NTSB Identification: LAX05LA166.
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Accident occurred Thursday, May 12, 2005 in Rancho Santa Fe, CA
Probable Cause Approval Date: 08/30/2007
Aircraft: Beech C35, registration: N709D
Injuries: 1 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

Following a loss of engine power, the pilot made a forced landing in an open field and collided with two fences. The FAA inspector who responded to the accident site reported that fuel was in the fuel tanks. A visual inspection of the engine revealed no obvious mechanical failures. Investigators made unsuccessful attempts to run the engine; it would start, but would not remain running. The engine driven fuel pump was removed and investigators noted that the mating splines in the drive shaft were severely worn. A review of the engine logbook revealed that a field overhauled engine and an overhauled fuel pump had been installed on the airframe about a year prior to the accident; an annual inspection had been completed at the time of the engine installation. The owner reported a total of 149.38 hours of operation since the annual inspection. An FAA approved repair station had overhauled the fuel pump. The fuel pump was submitted to the Safety Board Materials Laboratory for further examination. A senior metallurgist observed wear and metal flow on the square key portion of the fuel pump shaft. There was no evidence of cracking or wear of the drive gear splined teeth. The metallurgist manually rotated the fuel pump and was able to achieve only intermittent engagement between the square key and corresponding slot. A Rockwell Hardness Test (C-scale; HRC) of the gear was conducted. The hardness specification for the gear was between 50-52 HRC. Initially the gear results for the HRC were below acceptable limits and a Rockwell B (B-scale; HRB) test was performed with an average hardness of 94.5 HRB. Laboratory personnel determined that the gear had a cadmium coat, and conducted another test after removal of the cadmium coat. The HRC tests were performed with an average gear hardness of 40 HRC. The FAA issued a suspected unapproved part notification (UPN No. 2004-00053) regarding the overhaul/repair procedure of the accident fuel pump. Teledyne Continental Motors issued a Service Instruction Letter (SIL) SIL06-2 notifying owners and operators of the FAA's issuance of UPN No. 2004-00053.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

failure of the engine driven fuel pump due to the improper overhaul procedure of the fuel pump by an overhaul facility, and the use of parts that did not meet hardness specification.

Full narrative available

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