NTSB Identification: LAX98LA131.
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Accident occurred Wednesday, March 18, 1998 in THERMAL, CA
Probable Cause Approval Date: 02/11/2000
Aircraft: Callair A-9, registration: N7211V
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.

The aircraft lost power while towing a glider and made an emergency landing. Examination of the engine revealed that the crankcase upper surface near the number three cylinder was cracked and displaced outward. The oil pump drive coupling at the crankshaft gear displayed signatures consistent with heat distress. The oil pump drive at the oil pump would not rotate. The oil pump housing and mounting pad were free of any rotational scoring and did not display evidence of oil starvation or metal contamination. The crankshaft gear was a Lycoming part number 13S19648 and is the part number for the Lycoming IO-540 series engines. The engine in the accident aircraft is a Lycoming O-540-B2B5 and the crankshaft gear part number for this engine is 13S19647.

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

The failure of the oil pump drive shaft due to the installation of an incorrect oil pump crankshaft gear by maintenance personnel at the last overhaul.

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