Smokejumper aircraft experiences problem during landing

Due to an issue with an engine on the C-23A Sherpa, the crew idled it, but during landing the engine went to takeoff power uncommanded.

tire failure Sherpa
(Last Updated On: January 13, 2017)

Above: photo of the Sherpa’s tire failure from the Rapid Lesson Sharing document.

After an incident on April 13, 2016 while a C-23A Sherpa was transporting smokejumpers on a training mission, the Redmond, Oregon Air Group conducted an After Action Review and wrote a Rapid Lesson Sharing document. Below are excerpts:

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“NARRATIVE

On the morning of April 13, 2016, a crew of three experienced captains performed a Smokejumper Mission Check Ride during a practice jump. The Pilot in Command of the C-23A Sherpa retarded the left power lever in preparation for the jump run and the engine did not respond appropriately. The number 1 engine would not reduce to flight idle as commanded.

We elected to discontinue the check ride and return to the airport to land.

The crew reduced the engine RMP power lever back to almost idle and the left engine stabilized at idle. We consulted the emergency checklist and decided to leave the engine running.

During line up for final the crew elected to keep the engine running due to a 90 degree crosswind condition in case a go around was required. On landing the left engine went to take-off power, un-commanded, and aircraft started to depart the runway. During subsequent actions to control the aircraft, brakes were applied and on ground contact the right main tire failed. The pilot in command ordered the left engine shut down and second in command shut the engine down. PIC was able to exit the runway and airplane was shut down on an adjacent taxiway.

LESSONS

After the mission an AAR was conducted between the crew, maintenance, leadership and the participating smokejumpers. The only possible action in hindsight the crew indicated was not bringing the power levers over the gate into ground fine range which may of influenced the rapid RPM increase. The aircraft fuel controller was removed and sent in for overhaul. Disassembly of the fuel unit revealed a small burr on the throttle shaft bushing.

Questions for discussion between crews:

  • When would you declare an abnormal event an emergency and roll the trucks?
  • What situations would you consider it safer for the remaining jumpers to exit the aircraft than return with it?
  • What other abnormal conditions have you encountered that are not in the abnormal procedures (Chapter 4) section and how would you handle them?
  • What discussions need to take place with the guys in the back during occurrence of unplanned events?
  • Discussions on the above topics during ground time can save valuable time in the air when abnormal conditions do occur.

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