What happened
The incident occurred while the pilot was maneuvering the aircraft on the ground. The pilot attempted to navigate between two rows of parked aircraft by utilizing differential braking techniques. Specifically, the pilot applied pressure to the left brake pedal to initiate a sharp turn. However, the aircraft continued its rotation beyond the intended path because the pilot was unable to arrest the turn using the right brake pedal.
As the aircraft completed the uncontrolled maneuver, it struck a parked Cessna 172. The collision resulted in damage to both the moving aircraft and the stationary one. No injuries were reported during this ground contact event.
The investigation
Following the incident, investigators conducted a physical inspection of the affected aircraft's braking system to determine the mechanical cause of the loss of directional control. The examination focused on the hydraulic components associated with the right brake pedal, as the pilot had indicated that the right brake failed to engage effectively during the critical moment.
The inspection revealed two significant defects within the right brake system. First, there was a complete absence of fluid in the right brake circuit, which would prevent any hydraulic pressure from being transmitted to the brake assembly. Second, investigators identified a structural crack in the brake line itself. This damage likely allowed the fluid to leak out entirely, rendering the right brake inoperative during the taxi maneuver.
Findings
The primary factor contributing to this accident was the failure of the right braking system. The lack of hydraulic fluid and the cracked brake line prevented the pilot from stopping the turn as intended. This mechanical failure directly led to the collision with the parked aircraft while the pilot was attempting to navigate a confined space on the taxiway.
Brake line crack was identified as the root cause of the hydraulic failure. The loss of right brake functionality meant that differential braking could not be used to control the turn radius. The collision with a parked Cessna 172 was the direct result of this loss of control.
Safety message
Regular pre-flight inspections should include a thorough check of all hydraulic lines for cracks, leaks, or signs of wear. Ensuring that brake fluid levels are adequate in all circuits is critical for maintaining directional control during ground operations, especially when tight turns are required.