Accident Overview
On March 20, 2017, at approximately 0405 mountain daylight time, a Swearingen SA226TC, registration N158WA, was substantially damaged during the initial takeoff and climb from Boise Air Terminal/Gowen Field (BOI), Boise, Idaho. The airplane was operated by Western Airlines LC under 14 Code of Federal Regulations Part 91 as a positioning flight from BOI to Salt Lake City International Airport (SLC), Utah. The airline transport pilot was not injured. Visual meteorological conditions prevailed, and an instrument flight rules flight plan was active.
Flight and Damage Details
The pilot reported that before departure, he reviewed the airplane's maintenance records and found them current. A preflight inspection of the interior and exterior revealed no anomalies. After obtaining taxi clearance, the pilot taxied to runway 10L and began the takeoff roll. Everything was normal until rotation at 105 knots, when a "pop" was heard followed by a vibration. Suspecting a blown tire, the pilot waited for the vibration to change with wheel rotation, but it remained constant, leading him to consider a propeller issue. He informed the tower of his intention to return and was cleared for runway 10L. On the downwind leg, the pilot inspected both propeller spinners and found no indication of damage; both engines ran smoothly. He elected not to shut down an engine and landed uneventfully. After taxiing to parking, he shut down the right engine first, then the left. During the final rotations of the left propeller, he observed a slight wobble and noticed a blade tip missing. Exiting the airplane, he found about four inches of one propeller blade tip missing, two holes in the fuselage caused by blade fragments, and a third hole near the left wing root. Approximately 10 minutes later, airport operations personnel delivered another piece of propeller blade, along with what appeared to be a screwdriver blade and two pieces of a screwdriver handle.
Post-Accident Inspection
A Federal Aviation Administration aviation safety inspector reported that maintenance had been performed on the airplane before the flight. The mechanic was called away from the task before completion and left a screwdriver on the nose under the windshield wiper, out of the pilot's sight. During the takeoff roll, the screwdriver became dislodged and struck the left propeller. Fragments from two pieces of the propeller blade penetrated the left side fuselage and came to rest inside the cabin. The screwdriver was later found on the departure runway surface.