Go Back  RCU Forums > RC Airplanes > RC Jets
Reload this Page >

Air retracts - rebuild, o-rings, leaks, and sourcing parts

Notices
RC Jets Discuss RC jets in this forum plus rc turbines and ducted fan power systems

Air retracts - rebuild, o-rings, leaks, and sourcing parts

Old 10-24-2017, 10:32 AM
  #1  
sfaust
Thread Starter
My Feedback: (11)
 
sfaust's Avatar
 
Join Date: Sep 2002
Location: Boston, MA
Posts: 1,902
Likes: 0
Received 0 Likes on 0 Posts
Default Air retracts - rebuild, o-rings, leaks, and sourcing parts

I have a leak in one of my Airworld L-39 1:5 landing gear (left wing). The leak only occurs when the gear is up, and is leaking from the seal around the actuating arm/shaft. See photo below

I replaced the o-rings for the piston and housing as shown in the photo, but itís not clear that I can replace the seal for the shaft/arm. I canít tell if its an o-ring, or some other type of seal, and if I can get a replacement part for it. Also not sure how to disable the shaft and piston to get at the seal.

Has anyone replaced this seal? Know the procedure? And if I can source the parts?

The leak is significant enough that the pressure only holds for one or two cycles of the landing gear, and just long enough for a flight. Iím not comfortable with this for obvious reasons

Thats for the help in advance
Attached Thumbnails Click image for larger version

Name:	IMG_4284.JPG
Views:	264
Size:	1.43 MB
ID:	2242304  
Old 10-24-2017, 12:39 PM
  #2  
ravill
My Feedback: (11)
 
ravill's Avatar
 
Join Date: Jan 2003
Location: Granite Bay, Ca
Posts: 5,054
Received 2 Likes on 2 Posts
Default

If you don't see e-clips on the piston, I would venture to guess that the piston screws on. As you know, there are obvious inherent dangers when removing that.

Of the rare times I've had to disassemble cylinders, there is usually a small o-ring that goes inside the cylinder end. Sharpened tooth pics and LOTS of patience. A good place is the O-ring store. The O-Ring Store LLC, We make getting O-Rings easy!

Good luck!
Old 10-24-2017, 12:59 PM
  #3  
wfield0455
My Feedback: (7)
 
wfield0455's Avatar
 
Join Date: Sep 2005
Location: Holliston, MA
Posts: 1,151
Likes: 0
Received 0 Likes on 0 Posts
Default

From the photo it appears that there is at lest on hole (indent not a through hole) in the face that would indicate to me that plate screws in and the holes are there to insert the pins of a spanner into. I made such a spanner to remove the ends of the cylinders of my Skymaster small Hawk retracts. Once I got it started it screwed out pretty easily.
Old 10-24-2017, 02:29 PM
  #4  
sfaust
Thread Starter
My Feedback: (11)
 
sfaust's Avatar
 
Join Date: Sep 2002
Location: Boston, MA
Posts: 1,902
Likes: 0
Received 0 Likes on 0 Posts
Default

If its the hole I think you are looking at, very prominent in the photo, that is the air pressure inlet for pushing the piston up and retracting the gear. But it could be used for both, assembly and for air inlet.

I'll have to get a magnifying glass and really examine the seal and see what's what. If I can't resolve it, even though it works perfectly, it's junk if it can't hold pressure for a full flight.

In the gear down configuration, the air system only lost about 3 psi over a couple hours when pressurized to 80psi. In the gear up, well, from 80psi to 0 in about 15 minutes.
Old 10-24-2017, 05:51 PM
  #5  
sfaust
Thread Starter
My Feedback: (11)
 
sfaust's Avatar
 
Join Date: Sep 2002
Location: Boston, MA
Posts: 1,902
Likes: 0
Received 0 Likes on 0 Posts
Default

I checked the seal in more detail. It doesn't look like an o-ring, or even removable. Not sure if its serviceable. I sent an e-mail to Airworld, lets see if I get any response. Hopefully, I won't have to find a used left main gear, or have to replace the gear entirely.
Old 10-25-2017, 11:03 AM
  #6  
jetflyr
 
Join Date: Mar 2002
Location: Colorado Springs, CO
Posts: 712
Received 0 Likes on 0 Posts
Default

Looking at the picture, it looks a lot like a Behotec unit. Simple and easy answers would be from Peter at Altecare-RC.com since he is just a tiny bit north from you. Ultimate Jets in Houston is also a dealer, so another good source.

Hope this helps!
Greg
Old 10-25-2017, 03:39 PM
  #7  
sfaust
Thread Starter
My Feedback: (11)
 
sfaust's Avatar
 
Join Date: Sep 2002
Location: Boston, MA
Posts: 1,902
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by jetflyr View Post
Looking at the picture, it looks a lot like a Behotec unit. Simple and easy answers would be from Peter at Altecare-RC.com since he is just a tiny bit north from you. Ultimate Jets in Houston is also a dealer, so another good source.

Hope this helps!
Greg
Thanks Greg, I'll give them a shout.
Old 01-03-2018, 03:18 PM
  #8  
stegl
 
Join Date: Oct 2006
Location: kelowna, BC, CANADA
Posts: 411
Likes: 0
Received 0 Likes on 0 Posts
Default Locate air leakes

If. not already mentioned , the best way to locate leaks, is to use a mixture of dish soap in water brushed on ( or any other application) all the couplings or connections . Small bubbles will appear pretty quickly . Saves unnecessary disassembly to check O rings and seals as that might create further issues. (If it ainít broke ; donít need fixín) Once the point of a leak is found, just disassemble that part for further inspection.
Old 01-06-2018, 02:13 AM
  #9  
David Gladwin
 
David Gladwin's Avatar
 
Join Date: Feb 2002
Location: CookhamBerkshire, UNITED KINGDOM
Posts: 3,508
Received 2 Likes on 2 Posts
Default

I had similar problems of leaks developing on the retract units on my AirWorld Hawks , some years ago. I believe the units are the same as mentioned here.These models are now over 10 years old and fly with complete reliability. I traced the problem to corrosion on the shafts in the area of the small seal, which seemed to hold moisture.

I replaced the corroded shafts and installed new seals with plenty of BVM silicone grease.

I also now now use a water trap on my compressor, since when I have had zero problems and the system holds pressure indefinitely.

Might help you.

David G.
Old 01-06-2018, 09:06 AM
  #10  
sfaust
Thread Starter
My Feedback: (11)
 
sfaust's Avatar
 
Join Date: Sep 2002
Location: Boston, MA
Posts: 1,902
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by stegl View Post
If. not already mentioned , the best way to locate leaks, is to use a mixture of dish soap...
Thanks. That was how I initially found the leak. Definitely in the small seals on the cylinder shaft.

Originally Posted by David Gladwin View Post
I replaced the corroded shafts and installed new seals with plenty of BVM silicone grease.
I also now now use a water trap on my compressor, since when I have had zero problems and the system holds pressure indefinitely.
Might help you.
David G.
Do you know where you found the small seals for the shaft. I replaced the air cylinder seals, but haven't found a source for the small seals on the shaft. I also don't know the correct procedure to remove the shaft, and don't want to make it worse or break something just trying things. Any help in disassembly of the shaft and source for the small seals would be so much help and save me buying new gear as a solution.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.