A Swearingen SA226-TC Metro II was being pre-flighted by its pilot on this day in aviation history for a positioning flight from Boise (Idaho, USA) to Denver (Colorado, USA). As part of the flight preparation the Aircraft Technical Log was reviewed, and it was up to dare. With the internal and external preflight tasks completed clearance was requested from ATC at 04.00 am.
After receiving the necessary clearance, the engines were started and the aircraft taxied to runway 10L. Take-off was initiated and the aircraft accelerated normally. At 105 knots the aircraft was rotated and became airborne. At that time the pilot heard a "POP" and vibration started. As the vibration did not reduce with reducing wheel speed (the landing gear was still down) the pilot concluded the vibration was engine or propellor related, The pilot informed ATC of the situation and was given instructions for a return to runway 10L. Besides the vibration, no cautions, warnings or abnormal indications were presented in the cockpit. An uneventfully landing followed and the aircraft taxied to its assigned parking position and once stopped, both engines were shut down. With the engines and propellers spinning down the left spinner was observed to wobble slightly and it became apparent that the tip on one of the propellor blades on the left engine was missing.
The two holes in the forward fuselage (left) and the damaged propellor blade (right) (© NTSB)
When the propellor was inspected a 4 inch (10 cm) section of a propellor tip was found to be missing. Also, two holes were visible in the fuselage where it was pierced by debris.
Approximately 10 minutes after the aircraft was shut down airport operations staff brought a piece of propellor blade and the metal part of a screwdriver, as well as remnants of the screwdriver handle. A third hole in the fuselage was found a short while later.
Propellor debris retrieved from the Remnants from the screwdriver (© NTSB) aircraft cabin, (© NTSB)
An investigation was launched and in its report, the National Transportation Safety Board, gave the following 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."
The NTSB report is available by clicking here.