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On Oct. 18, 2019, a CC-150 aircraft was towed from the North ramp to 10 Hangar at 8 Wing Trenton. 10 Hangar is not routinely used by the CC-150, and the D-14 tow tractor normally used is too large for the limited space available inside 10 Hangar. Before entering the hangar, the ground crew were required to stop and swap the tow tractor from the bigger D-14 to the smaller D-12.
Once the aircraft reached a position in front of 10 Hangar, the contracted maintenance tow crew stopped the aircraft, installed chocks, set the parking brake, and disconnected the tow tractor. During the tow tractor change, the aircraft started moving forward and jumped over the chocks. Attempts to stop the aircraft by the tow crew were unsuccessful. The right engine struck the D-12 tow tractor parked inside the hangar, before the nose contacted the hangar far wall structure, finally stopping the aircraft.
The aircraft sustained serious damage (“C” category). The force of impact resulted in one minor injury.
The investigation could not positively determine the cause for the parking brake not holding the aircraft in position. However, it was found that the chocks used to secure the aircraft were not authorized in the technical support arrangement and not all wheels had chocks at the time of the accident. Brakeman training was found to be informal and lacking emergency procedures and reference to aircraft publications.
The investigation recommends the use of approved chocks on all wheels and improved training for towing operations.