Accident Details
On July 19, 2017, at about 1010 Pacific daylight time, an Enstrom F28-C helicopter, registration N5697B, experienced a rapid descent and hard landing in a dirt pasture approximately half a mile northeast of Chino Airport (CNO) in Ontario, California. The helicopter, registered to Dubois Aviation Inc, was being operated by a student pilot on a solo instructional flight under 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed. The flight had originated from Chino Airport about 1005.
The student pilot, who was the sole occupant, sustained serious injuries. The helicopter sustained substantial damage to the tailboom and main rotor blades.
Pilot Account
The student pilot reported that he entered the downwind leg to set up for the first landing of the day. When abeam his touchdown location, he conducted prelanding checks and noted no anomalies. Prior to turning base, he lowered the collective, reduced the throttle, and initiated a descent at about 100 feet per minute. During the descent, he observed engine RPM slightly above 2,900 RPM, so he reduced the throttle. The RPM decreased slightly but then returned to 2,900 RPM, with manifold pressure at about 10 inches of mercury. About 400 feet above ground level, he heard the engine sound increase and observed RPM between 3,300 and 3,500. Unable to reach the runway, he continued descending toward a pasture and landed hard in the dirt.
Postaccident Examination
A postaccident airframe and engine examination revealed no preimpact anomalies that would have precluded normal operation. Flight control continuity was established from the cockpit controls to the main rotor head. The tail rotor driveshaft was turned, and rotation was observed from the tail rotor gear to the main rotor mast. The main rotor blades remained intact and exhibited signatures consistent with coning.
The lower spark plugs were removed from the engine, and the engine was rotated from the cooling fan. Thumb compression was obtained on all cylinders in proper firing order, and the impulse coupling was heard clicking from the left magneto. The spark plugs were reinstalled, and the engine was prepared for a run. The engine ran normally for several minutes at various RPMs, with normal operating pressures and temperatures observed. No fuel or oil leaks were found. The engine was shut down normally with no anomalies noted.