B737-500 Pressurisation incident - December 2000.

[Centaurus]

The AAIU report on this incident involving a pressurisation problem stated that the aircraft landed safely with a maximum cabin pressure of 7 pounds per square inch. At first glance I thought it meant a max cabin pressure differential of 7psi which would be dangerous if the doors were opened - even if they could be.

But no, it said 7 psi cabin pressure. Now if 14 psi is normal sea level atmospheric pressure, wouldn't the negative relief valve come into play? After all this relief valve is supposed to prevent atmospheric pressure exceeding internal cabin pressure. Maybe it was just a proof reading error in the report and it really meant to say 0.7 psi differential?

The Report number is: 2001-014. AAIU File No: 2000/0064 published on 21 September 2001.

[CaptainSandL]

It reads like it means the differential pressure, which is the only gauge marked in psi.

The previous paragraph says:

"On downwind (approximately 3,500ft) to RWY 17 at EICK, it was observed by both flight crew members that the aircraft had started to pressurise, and the differential pressure between the aircraft altitude and the cabin altitude was increasing."

Also the crew were in Manual AC (CPCS aircraft) with the packs now ON and presumably still with the outflow valve closed from the mask drop. So it is possible that they landed pressurised. The FLT/GND switch would have safely dumped the pressure before the doors opened.

The report is at http://www.gov.ie/tec/aaiu/2001Reports/2001-014/2001-014.htm