Citation Longitude AP Issue

ISSUE DESCRIPTION

Description of the issue:
After SU3, in the Cessna Citation Longitude, the autopilot will sometimes fail to engage entirely. This has occurred in two different scenarios: once shortly after takeoff, and once after a long flight where the autopilot had been functioning normally until it failed on approach. When this happens, the autopilot master cannot be engaged either via joystick hotkey or by clicking directly in the cockpit. Other autopilot functions (heading or altitude hold) remain clickable, but they do not activate since the autopilot master is not engaged.


FREQUENCY OF ISSUE

How often does this occur for you (Example: Just once, every time on sim load, intermittently)?
It has occurred on 2 out of 3 flights in the Longitude after SU3. The behavior appears intermittent and does not follow a consistent pattern that I can put my finger on.


REPRODUCTION STEPS

Please list clear steps you took in order to help our test team reproduce the same issue:

  1. Launch Microsoft Flight Simulator and load into the Cessna Citation Longitude.

  2. Start the aircraft cold and dark from a gate/stand.

  3. First case: Departed from Charlotte. After takeoff, attempted to engage autopilot. The master autopilot button would not engage (neither via joystick hotkey nor cockpit click).

  4. Second case: Departed from Melbourne, Australia. Autopilot functioned normally throughout the flight. On approach into Sydney, attempted to re-engage autopilot and it would not activate, even though other autopilot functions (HDG, ALT, etc.) were clickable.


YOUR SETTINGS

What peripherals are you using, if relevant:
Turtle Beach VelocityOne joystick, standard mouse, and keyboard.

[PC Only] Are you using Developer Mode or have you made any changes to it?
Not using Developer Mode.

[PC, MSFS 2020 Only] Are you using DX11 or DX12?
Not sure which DirectX version is currently in use.

[PC Only] What GPU (Graphics Card) do you use?
AMD Radeon RX 7900XT.

[PC Only] What other relevant PC specs can you share?

  • GPU 7900XT

  • RAM: 32GB DDR4

  • Storage: 2TB Samsung EVO M.2 SSD


MEDIA

No screenshot or video available. When attempting to engage the AP master button in the Citation Longitude, nothing occurred. No TCAS warnings were present, and to my knowledge, the flight plan and FMC were fully set up prior to the incident.

Same for me, after a reasonable flight, it suddenly just stopped working, engaged heading mode but the plane refuses to budge as the AP is off and you can’t switch it back on no matter what you do.

And the autopilot isn’t disengaged at this point. If it is you won’t be able to switch it back on until you toggle the disengage autopilot button again.

I’m going to try some testing today. Just in case it was me….

I’ve experienced this a few times. What I have found that does work is the following. Make sure the APU is on (and if the engines shut down, double check it is on before attempting a restart, although they should stay on). Then, turn off all generators (both engines and the APU), close the BUS TIE, then turn off both batteries. If you’re in the clouds, you can leave the standby power on to keep the backup instrument working. Give it a few seconds then turn everything back on. The autopilot should be working then. Hope this helps!