Accident Details
On February 9, 2015, at 0615 eastern standard time, two De Havilland DH 6 Twin Otter aircraft, registration numbers N30EA and N70EA, collided at Sebastian Municipal Airport (X26) in Sebastian, Florida. The collision occurred when N30EA lost control during engine start. Both airplanes were operated by Eagle Air Transport of Ottawa, Illinois, and were preparing for a positioning flight under 14 Code of Federal Regulations Part 91 to Exuma International Airport (MYEF) in George Town, Bahamas. Instrument flight rules flight plans were filed for both flights, and visual meteorological conditions prevailed.
Sequence of Events
The two airplanes were parked adjacent to each other, with N30EA to the right of N70EA. The pilot of N30EA reported conducting a normal pre-flight inspection and setting the parking brake. After starting both engines, she advanced the throttles one at a time to bring the generators online. The airplane began to move forward and to the left because the steering tiller had been positioned sharply to the left when the airplane was last parked. When the pilot applied the brakes, there was no response, and the airplane turned nearly 180 degrees before colliding with N70EA, whose engines were also running.
Post-Accident Findings
Post-accident photographs revealed substantial damage to the right wings and engines of both airplanes. The propeller assembly from N70EA's right engine had sheared off, and each blade was damaged. The propeller assembly for N30EA remained partially attached to the engine, with all blades damaged. The area above the cockpit of N30EA was crushed from impact with N70EA's right wing.
Hydraulic Circuit Breaker Issue
After an emergency shutdown, the pilot of N30EA noticed that the hydraulic circuit breaker was pulled. She reported that a mechanic had allegedly pulled the circuit breaker to bleed down the hydraulic accumulator during maintenance the night before the accident, which may have resulted in insufficient hydraulic fluid for the parking brake and pedal brakes. However, a review of maintenance logs for N30EA revealed no hydraulic system maintenance prior to the accident. The pilot also stated that she later learned some pilots pull the hydraulic circuit breaker during shutdown to reduce wear on the hydraulic pump, though this is not in the checklist. It remains unknown how or why the circuit breaker was open before the accident.
Checklist Compliance
According to the airplane's normal operating procedures, the before-starting-engines checklist requires that all circuit breakers be confirmed as in. The pilot of N30EA acknowledged that she should have seen the pulled circuit breaker during her pre-start flow.
Injuries and Damage
The pilot of N30EA and the pilot and mechanic on N70EA were not injured. No other occupants were reported. Both aircraft sustained substantial damage.