Morning Perfrej,
Ground resonance is not an issue at anything other than flying RPM with a little collective pitch applied. It is stopped by either lifting off or lowering the collective from that point. It certainly won't happen with the engine shut down. Again related to the type I fly only.
Pilot Dar, I do that too and often sit for some time in the cockpit afterwards as well. Its a place of great tranquility after a flight - but sometimes the priority is to get the thing covered up and clear off so I go and get the cover. By the time I get back its stopped.
Minimal risk to me. No risk to aircraft. No risk to anyone else. Not illegal and was quite acceptable when I did my training.
Not acceptable to a lot of PPRuNers apparently though.
Last edited by Gaseous; 8th December 2007 at 13:32.
Reason: To highlight the bit that says it doesnt apply to all A/C