What was found
MCI - DURING OP 16 MAINTENANCE CHECK, FOUND HORIZONTAL STABILIZER UPPER AFT RT BARREL NUT IN FRONT SPAR FOR STABILIZER ATTACH TO CENTER SECTION WAS RUSTY AND EMITTING RUST FROM BOTTOM OF HOLE. REMOVED BOLT AND BARREL NUT AND CLEANED. REAMED AND BUSHED HOLE PER ARA 15271A. INSTALLED NEW BOLT AND NUT AND RETAINER PER MM 55-10-00 AND TWA STD PRACTICES. ACFT TT: 75,041 HOURS. ACFT TC: 81,086. (X)