"Remove before flight" items often also have a long red streamer attached.
One possible engineering solution would be to make the cover out of a material strong enough to keep out the weather, but flimsy enough that if the engine was running it would suck it in and harmlessly shred/burn it.
One possible engineering solution would be to make the cover out of a material strong enough to keep out the weather, but flimsy enough that if the engine was running it would suck it in and harmlessly shred/burn it.