We got a crack in one of the windows outer pane on our B737 classic during climb. We stopped climb and performed QRH which says no further action, resume normal operation. Now to the point, captain then selects a lower FLT ALT on the pressurization panel. He says because of the window damage. I understand you want to reduce the stress on the window, but to select a lower FLT ALT in AUTO mode on the pressurization panel, will this really reduce the stress?
The cruise mode is activated when the airplane climbs to within 0.25 psi of the selected FLT ALT. During cruise, the controller maintains the cabin altitude slightly below the selected LAND ALT, if the differential pressure between the selected LAND ALT and FLT ALT is less than or equal to 7.8 psid above 28,000 feet or 7.45 psid below 28,000 feet. If the differential pressure between the selected LAND ALT and FLT ALT is greater than these values, the controller maintains a pressure differential of 7.8 psid above 28,000 feet and 7.45 psid below 28,000 feet
-B737 classic FCOM