What happened
On November 29, 2015, a Bombardier DHC-8-Q400 operating at Warsaw Chopin Airport (EPWA) experienced an incident during its takeoff roll. While the aircraft was accelerating at a speed of 70 knots, a "PITCH TRIM" warning message appeared on the flight deck. Following standard operating procedures, the crew immediately aborted the takeoff and returned the aircraft to the parking stand.
This event marked the fourth instance of an aborted takeoff involving a pitch trim warning within a short period, following three similar occurrences on October 23 and October 24. Previous incidents had already been documented in a fleet bulletin, with instructions issued to flight instructors to monitor hand positioning on the control yoke during simulator sessions and line operations.
The investigation
The investigation focused on determining whether a mechanical failure or pilot input triggered the warning. During the flight analysis, it was noted that the control yoke was deflected to the left at the moment the warning appeared. However, the crew did not report any requirement to perform a takeoff using a crosswind aileron technique.
Maintenance personnel conducted a thorough inspection of the aircraft in accordance with task cards. No mechanical defects were found in the Air Data Computer (ADC), the Flight Control Electronics Control Unit (FCECU), or the pitch trim actuator itself. However, a review of the onboard computer error logs revealed that the warning was triggered by the unintentional activation of one half of the pitch trim control switch on the yoke.
Findings
- The primary cause of the incident was the unintentional use of one half of the pitch trim control switch on the control yoke.
- The crew's decision to abort the takeoff was appropriate and followed established safety protocols.
- No technical malfunctions were identified in the aircraft's flight control systems or sensors.