NTSB Identification: LAX86LA076.
The docket is stored on NTSB microfiche number 30220.
Accident occurred Friday, December 27, 1985 in SAN MANUEL, AZ
Aircraft: MOONEY M20F, registration: N234GA
Injuries: 4 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.

DURING CRUISE AT 10,500 FT MSL ON A NIGHT X-COUNTRY FLT, THE PLT SAID THE ENG RAN ROUGH WITH MODERATE VIBRATION LEVELS. PLT DECLARED AN EMERGENCY WITH ABQ ARTCC, WHO VECTORED THE ACFT TO AN UNLIGHTED AIRSTRIP. THE PLT SAID HE HAD DIFFICULTYIN SEEING THE RWY IN THE DARKNESS. THE ACFT LANDED LONG, BLEW A TIRE, VEERED OFF THE RT SIDE OF THE RWY & STRUCK A TREE.EXAMINATION OF THE ENG REVEALED THAT THE #3 CYLINDER WAS AJAR FROM THE CASE, WITH ALL THE TOP HOLD DOWN STUDS & NUTS IN PLACE BUT BENT UPWARD. THE NUTS WERE MISSING FROM THE LOWER FORE & AFT LARGE HOLD DOWN STUDS, & THE REMAINING CENTER STUDS HAD ALL FRACTURED AT THE CYLINDER FLANGE LEVEL. THE ENG WAS OVERHAULED 6 MONTHS AND 21 HRS PRIOR TO THE ACCIDENT. THE FAA AIRWORTHINESS INSPECTOR WHO EXAMINED THE ENG STATED HIS OPINION THAT THE NUTS ON THE LOWER LARGE STUDS WERE UNDERTORQUED AT INSTALLATION.

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

ENGINE ASSEMBLY,CYLINDER..LOOSE

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

MAINTENANCE,MAJOR REPAIR..IMPROPER..OTHER MAINTENANCE PERSONNEL

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

AIRPORT FACILITIES,RUNWAY EDGE LIGHTS..UNAVAILABLE

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

GROUND LOOP/SWERVE..INADVERTENT..PILOT IN COMMAND


Contributing Factors

OBJECT..TREE(S)


Contributing Factors

LIGHT CONDITION..DARK NIGHT


Contributing Factors

PROPER TOUCHDOWN POINT..NOT IDENTIFIED..PILOT IN COMMAND


Contributing Factors

GO-AROUND..NOT POSSIBLE..PILOT IN COMMAND

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