Accident Details
Probable Cause and Findings
The engine failure as the result of ingestion of pieces of carburetor into the cylinders, and the subsequent forced landing and nose over during the landing roll after encountering soft terrain.
Aircraft Information
Registered Owner (Historical)
Analysis
On Thursday, August 19, 1993, at 1525 eastern daylight time, a Cessna 172, N9845J, registered to Spy In The Sky Aviation, Inc., and piloted by David C. Thomas, sustained substantial damage during a forced landing in a field in Hope Valley, Rhode Island. The pilot and student pilot were not injured. Visual meteorological conditions prevailed, and no flight plan was filed. The flight was being conducted under 14 CFR 91.
The Certified Flight Instructor (CFI) simulated an engine failure, and the student conducted a simulated forced landing. After completing this maneuver, the throttle was advanced and a climb was initiated to cruise altitude. During the forced landing maneuver, the CFI stated that full carburetor heat was used, and the he added "full power for 2 to 3 seconds to clear out the engine." In his written report, the CFI stated:
We maintained a good rate of climb to approximately 1100 feet AGL, when the engine coughed, sputtered, and quit with the propeller continuing to rotate.
After waiting 3 or 4 seconds to determine this was an actual emergency...I told [the student] that I had the aircraft....After finding the nearest field...while re-doing the emergency checklist... I also instructed [the student] to start priming the engine.
The CFI's statement continued:
Immediately after touchdown the nose wheel sank into the soft field....causing the aircraft to roll over...
Mr. Don Micknak, Aviation Safety Inspector (Airworthiness) for the Federal Aviation Administration, examined the airplane wreckage. In his report, Mr. Micknak stated:
It was noticed that the pump discharge tube was missing from the carburetor throat. Two pieces of the tube were found in #3 cylinder and one piece, about 1" long was discovered in #2 cylinder.
From these findings, it is possible that the pump discharge tube pieces, lodged under the valves in the cylinders and disordered the firing sequence. Furthermore, the fuel flow towards the venturi was disrupted by the missing nozzle when full power demand was essential during a climbing stage of flight.
Data Source
Data provided by the National Transportation Safety Board (NTSB). For more information on this event, visit the NTSB Records Search website. NTSB# NYC93LA163