[f-AA] Checking the oleos on my no bounce gear

[whites...@gmail.com]

Hello All, I know this has been covered, maybe when I asked about it 4 yrs ago (which was the last time we had the oleos off the airplane.  I just hope someone can send me the link to the info and not have to re-explain.

The gear seems fine, no leaks and definitely cushions my hard landings.  Just want to check everything and especially make sure the 8.5 oz of fluid are still there.  I seem to remember a "dip stick" method to check,   but and also drain and refill with 5606.  My AP iA looks over my shoulder but he's never done this (except when he watched me last time).

Thanks!

Don

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[Richard Murray]

Don

Drain and refill if you previously did not construct a dip-stick.

Best solution is to have your A+P/IA READ this:

https://johnpropst.yolasite.com/resources/Aeronca%20Oleo%20Strut%20rev%2010.pdf

Richard in OH who still has nearly a gallon of John Deere Hy-Gard left over from ten years ago when I rebuilt my oleos

[whites...@gmail.com]

Thanks Richard!  I have  a printed version of that link from a few years ago, but this has some revisions.  I found the article David Rude sent to me in 2018 and will try to upload it for everyone to use.  It's titled "Service letter 42 oleo fluid levels".

Don

[whites...@gmail.com]

Sorry, can't figure how to upload this PDF file.  If anyone wants it, send me a message.  Don

['Botijo G' via aeronca]

Great info!!!

Sent from an NDB

On Jan 29, 2024, at 9:31 AM, whites...@gmail.com <whites...@gmail.com> wrote:

Sorry, can't figure how to upload this PDF file.  If anyone wants it, send me a message.  Don

[whites...@gmail.com]

Hello All, 

Servicing my No Bounce oleos and thought some of this might be helpful and/or interesting to others:

Background- 1947 Aeronca L-16A, mostly original equipment. Theoleo units were rebuilt/overhauled by Dave Rude 10 yrs ago. They have ~450 hrs and 1500 landings (nearly all of which were perfect, but a few…???) on them since then.  About 4 yrs ago I pulled them out of the case frames and drained and replaced the fluid.  Have worked just fine since then.  I have used 5-6 pumps from my grease gun about every 3-4 months but no grease as ever squirted out the bottom.  The oleos, when extended on the ground appear to have a thin layer of grease on them, but not much.

Today, when I pulled the oleos out of the frames I found out where all that grease went- the springs were complete full (see pic).  I think this has to do with the tight fit between the case frame outer tube and the oleo lower shaft. It’s close (maybe .010) so most of the grease, pumped through the zerk fitting,  must have gone “up hill”.  Well, the good news was the oleos looked smooth and un-scarred, and so did what I could see of the inside of the case tubes.

I drained the old 5606 hydraulic fluid and after some bouncing and compression pumping, about 7 ozs. came out.  Maybe more, but it was hard to measure the last bits.  The fluid was dark, but not dirty or contaminated with specs or junk. I squirted in an ounce of 5606 (used a $1.29 catsup dispenser), swished and drained it, just to clean things a bit.  Then I slowly poured in the recommended 8.5 ozs of 5606 and reinserted the plug. 

I’d already cleaned 95% of the old grease from the springs.  I coated the oleo shaft with fresh grease and reinserted it in the case frame tube.  VERY IMPORTANT  to make sure the top of the oleo goes ALL the way up and the bolt actually secures it.  If not, the gear will fall off after take off! I put a little was of paper towel in the oleo top bushing and when the bolt pushed it out I knew I had found the hole.

Reassembled the gear and put the wheel back on the axle. Repeated all above on the other side. Bounce the wings some and everything settled evenly and with about 1” between the “bulb” at the end of the oleo and the case frame tube.  Job done (I hope). BTW, the first one took 4 hrs, the second one took about one hour.

Other info- I’m still not sure how effective my shock absorption might be. Without removing the oleo springs, there isn’t a way (that I know of) to quickly compress the strut to see if the packing is working and the strut is absorbing and slowing the landing load.  But, the L-16 seems to settle in smoothly on any decent landing so I’m guessing all is OK inside the strut.

Hope this is helpful to some of you.

[Richard Murray]

Well done Don!

You said you used to lube the oleo with 5-6 shots from your grease gun. Somewhere I seem to recall you were only supposed to do 1 or 2 shots of grease.

Richard in OH hoping someone has an accurate amount of grease to add to an oleo and at what interval.

[whites...@gmail.com]

What I think remember is squirt it in until some oozes out.  As I say in my write up, it just never oozed out...

[whites...@gmail.com]

Best info I've found- http://www.hangar9aeroworks.com/Aeroncastrut/Aeroncastrut.html

[John Rodkey]

I remember being told that if you grease too much that the grease packs up around the spring and reduces the shock absorption capacity of the oleo.  

I do about 3 shots about every 6 months/30 hours, although it probably makes sense to go by number of landings.

--

John (poobah) Rodkey - N9361E 11AC at Goleta

[whites...@gmail.com]

Hey John!  Still remember our flight around Lake Cachuma that day.  I bet there is plenty of water in there now!  

Re "too much grease", I heard the same thing you did.  BUT, I realize since we squirt the grease in with the oleo's almost completely compressed (on the ground), it seems unlikely that you could put so much grease in that you'd interfere withe them compressing upon landing. Seem right??