50 FEET PER MINUTE RATE OF DESCENT DURING A CARGO COMPARTMENT SMOKE EVENT. SERVICE BULLETIN MOS 72 (5) I3-NOV-2008 SB 737-21-1144 I4-APR-2005 AIR CONDITIONING - PASSENGER CABIN CONDITIONED AIR DUSTRIBUTION SYSTEM - TRANSITION DUCT RECOMMENDED ASSEMBLIES AND SIDEWALL RISER DUCTS REPLACEMENT. SERVICE BULLETIN MOS SB