What was found
DURING ANNUAL INSPECTION, INTERGRANULAR CORROSION WAS FOUND IN ANGLE REINFORCEMENT AT RT WING SPAR BUTT WHERE SPAR BOLTS TO FUSELAGE SPAR CARRY-THROUGH. DIFFICULT AREA TO INSPECT WITHOUT REMOVAL OF COCKPIT HEADLINER. SUBMITTER STATED IMPROPER HEAT TREATMENT WHEN MANUFACTURED. RECOMMENDATION: AGING AIRCRAFT REQUIRE MORE DETAILED INSPECTION IN DIFFICULT TO SEE AREAS. SIDE NOTE: A PAIR OF PLIERS WERE FOUND INSIDE A VOID IN THE RIGHT WING. RUST OF PLIERS INDICATE IT HAD BEEN THERE A LONG TIME.