A small plane that crashed at the London International Airport nearly two years ago was brought down by an improperly installed rudder system.
The Transportation Safety Board of Canada (TSB) released its findings into the May 25, 2022 crash on Friday. The investigation found the four-seater, twin-engine Diamond DA-42 Twin Star took off on a test flight following a "major overhaul" completed at Diamond Aircraft Industries' facilities at the airport. However, shortly after takeoff, the aircraft abruptly veered to the left.
While trying to correct the unexpected yaw the pilot had difficulty maintaining control of the plane and attempted an emergency landing on one of the airport's runways. The difficulty controlling the aircraft continued, forcing the pilot to try to land on an airport taxiway before ultimately crashing on the grassy area between the runway and taxiway.
The pilot was not hurt.
A team of TSB investigators arrived at the airport a day after the crash to determine the cause. They examined the wreckage, interviewed witnesses and the crew, and reviewed maintenance records. The team found an undetected aircraft maintenance error which led to the control issue.
"The investigation determined that the installation of the rudder cable guide tubes was done without the aid of specific procedures, guidance, or supervision. As a result, the rudder cable guide tubes were installed incorrectly, running parallel to each other instead of crossing over at the rear of the fuselage as prescribed in the airplane maintenance manual," the TSB report states.
This error saw the rudder cables running in parallel when connected to the rudder's lower mounting bracket at the rear of the plane, which then moved the rudder in the opposite direction of the pilot's input.
"Since it is very difficult to see the rudder surface from the cockpit, and the rudder pedals from the tail area, the flight control portions of the annual and pre-flight inspections, which were accomplished by a single individual, did not identify that the rudder was rigged in reverse," the TSB stated.
The TSB concluded that if flight control inspection procedures do not provide specific instructions regarding how to ensure the rudder surface is moving in the correct direction, flight controls that have been rigged in reverse may not be recognized.
