History of Flight
On May 16, 2009, at approximately 1630 Pacific daylight time, a Cessna 172N, registration N738LF, experienced a partial loss of engine power and collided with terrain during a precautionary landing near Iron Mountain Pumping Plant Airport, Desert Center, California. The aircraft sustained substantial damage and came to rest inverted. The flight was operated by California Flight Academy under 14 CFR Part 91. The private pilot and one passenger were not injured. The local personal flight had departed Gillespie Field in San Diego, California, about 1415. Visual meteorological conditions prevailed, and a visual flight rules flight plan had been filed.
The pilot reported that after departing El Cajon, while maneuvering over the desert, the airplane experienced a loss of power to the avionics, rendering him unable to make or receive radio transmissions. The fuel gauges then indicated that the fuel tanks were empty, and the pilot noticed the airplane could not maintain altitude due to a partial loss of engine power. He performed an off-airport landing on the open desert terrain about a mile from a small airstrip. After touchdown, the airplane encountered uneven terrain and nosed over.
The operator's chief pilot relayed a summary of his interview with the pilot. During cruise flight at 7,500 feet mean sea level, the engine lost power. The pilot elected to make a precautionary landing at a nearby private airport. Believing he was within gliding distance, he shut off the engine by turning the fuel selector to "off" and fully retarding the mixture control. He overshot the runway and maneuvered the airplane in a left turn to circle back. During the turn, he observed power lines in his flight path and steepened the left bank. The airplane's altitude rapidly decreased, and he was forced to land adjacent to the runway.
In the chief pilot's written submission to the Safety Board, under the section titled RECOMMENDATION, he stated that the accident pilot needed "more training and testing on abnormal procedures" and that "a complete electrical failure is not an emergency situation in VMC conditions and should not lead to an off field landing."
The pilot reported no preimpact mechanical malfunctions or failures with the airframe or engine.
Tests and Research
Following recovery, investigators examined the airplane at the storage facility of Air Transport, Phoenix, Arizona, on June 27, 2009. Accompanying a Safety Board investigator was a representative from Textron Lycoming.
The engine representative removed the top spark plugs, which were clear of debris and showed no evidence of mechanical deformation. The spark plug electrodes were gray in color, corresponding to normal operation per the Champion Aviation Check-A-Plug AV-27 Chart.
A borescope examination of all cylinders found no foreign object damage, no evidence of detonation, and no indication of excessive oil consumption. The number one cylinder's intake valve had deposits on the valve seat that appeared to prevent complete closure. Investigators manually rotated the engine, establishing internal mechanical continuity during crankshaft rotation and upon attainment of thumb compression. The number one cylinder had lower pressure and less resistance than the other cylinders. Differential compression check results were: number one 14/80; number two 77/80; number three 75/80; and number four 73/80. During testing of the number one cylinder, air was heard leaking from the carburetor.
No electrical problems could be identified.