AC 20-71, ADVISORY CIRCULAR, DUAL LOCKING DEVICES ON FASTENERS (8 DEC 1970)

AC 20-71, ADVISORY CIRCULAR, DUAL LOCKING DEVICES ON FASTENERS (8 DEC 1970)., This advisory circular provides guidance and acceptable means, not the sole means, by which compliance may be shown with the requirements for dual locking devices on removable fasteners installed in rotorcraft and transport category airplanes.