Piper PA-46-310P N469CC accident near Elizabethtown, North Carolina

Probable cause

The improper securing of a “B” nut on the power turbine control (Py) line by unknown maintenance personnel, which resulted in a total loss of engine power. Contributing to the accident was the pilot's failure to use the manual fuel override switch.

NTSB analysis

According to the pilot, after takeoff and about 1,100 feet altitude, when turning from the crosswind leg to the downwind leg in the traffic pattern, the engine started to make a noise. The pilot said that he turned back to the runway. He said that the engine was "cutting off" and that the airplane was "sinking fast." He then feathered the propeller and kept the landing gear in the up position in order to extend his glide. He then put the gear handle down when he knew he would reach the runway, but the landing gear did not extend completely before the airplane's belly made contact with the pavement.

About 9 months before the accident, the airplane had incurred a propeller strike while being taxied over a portion of uneven pavement. As a result, it underwent maintenance that required removal of the propeller and engine, disassembly and reassembly of the engine, remounting of the propeller and engine, and rigging. This was accomplished over a 4-month period by multiple maintenance personnel and required safety-ing of multiple engine components. Safety-ing, when done correctly, should never result in nicked, kinked, mutilated, or overstressed safety wire, as it will result in the safety wire breaking under vibrations if twisted too tightly. Postaccident examination of the engine revealed that the power turbine control (Py) line propeller governor fitting lockwire was fractured at the loop through the “B” nut lockwire hole. The nut was found to be backed off about 1/3 to 1/2 turn, and the line could be moved by hand. Functional tests with the "B" nut in its as-found configuration revealed that the engine would stay at sub-idle and would not respond to power lever movement. Macroscopic inspection of the fracture showed features characteristic of overload fracture in tension and torsion at the location of a pre-existing nick. It is likely that the improper securing of the “B” nut on the power turbine control line resulted in the loss of engine power.

However, the pilot could have restored power to the engine by using the manual fuel override switch, which he did not attempt to use. Review of the pilot's operating handbook (POH) revealed that the POH contained guidance regarding the use of the manual fuel override, although all conditions for which it could be used were not clearly stated.

Regardless, the pilot should have been aware of the guidance contained in the POH. Since the accident, the manufacturer has updated the POH with more details on the use of the manual fuel override system.

Text from the NTSB. Open the NTSB docket for ERA11LA461 for the full record.