What happened
On 19 October 2016, a Piper PA-44-180 Seminole, registration G-BGCO, was performing a private flight from Cranfield to Warton Aerodrome. The pilot intended to perform a touch-and-go landing on Runway 25 under light north-westerly winds and dry conditions. After a successful touchdown on the main wheels, the nosewheel contacted the runway with significant force, causing the aircraft to veer sharply to the left.
As the aircraft slowed, it drifted off the paved surface and onto the adjacent grass. In an effort to clear the runway and avoid disrupting airfield operations, the pilot attempted to taxi the aircraft toward Taxiway C. During this ground maneuver, the right propeller struck the ground, resulting in damage to a blade tip. There were no injuries to the two crew members on board.
The investigation
The investigation focused on why the aircraft lost directional control during the landing roll. Investigators examined the rudder pedal and braking mechanisms and discovered that the cable for the emergency landing gear lowering system was contacting the left brake pedal.
Specifically, while the normal operation of the rudder pedals functioned correctly, moving the left rudder pedal aft in the right-hand pilot position caused the cable to tighten. This tension drove the left brake pedal forward against the pedal itself. As a result, any attempt by the pilot to steer the aircraft back toward the centerline by applying right rudder inadvertently applied the left brake, pulling the aircraft further off course.
Findings
- The primary cause of the runway excursion was the inadvertent application of the left brake caused by mechanical interference.
- A manufacturer service bulletin and subsequent Airworthiness Directive had previously been issued to install a fitting designed to prevent the emergency cable from contacting the brake pedals.
- Although the aircraft G-BGCO had the required fitting installed, the installation was performed incorrectly. The orientation of the new fitting actually increased the risk of the cable making contact with the pedal rather than preventing it.