Accident Summary
On April 27, 2017, at approximately 0945 mountain standard time, a Schweizer 269C helicopter, registration N521AR, was substantially damaged during a hard landing on open desert terrain near Coolidge, Arizona. The helicopter was operated by Canyon State Aero, LLC under 14 Code of Federal Regulations Part 91. The private pilot, who was the sole occupant, sustained minor injuries. The cross-country instructional flight had departed Falcon Field Airport in Mesa, Arizona, around 0915, with a planned destination of Coolidge. Visual meteorological conditions prevailed, and no flight plan was filed.
Pilot Report
The pilot stated that the flight was intended for training toward a commercial certificate. While traveling south at an altitude between 2,000 and 2,100 feet mean sea level and an airspeed of 65 to 70 knots, he monitored manifold pressure, altitude, airspeed, and engine/rotor rpm. All indications appeared normal until he detected a change in engine sound and a drop in the rpm gauge. He verified that the throttle had not rolled back out of friction, then attempted to roll the throttle further, but the engine did not respond. He tried rolling it slightly off and back, again with no response. As the helicopter was close to the ground, he selected a landing spot on the desert floor. Just before touchdown, he executed a flare, but the helicopter impacted the ground hard and rolled onto its right side.
Postaccident Examination
During the engine examination, the bottom spark plugs were removed and their electrodes showed coloration consistent with normal wear per the Champion Spark Plugs Check-A-Plug Chart AV-27. The crankshaft rotated freely by hand with no binding, and thumb compression was observed in each cylinder. Mechanical continuity was established to the accessory section. However, during the engine control continuity check, the throttle arm at the fuel injector servo would not move when input was applied at the collective throttle grip. Further inspection revealed that the throttle cable had separated within the cable housing, in an area where the housing was slightly bent. The cable housing was securely mounted at both ends and showed no evidence of damage from the accident. The cable was removed from the housing and was found worn, with separation near the servo end, about one inch from where it was swaged to the rigid portion. No kinking or binding was observed.
The engine was then prepared for a run. It was started using standard procedures and, once at operating temperature, the throttle was advanced to perform a magneto check via the cockpit ignition switch. Both magnetos operated within manufacturer specifications at their respective switch detents, and the engine ran smoothly throughout the operational check.
According to the engine manufacturer, the throttle cable is not subject to any hourly or calendar life limits, and it cannot be disassembled from the housing for internal inspection. Examination of the maintenance logbooks did not reveal a history for the cable.