Piper PA 18 N8589D accident near Livermore, California

Probable cause

The improper installation of the flight control stick, which resulted in separation of the flight control stick from the stick stub assembly and an uncontrolled descent and impact with terrain.

NTSB analysis

During a banner tow flight, the pilot successfully picked up the banner then pulled the flight control stick back to gain altitude. The flight control stick separated from the stick hub assembly at the floor and the airplane made an uncontrolled descent to the ground.

Examination of the airplane revealed that the hardware that secured the flight control stick to the stick hub assembly was connected to the flight control stick but was not attached through the mounting holes on the stick hub assembly. Given the wear marks on the stick stub assembly, it is likely that the control stick was in this position for some time and was not properly installed during prior maintenance; however, the airplane’s maintenance logbook did not specify when the control stick was last removed.

Text from the NTSB. Open the NTSB docket for WPR20LA026 for the full record.