Incident Overview
Witnesses reported observing the aircraft, registration N53899, nose over into a dive after the glider it had been towing released. They then saw the aircraft roll, and during the roll, the left wing separated from the aircraft.
Prior Flight Observations
The certified flight instructor (CFI) in the glider noted that on a prior flight, the pilot of N53899 performed what appeared to be a snap roll. After releasing from N53899 on the accident flight, both the CFI and his student heard engine noises similar to those heard during the observed roll maneuver on the earlier flight.
Wing Examination
Repeated detailed examinations of the separated wing did not reveal any pre-existing failure areas. No evidence of structural defects or fatigue was found in the wing attachment points or components.
No Official Cause Determined
As of the investigation, no probable cause has been identified for the wing separation. The aircraft's behavior during the maneuver and the absence of pre-existing damage suggest further analysis may be required.