Air transportation safety investigation A22O0060

Loss of control and collision with terrain

Diamond Aircraft DA-42 N591ER
London International Airport, Ontario
25 May 2022

The occurrence

At approximately 1329 Eastern Daylight Time on 25 May 2022, the Diamond Aircraft Industries DA 42 NG aircraft (U.S. registration N591ER, serial number 42.081) departed Runway 09 at London Airport, Ontario, on a local test flight following a major overhaul that had been completed at the Diamond Aircraft Industries facilities at the airport.

During the take-off roll, everything appeared to be normal; however, when the aircraft became airborne, it unexpectedly yawed to the left. The pilot attempted to correct for the unexpected yaw by adding full right rudder and full right aileron input, but he could not maintain directional control of the aircraft.

Despite the right control inputs, the aircraft continued to yaw and bank to the left at an estimated height of about 500 feet above ground level (AGL). The pilot initially intended to return to land on Runway 09 and, believing that there was a problem with one of the engines, began adjusting the throttle levers to troubleshoot the situation. When this did not resolve the problem, he altered his plan, declared an emergency with air traffic control, and headed for Runway 27.

While heading for Runway 27, the pilot could not regain complete control of the aircraft and instead attempted to land in a southwest direction on Taxiway A. The aircraft eventually landed on the grass between the runway and Taxiway A. The aircraft touched down hard on the grass, and the rudder and the left-wing aileron mass balance weight broke off. The landing gear collapsed, and the aircraft slid to a stop approximately 265 feet from the initial impact point. The pilot was not injured. The aircraft was substantially damaged. There was damage to both propellers, engine nacelles, and various sections on the underside of the fuselage. During the examination of the aircraft, it was discovered that the rudder moved in the opposite direction of pilot input.

The investigation has determined that, during the recent maintenance activities, the rudder guide tubes were installed running parallel to each other instead of crossing over at the rear of the fuselage as prescribed in the Aircraft Maintenance Manual. Consequently, when the rudder control cables were threaded through these guide tubes, they were connected to the opposite side of the rudder lower mounting bracket in the rear of the aircraft. Despite subsequent maintenance and pre-flight inspections, the incorrect installation went unnoticed.

Investigation status

To date, the TSB has conducted a comprehensive examination and analysis of the wreckage and has thoroughly reviewed all training and maintenance records and procedures, as well as the qualifications of all personnel. Additionally, numerous interviews have been conducted, and collaboration with Diamond Aircraft Industries and Transport Canada continues.

This accident investigation is ongoing. Information in this update is preliminary and may be supplemented or revised during the investigation.

Should a critical safety issue be identified during the investigation, the TSB will immediately notify relevant parties so appropriate and timely safety action can be taken.

A final report will be released at the conclusion of the investigation.

Media materials

Deployment notice

Investigation information

Map showing the location of the occurrence

Investigator-in-charge

Mr. Rowntree has 26 years of civil aviation experience. He joined the TSB in November 1997 as an investigator/technical specialist in the TSB Air Investigations Ontario Regional Office, in Richmond Hill, Ontario

Prior to joining the TSB, he worked as an aircraft maintenance supervisor in the arctic for a major Canadian air carrier. During that time, he maintained and supervised the maintaining of different aircraft types, from small aircraft to the larger commuter and jet aircraft. Mr. Rowntree was also certified flight attendant and volunteer fire fighter.

Since joining the TSB, Mr. Rowntree has participated in numerous investigations and several major TSB investigations, most notably; the 1998 investigation into Swiss Air 111 in Peggy's Cove, Nova Scotia, the 2004 investigation into the MK Airlines accident in Halifax, Nova Scotia, the 2005 investigation into Air France accident in Toronto, Ontario, the 2009 Cougar Helicopter accident in St. John's, Newfoundland and the 2011 First Air accident in Resolute, Nunavut. On behalf of the TSB, he has also assisted numerous foreign investigation agencies in their investigations of accidents abroad.

Class of investigation

This is a class 3 investigation. These investigations analyze a small number of safety issues, and may result in recommendations. Class 3 investigations are generally completed within 450 days. For more information, see the Policy on Occurrence Classification.

TSB investigation process

There are 3 phases to a TSB investigation

1. Field phase: a team of investigators examines the occurrence site and wreckage, interviews witnesses and collects pertinent information.
2. Examination and analysis phase: the TSB reviews pertinent records, tests components of the wreckage in the lab, determines the sequence of events and identifies safety deficiencies. When safety deficiencies are suspected or confirmed, the TSB advises the appropriate authority without waiting until publication of the final report.
3. Report phase: a confidential draft report is approved by the Board and sent to persons and corporations who are directly concerned by the report. They then have the opportunity to dispute or correct information they believe to be incorrect. The Board considers all representations before approving the final report, which is subsequently released to the public.

For more information, see our Investigation process page.

The TSB is an independent agency that investigates air, marine, pipeline, and rail transportation occurrences. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.