Amateur-built M24 N90HM accident near Mount Sterling, Illinois

Probable cause

The pilot’s failure to maintain gyroplane control on the downwind leg, which resulted in impact with terrain. Contributing to the accident was the pilot’s distraction.

NTSB analysis

The pilot reported that, while on the downwind leg of the traffic pattern, he was distracted while looking for other traffic in the pattern when he noticed that his airspeed had decayed to 37 mph, below the aircraft flight manual’s recommended traffic pattern airspeed of 65 mph. The pilot attempted to correct by increasing engine throttle but subsequently lost control. The gyroplane impacted terrain while in the left downwind leg, which resulted in substantial damage to the main rotor system and empennage.

Postaccident examination of the gyroplane revealed no preaccident mechanical failures or malfunctions that would have precluded normal operation. Based on the available information, the pilot likely unloaded the rotor blades inadvertently, known as buntover, when he applied engine throttle to correct for the decaying airspeed. The sudden throttle application caused the gyroplane to abruptly pitch forward and tumble. The FAA Rotorcraft Flying Handbook notes that, in most cases, the proper recovery procedure for the condition is to immediately remove power and load the rotor blades.

Text from the NTSB. Open the NTSB docket for CEN24LA013 for the full record.