Swearingen SA226 N158WA accident near Boise, Idaho

Probable cause

Company maintenance personnel's failure to remove a screwdriver that was left lodged in the windshield wiper area of the forward fuselage during maintenance and subsequently became dislodged on takeoff/initial climb and collided with a left propeller blade.

NTSB analysis

The airline transport pilot reported that he performed a preflight inspection of the airplane before departing on the repositioning flight. The takeoff roll was normal; however, just after the airplane lifted off, he heard a "pop" and felt a vibration. The pilot initially thought that one of the tires had blown, but as the vibration continued, he determined that he might have a problem with one of the propellers. The pilot subsequently returned to the airport and landed without further incident.

When the pilot shut down the left engine after landing, he noticed that the tip of one of the propeller blades was missing. Further examination of the blade revealed that about 4 inches of the blade tip had separated and penetrated the side of the fuselage.

Airport personnel later found additional pieces of propeller blade material on the runway, as well as what appeared to be the blade of a screwdriver and pieces of the handle.

Maintenance personnel reported that a mechanic had been working on the airplane just before the flight and had been called away from the task he was performing before it was completed; the airplane was subsequently returned to service. The mechanic left a screwdriver on the nose of the airplane in the windshield wiper area, in a position that the pilot could not see. It is likely that, during the takeoff roll, the screwdriver became dislodged from the area of the windshield wiper and impacted the left propeller.

Text from the NTSB. Open the NTSB docket for WPR17LA078 for the full record.