How can you do preflight fan inspection when it's windy? While sitting, bored to tears, intermittently scanning the 'Delayed' display next to my flight, I've looked out of the airport windows.

Out on the stand, amongst the baggage and fuel truck activity, I've seen a technician examining the engine fans with a torch (flashlight), presumably part of a mandatory pre-flight inspection procedure, looking for FOD, cracks etc.

It occurred to me: What does the techie do on a windy day when the fans are spinning too fast to examine by eye?  Is there some way of braking the shaft to stop the windmilling?
(YouTube) Reversers would slow down or stop the windmilling by blocking the majority of the bypass.

If repositioning the aircraft abeam the wind is not possible, then deploying the reversers does the trick. It's the same method used when starting a jet engine in strong tailwind.

Windmilling can be very fast. The clacking sound you hear is normal.

Jetliners don't have shaft brakes, but some turboprops do.