AINsight: Fatal In-flight Upset Poses Important Lessons
by Stuart “Kipp” Lau
– May 25, 2023
On March 3, 2023, a Bombardier Challenger 300 was involved in an accident en route from Keene, New Hampshire, to Leesburg, Virginia, killing one passenger. Initial media reports suggested that an encounter with severe turbulence was the cause, but this was later ruled out.
A recently published NTSB preliminary investigative report on the accident identified an in-flight upset caused by a pitch trim malfunction. The report raises many questions about the pitch trim system on this super-midsize business jet and yet more questions about the actions of the flight crew leading up to the in-flight upset event.
The Challenger 300/350 has been in service for nearly 20 years, with more than 800 examples delivered worldwide.
In recent years, both the FAA and Transport Canada have issued airworthiness directives (AD) related to the aircraft’s horizontal stabilizer trim system. Each AD identifies a scenario following a “STAB TRIM FAULT” advisory and autopilot disconnect, where flight crew commands for a nose-up trim resulted instead in the nose-down trim movement of the horizontal stabilizer.
On June 6, 2022, the FAA published an AD for all Bombardier Challenger 300/350s after “multiple incidents” involving malfunctioning horizontal stabilizers. This AD ordered pilots to perform additional preflight safety checks of the pitch trim system and revised trim malfunction procedures. The AD also includes revised “AP STAB TRIM FAIL” caution and “STAB TRIM FAULT” advisory procedures.
Story Credit: AIN Online