Solving the ATR Hotel Mode and the Prop Brake release issue in Microsoft Flight Simulator

Ever since the last major update to the ATR family of aircraft in Microsoft Flight Simulator, people have been having problems with Hotel Mode, and Prop Brake release. People espoused all manner of checklists that purported to either fix or work-around the issue. The actual problem is rather more intractable - I narrowed it down to a root cause.

Postscript - it turns out the bug still exists under specific circumstances. If you do a full work-up of the aircraft, you can still end up with a stuck prop brake, and nothing you can do to release it. I’ll investigate further when I get a chance.