Originally Posted by
Dave Therhino
Both the recent Pensacola and Philadelphia 737 CFM56-7B fan blade failures that caused inlet separations depressurized the fuselage. The skin on the 737 is quite a bit thinner than the skin of the larger airplanes. The pilot in the Philadelphia event reported significant control challenges. The drag study was done and the drag of a nacelle with the inlet missing is significantly greater than that of an intact nacelle with a windmilling engine. The critical scenario for setting ETOPS fuel reserves on a West Coast to Hawaii flight is an engine failure that causes depressurization at the critical point (equal time point). That required fuel is calculated based on the drag of an intact nacelle.
You are mixing in events that have released more than fan blades that resulted in loss of pressurization