Originally Posted by Dave Incognito
to get the correct differential pressure, they sealed the fuselage and then pressurised it using a ground air source. They then measured the pressure both inside and out, and from that, had a readout of the differential.
Thanks Dave, I understood that.
But atmospheric pressure at an airliner's cruise altitude of, say, FL300 is about 1/3 that of 3000', so surely in order to obtain a comparative pressure differential, they would have had to pressurise the aircraft fuselage to a level three times that of the normal pressurisation level - I doubt an aircraft fuselage could withstand that.