Incident Overview
A Piper PA-34-220T Seneca V, registration G-OXFF, experienced a serious incident on 2 November 2018 at Oxford Airport, Kidlington, during a training flight. The aircraft was about to enter the runway for takeoff when the instructor detected an unusual feel in the left rudder pedal. The flight was aborted and the aircraft was taxied back to the hangar for inspection.
Flight History
The aircraft had been prepared for an instrument rating examination with a student and an instructor on board. After engine start, the emergency battery circuit breaker tripped but was reset and operated normally thereafter. Taxi and power checks were completed without issue. While taxiing under ATC clearance to enter the runway, the instructor observed that the left rudder pedal felt abnormally soft and offered no resistance. The right rudder pedal felt normal in comparison. The instructor stopped the aircraft and informed ATC. The student confirmed the discrepancy. When the cockpit door was opened to observe rudder movement, pressing the right pedal moved the rudder correctly to the right, but pressing the left pedal produced no rudder movement. The instructor subsequently returned the aircraft to the hangar.
Engineering Findings
Inspection revealed that the right rudder cable had chafed against the standby battery wiring, creating an electrical short to earth. The heat from the short melted through the steel-braided rudder cable, causing it to part. The damage was documented with photographs showing the compromised rudder control cable and the chafe marks on the standby battery wiring.
Safety Actions
The potential risk to airworthiness was reported to the manufacturer, the UK Civil Aviation Authority (CAA), EASA, and the FAA. The CAA immediately informed owners and operators of similarly configured Piper Seneca V aircraft. Subsequently, the manufacturer issued mandatory Service Bulletin No 1337, which provides instructions for rerouting a portion of the emergency power wiring to increase clearance from the rudder control cables.