DEN03LA139

The pilot, with his three passengers, was climbing through 9,500 feet to fly over a mountain. He said that he encountered a severe downdraft and was unable to clear the mountain peak. He made a forced landing straight ahead, "for fear of a stall or spin into the trees." The airplane slid approximately 100 feet, separating the fixed landing gear and crushing inward the fuselage bottom. The density altitude at the accident location, an altitude of 8,795 feet, was calculated to be 11,955 feet. The density altitude at 9,500 feet was calculated to be 12,825 feet. The airplane manufacturer's representative said that "published engine performance charts indicate that the airplane had exceeded its certificated limitations." A postaccident engine test run was performed, and no anomalies were identified.

On August 6, 2003, at 1350 mountain daylight time, a Piper PA-28-161, N2973T was substantially damaged when it collided with terrain during a forced landing 6 miles west of Crowheart, Wyoming. The private pilot and his three passengers were not injured. Visual meteorological conditions prevailed. A VFR flight plan had been filed for the cross-country flight being conducted under the provisions of Title 14 CFR Part 91. The flight departed Riverton, Wyoming, at 1320.

According to the pilot, he was en route to Jackson Hole, and was climbing through 9,500 feet to fly over a mountain. He said that he encountered a severe downdraft and was unable to clear the mountain peak. The pilot made a forced landing straight ahead, "for fear of a stall or spin into the trees." The airplane slid approximately 100 feet. The left and right main landing gear, and the nose landing gear were sheared off. The bottom of the fuselage was crushed inward and torn.

The density altitude at the accident location, an altitude of 8,795 feet, was calculated to be 11,955 feet. The density altitude at 9,500 feet was calculated to be 12,825 feet. The airplane manufacturer's representative said, "Published engine performance charts indicate that the airplane had exceeded its certificated limitations."

On November 30, 2003, the pilot contacted the National Transportation Safety Board through a public correspondence. He stated that he "failed to include in [his] narrative that the engine was skipping during the flight." On January 14, 2003, the engine was run at Beelges Aircraft Company in Greeley, Colorado. The mixture control had been crushed during the impact sequence, and could not be adjusted; the other engine controls were fully functional. During the test run, the engine obtained 2,250 rpm. The magnetos were checked, and the right magneto showed a loss of 50 rpm and the left magneto showed a loss of 75 rpm. A maximum allowable rpm drop during a magneto check is 150 rpm, provided both magnetos are within 75 rpm.