Created Thursday, Nov 24th 2022 16:54Z, last updated Thursday, Nov 24th 2022 17:18Z
Transport Canada (TC), Canada's Civil Aviation Authority, have released Emergency Airworthiness Directive CF-2022-64, which was followed by FAA also releasing their Emergency Airworthiness Directive 2022-25-51 requiring all Bombardies C-Series CS-100 and CS-300 aircraft (also known as Airbus A220-100 and A220-300) to incorporate the following warning into the Airplane Flight Manual (AFM):
WARNING
Autopilot engagement during takeoff roll can result in premature
rotation, possibly leading to tail-strike, inability to climb or loss of
control. Immediate crew intervention is required.
TC stated as background of this EAD:
Several in-service events have been reported whereby the crew inadvertently engaged the autopilot while attempting to either engage the autothrottle late into the takeoff phase or when re-engaging the autothrottle. Engaging the autopilot below 400 feet (ft) above ground level is prohibited by the Airplane Flight Manual (AFM). Currently, the autopilot engagement is not inhibited and with sufficient speed will cause the aeroplane to command a pitch increase to capture the Pitch Target Marker which may cause premature rotation, including at speeds below V1 at the time of autopilot engagement. Premature aeroplane pitch up will require the crew to intervene immediately as required, and depending on the speed, could lead to a tail-strike. If the crew does not reject the takeoff, auto-rotation below Vr may result in low-energy lift-off.
The FAA added:
There have been 38 in-service events, including two nearly catastrophic events, whereby the flightcrew inadvertently engaged the autopilot while attempting to engage the autothrottle late into the take-off phase or when re-engaging the autothrottle. Engaging the autopilot below 400 feet (ft) above ground level is prohibited by the existing airplane flight manual (AFM). The control panel for autothrottle and autopilot engagement is structured in such a way that it is possible for the flightcrew to mistakenly engage the autopilot when attempting to re-engage the autothrottle. The autothrottle system is prone to disconnect due to different sources for airspeed between the autothrottle and the flight control system monitor, which can occur during turbulence. The disconnect may also occur due to different sources for pressure altitude between autothrottle application and autothrottle monitor. Additionally, the autopilot engagement is not currently inhibited during takeoff and with sufficient speed will cause the airplane to command a pitch increase to capture the pitch target marker, which may cause premature rotation, including at speeds below V1 at the time of autopilot engagement. Premature airplane pitch up will require the flightcrew to intervene immediately, and depending on the speed, could lead to a tail strike. If the flightcrew does not reject the takeoff, premature rotation due to autopilot engagement below Vr may result in low-energy liftoff.
In September 2022, there was an incident in which the autothrottle disengaged during takeoff, and when the flightcrew attempted to re-engage the autothrottle, they mistakenly engaged the autopilot, which resulted in the aircraft rotating below the V1 speed. This resulted in a low-energy takeoff, which is extremely hazardous as it could lead to the airplane stalling and/or impacting terrain.
A review of Canada's occurrence reporting system reveals an Air Canada BCS3 registration C-GVDQ performing flight
AC-497 from Montreal,QC to Ottawa,ON (Canada) rejected takeoff from Montreal's runway 27L at about 80 knots over ground on Sep 29th 2022 reporting a problem with the aircraft (no further details provided). There is no TSB report and no indication of an ongoing investigation into such an occurrence as of current. It thus remains unclear whether the event mentioned by the FAA references this event. Neither NTSB nor FAA databases show an occurrence like described by the FAA.
Related Flight:
AC497, Twitter:
#AC497,
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