Flight Purpose
A 10,000-hour Airline Transport Pilot (ATP) departed at approximately 0715 to train a new company pilot in locating and reporting oil spills or leaks in oil fields. Company procedure required flights below 500 feet AGL, and upon detecting a leak, the aircraft was to orbit the site with 10 degrees of flaps while making a report.
Accident Sequence
At 1307, another pilot performing pipeline patrol spotted the wreckage and reported its location. Radar data from Approach Control showed the accident airplane maneuvering "tracking back-n-forth" below 500 feet AGL in the general area of the accident. The last radar hit, at 0843, placed the airplane approximately two miles west of the accident site at an altitude of about 300 feet AGL.
Wreckage Examination
All components of the airplane were accounted for at the accident site. The initial impact mark was a ground scar with fragments of red navigational lens, consistent with the left wingtip, located approximately eight feet south of the left wing. The main wreckage, with the engine still attached to the fuselage, lay over a small crater. Impact marks were consistent with a left-wing-low and nose-down attitude. The elevator trim tab was found 15 degrees tab-up, and the wing flaps were extended to the 10-degree setting.
Flight Control and Fuel Systems
Control continuity to all flight controls up to the rescue cuts was established. Both wing tanks and/or fuel lines had been breached by impact. The right wing fuel tank contained approximately 3.5 inches of fuel, and the left wing tank approximately 2 inches. The main fuel tank selector valve was in the both position.
Engine Examination
A borescope inspection of the engine revealed no mechanical deformation on the valves, cylinder walls, or internal cylinder head. The left magneto produced spark at all posts at the magneto cap; the right magneto was destroyed by impact.