Accident Piper PA-18-150 N4473A,
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ASN Wikibase Occurrence # 352453
 
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Date:Sunday 10 October 1999
Time:19:05 LT
Type:Silhouette image of generic PA18 model; specific model in this crash may look slightly different    
Piper PA-18-150
Owner/operator:Great Plains Aviation LLC
Registration: N4473A
MSN: 18-4828
Year of manufacture:1956
Engine model:Lycoming O-320
Fatalities:Fatalities: 0 / Occupants: 2
Aircraft damage: Substantial
Category:Accident
Location:Granite, OK -   United States of America
Phase: Take off
Nature:Private
Departure airport:(810K)
Destination airport:
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The airplane was destroyed upon impact with terrain following a loss of control during the takeoff/initial climb. Severe corrosion was found at two structural tube clusters (one with a windshield pillar) located directly below the right wing forward and aft attach fittings. The portion of the forward structure available for carrying loads prior to the accident was less than 30% of the circumference of the pillar tube. Deformation associated with the separation of the pillar tube indicates that the pillar failed under compression loads. The manufacturer's representative stated that the 'windshield pillar is normally subjected to a tensile load during flight.' It is possible that compression loads generated during the takeoff roll led to a compression failure of the pillar. This failure would have changed the lift characteristics of the wing since the separation point was directly below the right wing forward attach fitting. The most recent annual inspection was performed in January 1999; the maintenance entry for the annual stated, in part, 'treated steel tubing as required.' In June 1999, a major repair was made to a tube cluster in the aft fuselage area 'due to external rust through from past acid spill.'

Probable Cause: Corrosion failure of the fuselage support tubing below the right wing forward attach fitting due to inadequate maintenance.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: FTW00LA010
Status: Investigation completed
Duration: 1 year 1 month
Download report: Final report

Sources:

NTSB FTW00LA010

Location

Revision history:

Date/timeContributorUpdates
07-Mar-2024 14:34 ASN Update Bot Added

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