Today's Message Index:
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1. 08:38 PM - Vibrations in Flight (Dennis Von Ruden)
2. 11:26 PM - Re: Vibrations in Flight (Gary L Vogt)
Message 1
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| Subject: | Vibrations in Flight |
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 <mailto:dvonruden@generalequip.com>
www.generalequip.com <http://www.generalequip.com/>
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Message 2
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| Subject: | Re: 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" <dvonruden@generalequip.com>
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
>
>
>
> <image003.jpg>
>
>
>
> 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.
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