CS 22.1327 Magnetic direction indicator
CAA ORS9 Decision No. 1
(a) Each magnetic direction indicator required must be installed so that its accuracy is not excessively affected by the sailplane’s vibration or magnetic fields.
(b) The compensated installation must not have a deviation in level flight, greater than 10° on any heading, except that when radio is in use or the engine of a powered sailplane is running, the deviation may exceed 10° but must not exceed 15°.