Landing Gear "Squeak"

[harrispa]

I have a squeak in my landing gear and I cannot determine the source.  I notice it when I step on the wing, or when I push up & down on the step, and also when going over a bump while towing the plane.  Just and inquiry to see if anyone else has noticed this on their plane and discovered the source.  I have been under the plane while someone else puts pressure on the step to cause the squeak, but still cannot determine where it is coming from.  It was fully greased about two months ago.

 

This is on a long body, but can't see that would make a difference.

Paul

 

[Jeff_S]

Yes, I have a similar thing. So far my plane hasn't fallen out of the sky and it's passed every annual. I attribute it to "one of those things."

[johnggreen]

The shop that services my vehicles has a listening device of some sort just for that purpose.  It doesn't pick up sounds except those really close or something and muffs background noise.  If a vehicle has an unknown noise the just put it in different parts of the vehicle, even while moving, and are able to track it down.

Since your squeak occurs with something like just stepping up on the wing, it would be pretty easy to isolate.

 

Jgreen

[Bob]

It should be simple to find, but is a 2 person job.  Have someone push on the step to cause the noise as you lay on the ground to find the noise.  To narrow it down, use a very long screwdriver or pry bar.  Place the tip end on the part that you suspect is squeaking and then place your ear on the handle end.  The sound will transmit very nicely thru the screwdriver.  Louder if you get closer and softer if farther away.  If that does not work, you can go the next step and buy a stethoscope. 

 

Just one example:

 http://www.ebay.com/itm/MECHANICS-STETHOSCOPE-IDEAL-FOR-PINPOINTING-WORN-BEARING-ENGINE-FAULTS-/400414050494?pt=UK_Motorcycle_Parts&hash=item5d3a8988be

[harrispa]

I have already tried the stethoscope with someone pushing on the step.  With the scope, the noise is transmitted through everything I touch.  Not as easy as it seems to isolate the source.

 

Paul

[RJBrown]

That stethoscope I don't like. The one made by Lisle and sold by Snap on, Sears and others is a better choice. With it you can unplug the soundbox and chase noises with just the open air tube. This type of noise will be easier to find with out the sound box and tip.

[carusoam]

Could it be as simple as disc brakes squeaking?

I think mine do sometimes while the plane is being moved on the ground.

Best regards,

-a-

[takair]

This same thing drove me crazy for a long time. Greased and lubed everything I could think of. Finally discovered it was coming from the shock disc assembly. In the middle of those rubber discs is a shaft that moves up and down in the steel plate at the top of the assembly. A little oil in the top of the assembly and the noise is gone.

[carusoam]

Interesting...

-a-

[Hank]

The only time I had a squeak while moving the plane was when the wheel bearings were going bad. They shouldn't squeak from boarding.

[harrispa]

thanks to Rob I think I found my problem.

Paul

[FTECraig]

On 3/18/2013 at 12:00 PM, harrispa said:

thanks to Rob I think I found my problem.

Paul

Paul, What was your fix, if you can remember?

[N201MKTurbo]

2 hours ago, FTECraig said:

Paul, What was your fix, if you can remember?

There is a shaft that goes through the (doughnuts, biscuits, shock disks). Just shoot a little lube on the top of that shaft and let it run down the shaft. The squeak is probably where the shaft goes through the top plate.

[carusoam]

Welcome aboard Craig!

Be on the lookout for corrosion on that tube while you are in there…

A small number of them have collected and not drained water in them… for some reason… (not common)

See how old the donuts are while you are looking…

There is a measurement to know if they are “worn”…

PP thoughts only, not a mechanic…

Best regards,

-a-

[Hank]

1 hour ago, carusoam said:

See how old the donuts are while you are looking…

There is a measurement to know if they are “worn”…

Manufacture.date is molded into the outer faces of the donuts. Take a picture, they're confusing when upside down. I thought mine said "9/96" but it was actually "6/69" so I replaced them at annual in 2012. Taxiing and landing immediately became nicer.

[A64Pilot]

Try to find a soap based lubricant if your putting it where it could get in the rubber disks, petroleum will break down the “rubber” I have rubber in parenthesis as I don’t know what’s it’s made of really.

Lithium grease is soap based?

Maybe a silicone lube?

[N201MKTurbo]

All greases are an emulsion of soap and oil. The soaps can be sodium, potassium or lithium based soap. The oils can be animal, vegetable, mineral or synthetic. The soaps are just to thicken the oil and hold it in place. The oil is the lubricant.

https://en.wikipedia.org/wiki/Lithium_soap

Before I rebuilt my engine it leaked oil. The disks on the nose gear were always soaked in oil. It didn’t seem to affect them. The disks are made out of the same rubber as the O rings in our engines.