Dear Gholamreza,
Correct. The unsteady airfoil aerodynamics calculations in AeroDyn are only valid in operational conditions, not at very high angles of attack that would be experienced in parked/idling conditions. For these cases, we typically assume quasi-steady aerodynamics. Modeling buffeting etc. in parked/idling conditions would require the addition of new physics models in FAST.
You may also find the following forum topic of interest: Designing for yaw errors using FAST.
Best regards,