Some of the foregoing posts aroused my curiosity. Are you saying that military 'ginger beers and magicians' are restricted in what they can do these days?
Throughout my career, both civil and military, technicians have always performed ground runs on fixed wing aircraft and at all power settings. In fact, since we also adjusted the limiters, we possibly ran them at power settings greater than those used by the Drivers, Airframe. [and that includes V Bombers in the sixties, Art] Ground testing of engines is an essential part of the powerplant engineers job, for no-one else is really qualified to do diagnostic engine running or adjustments. We never did ground runs in helicopters though, because of the attendant risks - manipulating controls to ensure blade clearances might involve becoming airborne and we weren't authorised to receive flying pay. In some civilian jurisdictions engineering staff may taxi aircraft types on which they are rated, in others driving is forbidden.
We did have a mad Kiwi here some years ago, who was wont to do thrust reverser tests by taxying up to 100 knots then deploying the reversers. He once did it with me in the flight deck, and I kept a hand on the fire axe handle, just in case!
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Through difficulties to the cinema