Accident Cessna 188B N731SV, Wednesday 7 September 1994

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Date:	Wednesday 7 September 1994
Time:	17:00 LT
Type:	Cessna 188B
Owner/operator:	Private
Registration:	N731SV
MSN:	18803127T
Year of manufacture:	1978
Total airframe hrs:	1863 hours
Engine model:	Continental IO-520D
Fatalities:	Fatalities: 0 / Occupants: 1
Other fatalities:	0
Aircraft damage:	Substantial
Category:	Accident
Location:	Oakdale, IL - United States of America
Phase:	Manoeuvring (airshow, firefighting, ag.ops.)
Nature:	Agricultural
Departure airport:	Sparta, IL (KSAR)
Destination airport:	(7H0)
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
THE PILOT REPORTED A LOSS OF ENGINE POWER DURING HIS THIRD AERIAL APPLICATION SWATH RUN. DURING THE SUBSEQUENT FORCED LANDING, THE AIRPLANE SUSTAINED SUBSTANTIAL DAMAGE. EXAMINATION OF THE WRECKAGE REVEALED THE ENGINE WAS SEIZED AND THE CASE WAS FRACTURED IN THE VICINITY OF THE NUMBER ONE CYLINDER. NO EVIDENCE OF PREIMPACT AIRFRAME MALFUNCTION WAS DISCOVERED. EXAMINATION OF THE ENGINE REVEALED THE CRANKSHAFT WAS FRACTURED FORWARD OF THE NUMBER ONE CONNECTING ROD JOURNAL. IT WAS CONCLUDED THAT A FATIGUE FRACTURE RESULTED FROM A MISALIGNMENT AFTER A RECENT OVERHAUL WHICH CAUSED DAMAGED TO THE NUMBER TWO CRANKSHAFT CHEEK.

Probable Cause: misalignment of the number one connecting rod during major overhaul. Factors were the subsequent scoring and fatigue failure of the crankshaft.

Accident investigation: