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Bad vibrations ???

A

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I have an RV-6A 0-360 c/s prop 650 hours Channel chrome cylinders burns 1 quart in 6 hours. SDS EM5F fuel and ignition systems run LOP. Dynon Hdx panel. I've owned it for 4 years flown 200 hours in that time.
Always thought about balancing the prop. Have normal vibrations,
Compressions just checked cold 80/75,76,79,79 borescoped exhaust valves look very good. cylinder walls no real scratches. Oil changes every 25-30 hours Blackstone labs are clean as is filter. Phillips X/C 20/50

Here's the kicker. I decided to put on an Active Balancer ring from Balance Masters to see if it would work. I like the concept.
We Dyna-Vibed the engine before install 0.41 At 71 degrees. After install 0.31 at 61 degrees. Not real good HUH?
Flew aircraft on autopilot: 4500 feet 2300 RPM WOT (26.0 Inches) First hour and half smoother than before. Liking it!!!
Then out of the blue, the engine/prop started going WA WA WA no up and down of RPM just a vibrating/pulsing like the prop was going to come off. Checked all parameters of engine all good.
Pulled throttle back to 20" and 2200 RPM and it smoothed out enough for me to not land and check it out. Anything over 2220 and the vibration came back.
Headed home at that rate. Still at 4500 feet and 100 miles from home. When descending through 4100 feet 20" 2200 RPM I could make the vibration come back 21.5" through 15.0"
Getting close to home I started to play with it:: The higher the RPM (2400) the greater the vibration. Wa Wa Wa
AS long as I keep the RPM below 2300 in cruise and 20" it's fine. Oh ya when taking off RPM is 2740 WOT no problem.
I checked the valve travel and all are in spec, Ranging from .392-.410
Oh ya I even got a second Balance Master ring and it was no different. Worse yet, is I now have a vibration/pulsing noise without the Balance ring. Something is going BAD and I think it just popped it's ugly head up. And the RPM is steady.
But what????? I could say a ton more, But, this is the jest of it. Something is happening and it ain't good for sure.
Any ideas would be helpful.
My luck usually varies FIXIT
 
My nose wheel went out of balance and started spinning on decent from altitude. When I was above 180mph it felt like the prop was severely out of balance. Slowed down and it went away. Marked the nose wheel with a stripe and my wing man confirmed it was spinning on next flight. Might apply brakes on main wheels to rule them out.
 
Something is going on with that prop. I‘ve only seen a few which were initially that far out of balance. Most start around .2-.3. Carefully check it and measure the blade angles with a smart level. Also, make sure there aren’t any dings in the blades

Vic
 
I also didn’t have much luck with the balance master ring. I had a .31 vibe at full static on the ground, which is in the rough range. That level of vibration was the same at any RPM above about 1200. RV6, O-36-A1A, Sensenich carbon GA prop. I flew it with the ring still on and it was definitely rougher at all power settings. I removed the ring and reset the blades using the pitch pin system Sensenich has,, and that gets it close but not always perfect. I then set pitch of each blade using the Vans tool and my digital smart level as Vic recommends to get them within .1 degree. It Is very smooth now, although I haven’t checked again with the DynaVibe yet.
I think you should try the digital level as suggested, and also check blade runout to make sure they are tracking the same. I don’t know how to check low pitch stops on a CS prop, but I’ve read that it’s something else you could check.
 
vic syracuse said:
Something is going on with that prop. I‘ve only seen a few which were initially that far out of balance. Most start around .2-.3. Carefully check it and measure the blade angles with a smart level. Also, make sure there aren’t any dings in the blades

Vic
Click to expand...
Thanks for the note Vic. NO nicks in blades. Was overhauled a year ago. I also was aghast as to the 0.41 on the Dyna-Vibe. And then the only 0.31 reading after the Balance wheel was on. I will be checking again when my buddy gets back to the airport to help me. It's his tool.
The thing that got me was the fact I flew for an hour and half and was fine with no flight parameters changed just direction. Then HEY I'm going to wake you up in there!!!!
All my looking at the engine has found nothing. Probably heading to the prop shop next week. Thankfully it only an hour away.
Before I do I'll check the blade pitch.

My luck still varies Thanks FIXIT
 
Have you tried balancing the prop with the Dyna-Vibe but without the auto-balancing gizmo? It's really pretty easy and you should be able to get pretty close to "sewing machine" smooth in just a few ground runs. Of course, that's assuming there's no other problem with wheels, prop or engine, as others have said.
 
D-Dubya said:
Have you tried balancing the prop with the Dyna-Vibe but without the auto-balancing gizmo? It's really pretty easy and you should be able to get pretty close to "sewing machine" smooth in just a few ground runs. Of course, that's assuming there's no other problem with wheels, prop or engine, as others have said.
Click to expand...
The direct answer is no.
I believe in the Balance Masters concept of balancing something. I use 5 ounces of BB's in my 16" work van tires and have for 20 years with great success.
I'm concerned about the Wa Wa Wa along with vibration that started an hour and half after with no changes in anything. And was repeatable on the second flight closer to home. Then after the balance wheel was removed it still did it. Especially showing up on decent.
Me the thinks something might be or is amiss in the prop.
More research Monday after the Easter doings.
I'm smoking a 19 pound brisket for the gathering we have here.
Yum!!!!
My luck will surely vary with the amount of money I spend fixing the problem FIXIT
 
Methinks you may be right about something being amiss with the prop and taking it to a prop shop. While that's an inexpensive procedure, it may prevent that smoked brisket from being a last supper.
 
D-Dubya said:
Methinks you may be right about something being amiss with the prop and taking it to a prop shop. While that's an inexpensive procedure, it may prevent that smoked brisket from being a last supper.
Click to expand...
I don't know about inexpensive. The last overhaul was about $3,200.00. Most won't tear one down and just put it back together again.
But like you mentioned. The brisket is done just and will hit the table in a couple hours or so. Then it's "" Over the lips and past the gums Look out tummy here it comes""
My luck varies and I'm gonna be a bit cautious on this one. FIXIT
 
DOH! My bad. My brain said "expensive" but my fingers (or maybe autocorrect) said inexpensive. And yes, I would absolutely be cautious with this one.
 
D-Dubya said:
DOH! My bad. My brain said "expensive" but my fingers (or maybe autocorrect) said inexpensive. And yes, I would absolutely be cautious with this one.
Click to expand...
NO bad.
I took it to the prop shop Monday morning and they had serious doubts the prop is causing the problem. But it had been three years since overhaul.
BUT I needed to have a go at the governor.
Haven't bought a governor for a while and WOW have the prices gone through the roof.
It's the MT Czech Republic P-420-003 Model and the OH shop won't/can't over haul it. OUCH!!! In case anybody has one laying around they want to part with. He HE HE
Probably into the new market again. And this one is only 650 hours old.
Oh Well that's what money is for SPENDING Woo Hoo.
I'll update after I get to spend money on a new governor and see how it works.
My luck varies FIXIT
 
thiggins said:
Update?
Click to expand...
OK here is an update to my prop vibration that wasn't a prop vibration at all.

Went to a local shop and talked to an aviation guru of 55 years. Explained all the thoughts and efforts.
He was convinced it was a bad front main bearing and suggested I DO NOT fly the airplane and pull the motor and split the case. He had seen it before, and even on a brand new Lycoming engine.
OK serious job ahead.
I pulled the motor tore down and OOPS!!!!!! no bad bearings, But I did find broken rings on #4 so good to pull the motor.
But because I had another 0-360 in my hangar, I installed it before I tore down the old motor.
Upon flying with new motor there came a holy #$^*&%* moment as the vibration was still there. WHAT on earth is going on here?????
I had inspected the airframe early on in this vibration problem to assure nothing was loose, falling off etc.
took off the wheel pants and went flying. Guess what YES the vibration was gone.
The problem was a couple slightly loose rivets on the left wheel pant.
The baffling thing about the vibration is it started at one point and never changed over 6-8 hours of trying to figure it out.
OH well now I have my freshly overhauled motor in the bird and the oil stays looking quite clean even after 25 hours. It used to get very dark after 4-6 hours.
I'm not totally unhappy to have pulled the engine because I found the very broken top ring on #4 ( Broken into 16 pieces)
NO more vibrations, And I did reinstall the Balance wheel.
life goes on and the plane is reusable. It may not have been if the ring migrated out of the where it is supposed to be.
My luck varies FIXIT
 
[email protected] said:
OK here is an update to my prop vibration that wasn't a prop vibration at all.

Went to a local shop and talked to an aviation guru of 55 years. Explained all the thoughts and efforts.
He was convinced it was a bad front main bearing and suggested I DO NOT fly the airplane and pull the motor and split the case. He had seen it before, and even on a brand new Lycoming engine.
OK serious job ahead.
I pulled the motor tore down and OOPS!!!!!! no bad bearings, But I did find broken rings on #4 so good to pull the motor.
But because I had another 0-360 in my hangar, I installed it before I tore down the old motor.
Upon flying with new motor there came a holy #$^*&%* moment as the vibration was still there. WHAT on earth is going on here?????
I had inspected the airframe early on in this vibration problem to assure nothing was loose, falling off etc.
took off the wheel pants and went flying. Guess what YES the vibration was gone.
The problem was a couple slightly loose rivets on the left wheel pant.
The baffling thing about the vibration is it started at one point and never changed over 6-8 hours of trying to figure it out.
OH well now I have my freshly overhauled motor in the bird and the oil stays looking quite clean even after 25 hours. It used to get very dark after 4-6 hours.
I'm not totally unhappy to have pulled the engine because I found the very broken top ring on #4 ( Broken into 16 pieces)
NO more vibrations, And I did reinstall the Balance wheel.
life goes on and the plane is reusable. It may not have been if the ring migrated out of the where it is supposed to be.
My luck varies FIXIT
Click to expand...
Surprised you didn’t catch the cracked ring via compression test. I had a cracked top ring on my 540 and it was blowing 50/80.
 
lr172 said:
Surprised you didn’t catch the cracked ring via compression test. I had a cracked top ring on my 540 and it was blowing 50/80.
Click to expand...
The compressions were always 80/78-75 hot or cold. And I did the ring flush 3 times to try to help the 6/1 oil burn because of Channel Chrome cylinders, NO it didn't help the oil burn rate.
The engine I used to replace this one was overhauled 31 years ago and only ran 4.1 hours on a test airplane. I had it stored in my house/shop/hangar for 20 years,. It runs great and because it has Channel Chrome cylinders, It also burns 7/1 oil consumption.
But the oil is virtually still clean after 25+ hours. The old one's oil was black in 5
I was totally surprised when the top ring on #4 fell out on the bench also. I've overhauled hundreds of engines and never had a ring so broken up and still in the lands.
I assure you, I was as baffled as you may be. But a weeks worth of work and I was flying again. Wide deck swap to narrow deck takes a bit of baffle rework.
Learn something every day in this life
But, my luck varies FIXIT
 
[email protected] said:
The compressions were always 80/78-75 hot or cold. And I did the ring flush 3 times to try to help the 6/1 oil burn because of Channel Chrome cylinders, NO it didn't help the oil burn rate.
The engine I used to replace this one was overhauled 31 years ago and only ran 4.1 hours on a test airplane. I had it stored in my house/shop/hangar for 20 years,. It runs great and because it has Channel Chrome cylinders, It also burns 7/1 oil consumption.
But the oil is virtually still clean after 25+ hours. The old one's oil was black in 5
I was totally surprised when the top ring on #4 fell out on the bench also. I've overhauled hundreds of engines and never had a ring so broken up and still in the lands.
I assure you, I was as baffled as you may be. But a weeks worth of work and I was flying again. Wide deck swap to narrow deck takes a bit of baffle rework.
Learn something every day in this life
But, my luck varies FIXIT
Click to expand...
thanks for sharing. i never would have expexted a broken ring to show 75+, but this is how we learn.
 
My buddy just returned from a long cross country. 1 jug consuming a little too much oil, compression is 65/80 on his ContiSaurus O-470.. End of story: ALL rings on that jug were broken. He said it was flying great
 
sansoneservices said:
My buddy just returned from a long cross country. 1 jug consuming a little too much oil, compression is 65/80 on his ContiSaurus O-470.. End of story: ALL rings on that jug were broken. He said it was flying great
Click to expand...
I get how a 6 cyl engine runs fine with a weak cylinder, but I don’t understand how you get 65/80 with all three rings broken. That just seems to defy all of the physics of how an ice works. Maybe all the gaps got plugged up with carbon from all the oil burning. I guess that shows a real weakness in using differential compression tests. I can’t see how that would pass with a traditional dynamic compression test.
 
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