What happened
On February 22, 2019, a Piper PA-3-325, registration PR-RCS, was performing a local flight at Aeródromo 14 BIS in Londrina, Brazil. The aircraft had been out of service for seven months prior to this flight. During the operation, the pilot performed a runway roll to align with runway 29. As the aircraft approached the runway threshold, the pilot attempted to decelerate. While the braking initially functioned normally, the right brake began to malfunction approximately 150 meters before the threshold. This failure caused the aircraft to exceed the runway limits and fall into an embankment. The pilot was uninjured, but the aircraft sustained substantial damage.
The investigation
CENIPA investigators examined the aircraft's maintenance history and the mechanical state of the braking system. The investigation revealed that while the pilot was properly licensed and the aircraft held a valid airworthiness certificate, the aircraft's logbooks for the airframe, engine, and propellers were not up to date. Specifically, there were no records regarding the storage or preservation of components during the seven-month period the aircraft had been inactive.
Post-accident functional tests were conducted to replicate the failure. By applying continuous pressure to the brake pedals, investigators observed the right pedal sinking significantly further than the left. A subsequent teardown of the right-side brake assembly identified a fluid leak originating from the lower piston. The inspection uncovered wear patterns (striations) on the O-ring and internal wear within the brake cylinder housing, along with an accumulation of dirt and oil within the assembly.
Findings
- The right brake assembly experienced a fluid leak due to a worn O-ring and internal cylinder wear.
- The aircraft had been inactive for seven months without documented preservation or storage procedures.
- Maintenance records for the airframe, engine, and propellers were not updated since July 2017.
- Inadequate preventive maintenance during the aircraft's last 100-hour inspection may have contributed to the component failure.
Safety action
CENIPA recommended that the National Civil Aviation Agency (ANAC) disseminate the findings of this investigation to alert pilots, operators, and maintenance organizations regarding the critical importance of verifying aircraft preservation/storage procedures and ensuring all maintenance actions are accurately recorded in aircraft logbooks.