Accident Overview
On August 1, 2011, at approximately 2105 mountain daylight time, a Cessna 172S, registration N235GW, experienced a loss of engine power and nosed over in a field during landing rollout in Syracuse, Utah. The private pilot, the sole occupant, received minor injuries. The aircraft sustained substantial damage. The airplane was registered to Mount Olympus Aviation, LLC and operated by Leading Edge Aviation of Salt Lake City, Utah, under 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed. The flight departed Salt Lake City, Utah, around 2050 with Ogden, Utah as the intended destination.
Pilot Report
According to the pilot, during cruise flight the engine began running rough and progressively lost power. The pilot manipulated the throttle and mixture controls, but the power loss continued. All engine power was lost on approach, resulting in a forced landing in an alfalfa field.
Engine and Airframe History
The engine, a Lycoming IO-360-L2A (serial number L-30858-51E), had received a major overhaul by Lycoming Engines on June 21, 2011, and was installed on the aircraft on July 27, 2011, at a tachometer reading of 1,830.8 hours. Since installation, it had not received any maintenance. The airframe (serial number 172S9235, manufactured in 2002) underwent its annual inspection on July 27, 2011. After the accident, the tachometer read 1,845.0 hours, indicating approximately 14.2 hours of operation post-overhaul.
Post-Accident Inspection
On August 4, 2011, a Federal Aviation Administration airworthiness inspector examined the airframe and engine. The engine rotated easily with no noticeable resistance. Spark plugs were removed; those in the number 3 cylinder were oil-soaked, with oil pooling at the bottom of that cylinder and some scoring on the cylinder wall. The engine had been inverted in the field for several days, which may have affected the observed conditions.
The magnetos (Slick magnetos, part number 66GC20SFNN) showed no external damage. Timing checks revealed one magneto at 24 degrees BTDC and the other at 27 degrees BTDC, while the engine data plate specifies 25 degrees BTDC. Bench testing of the magnetos yielded satisfactory results.
The gascolator was displaced into the firewall. The outlet hose remained attached, but the fitting on the other end was pulled from the fuel pump housing. The gascolator bowl and screen contained no fuel; the screen had a very small amount of foreign material.
The fuel pump (part number LW-15473) had both inlet and outlet fittings torn from the housing during impact and could not be tested.
The fuel injection servo (part number 61J22088-70) had two attachment points broken during impact, and its inlet and outlet fittings were torn from the housing. The B-nut on the outlet hose (which leads to the distribution spider) was loose.
The fuel servo diaphragm (part number AV2538295) was intact and not subject to Airworthiness Directive 2011-15-10 (effective August 16, 2011).
The fuel injection spider (part number 2576624-1) was examined; the B-nut on the inlet hose at the spider was not tight. The diaphragm had a small amount of viscous fluid on the dry side (possibly assembly fluid) and fuel on the wet side. No impact damage was noted.
Conclusion
The investigation did not state a probable cause for the accident.