The student pilot contacted a friend who was in a fishing boat and told him he was going to fly over the lake in Kingston, Oklahoma. The friend then saw the RV-9A circle over his fishing boat, which was a prearranged signal by the student pilot to notify the friend to drive his fishing boat towards a better fishing spot.
The plane was flying in a descending left turn and hit the water and sank.
The plane was located the following day and was recovered to the shore. The pilot was killed in the crash.
Although damage was sustained during the recovery phase, an examination of the airframe did not find any preimpact anomalies.
The circumstances of the accident are consistent with an accelerated stall while maneuvering at low altitude.
An examination of the engine found that continuity to the engine controls was established with the exception of the carburetor heat gate cable. An examination of the carburetor heat gate cable did not find any deformation consistent with the set screw being installed properly at the time of the impact.
A family member reported that the pilot previously had the carburetor heat repaired, but no logbook entry could be found to tell when and by whom the carburetor heat was repaired.
A review of the carburetor icing probability chart found that, at the time of the accident, the airplane operated in an area with the potential for serious icing at glide power.
During the circling maneuver, it is likely the pilot was operating the airplane a reduced power setting, which resulted in the formation of carburetor icing and led to a loss of engine power.
However, once power was lost, he continued in a bank turn, which resulted in the accelerated stall, rather than maintaining level flight.
The NTSB determined the probable cause as the pilot’s continuation of a banked turn following the loss of engine power, which resulted in his failure to maintain adequate airspeed and the airplane exceeding its critical angle of attack and entering an accelerated stall at low altitude. Contributing to the accident was the loss of engine power due to carburetor icing as a result of the airplane’s degraded carburetor heat system.
NTSB Identification: CEN15FA127
This January 2015 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.