The pilot departed on the initial test flight of the homebuilt Sopwith Baby.
At the speed when the tailwheel lifted from the runway at the airport in Lee’s Summit, Missouri, the airplane began an uncommanded left roll.
The pilot attempted to arrest the roll, but was unsuccessful. He aborted the takeoff but lost control of the airplane as it settled down in a crab.
The airplane exited the side of the runway and resulted in the failure of the left landing gear, and subsequent nose over of the airplane. The lower left wing sustained substantial damage.
The airplane builder conducted a post-accident examination and reported that the right wing had a different “angle-of-attack” than the other wings, due to a construction error. This difference likely resulted in the uncommanded left roll during takeoff. This rolling tendency was not detected during the previous four high-speed taxi tests.
Probable Cause: The airplane builder’s improper installation of the lower right wing which resulted in an uncommanded left roll and the subsequent loss of control.
To download the final report. Click here. This will trigger a PDF download to your device.
This May 2020 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
A digital protractor and STICK are PRICELESS when setting wing incidence and also to detect any wing twist. Even better is a digital protractor that allows zeroing out at any given setting to read angle changes directly without the need for math.