Text in force at CAR3R-8: from CAR3R-0, effective 15 May 1956. OCR text
The magnetic direction indicator shall be so installed that its accuracy shall not be excessively affected by the airplane’s vibration or magnetic fields. After the direction indicator has been compensated, the installation shall be such that the deviation in level flight does not exceed 10 degrees on any heading. A suitable calibration placard shall be provided as specified in § 3.758.