The screw is to adjust zero. When you make the instrument panel it is a good idea to put a hole there so it can be readjusted in the panel. They tend to be a bit touchy near zero. I have two that I have adjusted to zero then found that they were 100 FPM off later. The adjustment doesn't really wander much, but the needles are a bit sticky without the vibration and changing air pressure in flight so you don't always get it right the first time on the ground and having the hole in the panel to readjust it helps a lot.
Brian Kraut Engineering Alternatives, Inc. www.engalt.com -----Original Message----- From: krnet-bounces+brian.kraut=engalt....@mylist.net [mailto:krnet-bounces+brian.kraut=engalt....@mylist.net]On Behalf Of AVLEC Sent: Friday, September 15, 2006 1:20 AM To: KRnet Subject: KR> VSI Hi Guys I have just taken delivery of a UMA VSI unit and noticed something that needs attension. The needle does not sit on zero. If I place my finger over the rear port and apply slight pressure it will zero or even show a descent depending on the amount of pressure applied. This is understandable and proves that it is working I suppose. It has an adjustment screw in the bottom left mounting screw position. Would this be the zero adjustment for the unit or something else? The literature that came with the unit is of no help in this regard at all. For interest sake, does anybody know exactly how these things work. I know it measures the rate of change in static pressure but then the needle should return to zero or at least move in that direction if I keep a constant pressure on the rear port with my finger. Thanks Regards Dene Collett KR2SRT builder South africa Whisper assembler See: www.whisperaircraft.com mailto: av...@telkomsa.net _______________________________________ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
