Accident Cessna 172N N109DP,
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ASN Wikibase Occurrence # 289149
 
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Date:Monday 4 July 2011
Time:13:30 LT
Type:Silhouette image of generic C172 model; specific model in this crash may look slightly different    
Cessna 172N
Owner/operator:Gulf Coast Aerial Advertising Inc
Registration: N109DP
MSN: 17270607
Year of manufacture:1978
Total airframe hrs:2927 hours
Engine model:Lycoming O-360-A4M
Fatalities:Fatalities: 0 / Occupants: 2
Aircraft damage: Substantial
Category:Accident
Location:Orange Beach, Alabama -   United States of America
Phase: En route
Nature:Banner and glider towing
Departure airport:Foley, AL (0AL1)
Destination airport:Foley, AL (0AL1)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The airplane had been modified by several Supplemental Type Certificates (STCs) allowing the use of 91 minimum octane alcohol-free fuel, or a combination of 100LL and 91 minimum octane ethanol-free fuel. After takeoff while operating the engine on a mixture of 100LL and 87 octane automotive fuels with 10 percent ethanol additive, the engine experienced abnormal combustion in the No. 3 cylinder, which burned a hole through the cylinder near the lower spark plug hole. The resulting loss of engine power necessitated a forced landing in water. Postaccident examination of the engine revealed no discrepancies with the power train, ignition, lubrication, or air induction systems that would have led to the event. Metallurgical examination of the No. 3 cylinder revealed no manufacturing defects that would have damaged to the cylinder. No placards were noted by either fuel cap; these were required by the installed STCs specifying minimum octane rating of 91 without alcohol; however, on the day of the accident, the airplane underwent a 100-hour inspection by the pilot-in-command who held a mechanic certificate with airframe and powerplant ratings and inspection authorization; he had also performed the modification allowing the airplane to use automotive fuel. Although no fuel samples were retained for testing, the damage to the cylinder was consistent with the usage of unapproved fuel with too low an octane rating.

Probable Cause: The operation of the airplane using unapproved fuels, which resulted in abnormal combustion and subsequent damage to the No. 3 cylinder. Contributing to the accident was the inadequate 100-hour inspection because the mechanic failed to note the lack of placards by either fuel filler cap specifying the minimum automotive fuel grade and no alcohol allowed as specified by the installed STC's.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: ERA11LA388
Status: Investigation completed
Duration: 1 year and 7 months
Download report: Final report

Sources:

NTSB ERA11LA388

Location

Revision history:

Date/timeContributorUpdates
05-Oct-2022 10:23 ASN Update Bot Added

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