qasimzaheer Posted June 24, 2010 Share Posted June 24, 2010 i m facing a problem that is quite weird. ON GROUND whenever we try to pressurize the aircraft on MANUAL PRESSURIZATION MODE, the cabin climb rate first increases to 1000 fpm, when the differential pressure increases to 1.5 in HG, the under floor heating shut off valve become open and heavy bleed comes out of it with opening the underfloor heating switch. the cct is ok. plz help me out. Quote Link to comment Share on other sites More sharing options...
NATOPS1 Posted June 25, 2010 Share Posted June 25, 2010 Take off the electrical connector (UFH valve) and see what happens.... if it still opens you have a structural issue. If not electrical... have you place the master in auto to see what happens? Quote Link to comment Share on other sites More sharing options...
qasimzaheer Posted June 25, 2010 Author Share Posted June 25, 2010 we have tried every possible trouble shoot. we have disconnected the electrical connectors. the interesting fact is that, it remains close when the airconditioning is turned on but when the aircraft is pressurized to 1.5 in hg, it opens whereas the UHV is de-energized closed. Quote Link to comment Share on other sites More sharing options...
NATOPS1 Posted June 27, 2010 Share Posted June 27, 2010 SO with the electrical connector removed and you pressurize to 1.5 the valve opens? Also is it very rapid opening or slow? It (UFH valve) is a motor driven valve so it may just be bad (motor shaft) not holding position. Once there is an external force (1.5 in hg) of pressure the valve is "pushed" open.... You say "Heavy Bleed comes out" please explain. Do you have the floor plates removed so you can see under the floor? Quote Link to comment Share on other sites More sharing options...
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