66 M20E vibration

[CJ]

66 E model has a small med freq vibration in staright and level flight.  Just enough to shake the yokes a little.  My mechanic suggested it might be the tail bushings or the screw jack assembly so we decided to try this....we would trim it up and push the nose down and trim it down and push the nose up in flight in an attempt to put pressure on the tail hinges/screw jack to see if that stopped the vibration.  It did not   However in staright and level flight if you begin a climb or a decent the vibration stops until you level out again.  Any thoughts????

[gsxrpilot]

How far are you from KGGG? I'm pretty sure Don could fly it and immediately tell you which screw, nut or bolt is loose.

[CJ]

Im in the NE corner of KS.  Was hoping someone would have some advice to check first before I take it somewhere.  Does this Don guy take phone calls?  Maybe I could just visit with him first.

THX

[takair]

Have you tried changing prop RPM?  What power settings does it happen at?  How are the engine mounts?  Did it just start?  Have you had a prop balance?  Unless it is pulsing fore and aft only, I would look forward toward the engine/prop as the source.

[Hank]

You can check the tail bushings and jack screw in the ground by simply wiggling the tail. Push on the outer edge of the horizontal stabilizer, see if if moves. Then try lifting the rudder. Nothing should move 1/4". If it does, you know the problem and Don can tell you what to fix, or what he will charge to fix it for you.

[Bob_Belville]

12 hours ago, CJ said:

Im in the NE corner of KS.  Was hoping someone would have some advice to check first before I take it somewhere.  Does this Don guy take phone calls?  Maybe I could just visit with him first.

THX

CJ, DMax is about as generous at it gets when it comes to helping folks over the phone. Are you a MAPA member? Don is an active contributor to our discussion group there.

 http://www.donmaxwell.com/

[CJ]

Thanks!  I appreciate the replies.  The prop is a three blade and it is nearly new.  I havent checked the engine mounts.  The tail has some movement but not much.  I am leaning toward engine mounts too.  Thanks again and more comments are welcome!

 

Thx!

[carusoam]

Welcome aboard CJ.

You have come to the right place for all things Mooney.

Some people take videos and post what they are seeing.  It may be more descriptive than trying to write about vibration. 

Engine vibrations can usually be identified or affected by changing power settings and prop rpm.

Some prop vibrations can be smoothed by a dynamic balancing.

ancient engine mounts are really good at transmitting vibrations. (Check your logs to see how ancient they are).

Are you seeing the instrument panel vibrate with that?  Or are you just feeling it?

I think vibrating controls would make me nervous.  Use your eyes to see if any ailerons or elevators are misbehaving.  This is in the not normal category.

yokes can vibrate because they are attached to the airframe. Transmitting engine and other vibrations.

I am only a PP, not a mechanic.

Best regards,

-a-

[larryb]

I replaced my engine mounts at last annual and it made a big difference in the smoothness. Mine were probably factory original from 1984.

[MyNameIsNobody]

12 hours ago, CJ said:

Thanks!  I appreciate the replies.  The prop is a three blade and it is nearly new.  I havent checked the engine mounts.  The tail has some movement but not much.  I am leaning toward engine mounts too.  Thanks again and more comments are welcome!

 

Thx!

I also have a three-blade (McCaulley) prop.  There are a lot of haters due to weight, speed loss and vibration.  Vibration CAN be an issue, but I don't experience it with my prop.  I generally fly 2500-2550 in cruise.  Good luck sorting the issue.  Enjoy your climb with your 3-blade it should NOT be causing yokes to vibrate...

[47U]

A landing light cover cured the vibration on my Dad's C when he put the McCauley three-blade on some 20+ years ago.  Not sure if the IO-360 generates the same harmonics though, C vs. E.

[MyNameIsNobody]

Plexi-Vodoo.  Dark and mysterious it is...