Incident Overview
On 1 January 2020 at 19:12 local time, a Cessna 337G (Skymaster), registration N21911JA, landed on runway 19 at Aeródromo Eulogio Sánchez (SCTB) in La Reina, Metropolitan Region, Chile. The aircraft was operated by a commercial pilot with two additional crew members. During the landing roll, when the pilot applied the brakes, the aircraft veered left due to lack of response from the right brake. The pilot corrected with the right pedal but was unable to stop before the runway end. The aircraft departed the paved surface and came to rest 38 meters south of threshold 01. The three occupants were uninjured, and the aircraft sustained no damage.
Flight History
The flight originated from Aeródromo de San Fernando (SCSD) in the Libertador Bernardo O'Higgins Region to support firefighting operations near Coltauco. After completing the mission, the pilot returned to San Fernando, but because that airport was closed due to an accident, he diverted to his alternate, Eulogio Sánchez. The pilot intended to exit via taxiway Delta at the end of the runway.
Aircraft and System Examination
Post-incident inspection of the runway revealed braking marks starting from the centerline and veering left, extending 60 meters to the runway end. Ground scars continued 38 meters beyond. Visual inspection of the aircraft found no structural damage. Tires, flight controls, and engines were normal. Functional tests of the brake system showed that pressing the brakes from the cockpit pedals did not actuate braking on the right wheel, causing the aircraft to yaw left. Inspection of the right master cylinder revealed hydraulic fluid residue near the piston rod. Upon disassembly, two fragments of cleaning tissue paper were found obstructing the pressure outlet of the right master cylinder. The hydraulic fluid was drained and no other foreign material was found.
Maintenance History
The last annual inspection was performed on 28 December 2019, 20.3 flight hours before the incident, at a maintenance center authorized by the DGAC. The inspection included a check of both brake systems for condition, fluid level, and line condition, but did not include disassembly of the master cylinders. No brake-related discrepancies were recorded in the logbook or flight records after that inspection.
Meteorological and Operational Conditions
Weather at the time was reported by the Chilean Meteorological Directorate as clear skies with wind from 240° at 8 knots, provided by air traffic control. The pilot held a valid commercial pilot license and medical certificate, with 520.08 hours on type and 829.02 total hours. The aircraft weight and balance were within limits.
Communication
Radio communications with ATC were normal before landing. The pilot reported the runway excursion due to a right pedal failure, suspected brake failure or a flat tire.