Amateur-built JETEZ N815EY accident near Covington, Tennessee

Probable cause

The improper manufacture of the left wing, which resulted in a left wing flutter event and failure at low altitude and high speed.

NTSB analysis

The airline transport pilot was flying the experimental amateur-built airplane about 200 ft above ground level when its left wing failed, causing the airplane to abruptly depart controlled flight and subsequently impact terrain. Two witnesses indicated that the left wing began a flutter-like movement (described as an oscillation and a "wave like movement"/"wiggle") immediately before the wing failed at its mid-span. The speed of the airplane at the time of the left wing failure could not be determined. However, a witness who had extensive experience observing the accident airplane during flight reported that the pilot performed an intentional low pass over the airport at a speed that may have been near the airplane's maximum structural limits.

The National Transportation Safety Board's Materials Laboratory examined portions of the internal left wing material and found a lack of penetration and bonding of epoxy resin, which resulted in wing sections in which the adhesive had disbonded, leading to the wing's failure. This finding indicated a fabrication problem during manufacture and not wear over time or an environmental degradation failure. The lack of impregnation of the resin into the wing skin pieces indicated a lack of a vacuum seal during the curing process. The airplane's builder records were not located during the investigation; therefore, the method and timeline for manufacturing the wings could not be determined. Nevertheless, the findings indicated that the left wing was not properly designed and manufactured, which resulted in flutter at high speeds.

It is likely that the airplane's left wing entered a flutter condition during the high-speed low-pass maneuver and that the left wing's internal composite structure near the wing's mid-span subsequently experienced a failure of the adhesive between the composite layers.

Text from the NTSB. Open the NTSB docket for ERA18FA240 for the full record.