There are no special mods to the machine except some have a separate switch for the radio altimeter which tends to dislike it when going "live", therefore switch it off beforehand. Helicopter types are tested on a ground testing facility up to about a million volts before going "live" and some do not pass the test. Older types like the MD500 and Bell 206 work well with no adverse effects but the Bell 407 cannot be used since the current plays havoc with the bonding paint on the main blades. At least that is my experience. Great work, challenging and rewarding.