On September 15, 1986, a Cessna 195 (registration N3879V) was involved in an aviation accident near Porterville, CA. Investigators recorded the probable cause as: Failure of the left brake disc drive key retaining screw, which allowed the key to float loose, break the lower part of the brake housing, and cause loss of the brake lining. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During landing rollout, a pilot experienced left brake failure after feeling a jerk and snapping sounds. The aircraft veered right and entered a ground loop. Examination found a failed brake disc drive key retaining screw allowed the key to break the housing.
Incident Description
After a normal landing, the pilot began to apply moderate brake pressure to make the mid-field taxiway turnoff. The pilot then felt what he described as "a light jerk in the left gear" followed by a "snapping sound which occurred two or three times." Subsequently, the left brake failed completely, and the "aircraft veered to the right and entered a ground loop."
Examination Findings
Examination of the left brake revealed that the left brake disc drive key retaining screw failed. This failure allowed the key to float loosely in the brake housing. The mechanic who examined the brake system stated that the loose key "broke out the lower part of the housing allowing the brake lining to fall out."
Probable cause
Failure of the left brake disc drive key retaining screw, which allowed the key to float loose, break the lower part of the brake housing, and cause loss of the brake lining.