Serious incident Beechcraft 90B King Air N37OU,
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ASN Wikibase Occurrence # 314511
 
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Date:Monday 11 April 2011
Time:09:15 LT
Type:Silhouette image of generic BE9L model; specific model in this crash may look slightly different    
Beechcraft 90B King Air
Owner/operator:University Of Oklahoma, Dept Of Aviation
Registration: N37OU
MSN: LJ-1428
Total airframe hrs:2789 hours
Engine model:P&WC PT-6A-21
Fatalities:Fatalities: 0 / Occupants: 4
Aircraft damage: Minor
Category:Serious incident
Location:Chickasha, Oklahoma -   United States of America
Phase: Approach
Nature:Training
Departure airport:Norman-University of Oklahoma Westheimer Airport, OK (KOUN)
Destination airport:Norman-University of Oklahoma Westheimer Airport, OK (KOUN)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The certified flight instructor (CFI) reported that the airplane was on a downwind leg for landing when a pilot-rated passenger who was sitting in the cabin told him that the right aileron was partially separated from the airplane. The CFI took control of the airplane and landed it uneventfully. The post incident inspection of the airplane revealed that the two inboard aileron hinges were separated from the airframe. The screws (8 screws, 4 upper, 4 lower) which attached the aileron to the aileron hinge points were seated in the aileron skin, but did not screw into the corresponding nut plates on the aileron hinge points. The aileron was not damaged so a mechanic attached the aileron properly to the aileron hinge points and the airplane was returned to service. Maintenance records indicated that the airplane had undergone a phase inspection 10 days prior to the incident. During the phase inspection, the right aileron was removed to repair some light surface corrosion and was reinstalled on the airplane. The incident occurred 5.3 hours after the phase inspection was performed. Eight years prior to the accident, the aircraft manufacturer issued a communique which stated that their technical support department had received reports that during aileron installation, screws missed the nut plates on the aileron hinge points. It stated that this condition can go unnoticed.

Probable Cause: The mechanic's improper installation of the aileron.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: CEN11IA280
Status: Investigation completed
Duration: 3 months
Download report: Final report

Sources:

NTSB CEN11IA280

Location

Revision history:

Date/timeContributorUpdates
02-Jun-2023 17:57 ASN Update Bot Added

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