Accident Overview
On May 9, 2022, at about 1145 eastern daylight time, a Diamond Aircraft DA42, registration N988JA, was substantially damaged when it came to rest in a ditch following a forced landing near Lehighton, Pennsylvania. The flight instructor, pilot receiving instruction, and a pilot-rated passenger sustained minor injuries. The airplane was operated by Gateway Aviation as a Title 14 Code of Federal Regulations Part 91 instructional flight.
Flight Narrative
According to the flight instructor, during the instructional flight, the right engine was shut down and secured to simulate an engine failure. The airplane descended “a few hundred feet” during this process. Following the checklist, the pilots attempted to restart the right engine but determined it was not producing power. They elected to perform a forced landing to a field, during which the airplane slid into a ditch.
The pilot receiving instruction stated that at about 5,000 ft mean sea level (msl), the engine failure simulation was conducted. After shutting down and securing the right engine per the checklist, they attempted to restart it. The right propeller was observed spinning at 1,970 rpm instead of the normal 2,500 rpm. As they troubleshooted, the airplane descended. At about 2,500 to 3,000 ft msl, descending at roughly 500 ft per minute, control became difficult. The pilot and instructor became “task-saturated” while managing control, checklists, air traffic control communication, and navigation. An emergency was declared and an off-airport landing was planned.
The pilot-rated passenger reported that the flight was uneventful until the “drag demonstration,” when the engines were shut down. After the restart procedure, the propeller was turning, and the passenger believed the engine was running. The flight instructor then said, “there is a problem, but I don't know what it is.” The passenger observed the right engine at 1,950 rpm with fuel and oil pressure in the green range, while the left engine operated at a higher rpm. The instructor asked for the nearest airport, and the passenger directed the crew to an airport 7.5 miles east. The passenger noted a “lack of communication” and “confusion on roles and responsibilities,” and did not hear any checklist items being reviewed. At about 1,500 ft msl, the instructor took control and declared an emergency.
Postaccident Examination
On-scene photographs showed the mixture control levers in the full rich position, propeller control levers in the fine pitch/high rpm position, electric fuel pumps on, and fuel selectors on. Digital data cards from the avionics contained no usable data.
The airplane sustained substantial damage to the fuselage. A detailed examination of the airframe and systems revealed no preimpact failures or anomalies that would have prevented normal operation.
The left engine remained attached to the wing. Its three propeller blades were in the low pitch/high rpm position and fractured midspan. The engine was test-run using external power and fuel, starting and operating normally at low rpm due to shortened blades. No anomalies were noted.
The right engine remained attached to the firewall and appeared undamaged. Its propeller blades were also in the low pitch/high rpm position with midspan damage. The magneto timing was within specifications. The engine started and operated normally during a test run, with no anomalies.
Aircraft Performance Considerations
The Airplane Flying Handbook notes that in multiengine airplanes, loss of thrust from one engine affects performance and control, reducing climb performance significantly. Feathering the propeller of an inoperative engine minimizes drag, which is critical for continued flight. The manufacturer’s Airplane Flight Manual indicated that under the prevailing conditions, if the dead engine were feathered and secured and the operating engine set for maximum continuous power, the airplane could maintain a positive rate of climb. The emergency procedures for unfeathering and restarting the engine in flight advised that if restart was not possible, the pilot should continue with the engine securing (feathering) procedure.