What happened
The pilot reported that the aircraft's electrical system was inoperative due to a discharged battery, preventing engine startup. To resolve this issue, the pilot obtained a battery charger along with a long extension cord from an external source. After connecting the equipment, the pilot successfully charged the battery and restarted the engines.
Following the successful start, the pilot prepared to move the aircraft back toward its parking area. The pilot stated that he had applied the brakes the previous night before shutting down the aircraft. However, while the pilot was walking away from the cockpit to return the charger and extension cord to the hangar, the aircraft began to move on its own. It rolled forward uncontrollably and collided with a loading dock.
The investigation
The incident occurred during ground operations after a maintenance-related power loss. The primary mechanical factor identified was the failure of the parking brake system to hold the aircraft stationary. Although the pilot confirmed that the brakes were set prior to leaving the cockpit, the force generated by the rolling aircraft indicates that the braking mechanism did not engage sufficiently to counteract gravity or residual momentum.
Findings
- Battery depletion prevented initial engine start, requiring external charging equipment.
- The aircraft rolled into a loading dock while unattended.
- The pilot had set the brakes before leaving the area, but they failed to secure the aircraft.
- Lack of wheel chocks or additional restraint measures contributed to the movement.
Safety message
Grounding procedures require more than just setting the parking brake. Pilots must ensure that wheel chocks are deployed and that the parking brake is verified as holding pressure before leaving the cockpit, especially after electrical system interventions.