What was found
AT 350 AFTER 2HRS GOT A LOUD SQUEAL FOLLOWED BY A CHOO CHOO SOUND. CABIN ALT 5200 DIFF 8.3 CONTINUED UNTIL CABIN ALT 4000, DIFF 7.3 & NOISE STOP AT 3500, 6.8. NOISE WAS INVERT DIVIDER IN CAPTAIN'S WINDOW. NR 2 CAPTAIN`S OPEN ABLE WINDOW SEAL INSPECTED IAW MM 56-11-02, MISSING SEALANT AT THE LOWER LATCH STUD. ACCOMPLISHED INTERIM REPAIR IAW AMM 56-11-11 PB 401 PARA 1 F. OPERATIONS CHECKED OF WINDOW PERFORMED OK FOR CONT OPERATIONS. USED ALUMINUM TAPE IAW ECRA 5611-01164. INSPECTED INTERIM REPAIR, NO FAULTS FOUND. ACCOMPLISHED PERMANENT REPAIR FOR L2 COCKPIT WINDOW.