What happens when the autopilot is engaged if the Mach trim is inoperative?

When the autopilot is engaged and the Mach trim is inoperative, there are generally no specific limits imposed on the operation of the aircraft. This means that while pilots should be aware of the inoperative Mach trim and understand its implications for aircraft handling, it does not automatically lead to defined restrictions from the autopilot perspective.

Typically, Mach trim assists with stability issues during flight at higher speeds, and if it becomes inoperative, pilots must manage the aircraft manually concerning speed and stability. However, the autopilot will still function without imposed limitations solely due to the inoperative Mach trim. Pilots need to maintain an awareness of their speed to avoid adverse flight conditions, such as stalls or exceeding structural limits, but this awareness is part of ongoing pilot responsibilities rather than restrictions initiated by the autopilot system itself.

The other options can mislead or imply negative outcomes related to operating the autopilot without functioning Mach trim. Stalling is a potential risk if speed is not managed properly, and while speed restrictions are an important aspect of flight safety, they are not directly applied by the autopilot when Mach trim is inoperative. Conversely, the autopilot does not simply disengage due to this specific scenario, further clarifying that there are no explicit operational limits in place