N2870SCessna 150G · 1967

On August 23, 2011, about 1138 Pacific daylight time, a Cessna 150G, N2870S, crashed 150 yards east of the southern running grass landing strip at Cavanaugh Bay Airport, Coolin, Idaho. The airplane's owner operated the airplane under the provisions of Title 14 Code of Federal Regulations Part 91. The private pilot was seriously injured, and the airplane was substantially damaged. Visual meteorological conditions prevailed, and no flight plan had been filed. The flight originated from Chattaroy, Washington, around 0900.

Witnesses reported to a Federal Aviation Administration inspector, who responded to the scene of the accident, that they observed the airplane as it approached the grass landing strip. One witness stated that he saw the airplane's left wing dip down, then the airplane pitched up into a high angle of attack, and descended vertically; he then lost sight of it behind some trees. He could hear the engine developing high power until it contacted trees and terrain.

The Cavanaugh Bay Airport is located on the southeastern side of Priest Lake. The airplane wreckage was located 150 yards east of the grass runway, among a large grove of conifer trees. The airplane was resting on its nose, with the wing leading edges parallel to the ground, and the tail buckled and skewed to the left of center. First responders reported that there was fuel leaking from the airplane, and the pilot was seriously injured with head, arm, and chest injuries.

The pilot stated that he had flown into the airstrip on Cavanaugh Bay at Priest Lake about 10 times over the last 10 years. The purpose of the accident flight was recreational in nature, and he made a normal approach to the southern runway. The runway is sloped, and a landing to the south would be an upslope landing. As he made his approach he noted the wind on the water of Priest Lake, and estimated an 8- to 10-knot tail wind. Additionally, the pilot stated that there were 100-foot-tall trees at the approach end of the airstrip that make the approach and landing difficult. He could not recall his attempt to abort the approach, perform a go-around, or the crash itself.

The pilot, age 85, held a private pilot certificate for airplane single engine land issued December 18, 2003, and a third-class medical certificate issued June 16, 1994, with the limitation that he wear glasses for near vision. The pilot said that he had about 900 hours of total flight time, with the majority of that time in the Cessna 172 series, with between 30-40 hours in the accident model airplane. The pilot’s most recent flight review was conducted on July 1, 2011, in the accident airplane.

The two seat, high-wing, fixed landing gear airplane, serial number 15066770, was manufactured in 1967. The airplane was equipped with an Alpha Systems angle of attack (aoa) indicating system, with an aoa gauge mounted on the pilot's glare shield. The airplane was powered by a Lycoming O-320-E2D, 150-hp engine and equipped with a McCauley fixed pitch propeller, model TM7456. An FAA Form 337, Major Repair and Alteration, documented that on December 8, 1986, the original Continental Motors, 100-hp, O-200 series engine was replaced with the Lycoming O-320-E2D engine. Review of the airplane maintenance logbook revealed an annual inspection was performed on November 17, 2010, at an airframe total time of 5,803 hours, and engine time since major overhaul of 2,081 hours.

On September 14, 2011, the NTSB investigator-in-charge and a technical representative from Cessna Aircraft Company examined the airplane wreckage at a facility in Deer Park, Washington. The airplane’s wings had been separated from the main fuselage to facilitate wreckage transportation from the accident scene. Airplane controls were continuous from the cockpit to ailerons, elevator, and rudder though multiple cable cuts that were performed by the recovery crew. The flaps appeared to be retracted on their tracks, and the flap actuator was observed retracted. The elevator trim was measured at 1.44 inches; per the Cessna representative, 1.45 inches is neutral. The stall warning horn was clear of debris and sounded when air was passed through the horn/reed.

The throttle cable remained connected from the cockpit to the carburetor. The mixture cable was connected at the cockpit, but was severed from the carburetor mixture lever. The carburetor bowl had been separated from the upper half of the carburetor body; the brass floats were mechanically damaged and crushed. The top, Champion REM37BY, were removed. All gaps were measured to be greater than 0.016 inches, and all exhibited a light gray coloration, as well as wear signatures consistent with normal operation per the Champion Check-a-Plug AV-27 card. The McCauley fixed pitch propeller exhibited slight leading edge polishing and chordwise scratches on one blade, the other blade tip was bent forward 90 degrees, and had substantial blade polishing along the leading edge and face of the blade tip.

No preaccident mechanical failures or malfunctions were found that would have precluded normal operation of the airplane.