Bad vibration on wing strut

[Pearson]

Re: Bad vibration on wing strut

fearof pavement,when the engine is at idle,no vibration,as I did run up ,instilly the vibration start,that was with or with the wing on.

Ricky, I think some of us are having a difficult time understanding parts of your posts. So I want to confirm what I think you are saying. Please let me know if I do not have it correct. As I understand your statement quoted above, you did an engine run up with the wings removed and you had vibration. Is that correct? If so, then the problem is obviously with the engine, prop, or mount.

Regarding the insulation, there is an insulation that is very commonly installed between the forward fuselage tubes and the firewall. It is usually glued into the back side of the firewall before the boot cowl is installed. But the insulation is supposed to have holes large enough so that there is "no insulation" in the area next to where the bolts are.

Something that I am curious about comes from something I read in one of your posts. You wrote that one of your props was bent. You have to have a straight prop and crankshaft to get a smooth running engine. Have your AME check the tracking on your prop. This will confirm that everything is straight. The next thing to check is all of your engine mounts and bolts. I would also check the bolts that hold the engine mount to the firewall. SOMETHING somewhere is either bent or loose. I would not fly until you find it.

[fearofpavement]

Re: Bad vibration on wing strut

Ok, based on the fact that you said the vibration occurs with or without the wings on I think that eliminates airframe vibration and narrows it down to your powerplant set up. Even a miss in the engine doesn't seem like it would shake the whole plane that much so probably something that is large and rotating is out of whack. ie, the propeller. Did a prop shop overhaul the prop after it got bent? They usually do a good enough job on these to make sure it is in track and balance.

[Hank Jarrett]

Re: Bad vibration on wing strut

There are several types of insulation that may be inside the boot cowl (some legal and some not). I just finished removing contact cemented fiberglass batting attic insulation from mine (the NOT legal kind that some idiot contact cemented the actual fiberglass fibers to the firewall then hid the mess under a foil backed mat).
There had been NO vibration problems with my plane. The other major type of insulation you will likely see is some dense pads on the sides of the boot that damp out the sheet metal "drumming". They are the normal (and legal) kind and look a lot like thick pieces of tar paper glued to the metal.
The only way I can see insulation in the boot causing a problem like this is if it is compressed between the airframe tubes and the firewall so the engine mount can't be tightened to the airframe properly. The mount bolts should go from the fuselage tube fitting, through the firewall holes, through some spacer washers (as needed to make sure the nose bowl has clearance), through the engine mount to the nuts. There should be a solid connection from the fuselage to the engine mount with no play or looseness.
The engine mount to the engine connection has rubber mounts in the engine lugs. If those are damaged or worn out, or the bolts aren't tightened properly, the engine can shake.
Sounds like you can forget everything I said about wing problems if the vibration is there with them off.
Hank

Not much risk of an in flight structural failure with the wings off.

[ricky]

Re: Bad vibration on wing strut

Terry,Mr Pearson,Hank, the propeller that got bent,was look at,an the plane
is in owner maintance,prop shop
siad try it,if it work good,but if not,it good wall
mounument,the other perpeller is wooden prop from manufacture,im sorry forgot
name,they make metal,wooden prop certified plane,wood prop is brand new right from factory

The insulation im talking about white foam in middle,silver/crome like on both side,it is between the frame an the boot,the engine insulator,(rubber) I installed
new,with about 1/8 thickness between engine frame an the engine.

As we track both prop,metal/wooden they read true on the rotation,the flane also read true also,since im not at home,it in the log book with number.

So when I get home,going to remove that insulation between the boot/
frame,install the new prop from my ame,im hopeing this is problem, thank again guy for your input,will let you all know what end result is!
Rick

[Pearson]

Re: Bad vibration on wing strut

Ricky,

IF the crankshaft is not bent, and the prop is not bent, it has to be either something loose on the engine mount, or possibly a severe loss of compression on one cylinder.

[fearofpavement]

Re: Bad vibration on wing strut

it could still be the prop if it is out of balance. ie, the tracking can be good but the two blades may not weigh the same.

[Pearson]

Re: Bad vibration on wing strut

Well whatever it is, I would certainly like to hear all the details when the cause is found.

[ricky]

Re: Bad vibration on wing strut

Hello everyone,well we found our vibration,but first,I like to thank everyone
for there input in this problem,Thank You All!!!!

The problem was a brand new Sensench Wooden prop,my ame could not believe that brand new prop,with no hour would cause us to pull an engine
off,an an have same vibration. It is W72CK-2-43 type.

It was little windy to day,so didn't fly it,but ran it up to 2100 static
it was smooth running, was very happy guy.
The prop was bought in Oct 31/07, will contacting wag areo, sensenich
see what there going do with that prop,saga continue!!!

Thank you all for your input!!!
Rick

[Pearson]

Re: Bad vibration on wing strut

Rick,

I doubt if you are going to like what you hear when you contact the place where you bought the prop. Those wood props are sensitive to how and where they are stored. I don't know if they can be balanced or not, but that one sounds like it is out of balance pretty bad. And with over two years since you bought it, they are going to tell you there is nothing they can do for you. Make your self a nice wall clock.

[ricky]

Re: Bad vibration on wing strut

Hey Richard,how many prop wall clock can you have,now have three LOL

[Ragwing nut]

Re: Bad vibration on wing strut

How were you storing it on the plane? Vertically or horizontally? Wood props do not create vibration unless the were under improperly torqued, by either under torqued due to climate change, out of track, or stored vertically which is a no no. Wood by nature will absorb vibration.

[Len Petterson]

Re: Bad vibration on wing strut

Rick, if you dont have the wing on and you are runing the engine, and the vibration is there it has to be engine related.
runing the engine witout the wings can the fuselage flip over, should it be tied down?
Check evrything from engine mount attchement points in the airframe to rubber mount and the bolts any broken welds anything not straigth anymore.
You mentioned what the plane been on its back, your engine mount could be broken, maybe not right trough just a severe crack. Dismantel and remove all paint do the same with the airframe- engine mont attchment behind the firewall. Lots of work man but it is your life what is riding on it!!!!!!!!
When you fly safly you can smile again.
Len

[ricky]

Re: Bad vibration on wing strut

Hey ragwing,the prop was stored in the box came in,in the house,then in warm shop,,the prop was possision horzontally when on plane an in the house,then flew to my airstrip
an that where she now,in side cold hangar.

Find out from wag an sench what where going to do.

Len when we ran engine with out wing,had tail tied down,

[Pearson]

Re: Bad vibration on wing strut

Ricky,

Wow, it sounds like you took all the necessary precautions on storing the prop. Maybe it was bad from the begining. But since it is so long after you bought it, the factory may not be very sympathetic. But you never know. See what they say. Maybe they have a way of rebalancing it, or can dry the moisture out of it somehow. I have never had to deal with that kind of problem. Maybe someone else here on the forum has experienced what you are going through and can offer some idea of what your possible solutions might be.

After the first one, a clock made from a prop isn't as interesting anymore. I have a wooden prop hanging in my living room, but it isn't a clock. It is just a prop. My dad "aquired" it from the navy during WWII. It is from a target drone.

[Len Petterson]

Re: Bad vibration on wing strut

Running the engine with out the wings, tie down the fuselage so it would not flip sideways,is what I was thinking, The has to be tied down as well. I heard of what type of accidents, there the fuselage is not stable enough on its own.
If you stored the propp propperly have checked it is ballance?
Is the fit onto the proppflange good?
Len