What was found
(CAN) DURING ROUTINE MX AND ENGINE CHANGE, NLG WAS REMOVED FOR ACCESS TO REPLACE LOOSE RIVETS IN ENG NACELLE AREA. INSP OF NLG ATTACH BOLTS SHOWED SIGNS OF CRACKS JUST UNDER THE HEAD OF THE BOLT. LPI INSP OF THE BOLT SHANKS CONFIRMED CRACKS. BOLTS WERE BOTH REPLACED. AFTT 12484.6 HOURS, A REVIEW OF ACFT HISTORY FOUND NO RECORD OF THESE BOLTS HAVING BEEN REPLACED. A REVIEW OF THE MFG SERIES CAP, CONTINUED AIRWORTHINESS PROGRAM, SHOWED NO INITIAL INSP OR REPLACEMENT REQUIREMENTS.