What was found
INTMT LVL 3 APU FIRE ALERT AFTER 1 50, EN ROUTE-SUSPECTED BLEED/DUCT LEAK COMPLIED W/QRH, BOTTLE BLOWN INSTALLED SERVICEABLE FIREX CONTAINER AND CARTRIDGE IN THE NR 1 POSITION AND REINSTALLED FIREX CONTAINER IN THE NR 2 POSITION IN REF FOUND FLEX DUCT AT EXHAUST DISCONNECTED AND CLAMP MISSING. RAN APU FOUND AIR LEAKING AT PRESS REG VALVE CLAMP, TIGHTENED CLAMP. RAN NR 2 ENG AND COULD HEAR A MASSIVE AIR LEAK RUMBLE, WITH ENG RUNNING SHUT DOWN APU AND FOUND AT THE FORWARD FIREWALL THE NR 2/APU MANIFOLD LEAKING AT THE CLAMP. TIGHTENED CLAMP AND AIR LEAK STOPPED. CLAMP WAS EXTREMELY LOOSE. ALL OTHER CLAMPS AND CONNECTIONS LEAK CHECK GOOD.