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2015 C-208 Caravan Maintenance Flight Non-Fatal Non-Fatal Single-Engine OK Virdigris

C-208 Supervan Non-Fatal Virdigris, OK March 24, 2015

The pilot reported that, during the postmaintenance test flight, the turboprop engine lost power. The
airplane was unable to maintain altitude, and the pilot conducted a forced landing, during which the
airplane was substantially damaged.
The engine had about 9 total flight hours at the time of the accident. A teardown of the fuel pump
revealed that the high-pressure drive gear teeth exhibited wear and that material was missing from them,
whereas the driven gear exhibited little to no visible wear. A metallurgical examination of the gears
revealed that the damaged drive gear was made of a material similar to 300-series stainless steel instead
of the harder specified M50 steel, whereas the driven gear was made of a material similar to the
specified M50 steel. Subsequent to these findings, the airplane manufacturer determined that the gear
manufacturer allowed three set-up gears made from 300-series stainless steel to become part of the
production inventory during the manufacturing process. One of those gears was installed in the fuel
pump on the accident airplane, and the location of the two other gears could not be determined. Based
on the evidence, it is likely that the nonconforming gear installed in the fuel pump failed because it was
manufactured from a softer material than specified, which resulted in a loss of fuel flow to the engine
and the subsequent loss of engine power.

Read the NTSB report.

The pilot reported that, during the postmaintenance test flight, the turboprop engine lost power. The
airplane was unable to maintain altitude, and the pilot conducted a forced landing, during which the
airplane was substantially damaged.
The engine had about 9 total flight hours at the time of the accident. A teardown of the fuel pump
revealed that the high-pressure drive gear teeth exhibited wear and that material was missing from them,
whereas the driven gear exhibited little to no visible wear. A metallurgical examination of the gears
revealed that the damaged drive gear was made of a material similar to 300-series stainless steel instead
of the harder specified M50 steel, whereas the driven gear was made of a material similar to the
specified M50 steel. Subsequent to these findings, the airplane manufacturer determined that the gear
manufacturer allowed three set-up gears made from 300-series stainless steel to become part of the
production inventory during the manufacturing process. One of those gears was installed in the fuel
pump on the accident airplane, and the location of the two other gears could not be determined. Based
on the evidence, it is likely that the nonconforming gear installed in the fuel pump failed because it was
manufactured from a softer material than specified, which resulted in a loss of fuel flow to the engine
and the subsequent loss of engine power.

Read the NTSB report.

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