Accident Cassutt Sport N86T, Thursday 20 March 1997
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Date:Thursday 20 March 1997
Time:18:35 LT
Type:Silhouette image of generic CASS model; specific model in this crash may look slightly different    
Cassutt Sport
Owner/operator:Daniel K. Stone
Registration: N86T
MSN: T1
Engine model:Continental O-200-A
Fatalities:Fatalities: 1 / Occupants: 1
Other fatalities:0
Aircraft damage: Destroyed
Category:Accident
Location:Stilwell, OK -   United States of America
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Nature:Private
Departure airport:Cookson, OK (44M)
Destination airport:(011)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The pilot (plt) departed Cookson, OK, in a homebuilt aircraft (acft) for an approximate 30 minute flight to Stilwell, OK. Witnesses at Stilwell said he made a low pass on a northerly heading (about 50 ft off the ground) at a high rate of speed. One witness estimated the acft was traveling faster than 200 mph, when he saw the acft's right wing skin separate from the acft. The right wing then came off. The acft was observed to roll several times & travel about 1100 ft before it impacted the ground. Postimpact examination of the wreckage revealed a fracture in the wing spar about 18 inches in from the right wing tip. There was a discoloration in the fracture, which had the appearance of a varnish like substance. An FAA inspector reported that 'there were different color glue joints in the wing construction indicating that there were different kinds of glue used.' Also, the failure mode differed; the dark glue joints failed in the wooden structure, where as, the other glue joints failed in the bond. Some of the wing joints that had failed had discoloration between the rib & the wooden skin. The inspector suggested that 'either improper clamping during construction, prevarnishing of the contact surfaces, or bond separation followed by moisture weathering could have caused this.' The plt had purchased the homebuilt acft on 10/1/96. It had been originally certificated for flight on 10/27/72. On 2/11/73, it had been damaged during a takeoff mishap, & 'new wing construction' had been performed.

Probable Cause: failure of the right wing spar and/or debonding of the right wing skin, which resulted in separation of the wing skin and a portion of the right wing, during high speed flight. Factors related to the accident were: previous wing damage and inadequate maintenance by other (unknown) personnel.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: FTW97FA135
Status: Investigation completed
Duration: 1 year and 2 months
Download report: Final report

Sources:

NTSB FTW97FA135

Location

Revision history:

Date/timeContributorUpdates
24-Oct-2008 10:30 ASN archive Added
21-Dec-2016 19:23 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
08-Apr-2024 16:29 ASN Update Bot Updated [Time, Operator, Other fatalities, Destination airport, Source, Narrative, Category, Accident report]

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