What happened
The aircraft, a multiengine airplane, was performing single-engine training maneuvers at 4,500 feet MSL when the flight instructor secured and feathered the left engine. Following several unsuccessful attempts to restart the left engine, the right engine began experiencing power loss accompanied by a decrease in manifold pressure.
During the emergency, the pilot attempted to use the hydraulic system hand pump but was unable to keep the landing gear retracted. Due to the loss of flight altitude, the crew performed a forced landing into a field containing a gravel pit. The landing gear remained partially extended upon impact. All occupants were not injured.
The investigation
The investigation reviewed the aircraft's operator manual, which specifies that the hydraulic system used for landing gear extension is driven by the left engine. While the manual notes that a hand pump is available to extend the gear during a hydraulic failure, the pilot could not maintain the gear in the retracted position. The investigation could not determine the specific reasons for the loss of power in the right engine or the lack of hydraulic system pressure.