---------------------------------------------------------- TeamGrumman-List Digest Archive --- Total Messages Posted Tue 07/26/11: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:38 PM - Vibrations in Flight (Dennis Von Ruden) 2. 11:26 PM - Re: Vibrations in Flight (Gary L Vogt) ________________________________ Message 1 _____________________________________ Time: 08:38:00 PM PST US Subject: TeamGrumman-List: Vibrations in Flight From: "Dennis Von Ruden" I realize this list is directed mostly to the four seat Grumman aircraft, but I have an issue with my AA-1B that I am searching for some insight. Hope someone can help me. I have a 1974 AA-1B that I purchased new while in college. Stock O235. I've owned it since new. I am the only person that flies it. Approximately 850 hours total time. All four cylinders have been topped in recent years. Here's some additional information: 1) Just completed a very thorough annual inspection. 2) New mags approximately 5 years ago. 3) New ignition harness last year. 4) New plugs. 5) Carburetor was rebuilt by a certified shop with the new composite float installation. 6) Just checked cylinders for excessive valve guide wear or sticking...none detected. 7) Installed an EDM 700 a few years ago. All cylinders normally run within 20 to 80 degrees F (depending upon OAT and RPM) in terms of cylinder heard and exhaust temps. Number three will run maybe 20 to 40 degrees F higher at times, but later during the flight these temps are "reduced" to the other cylinder values. With proper leaning, all cylinders run very even temperatures. 8) Prop was overhauled by a certified shop two years ago. 9) Engine exhaust is a consistent, light brown. 10) No abnormal oil consumption. 11) Burn 100 LL with a little Marvel thrown in from time to time. 12) New engine mounts two years ago. I know this aircraft very well, and I am now experiencing a strange set of vibrations from the rudder pedals. Almost a impulse type of force like you would experience while the engine is at low idle speed. Nothing with huge amplitude, but it is noticeable. In the past, you could rest your feet on the rudder pedals and the vibration was constant. Not now...you can feel an "impulse" type of vibration. It's not constant, as it comes and goes while in flight. Tonight, I felt an impulse vibration from the pedals right after liftoff. I did not have time to glance at the EDM 700, but it lasted less than a second. It got my attention. The EDM read normal during my local flight. At the risk of coming across as some type of nut case, I'm wondering what is going on. Is my imagination getting to me? Anyone have any ideas besides seeing shrink? I have a number of aircraft and insist on high maintenance. This aircraft has always been well maintained. Thank for your help. Dennis Von Ruden President 620 Alexander Drive S.W. P.O. Box 334 Owatonna, MN 55060 800.533.0524 voice +5074515510 voice 877.344.4375 fax +5074515511 fax dvonruden@generalequip.com www.generalequip.com ------------------------------------------------------------------------- ------- ALL INFORMATION IN THIS EMAIL, AND/OR ATTACHMENT(S) IS CONFIDENTIAL. If y ou received this e mail in error, and are not the recipient(s) or responsib le for receiving this e mail for the recipient, please inform the sender im mediately, delete the e mail and any attachment(s) associated. This email has been scanned by Barracuda - Email Security System. ________________________________ Message 2 _____________________________________ Time: 11:26:00 PM PST US From: Gary L Vogt Subject: Re: TeamGrumman-List: Vibrations in Flight Dennis, This this is for anything you want to talk about. Corvettes? Direct injecti on? Vibrations? Of the 3 AA1s I've worked on, only one had a weird rudder feel. I never did f ind it. I thought it was the rudder bearings at first. Then I looked at the e levator attachments. Then the bungy set up. Then the flap and aileron bearin gs. One thing . . . . . do you have wheel pants? Or the gear leg fairings? Loo k for something vibrating there. Look for a cracked engine mount. Gary Sent from my iPad On Jul 26, 2011, at 8:34 PM, "Dennis Von Ruden" wrote: > I realize this list is directed mostly to the four seat Grumman aircraft, b ut I have an issue with my AA-1B that I am searching for some insight. Hope s omeone can help me. > > > > I have a 1974 AA-1B that I purchased new while in college. Stock O235. I =99ve owned it since new. I am the only person that flies it. Approximate ly 850 hours total time. All four cylinders have been topped in recent years . Here=99s some additional information: > > > > 1) Just completed a very thorough annual inspection. > > 2) New mags approximately 5 years ago. > > 3) New ignition harness last year. > > 4) New plugs. > > 5) Carburetor was rebuilt by a certified shop with the new composite fl oat installation. > > 6) Just checked cylinders for excessive valve guide wear or sticking none detected. > > 7) Installed an EDM 700 a few years ago. All cylinders normally run wit hin 20 to 80 degrees F (depending upon OAT and RPM) in terms of cylinder hea rd and exhaust temps. Number three will run maybe 20 to 40 degrees F higher a t times, but later during the flight these temps are =9Creduced=9D to the other cylinder values. With proper leaning, all cylinders run very e ven temperatures. > > 8) Prop was overhauled by a certified shop two years ago. > > 9) Engine exhaust is a consistent, light brown. > > 10) No abnormal oil consumption. > > 11) Burn 100 LL with a little Marvel thrown in from time to time. > > 12) New engine mounts two years ago. > > > > I know this aircraft very well, and I am now experiencing a strange set of vibrations from the rudder pedals. Almost a impulse type of force like you w ould experience while the engine is at low idle speed. Nothing with huge amp litude, but it is noticeable. In the past, you could rest your feet on the r udder pedals and the vibration was constant. Not nowyou can feel an =9Cimpulse=9D type of vibration. It=99s not constant, as i t comes and goes while in flight. > > > > Tonight, I felt an impulse vibration from the pedals right after liftoff. I did not have time to glance at the EDM 700, but it lasted less than a secon d. It got my attention. The EDM read normal during my local flight. > > > > At the risk of coming across as some type of nut case, I=99m wonderi ng what is going on. Is my imagination getting to me? Anyone have any ideas b esides seeing shrink? I have a number of aircraft and insist on high mainten ance. This aircraft has always been well maintained. > > > > Thank for your help. > > > > > > Dennis Von Ruden > > President > > > > > > > > 620 Alexander Drive S.W. > > P.O. Box 334 > > Owatonna, MN 55060 > > > > 800.533.0524 voice > > +5074515510 voice > > > > 877.344.4375 fax > > +5074515511 fax > > > > dvonruden@generalequip.com > > www.generalequip.com > > > > > -------------------------------------------------------------------------- ------ > ALL INFORMATION IN THIS EMAIL, AND/OR ATTACHMENT(S) IS CONFIDENTIAL. If yo u received this e mail in error, and are not the recipient(s) or responsible for receiving this e mail for the recipient, please inform the sender immed iately, delete the e mail and any attachment(s) associated. > This email has been scanned by Barracuda - Email Security System. ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message teamgrumman-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/TeamGrumman-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/teamgrumman-list Browse Digests http://www.matronics.com/digest/teamgrumman-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.