NTSB Identification: FTW91FA158.
The docket is stored on NTSB microfiche number 45086.
Accident occurred Sunday, August 25, 1991 in TULSA, OK
Probable Cause Approval Date: 01/25/1993
Aircraft: BEECH K35, registration: N817R
Injuries: 2 Serious.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

DURING ROUTINE MAINTENANCE, THE ENGINE WAS RUN UP TO FULL POWER WITH THE AIRPLANE TOW BAR ATTACHED. AS THE NOSE STRUT COMPRESSED, THE PROPELLER STRUCK THE TOW BAR. A SERVICE BULLETIN ADDRESSES THIS ISSUE STATING THAT THE ENGINE SHOULD BE DISASSEMBLED AND INSPECTED FOR DAMAGE. THE MAINTENANCE FACILITY DID NOT ADVISE THE OWNER OF THE EXTENT OF THE DAMAGE INCURRED. AS A RESULT OF THE PROPELLER STRIKE, THE CRANKSHAFT MAIN BEARINGS ROTATED IN THE SADDLES, FAILING MECHANICALLY. THIS RESULTED IN THE BLOCKAGE OF OIL PASSAGES AND THE SUBSEQUENT FAILURE OF THE NUMBER TWO CYLINDER CONNECTING ROD CAP BOLTS. TOTAL ENGINE FAILURE RESULTED. SUITABLE TERRAIN FOR THE FORCED LANDING WAS NOT AVAILABLE. IMPACT OCCURRED IN SOFT CULTIVATED TERRAIN.

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

TOTAL POWER LOSS DUE TO FAILURE OF THE CRANKSHAFT BEARINGS AND CONNECTING ROD CAP BOLTS RESULTING FROM THE MAINTENANCE FACILITIES' FAILURE TO OVERHAUL THE ENGINE. A FACTOR WAS THE LACK OF SUITABLE TERRAIN FOR THE FORCED LANDING.

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