ASN Wikibase Occurrence # 42405
Last updated: 24 May 2013
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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. 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.
|C/n / msn:|| 820101D|
|Fatalities:||Fatalities: 2 / Occupants: 2|
|Airplane damage:|| Written off (damaged beyond repair)|
|Location:||Indiantown, FL -
United States of America
|Phase:|| Manoeuvring (airshow, firefighting, ag.ops.)|
|Departure airport:||West Palm Beach, FL (F45)|
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