NTSB Identification: MKC85LA071.
The docket is stored on NTSB microfiche number 29405.
Accident occurred Thursday, March 14, 1985 in NORWALK, IA
Aircraft: CESSNA 152, registration: N67399
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.

APPROACHING DES MOINES AIRPORT THE PLT RPTD TO APPROACH CONTROL OF ENG PROBLEMS AND WANTED TO KNOW WHAT AIRPORT WAS CLOSE FOR AN PRECAUTIONARY LANDING. AN ATTEMPT WAS MADE TO LAND AT AN AIRSTRIP 3 MI EAST OF HIS PRESENT POSN. UNABLE TO LAND AT THE AIRSTRIP THE ACFT MADE A LANDING TO A FIELD WHERE IT SUSTAINED SUBSTANTIAL DAMAGE. INSPECTION OF THE ENG REVEALED A BROKEN CRANKSHAFT IDLER GEAR. FATIGUE PROGRESSION WAS EVIDENT ON THE FRACTURE SURFACES EXAMINED. ALSO NOTED WAS AN ELLIPTICAL DEFORMATION OF THE THREADED PORTION OF THE RETAINING BOLT BELOW THE BOLT HEAD. THIS DEFORMATION WAS OF THE SAME THICKNESS AS THE BOLTFLANGE AND LOCKNUT PLATE. VISUAL INSPECTION OF THE FRACTURE SURFACES GAVE NO EVIDENCE OF UNUSUAL CONTACT OR WEAR PATTERN PRIOR TO FAILURE.

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

ACCESSORY DRIVE ASSY,DRIVE GEAR..FATIGUE

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

ACCESSORY DRIVE ASSY,DRIVE GEAR..FAILURE,TOTAL

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

MAINTENANCE,OVERHAUL..INADEQUATE..OTHER MAINTENANCE PERSONNEL


Contributing Factors

TERRAIN CONDITION..GROUND


Contributing Factors

TERRAIN CONDITION..SOFT

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