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Asked by: Asad
Aircraft Systems, Instrument Rating
Why should we open heater ( on ) When STATIC PORT BLOCKED , and stby static in the cabin is on ?
Of course it is a part of PA-28 procedure but i dont know The reason, i will appreciate if anyone answer it.
John D. Collins
on Nov 17, 2012
Are you sure the procedure is to turn the cabin heat on? It would make more sense to me if it were recommending you turn Pitot heat on as the cause of the static port blockage could be ice.
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Jim F. on Nov 18, 2012
Page 7.12 from the POH: “The storm window and cabin vents must be closed and the cabin heater and defroster must be on during alternate static source operation.”
Why would pitot heat clear a static port blockage?
From what I’ve heard (which was pure speculation), it is due to a slight negative pressure in in the cabin during flight. Turing on the heater and closing the cabin air vents will sightly increase the pressure in the cabin, reducing the altimeter error to less than 50 feet. Again, this was not from a verified source, but I have heard it from a couple independent sources.
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on Nov 18, 2012
Whoops, sorry John. I had my mind set on the BE-76, not the PA-28. Your right, the static port could be unblocked by pitot heat, since they’re located on the same fin.
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Brian on Nov 20, 2012
“Whoops, sorry John. I had my mind set on the BE-76, not the PA-28. Your right, the static port could be unblocked by pitot heat, since they’re located on the same fin.”
Really depends. Piper likes to use that fin, but there is nothing stopping the owner from installing a static port on the fuselage to use instead. All of the arrows (half dozen or so) I’ve flown have a static port on the fuselage and don’t use the port on the fin.
Interesting concept on the heat in the cockpit! I’ve not heard that before.
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