Incident
On April 16, 2019, at 0730 central daylight time, a Bell OH-58A helicopter, registered as N109PD, impacted terrain during an autorotation near Omaha, Nebraska. The pilot reported a partial loss of engine power shortly after takeoff from North Omaha Airport (3N0). The helicopter was destined for Blair, Nebraska. Visual meteorological conditions prevailed at the time. Both the pilot and co-pilot were uninjured. The helicopter sustained substantial damage to the tail boom.
According to the pilot, while climbing through 200 to 250 ft above ground level in a left turn, the crew heard an audible horn, observed low rotor RPM, and experienced a loss of altitude, indicating a loss of rotor RPM and engine power. The right-seat pilot entered an autorotation to recover rotor RPM. The crew identified the best suitable landing area north and west of the airport. Upon touchdown in soft terrain, the forward landing gear skids dug in, causing the helicopter to rock forward and backward. The main rotor blades then contacted the tail boom, which separated from the airframe. The helicopter came to rest upright. The pilots shut down the engine, which continued to operate at about 35% N1, and exited after the engine stopped.
Maintenance History
Review of maintenance records showed two prior uncommanded engine shutdowns during cool-down cycles, on March 15 and March 21, 2019. After the first event, a 200-hour inspection was completed on March 16, 2019, at a total airframe time of 12,089.3 hours. This inspection included removal of the fuel control and fuel pump, replacement of fuel filters, and checks by a certified repair station. No mechanical anomalies were found during subsequent ground and flight tests. After the second shutdown, the fuel control throttle rigging was checked, and the intake/particle separator was inspected for obstructions; none were found, and the helicopter was returned to service. At the time of the accident, total airframe time was 12,099.2 hours and engine time was 6,588 hours.
Investigation
On April 23, 2019, the helicopter was examined by a Federal Aviation Administration (FAA) inspector, along with representatives from the Omaha Police Department and Rolls-Royce. No preimpact mechanical anomalies were noted with the airframe or engine. The engine was removed for further examination.
On July 16, 2019, the engine was examined at a Rolls-Royce authorized maintenance center in Lafayette, Louisiana, under FAA supervision. The engine was placed in a production test cell and successfully completed ground idle, flight-idle, max-continuous-power, takeoff power runs, and wave-off maximum power increases. The engine responded normally to all power demands without surging or hesitation.