The commercial pilot of the Pacific Aerospace 750XL reported he was preparing to release skydivers when he noticed that the engine torque indication was in the red arc.
The gauge was indicating a torque of 70 pounds per square inch (psi) when it should have been indicating about 25 psi. The maximum allowed torque indication was 64.5 psi.
The skydivers jumped uneventfully. As the pilot was returning to the airport, the torque gauge was indicating 80 psi while the engine was at idle. At that time, he decided to perform a precautionary engine shutdown and land with no engine power.
During the landing, the plane was fast and touched down about halfway down the 3,402′ asphalt runway at the airport in Raeford, N.C.
He applied heavy braking, but the plane traveled about 1,000′ beyond the departure end of the runway before coming to rest upright in a field with a collapsed left main landing gear.
Two examinations of the engine did not reveal any pre-impact anomalies or evidence of overtorque.
A test of the torque-indicating transducer and gauge also did not reveal any anomalies.
The examinations did reveal that an automotive-type wiring bundle was used to wire the torque transducer to the airplane’s electrical system. Although it is possible that the wiring bundle could have caused an intermittent faulty torque indication, subsequent testing was unable to duplicate the problem.
The airplane was manufactured about 10 years before the accident, and the torque meter manufacturer upgraded the wiring connectors about four years before the accident.
Probable cause: The pilot’s failure to obtain the proper touchdown point and speed during a precautionary landing with the engine shut down. Contributing to the accident was an erroneous engine torque indication, which led the pilot to shut the engine down, for reasons that could not be determined during post-accident testing.
NTSB Identification: ERA16LA059
This December 2015 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.