WPR24FA213 · Grumman Acft ENG COR-Schweizer G-164A

Before the accident pilot departed on his first solo flight in the single-seat, turbopropeller-equipped biplane, the chief pilot instructed him to depart to the north, climb to altitude, practice turns, climbs and descents, and then return to the departure airport. The chief pilot and the accident pilot were unable to communicate via radio and instead exchanged several text messages during the flight. The accident pilot sent a message stating, “it shakes a little bit, I don’t know if its normal,” to which the chief pilot replied, “Yeah it’s just a lot of horsepower on the front of the plane.” There were no further communications from the accident pilot. Shortly thereafter, the chief pilot observed smoke rising from the area where the pilot was operating. He departed in another airplane and subsequently located the accident site. Two witnesses saw the airplane flying low from north to south. Both witnesses reported that the engine sounded normal. One witness stated that he saw the airplane’s wings rocking left and right several times. The airplane came to rest in sandy desert terrain and was largely consumed by a postimpact fire. No ground scars were observed near the accident site. All major components of the airplane were present, and impact damage was consistent with a right-wing-low, nose-down pitch attitude at the time of impact. Control continuity was established for the left and right lower wing flaperons from the cockpit to the control surfaces. Rudder control continuity was established from the cockpit to the rudder. Elevator control continuity could not be confirmed due to impact and thermal damage. Postaccident examination of the propeller revealed operational signatures consistent with low-to-moderate engine power. Postaccident examination of the engine revealed evidence consistent with the engine producing power at the time of impact, with no indications of preimpact mechanical malfunctions or failures that would have precluded normal operation. Review of the airplane’s maintenance records indicated that its most recent annual inspection was 13 months before the accident. The airplane was issued a special flight permit 20 days before the accident that was valid for 10 days and allowed the airplane to be ferried for repairs or maintenance. The chief pilot reported that the accident flight was the airplane’s first flight following maintenance and that the mechanic had not completed a logbook entry. The mechanic who performed the maintenance stated that she had started the airplane’s annual inspection but did not complete it, because the owner wanted to fly the airplane. When asked, the chief pilot stated that he made the decision to fly the airplane. Review of records provided by the operator after the accident revealed a new entry for an annual inspection, dated the day of the accident. Review of the pilot’s logbook indicated that, in the months before the accident, he received agricultural application training in several models of tailwheel-equipped airplanes, including a high performance, piston-engine-powered biplane; however, other than referring to “chair flights” performed before the accident flight, the operator did not provide additional information regarding the pilot’s transition training for the turbine-powered accident airplane. The orientation of the airplane at the accident site and the lack of ground scarring around the wreckage was consistent with the nose-low, near-vertical descent characteristic of an aerodynamic stall; however, the reason for the loss of control could not be determined based on the available information. Although examination of the wreckage did not reveal any mechanical malfunctions or anomalies, the scope of the examination was limited due to the thermal damage sustained during the postcrash fire. Given the pilot’s unfamiliarity with the accident airplane, it is possible that attempting to communicate with the chief pilot via text message during the flight provided an additional distraction that may have contributed to the loss of control.

Verbatim NTSB analysis and probable cause from the NTSB dataset