N34C

On May 9, 1999, about 1100 eastern daylight time, a Freeman RV-6 experimental airplane, N34C, registered to a private individual, impacted with a tree during a forced landing at the Apalachicola Municipal Airport, Apalachicola, Florida. Visual meteorological conditions prevailed at the time, and no flight plan was filed for the 14 CFR Part 91 local personal flight. The airplane was substantially damaged. The private-rated pilot reported minor injuries. The flight was originating at the time.

The pilot said that during takeoff from runway 06, "....acceleration, engine instruments, and general feel of the airplane was normal. After lift-off I accelerated to 75 knots and climbed to 500 feet, at which time I began a left turn and commenced setting the power to 25 squared [rpm 2500 and 25 inches manifold pressure]. At about that time I began losing power and turned back to the field complex. The engine quit...and [I] tried to maintain about 70 to 75 knots. At this time I was extremely busy maintaining aircraft control and trying to steer the aircraft to the airport clearing...it became apparent that I was not going to make the clearing I stalled the airplane into the top of pine saplings at about 45 knots or so. After the aircraft came to rest I turned all switches off and rotated the fuel selector off."

The engine was test run under the supervision of the FAA, after it was removed from the crash site. According to the FAA inspector, "...the engine started and was run for 30 minutes...the maximum rpm achieved was 2460 rpm (static) when the mixture control was placed in the fully leaned position. The engine would not exceed 2000 rpm (static) when [the] mixture control was in the full rich position."

According to the FAA's report, examination of the carburetor revealed, "...heavy rust on throttle plate shaft and linkage (internal) between [the] throttle plate shaft and accelerator pump...heavy rust on exterior side plate...throttle would not return to full open (fail safe) position with linkage disconnected due to the rust found. The throttle shaft spring had insufficient force to overcome resistance caused by rust."

The fuel selector valve was examined and according to the FAA's report the following was revealed, '...the selector cone and body seat were both galled resulting in the need for excessive force to reposition the cone for selecting a fuel cell or off position...it was nearly impossible to feel the detentes which identified the selector was in its proper position due to the resistance caused by the galling and internal cone damage...the selector cone shaft pin was bending the cone at its mating point...the selector arm was warped where it mated with the shaft allowing 10 degrees play in the positioning of the selector."

The FAA inspector's report reflected the following conclusions about the engine run and component checks, "...the engine should have been able to operate sufficiently to return the airplane to a safe landing site...the fuel selector valve showed evidence of internal failure, but when used in the post accident ground test [engine run], it did not cause engine failure...the carburetor was setup and functioned properly, but due to the amount and location of rust found internally, the possibility exists that it might have been affecting engine operation...the aircraft had sufficient fuel onboard for the intended flight...the specific cause for failure of the engine after takeoff could not be positively determined."