Beech K35 N5300E accident near St. Augustine, Florida

Probable cause

An unintended brake application of the right main landing gear brake system during the landing rollout due to excessive play between the brake caliper anchor bolts and their bushings.

NTSB analysis

The pilot was conducting a personal flight when, about halfway through the landing rollout and before the pilot could apply the brakes, the airplane suddenly veered to the right. The pilot attempted to correct the veer with left pedal and brake but was unsuccessful. The airplane departed the runway into the grass, struck a berm, flipped over, and came to rest inverted. The airplane sustained substantial damage to the forward fuselage, horizontal stabilizers, and left ruddervator.

Postaccident examination of the airplane revealed that the right main landing gear tire had a flat spot in its tread that was worn to the reinforcement chords. The tire left a black skid mark on the runway that led from the right edge to the grass, consistent with a locked right wheel. The wheel rotated smoothly during recovery of the airplane; therefore, damage or malfunction of the wheel’s bearings was unlikely. The airplane did not have the optional copilot-side brake pedals installed.

Examination of the brake system revealed that the brakes functioned normally; however, the right caliper was found to have some play between the two anchor bolts and their bushings in the torque plate. Excessive caliper play can result in too much clearance between the brake pads and the brake disc. The excessive clearance can cause the brake pads to shift out of place and jam against the brake disc, which could result in an unintended brake application. Disassembly and further examination of the primary brake system components revealed no other anomalies that would have precluded normal operation. Therefore, the right brake was likely applied unintentionally due to the play between the caliper anchor bolts and their bushings. The play likely developed due to wear on the anchor bolts, the bushings, or both.

Text from the NTSB. Open the NTSB docket for ERA19LA268 for the full record.