NTSB Identification: LAX88FA042.
The docket is stored on NTSB microfiche number 38162.
Accident occurred Sunday, November 15, 1987 in GRAND CANYON, AZ
Probable Cause Approval Date: 07/03/1989
Aircraft: MOONEY M20C, registration: N6670R
Injuries: 4 Fatal.

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.

WHILE CRUISING EN ROUTE ALL ENGINE POWER WAS SUDDENLY LOST AND THE PLT ATTEMPTED AN EMERGENCY LDG AT THE GRAND CANYON ARPT. DURING THE GLIDE, THE ACFT CRASHED INTO AN OUTCROP OF ROCKS ON A STEEP CLIFF, 0.5 MI FROM THE END OF THE RWY. EXAM OF THE ENGINE REVEALED THAT ONE OF THE #3 CONNECTING ROD BOLT NUTS HAD BACKED OFF THE BOLT, AND OTHER NUT HAD BEEN PARTIALLY STRIPPED OFF ITS BOLT. THE ENGINE HAD BEEN OPERATED FOR 212 HRS SMOH. LAB EXAM OF THE BOLT/NUT INTERFACE INDICATED THAT THE NUTS HAD BEEN UNDERTORQUED WHEN THEY WERE LAST INSTALLED.

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

ENGINE ASSEMBLY,CONNECTING ROD BOLT..UNDERTORQUED

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

ENGINE ASSEMBLY,CONNECTING ROD CAP..DISCONNECTED


Contributing Factors

TERRAIN CONDITION..RAVINE


Contributing Factors

IN-FLIGHT PLANNING/DECISION..IMPROPER..PILOT IN COMMAND


Contributing Factors

MAINTENANCE,OVERHAUL,MAJOR..IMPROPER..OTHER MAINTENANCE PERSONNEL

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