What happened
A student pilot was conducting a practice NDB approach to runway 34 when the aircraft began descending during the procedure turn. The crew rolled out on an inbound heading of 354 degrees. During the approach, the instructor pilot contacted Omaha Approach and received approval to switch to Plattsmouth Advisory. While the instructor was changing radio frequencies, the student pilot descended to the minimum descent altitude of 1,820 feet MSL.
At 7 DME, the instructor completed the radio call to Plattsmouth Advisory. The student pilot then performed the pre-landing checklist at 5 DME, which included extending the landing gear and switching the fuel tanks. While the instructor did not visually witness the student performing the switch, he observed that the fuel pump was on and the fuel selector had been moved to the left tank. All engine instruments appeared normal at that time.
At 1.8 DME, the aircraft experienced a drop in manifold pressure and RPM, causing the airplane to nose down. The instructor pushed the control levers full forward and directed the student pilot to execute the emergency checklist. Despite attempting to maintain speed, the crew determined they were too low to reach the runway even at best glide speed. The instructor moved the throttle up and down twice, noting that the throttle felt loose, but there was no engine response despite the engine sounding as if it were still running.
To clear a tree line, the crew maintained a clean configuration with flaps up. After passing the trees, the crew encountered a fence with large posts in their path and maneuvered the aircraft over it. As the terrain angled upward on the other side, the crew flared the aircraft; the stall warning sounded, the main gear contacted the ground, and the nose wheel struck the ground with significant force.
The investigation
An examination of the aircraft at the accident site revealed no anomalies. An inspection of the engine, conducted eight days after the accident, also showed no mechanical anomalies.