What was found
DURING CLIMB, AFTER SETTING CLIMB POWER, LOWER AFT BODY OVERHEAT LIGHT CAME ON. RAN CHECKLIST 'C'. LIGHT EXTINGUISHEDWITH RETARD OF NR 1 THROTTLE, RETURNED TO MEM. REMOVED ANDREPLACED APU KEEL BEAM FIRE LOOP. MEG BOTH LOOPS, CHECK OK. INSTALL APU, OPS CHECK GOOD. INSPECTED PNEUMATIC DUCTS IN KEEL BEAM AREA, CHECK GOOD. RAN ENG, CK NORMAL. RAN PACKS WITH A/C CLOSED UP FOR SEVERAL HOURS, NO OVERHEAT NOTED. OK TO CONTINUE.