Accident
On August 3, 2019, at 1615 central daylight time, a Robinson Helicopter Company R44 II helicopter (registration N440EM) experienced a loss of engine power during an aerial application operation near Lyons, Nebraska. The helicopter impacted the ground during an attempted recovery by the pilot. The helicopter sustained substantial damage. The airline transport pilot received minor injuries. The helicopter was registered to an individual and operated by Wallin Agricultural Aviation under Title 14 Code of Federal Regulations Part 137 as an agricultural flight not operating on a flight plan. Day visual meteorological conditions prevailed. The flight originated from an unknown location and time.
Pilot Report
The pilot reported entering a field to be sprayed. At an altitude of about 100–120 feet above ground level, the low rotor rpm annunciation sounded. As he attempted to recover rotor rpm, the rpm continued to decay rapidly. He then used the remaining rotor rpm to cushion a landing onto the field. Upon touchdown, the helicopter slid approximately 150–200 feet before a skid dug into soft dirt and the helicopter rolled over.
Post-accident Examination
A post-accident examination of the engine by the operator revealed that the no. 6 cylinder had more leakage and lower compression compared to the previous 100-hour recorded compression checks. At the prior check, the no. 6 cylinder had 8.75% leakage (73 psi held from a reference of 80 psi). During the examination, the no. 6 cylinder had 35% leakage (52 psi held from a reference of 80 psi). No further examination of the cylinder was conducted.