compass swing at Scampton years ago, I can assure you that it took 3 of us and no engines were running
3 $odding hours of being towed behind a tractor it took us!
Baffling.
The aircraft is supposed to be as near as possible to flight state. Here from Kiwi CAA.
Civil Aviation Authority of New Zealand
AC43.7 7 Revision 1.
Preparation. Prior to calibration the compass should be checked for general serviceability and it should be verified that angle of dip correction for the southern hemisphere has been made. The compass should be calibrated with;
•
engine(s) running
• all equipment correctly stowed for normal operation
• all doors closed
• flight controls as closely as practicable to cruise position
• aircraft systems operating for normal cruise configuration, including—
• electrical systems
• navigation systems
• communications
Communications systems do not have to actually be transmitting or receiving during the calibration.