Here’s a Cessna type throttle lock. So you’re plane doesn’t get nicked while it’s parked. They can cost as little, and be as simple, as this one for $13.95: http://www.aircraftspruce.com/catalog/pspages/skylock.php I would think that the fuel control switches might be an easy place to fit a “thing” over, preventing unauthorised or unintended use. Crew or Mx arrive, take it off, end of checklist. And judging by the $13.95 model, they wouldn’t have to cost $50,000 apiece.