14-13 gear struts

sillsaviation1

sillsaviation1

New member
OK, all you Cruisair owners: What are you using as replacement seals p/n 9899-27 packing for the main gear struts ? Supplier ? Modifications ?
 
My struts have V seals in them that are made if a material kind of like a fan belt. The Greene's told me about some Buna-n seals that seal better because they are more pliable. They sent me some but they were kind of old and not real soft. I found some at this site that are fresh and soft. I will be putting them in next month. part number 31986953

http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=1852675&PMT4NO=0

Kevin
 
Larry Lowenkron said:
sent you a picture
Click to expand...

Thanks , i got it. It showed me that your gear are modified from the original.

I thank you all for your response. I ordered a stock of the seals that will stack on each other. I also had a machien shop cut a grove in the brass nut for an o ring . This should do the job.


thanks again:

joe:
 
I have found that the chevron 'V' packings are still available at most hydraulic supply stores. A lot of Ag equipment still uses this 'stuff.' I have found that Granville Strut Seal will keep these packings pliable for years, without the customary drops of oil on the hangar floor. Dan
 
part number 31986953

http://www1.mscdirect.com/CGI/NNSRIT?PM ... 5&PMT4NO=0


These seals worked ok, stacked them in place of the original. I also had a shop cut an O'ring groove in the brass nut and fit a AN6227B-30 O'ring in it. Looks to be holding oil for now.
 
Good deal, maybe I will have the groves cut in mine when I put the new seals in. Did you have to give them the dimensions of the grove or did they know?

Kevin
 
I took a new O'ring with me and gave it to the man in charge. He did the measurements and fit and it came out just fine. Not too tight , not too loose. no leaks yet ..
 
Another thing that helps is to follow the factory recommendation and NOT tighten the nut on the top of the strut to seal off that hole. You do want to make sure that you insert the cotter key. This reduces the air pressure as the strut compresses. This air pressure is what forces the oil between the bushing out past the seal. The air has to go some where. When it is forces past the seal, it pushes out the oil.
 
Factory drawing SK 468 has the notation... for the top nut; "Note: Piston assembly should remain free to turn after nut is tight." As this drawing was part of the kit to change from the V-packing to the o-ring, it also has as part of this conversion to enlarge the 5/16 hole for the stud to 1/2" I believe the factory also had strut oleo leaks from the entrapped air having to go some where on landing compression, so it went out past the sleeve bearing forcing the oil that gets past the top sleeve while in the retracted position to be forced past the packing. Not tightening down the top stud relieves some of the pressure and to reduce it even further, they opened up the hole to 1/2" They also pack the space above the seal to the top bushing or sleeve with "hard grease" as this space is where the hydraulic oil accumulates in flight. Drawing is dated 1949. As part of the conversion, the plain piston has an o-ring added.

I also have a letter from Miller stating that you can't get the "leather Chevron Seals" anymore and to replace them with two wheel bearing Chicago Rawhide # 17286 seals and a seal those with an oil ring top and bottom on each strut.

Miller was probably right that the "leather" chevrons aren't available but one can still get new rubber chevron seals from an industrial supply house like MCS.

Finally, Miller says not to use the 5606 red fluid but 10 weight motor oil.
 
Cy, I'd like to see a copy of those instructions and drawing.........maybe in the next newsletter. A couple of the struts that I have overhauled had a lead washer between the top of the piston/stud and the inside of top of the main gear leg. I assumed this was original. As I said earlier, the chevron V packings for the main and tailwheel struts are available. They are a composite of fabric and rubberlike material........kinda like a fan belt. I think part of the reason that oil gets by the packings is the fact that most of the lower gear legs are not 'true.' The airplanes that got flown a lot wore the lower portion undersize and the airplanes that sat around developed pits in that area. The only solution is to hard chrome back to standard. I had to do this on both my 14-13 and 14-9. Dan
 
The 14.13 I just annualed and resealed the gear struts had the lead washers also. Why wouldn't you just dril a small hole in the top plug to vent the strut ? Leaving the nut loose let's the piston slop around. :?
 
I think if the top of the strut was vented or allowed air to pass, that oil could also leak here. If you service the gear, according to the manual, a lot of air is purged out of the strut assembly. When the the strut is extended, prior to landing, the piston should be riding on or near the top of the oil. When you land, the piston plunges down through the oil to ride on the taxi spring. The air chamber on top of the oil should remain a relatively constant volume. This is a different system than the oleo struts found on airplanes like the Bonanza or Cherokee. More thoughts?????????? Dan
 
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