Happy Jack, AZ, USA
N5229T
Piper PA-28R-200
The pilot landed on a rough dirt road and damaged the wings following a partial loss of power. The airplane was in cruise flight about 10,500 feet mean sea level (msl) when it began to slowly lose altitude. Efforts by the pilot to increase engine power and arrest the descent failed. The pilot determined that the engine was capable of producing only partial power. In order to avoid an uncontrolled descent into terrain, he landed on the dirt road. Examination of the engine revealed an intake leak on cylinder no. 3. A piece of the intake valve was missing, and the edges of the fracture surface were jagged.
On June 16, 2005, about 1435 mountain standard time, a Piper PA-28R-200, N5229T, experienced a partial loss of engine power and performed a forced landing on a rough dirt road near Happy Jack, Arizona. The rough nature of the landing area resulted in structural damage to the wings. American Aviation, Inc., Peyton, Colorado, was operating the airplane under the provisions of 14 CFR Part 91. The private pilot and one passenger were not injured; the airplane sustained substantial damage. The personal flight departed Gallup, New Mexico, about 1354 mountain daylight time, with a planned intermediate destination of Needles, California. Visual meteorological conditions prevailed, and no flight plan had been filed. The approximate global positioning system (GPS) coordinates of the accident site were 34 degrees 57 minutes north latitude and 111 degrees 19 minutes west longitude. According to the pilot, he was in cruise flight about 10,500 feet mean sea level (msl) along a 7,000-foot-high ridge line south of Flagstaff, Arizona, where "mountain wave action" was present. The airplane began to slowly lose altitude, and efforts by the pilot to increase engine power and arrest the descent failed. The pilot then turned east, away from the ridge line, to avoid an uncontrolled descent into terrain. Once clear of the ridge line and any possible effects of the mountain wave, the pilot determined that the engine was capable of producing only partial power. Unable to maintain altitude, the pilot landed on a rough dirt road causing damage to the nose wheel and left main gear. Further examination of the airplane revealed compression buckling on the lower wing surfaces and popped rivets on the upper wing surfaces at the spar. TESTS AND RESEARCH Investigators from the National Transportation Safety Board examined the wreckage at Air Transport, Phoenix, Arizona, on June 23, 2005. They removed the cowling and removed the top spark plugs. The spark plug electrodes were oval and gray, which corresponded to normal operation according to the Champion Aviation Check-A-Plug AV-27 Chart. The top spark plug electrode for cylinder 3 had a slight wet appearance. They examined the fuel bowl and fuel screen. They observed no sediment, but observed a blue fluid that smelled like aviation fuel. Recovery personnel connected a fuel source in order to run the engine. The engine ran through a range of power settings, which included idle, 900 revolutions per minute (rpm), and up to 2,450 rpm. When checked, the magnetos had a drop of 50 rpm each. At the maximum rpm of 2,450, the manifold pressure was at 28 inches and the fuel flow was at 14 gallons per hour. Investigators rotated the engine, and obtained thumb compression on all cylinders except cylinder no. 3. They performed a differential compression test on the cylinders. Cylinder 3 had a compression of 0/80; all other cylinders tested were at least 65/80. During the compression test on cylinder no. 3, they heard air leaking through the intake system. They staked the valves on that cylinder, but noted no increase in compression. The salvage company that purchased the wreckage reported to the owner's agent that the intake valve for cylinder no. 3 had a piece of the valve missing. The edges of the fracture surface were jagged.
The fracture/separation of an engine intake valve during cruise flight, which resulted in a partial loss of engine power and a forced landing.
Source: NTSB Aviation Accident Database
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