Power Pack Again

J

jec wood

New member
Some how my Sunday new topic "Power Pack" got mixed up with Jonathan's "Brute Force" topic. Here's my power pack question again as a stand-alone topic. Sorry for the redundancy.

I know there have been posts on this subject before, but I don't recall this issue. My search function won't work either so I can't look up the old posts. First this is the old type system, that is pure hydraulic, no electrics. This is among the last of these, on a 1968 17-30 Viking, but I believe this to be identical to the 14-19-3 & 3A. Problem is the gear goes up fine, but about half or maybe a third of the time the right main sneaks down. First the red indicator goes out, then if ignored long enough the right green will come on. The micro-switches are correct, the right main actually comes down. If I cycle the gear 2 times in short cycles (not fully down, fully up) it will then stay up. It is always only the right main, never any other.

Corrective measures taken so far: 1. remove res from firewall & thoroughly flush-clean. It was very dirty & had chunks of debris. 2. remove res on the pack itself, clean all the black off the accessible plates and reassemble with new big O ring. 3. Flush the whole system, draining at at all 3 cylinders, went through 3 quarts of fluid. Also put her up on jacks & with the hand pump the gear remains locked & welded up...won't budge.

Prior to corrective measures got so as I could hardly keep the right retracted. Now, while much better, it still needs something. As with all intermittent problems there is lots of guessing. Anyone have similar experience?

Thanks
 
From what I've heard, your corrective measures have given you all you can get, they all seem to lag after a while and you need to "pull" the handle up once in a while. Call Rocket, Weber, or Witmer and see what they say.
 
Pull one of the hydralic cylinders and pull out all the o rings. Go to a hydralic supply house and buy a couple of sets (should cost about $5. for 3 or 4 sets). install. Should solve your problem. :lol: :lol:
 
Also when you have the cylinder apart, make sure you look at the cylinder bore. Often there will be corrosion pits and the best O-ring in the world won't seal fully against the surface if the pitting is medium sized or worse. Light corrosion can be polished out.
 
Can one use regular o-rings from the hardware store or must they be aviation? Resealing the gear on my cruiseair many years ago, my mechanic sent me to the autoparts store because he didn't have big enough o-rings. I still have the bill for the job-total labor charge (with me helping which usually sends the charge up) was $15 plus the cost of the rings (I recall it being about a $1) I think my mechanic charges me more than that to just talk to me nowadays. If one did have pitting of the actuator cylinder, what would one do? Ream it out a few thousandths and hope the o-ring still seals it? If you ream too much, you are thinning the already thin wall of a vessel that loves high pressure.
 
I don't know what the hardware store o-ring composition is and whether it'll stand up to 5606 hydraulic fluid. If you buy an AN part or talk to a hydraulic shop then you should be ok.

A minor reaming isn't going to affect the cylinder much, it is a very beefy, relatively thick walled piece of steel. Polishing will take care of minor pitting. If you've got major corrosion pits, then I'd suggest finding a new cylinder. I suppose you could try plating up the old one but I think finding a serviceable one from a junkyard would be easier and less expensive.
 
I actually got some o-rings from a hydraulic supply co. and while they looked like the right size, they weren't. Get the proper AN/MS o-ring and save yourself the trouble. I would guess that you would want MS28775-XXX (old number is AN6227 or 6230). They are for service with Mil-H-5606.

Larry
 
Larry I have a complete O ring set from a hydrolic shop and used them on the cruiseair and the Viking with no problems. There are not that many differant sizes for hydrolic cylinders our size. If you take the old one they will measure inside outside and thickness. :lol: :lol: :lol:
 
Hi Randy,
What can I say. That is what happened to me. The o-rings I got from a hydraulic shop measured right for my MLG, but when I installed them, they didn't work well. Bought some MS o-rings from Genuine A/C Parts and they worked fine!??! :?: :?:
 
You need MS28775 o-rings of the proper sizes for the cylinder. DO NOT SUBSTITUTE THEM WITH ANYTHING ELSE! MIL-H-5606 fluid will often attack generic o-rings and cause failure. MS28775 o-rings are not expensive. Using them is the cheapest insurance you can find.
 
Wow,all you have to do is open the Aircraft Spruce Catalog and order some rings. If your not sure buy the complete O ring kit ! In the words of Leno What were you thinking. The gear is the weak link on all Cruisemasters watch it like a hawk and don't take any chances. Lynn the crate :p
 
When I rebuilt my acuators I found the proper part numbers in an old post on this forum, and bought them from Aircraft Spruce for total of $1.25 per side. The part # are AN6227B-19 three each, AN6227B-7 one each, AN6227B-10 ,one each. 5 o-rings per cylinder. I also had badly pitted shafts and ended up buying Viking cylinders from a salvage yard and used the shafts in my cylinders. I had to change the piston on the end of the shaft to my 14-19-2 piston so that it had the correct travel. The great advantage of the Viking shaft is that it has an adjustable end so you dont have to go through the machining process of the 14-19-2 cylinders to adjust your retract struts. This was done on a 14-13-2 with the Slim Kidwell hydraulic gear STC. For $2.50 and a phone call to Aircraft Spruce you can go through both sides and not guess at a hydraulic shop that you have the correct parts._____I hope this helps.___Grant.
 
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