listed the pilot's first name as "Bob" (the nickname the pilot went by, according to local acquaintances), contained a St. Anthony post office box in the address listing, and indicated that he held a student pilot certificate dated November 30, 1995, and that his medical certificate (also dated November 30, 1995) had been denied (see Medical and Pathological Information below). The second entry, updated May 24, 1996, listed the pilot's first and middle names as "Keith Robert" (the pilot's full name) and contained a St. Anthony street address listing. This entry indicated that the pilot held a private pilot certificate with a date of issuance of March 18, 1996, but contained no medical certificate information on the pilot. The Social Security number in the second listing differed from that of the first registry entry by one digit.

Aircraft information

The accident aircraft had been modified per FAA Supplemental Type Certificate (STC) number SA00152WI, held by Air Plains Services Corporation of Wellington, Kansas. The principal modification consisted of replacing the airplane's original 230 horsepower (hp) Continental O-470-S engine and two-blade McCauley constant speed propeller with a factory-remanufactured 300 hp Continental IO-520-D engine installation and three-blade Hartzell constant speed propeller. Copies of the aircraft logbooks furnished by Bob's Airmotive of Challis, Idaho, which performed the conversion, indicated that the new engine installation was completed on July 27, 1996, 11 days before the accident. The aircraft tachometer, which the aircraft logbook indicated was replaced with the engine and indicated zero time when installed, read 23.1 hours at the accident scene.

Meteorological information

Sunset at St. Anthony occurred at approximately 2042 on the evening of the 7th with evening twilight lasting until 2154. Moonrise occurred at 0145 on the morning of the 8th with 29 percent moon illumination. Morning twilight began at 0511 on the 8th, with sunrise on the 8th at 0623.

Aerodrome and ground facilities

The airstrip is an unlighted dirt airstrip approximately 2,850 feet long and 50 feet wide and is oriented approximately 020/200 degrees magnetic. The airstrip elevation is approximately 5,300 feet above sea level. The gully in which the aircraft wreckage was located approximately parallels the west edge of the airstrip, and consists of a relatively shallow slope for a vertical drop of approximately 200 feet followed by a relatively steep slope for the last 100 vertical foot drop.

Wreckage

The aircraft wreckage was examined at the accident site on August 8-9, 1996. During the on-scene investigation, a set of three parallel tracks in the strip's dirt surface, generally matching the landing gear geometry of the accident aircraft, was found curving off the west edge of the strip in a southwesterly direction. The tracks exited the edge of the strip at a point approximately 1,080 feet southwest of the northeast end of the strip. Just southwest of the runway edge exit point of these tracks, to the right of the strip (looking southwest) were several pieces of debris composed of painted plastic material, which matched material missing from the aircraft's left wingtip fairing, along with bushes broken in a southwesterly direction. The track off the right edge of the runway continued down the shallow slope in a southwesterly direction away from the strip for approximately 400 feet, at which point the track terminated.

The main aircraft wreckage was in the bottom of the gully, west of the tracks which exited the west edge of the strip. It was abeam a point approximately 1,600 feet southwest of the northeast end of the airstrip, or 520 feet down the strip beyond the point where the tracks curved off the right edge of the strip. A 67-foot-long ground scar, oriented 340 degrees magnetic running down the slope, was found on the steep bottom portion of the eastern slope of the gully. This ground scar terminated at a point near the bottom of the gully where the slope abruptly leveled. The aircraft's propeller, separated from the engine, was found at the termination point. The main wreckage was 40 feet northwest of the termination point. The pilot was found at a location in line with the 340-degree ground scar, approximately 30 feet beyond its termination point. Segments of broken windscreen glass were also found in line with this ground scar, beyond the pilot.

The main aircraft wreckage, which included all major sections of the aircraft minus the propeller, was lying on its right side with the nose pointed generally down the gully to the southwest. Both wings were fractured at approximately the roots, and the empennage was broken back approximately 180 degrees to the right. Both flaps were down.

The propeller, located at the termination point of the 340-degree ground scar, had two blades and the spinner still attached to the hub, with one blade (adjacent to the rest of the propeller assembly) broken off at the blade root. Two blades were bent forward, and one blade was bent aft about 30 degrees in mid-span. All three blades exhibited leading edge damage and chordwise scratching.

Investigators found the pilot's seat belt buckle unfastened. There was no evidence of mechanical distress to the mating parts of the buckle, and both ends of the seat belt were properly anchored to the airframe with no evidence of anchor point damage or strain. The buckle snapped together and held fast when pulled on by the investigators. The aircraft was equipped with a shoulder harness, but the shoulder harness was not hooked to the seat belt at the accident scene.

The on-scene investigators found no evidence of preimpact malfunction or failure in either the airframe or the engine. There was also no evidence of fire. Fuel was found in both fuel tanks as well as at other points in the aircraft fuel system.

Medical and pathological information

The pilot was issued a third-class medical certificate by an aviation medical examiner (AME) in Rexburg,