Accident Grob G115D N234VW,
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ASN Wikibase Occurrence # 42405
 
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Date:Saturday 24 August 1996
Time:10:30 LT
Type:Silhouette image of generic G115 model; specific model in this crash may look slightly different    
Grob G115D
Owner/operator:Sunquest Aviation
Registration: N234VW
MSN: 820101D
Total airframe hrs:589 hours
Engine model:Lycoming AEIO-360-B1F
Fatalities:Fatalities: 2 / Occupants: 2
Aircraft damage: Destroyed
Category:Accident
Location:Indiantown, FL -   United States of America
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Nature:Training
Departure airport:West Palm Beach, FL
Destination airport:
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The flight was scheduled as an aerobatic flight, but no witnesses actually saw the airplane maneuvering. Hunters reported hearing the engine 'revving up' and saw pieces of the airplane falling to the ground. Wreckage was scattered over an area about 2400' long by 400' wide. Separated pieces of the airplane included: an 8' section of the left wing, pieces of the left and right elevators, and other debris from the empennage & canopy. The top portion of the rudder assembly was found about 2400' from the main wreckage. The left aileron was found intact, and it weighed 7.15 pounds; balance checks of the left aileron showed that its residual hinge moment was between 0.138 and 0.200 foot-pounds (trailing edge heavy), exceeding the Grob specification which ranges from -0.22 (leading edge heavy) to 0.074 foot-pounds (trailing edge heavy). A review of the aircraft maintenance logs revealed the airplane had been repainted, but the flight control surfaces had not been rebalanced. Manufacturing records showed that when the left aileron was originally installed, it weighed 6.40 pounds and had a residual hinge moment of 0.071 pounds. Estimates of the residual hinge moments of the other flight control surfaces, including the rudder, disclosed that they also exceeded Grob's trailing-edge-heavy service limits. Grob's flutter analysis, based on control connection stiffness, indicated potential rudder flutter under these conditions. Oxide deposits found on several of the elevator hinge contact surfaces evidenced disbonding/delamination.

Probable Cause: failure of maintenance personnel to rebalance the flight controls after the airplane had been repainted, which resulted in rudder flutter and in-flight breakup of the airplane.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: ATL96FA123
Status: Investigation completed
Duration: 10 months
Download report: Final report

Sources:

NTSB ATL96FA123

Location

Revision history:

Date/timeContributorUpdates
24-Oct-2008 10:30 ASN archive Added
21-Dec-2016 19:24 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
08-Apr-2024 19:25 ASN Update Bot Updated [Time, Other fatalities, Departure airport, Source, Narrative, Category, Accident report]

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