As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING INSPECTION OF IMPULSE COUPLING, I.E., AD 78-09-07R3, NUT WAS LOOSE DUE TO CRACK IN BORE OF IMPULSE COUPLING. TCM BENDIX SB 639 REFERS TO INSTALLATION OF COUPLINGS. AD 78-09-07R3 DOES NOT REQUIRE REMOVAL OF COUPLING FOR INSPECTION. MAYBE IT SHOULD TO DETECT CRACKS IN BORE OF COUPLING. BOTH MAGS AND IMPULSES REPLACED WITH REBUILT TCM UNITS.