AirTalk.org Aviation discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  AI pitch bounce          AirTalk.org Forum Index -> Owning Airplanes View previous topic :: View next topic   Author Message Mike Noel Guest Posted: Sun Nov 28, 2004 12:05 am    Post subject: AI pitch bounce I just noticed today a tendency for my vacuum AI to vibrate a few millimeters in its pitch axis occasionally, then the movement damps out. The roll and pitch indication seem to be OK, and the vacuum DG is working fine. The vacuum guage is at 5.0, right where it belongs. I'm wondering if this is an early failure indication. -- Regards, Mike [email]mikenoel (AT) comcast (DOT) net[/email] http://mywebpage.netscape.com/amountainaero/fspic1.html Back to top JDupre5762 Guest Posted: Sun Nov 28, 2004 2:51 am    Post subject: Re: AI pitch bounce Quote: I just noticed today a tendency for my vacuum AI to vibrate a few millimeters in its pitch axis occasionally, then the movement damps out. snip I'm wondering if this is an early failure indication. An instrument shop owner told me once that it is. How long it will take to fail is the question. This tech also told me that if you put any gimbaled instrument down on a surface and could hear the case touch the surface you have damaged the bearings. John Dupre' Back to top Ross Oliver Guest Posted: Sun Nov 28, 2004 11:46 pm    Post subject: Re: AI pitch bounce On Sat, 27 Nov 2004 17:05:54 -0700, Mike Noel <mrnoel (AT) attglobal (DOT) net> wrote: Quote: I just noticed today a tendency for my vacuum AI to vibrate a few millimeters in its pitch axis occasionally, then the movement damps out. The roll and pitch indication seem to be OK, and the vacuum DG is working fine. The vacuum guage is at 5.0, right where it belongs. I'm wondering if this is an early failure indication. My AI has done this for as long as I have owned the aircraft (coming up on 4 years). Of course the gyro shop said, "Needs overhaul" so last year I sprung for the $200 overhaul. No difference whatsoever. Although it does spin up a lot faster now. Used to take several minutes, now it snaps to attention within 5-10 seconds of engine start. The needle on the vacuum gauge seems to vibrate in sync with the AI, The face of the gauge also seems to be loose, so my latest theory is a leaky gauge causing variations in vacuum level. If this is still the case at the next annual, I may try replacing the gauge. Back to top Dan Thomas Guest Posted: Mon Nov 29, 2004 11:43 pm    Post subject: Re: AI pitch bounce "Mike Noel" <mrnoel (AT) attglobal (DOT) net> wrote Quote: I just noticed today a tendency for my vacuum AI to vibrate a few millimeters in its pitch axis occasionally, then the movement damps out. The roll and pitch indication seem to be OK, and the vacuum DG is working fine. The vacuum guage is at 5.0, right where it belongs. I'm wondering if this is an early failure indication. It's caused by engine or prop vibration. The instrument panel shock mounts might be old and hard, or the prop may need balancing. Either way, the vibration is reaching the indicator. Next time you fly, play with RPM settings to see if you can make the indicator resonate with vibratory fequencies. Dan Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         AirTalk.org Forum Index -> Owning Airplanes All times are GMT Page 1 of 1   Jump to: Select a forum Aviation----------------alt.aviationAviation safety EnhancementPlanes, gliders and flying in AustraliaAviation et pilotage (Français)rec.aviationAviation (Aerobatics)Hot air, gas balloons and airshipsHang-gliding, paragliding, foot-launched flightAircraft Design & BuildingInstrument Flight RulesAviation (Classifieds)Military AircraftNaval AviationAviation (Miscellaneous Topics)Owning AirplanesAviators (General Discussions)Aviation related productsAircraft RestorationHelicopters and rotary wing aircraftsFlight SimulationSailplanesAviation (Students)Light aircraftFlying related activities in the UK Airports----------------alt.airportsEdinburgh Airport Glasgow Airport Humberside Airport Luton Airport Aberdeen Airport Glasgow Prestwick Airport  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.