Hi... I've just been looking at some photos of one of Sabena's B737-200s, OO-SDR (now Palmair European's G-CEAC). I've just noticed that in the older, Sabena photos it's a combi - but in the newer, Palmair photos the cargo door has gone!Does this mean that a 737 can be converted from a combi to normal? I never knew thay could do that!BTW... does anyone know what the pressure (psi) is pushing on the cabin sides at cruising altitude, when the cabin is pressurized? I just wondered... thanks!

Don't think that 're-converting' from a cargo door equipped aircraft to a non cargo door equipped one has ever been done. What some airlines do is to permanently lock the main cargo door. An airline I used to work for did just that on two B737-200C for carrying passengers.As for the differential pressure: It can get as high as 8,6 PSI (that is pounds per square inch for the 'metric' readers) during normal operations on the 737. At 9,6 PSI the safety valves will open to relieve the excess pressure. Given the size of a main cargo door this is a lot of force. You do the math.Hope this helps.

Thanks 72737!In the photos of G-CEAC, the cargo door seems to have completely gone. The photos I've been looking at are:[link:www.airliners.net/search/photo.search?id=214678,242862]After: G-CEACSo is (on a 737 without a cargo door in the side) 8.6 psi quite large? I thought it was very small force, since for example car tyres are a lot more than that!

Well in terms of cabin pressure it is quite small. All it does is to keep the cabin altitude at a comfortable level. From sea level pressure to about 8000 feet inside the cabin. In terms of pressure exerted to the walls of a fuselage it is tremendous. Multiply the number of square inches of pressurized fuselage area times 8.6(I don't know how many square inches of surface area a 737 fuselage has.)But it must be a LOT.