Summary of Event
A helicopter conducting a practical flight test for a private pilot certificate experienced a loss of engine power during a simulated emergency maneuver. The Designated Pilot Examiner (DPE) had retarded the throttle to idle to simulate a loss of engine power. The student pilot lowered the collective and initiated an autorotation. Shortly after, the DPE noted a loss of engine noise and detected that the engine had actually lost power. The student pilot attempted to restart the engine but was unsuccessful. During the landing flare, the tail rotor stinger and blades struck the ground. As the helicopter slid to a stop, it veered left and rolled onto its side.
Investigation Findings
Examination of the helicopter's systems and engine revealed no malfunctions. An engine operational run test was conducted. After starting, the cockpit-mounted oil pressure gauge showed normal pressure. The electrical fuel boost pump and engine-driven fuel pump operated properly. With the engine at operating temperature, the throttle was advanced to approximately 2,500 rpm, and the magnetos were checked using the ignition switch. Both magnetos functioned within manufacturer specifications. The engine ran smoothly during the operational check, with no unusual indications, fuel leaks, or oil leaks.
Relevant Flight Manual Procedures
The Rotorcraft Flight Manual for the Schweizer 300C Helicopter Model 269C provides the following guidance for practice autorotations: "Split the needles by lowering the collective while maintaining throttle setting. The throttle correlation will establish a high idle rpm (approximately 2,500 rpm), which will aid in preventing the engine from loading up or stalling during recovery."
No determination was made regarding the cause of the engine power loss during the test maneuver.