Accident Overview
On September 7, 2008, at 1210 mountain daylight time, a Gulfstream American Corporation AA-5A Cheetah airplane, registration N26930, impacted terrain while conducting a pipeline patrol near Baxter Pass, Colorado. The commercial pilot and non-pilot rated passenger were fatally injured. The airplane was destroyed. The flight was conducted under Title 14 Code of Federal Regulations Part 91 without a flight plan. Visual meteorological conditions prevailed.
Flight History
The pilot departed Alamogordo, New Mexico, on the morning of the accident and landed at Canyonlands Field Airport (CNY), Utah. The pilot picked up an employee of Mid-American Pipeline Company at CNY and departed at approximately 1120. Witnesses observed an airplane matching N26930's description approximately 18 miles south of the accident site and 90 miles from CNY flying north at low altitude. The witnesses reported clear weather, temperature between 70 and 80 degrees Fahrenheit, and calm winds. Passing motorists discovered the wreckage at approximately 1430.
Aircraft Information
The 1979-model Gulfstream American Corporation AA-5A, serial number AA5A0817, was a low wing airplane with fixed landing gear, configured for four occupants. It was powered by a Lycoming O-320-E2G engine rated at 180 horsepower, driving a two-bladed McCauley propeller. The airplane had a cruise speed at 75 percent power of 128 knots and a stall speed (VSo) of 53 knots. The airplane was privately owned by the pilot and two other individuals but was being operated by L H Underwood Aerial Patrol, Inc. at the time of the accident, as determined by the FAA.
Wreckage and Impact
The airplane impacted terrain on the edge of 201 Road, about two miles southeast of Baxter Pass. The terrain consisted of low brush and grass in a valley. Terrain rose moderately from the valley floor, and the point of impact was near a split in the valley where the pipeline being followed made an almost 90-degree turn to the west. The wreckage was contained in an area approximately 100 feet wide and 200 feet long. A ground scar indicative of an initial impact point was aligned on a 150-degree heading. The fuselage was shaped into a backwards "L" shape. The left and right wings were separated from the fuselage. The engine and forward cockpit areas showed significant impact damage.
Examination Findings
Engine examination at an off-site location on October 21, 2008, revealed no anomalies. The top spark plugs were removed, cylinders were borescope inspected, and thumb compression was observed on all cylinders. Engine drive train continuity was established. The oil pickup and pressure screens were free of debris. The carburetor showed no external damage or leaking, and the fuel screen was debris-free. The propeller was broken off with the crankshaft flange; one blade was bent forward, the other twisted and bent aft, both with leading edge polishing and chordwise scratching. No evidence of an in-flight engine failure was found.
GPS data from a Garmin GPSMap 396 recovered from the wreckage showed the last five waypoints recorded on the accident tracklog. The final waypoint at 12:09:52 indicated a GPS altitude of 6,647 feet, with no speed or heading data. The GPS track overlaid on a map of the pipeline route showed the track diverging to the right of the pipeline and turning left prior to the pipeline making a 90-degree left turn.