I had mentioned on several occasions about magnetic interference on the VOR on the Bell 214. The blades were not earthed to the airframe and as a result developed a torroidal shaped magnetic field with the center of the field at the mast. Bell said it was the flicker of the rotor that interfered with the reception of the VOR and suggested that the pilots reduce rotor speed so as to eliminate the interference. The magnetic field magnetized the mast to the point that the flux level of the mast was 18 times the allowable magnetic level for the mast. Those pilots that tried Bells suggestion said the helicopter was about to stall due to low rotor speed. They just had to endure the ineffectiveness of the VOR. Being in Iran it really did not matter because the helicopters did not venture far from the base. I don’t know if the problem still exists but now the 214s are equipped with GPS and I wonder if they have any problems flying using GPS as a navigation aid.
