AirTalk.org Aviation discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Engine Balancing and Resonance Vibration Problem          AirTalk.org Forum Index -> Owning Airplanes View previous topic :: View next topic   Author Message AllanFuller Guest Posted: Tue Sep 06, 2005 8:43 pm    Post subject: Engine Balancing and Resonance Vibration Problem nrp Wrote: Quote: Possibly you might have both a small crankshaft flange runnout, and a prop out-of-balance situation. Your measurements are probably in inches per second (ips). If so. reversing the prop should not give that much change in the optimum vibration compensation vector. That makes the prop balance as rebuilt suspicious. Nevertheless, there is probably an inherent engine imbalance too which could come from a number of things besides just flange runnout. You mentioned both a 750 RPM and a 1500 RPM rough spot. Is the airframe responding at 12.5 Hz and 25 Hz - or is the response alway at the same frequency? I realize it may be hard to tell the difference. It isn't the governor, and if the vibration came on suddenly on prop rebuild - not related to the crankshaft recall. nrp, Thank you. What is the significant of the 25 Hz and 12.5 Hz? There is a vibratio that occurs when I reduce engine RPM's. When I approach 1500 RPM' there is a noticeable vibration that peaks at 1500 RPM’s and fall off. The vibration re-accrues at a much lower amplitude as the engine RP pass through 750. I really do not know the frequency of this resonanc vibration. I talked to Memphis Propeller and I will be sending the prop with th bulk head to them to check static balance and if one of the blades i out of track or angled. It is nice to rule out the governor. I am going to try to address this is a logical way and try to throug the possibilities quickly so that I can get the bird back in the air. I use it for business and flying is faster and more productive tha driving to customer sites. Alla -- AllanFuller 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.