Overview
On September 16, 2015, about 1030 central daylight time, a Cessna 172P airplane (registration N65191) was substantially damaged during a forced landing near Nutwood, Illinois. The pilot sustained minor injuries. The airplane was registered to and operated by Sixninethreeone LLC under 14 CFR Part 91 as a personal flight.
Flight Details
The flight departed from St. Charles County Smartt Airport (SET) in St. Charles, Missouri, about 1000. Day visual meteorological conditions prevailed for the local flight.
Engine Power Loss
While maneuvering at 3,000 feet msl, the pilot reported that the engine lost partial power and ran rough. Attempts to restore normal engine power were unsuccessful, prompting the pilot to execute a forced landing into a field. During the landing rollout, the airplane nosed over, damaging the right wing.
Post-Accident Examination
Federal Aviation Administration personnel examined the carburetor and found a gap between the throttle body and bowl assembly. The four bolts connecting the throttle body to the bowl assembly were loose.
Service Bulletin Compliance
Marvel Schebler Service Bulletin SB-17, dated August 12, 2010, titled "Body to Bowl Fuel Leaks," directs carburetor inspections every 100 hours of engine operation. The SB notes reports of loose body-to-bowl joints and potential fuel leakage past the gasket. It also mentions that loose bowl-to-throttle body screws may accompany such leakage. The inspection involves checking for looseness between the bowl and throttle body; if detected, the carburetor must be removed, threads inspected, and new gasket and lock tab washers installed, followed by testing per the service manual.
Lycoming mandatory Service Bulletin SB-366B, dated April 18, 2008, also requires carburetor inspections every 100 hours. Its compliance section parallels that of the Marvel Schebler SB. The last 100-hour inspection occurred 89 hours before the accident. The director of maintenance stated that maintenance personnel were aware of the Lycoming SB and checked carburetor screws for looseness, but they did not document the SB's accomplishment in the engine logbooks.