SCOTTSDALE, AZ, USA
N7456T
ROTORWAY EXEC-90
PRIOR TO THE ACCIDENT FLIGHT, THE HELICOPTER WAS EXAMINED BY THE FAA AND ISSUED AN EXPERIMENTAL AIRWORTHINESS CERTIFICATE. THE AIRCRAFT THEN DEPARTED ON A FERRY FLIGHT OF TWO HELICOPTERS TO RETURN TO THE HELICOPTER COMPANY BUILDING. AFTER DEPARTURE, THE SECOND AIRCRAFT OBSERVED AN OBJECT GO THROUGH THE ROTOR SYSTEM OF THE ACCIDENT HELICOPTER. THE PILOT BEGAN A PRECAUTIONARY LANDING AND, SUBSEQUENTLY, EXPERIENCED AN ANTI-TORQUE SYSTEM FAILURE. AFTER TOUCHDOWN, A POSTCRASH FIRE CONSUMED 2/3 OF THE AIRCRAFT. ONE TAIL ROTOR BLADE HAD BEEN STRUCK BY A FIBERGLASS COWLING PANEL THAT WAS LATER LOCATED ALONG THE FLIGHT PATH.
On December 28, 1993, about 1120 hours mountain standard time, a Rotorway Exec-90 helicopter, N7456T, crashed during a forced landing about 6 miles east of Scottsdale, Arizona. The helicopter was being operated as a visual flight rules (VFR) cross-country ferry flight to Stellar Airpark, Chandler, Arizona, when the accident occurred. The helicopter, operated by Rotorway International, was destroyed by impact and postimpact fire. The certificated commercial pilot, the sole occupant, received minor injuries. Visual meteorological conditions prevailed. The flight originated from the Scottsdale Municipal Airport about 1115 hours. The pilot reported that the helicopter was one of two aircraft being ferried back to the factory after having been inspected at the Federal Aviation Administration (FAA) Scottsdale Fight Standards District Office (FSDO). After departure, the pilot heard a "popping" sound, and the pilot of the second helicopter in the flight observed an unknown object go through the accident helicopter's rotor system. The pilot began a precautionary landing approach to an open area. During the approach, the pilot began to smell burning rubber and suspected a malfunction of the tail rotor drive belts. Several seconds later, the pilot heard and felt a "bang" and the helicopter began to spin to the left. The pilot applied right rudder pedal with no response, and attempted to control the helicopter by utilizing varying amounts of power, collective, and cyclic pitch. The helicopter descended at a high rate and struck the ground in a level attitude, collapsing the landing gear skids. After ground impact, a fire began near the engine compartment and consumed about 2/3 of the helicopter. An FAA operations inspector from the Scottsdale FSDO inspected the helicopter at the accident site. He reported that one tail rotor blade exhibited an aft crush and splitting of the leading edge of the blade at the outboard end. He also reported that a portion of a fiberglass cowling panel was located in a field, southeast of the Scottsdale airport, along the helicopters' route of flight. The panel was fragmented into several pieces and is normally attached by "dzus" fasteners to the top area of helicopter cowling. The underside of the panel exhibited "56T" written on the cowl. The helicopter had accumulated a total time in service of 612.2 flight hours. Examination of the maintenance records revealed the most recent inspection was accomplished on December 27, 1993. The accident flight was the first flight following inspection by the FAA Manufacturing Inspection Satellite Office (MISO), Scottsdale, and issuance of an experimental airworthiness certificate for the purpose of market survey.
A failure of the pilot-in-command to adequately conduct a preflight inspection and properly secure a fuselage cowling panel that struck a tail rotor blade, resulting in a subsequent failure of the tail rotor drive system. Factors in this accident were an in-flight separation of the cowling panel, and the inability of the pilot to effect directional control of the helicopter.
Source: NTSB Aviation Accident Database
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