NTSB Identification: FTW89LA167.
The docket is stored on NTSB microfiche number 39881.
Accident occurred Sunday, September 17, 1989 in BRENHAM, TX
Probable Cause Approval Date: 07/29/1992
Aircraft: MOONEY M20E, registration: N9462V
Injuries: 2 Minor.

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

DURING CRUISE AT 6500 FT, OIL APPEARED ON THE WINDSCREEN. FORWARD VISIBILITY WAS SOON RESTRICTED & SEVERE VIBRATIONS PROMPTED THE PLT TO SECURE THE ENG. SUBSEQUENTLY, THE ACFT WAS DMGD WHEN IT HIT A SMALL TREE & ENCTRD UNEVEN TERRAIN DRG A FORCED LNDG. INV REVEALED A 90 DEG ALUMINUM FITTING ON THE PROP GOVERNOR OIL LINE HAD FAILED WHERE IT ENTERED THE ENG CASE. THE OIL LINE WAS STAINLESS STEEL & ITS MOVEMENT WAS DESIGNED TO BE RESTRAINED BY CLAMPS, WHICH WERE NOT IN PLACE. A SVC INSTRN, ISSUED IN 1986, RCMNDD THAT ALUMINUM FITTINGS BE UPGRADED TO STAINLESS STEEL. A SVC BULLETIN DATED 9/8/89 RELATED TO NUMEROUS 'ENGINE FAILURES DUE TO OIL STARVATION RESULTING FROM BROKEN GOVERNOR LINES.' ACCORDING TO THAT BULLETIN, FAILURE TO RE-INSTALL THE GOVERNOR LINE CLAMPS AFTER MAINT HAD BEEN THE CAUSE OF NUMEROUS ENG FAILURES. MAINT PERSONNEL ACCOMPLISHED BOTH A TOP OVERHAUL & AN ANNUAL INSPN, 50 & 12 HRS, RESPECTIVELY, BFR THE ACDNT.

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

IMPROPER MAINTENANCE, IMPROPERLY SECURED OIL LINE TO THE PROPELLER GOVERNOR, FAILURE OF THE PROPELLER GOVERNOR OIL LINE, AND SUBSEQUENT LOSS OF OIL, WHICH RESULTED IN OIL EXHAUSTION. FACTORS RELATED TO THE ACCIDENT WERE: FAILURE OF MAINTENANCE PERSONNEL TO FOLLOW THE SERVICE BULLETIN/INSTRUCTION, AND THE TREE AND ROUGH TERRAIN IN THE EMERGENCY LANDING AREA.

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