What happened
During the landing roll, the pilot was applying heavy braking to turn off the runway at taxiway Echo. During this maneuver, the aircraft suddenly and rapidly ground-looped to the left.
The investigation
An initial post-accident inspection of the aircraft revealed that the right main gear brake rotor assembly had torn loose from the wheel, which rendered the right wheel brake totally inoperative. The wheel hub and brake disk assembly were examined at the NTSB Materials Laboratory. Investigators determined that the brake disk attachment flange failed due to fatigue in the bend around the attachment flange.
Findings
- The brake disk exhibited a substantial amount of general corrosion.
- While the attachment flange met minimum thickness requirements, most of its surface was covered by corrosion and corrosion pitting.
- The fatigue crack propagation that led to the failure originated in one of these corrosion pits.