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  #1  
Old 11-02-2018, 03:03 PM
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Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 1,153
Default Rotax 912 Conductive Teflon Oil Hose Retrofit

Earlier this year I installed Aircraft Specialty Conductive Teflon Fuel hoses on my early SN RV-12 to begin compliance with Rotax 5-year rubber hose replacement. Now I’m changing out the oil lines with Aircraft Specialty Conductive Teflon hoses. This will complete all rubber hose change-out with exception of coolant hoses, which I will monitor and plan for replacement in the near future.

I bought my 12 as a flying airplane three years ago from the original builder with 48TT. On my first thorough inspection of the engine I noticed the 90-degree fitting on the crankcase drain was almost touching the muffler. I estimate the clearance to be no more than 1/8”. I suspect there is a tolerance stack in the exhaust components and each installation is a little bit different. I surfaced my concern in a VAF thread and was told, “That’s the way it is.” I now have 400TT and still don’t like it…

Aircraft Specialty offers the Teflon drain hose in two different configurations. The configuration that I chose comes with an OEM Rotax Banjo fitting to provide extra clearance from the muffler. The Banjo fitting requires safety wire to secure it. Clearance to muffler is now ~ ˝”. This option is the more expensive of the two replacement options due to the added cost of the Banjo fitting, however, I value my safety and piece-of-mind. Even with the added cost of the Banjo fitting, the Aircraft Specialty Conductive Teflon hose kit is significantly less expensive than purchasing the OEM hoses from Rotax/Vans.

The crankcase drain line can be installed dry but the two remaining supply lines must be filled with oil during assembly so air doesn’t get into the oil pump and hydraulic valve lifters. This is simple to accomplish by first installing the hose fitting at the lowest end and then pouring oil into the raised hose before installing and tightening the upper end fitting. When oil hose installation is complete, I remove the upper sparkplugs and hand turn the engine until the EMS shows positive oil pressure. A ground run of the engine with the cowling removed is necessary to assure no oil leaks.

Original 90 degree fitting with ~ 1/8” muffler clearance…


New Banjo fitting with ~ ˝” muffler clearance…


Safety wire through eyelet on bottom of crankcase…


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Jim Stricker
Hinckley, Ohio
EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 406

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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  #2  
Old 11-02-2018, 07:36 PM
TS Flightlines TS Flightlines is offline
 
Join Date: Apr 2010
Location: Ridgeland, SC
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Jim and others, WE dont have them yet, but have designed a banjo hose end, not an adapter, that crimps onto the hose, like hose end. Benefit of increased clearance versus a standard AN 90* hose end, AND a banjo adapter fitting that needs a -8 AN nut. There's that little boss on the engine at the B Nut that we are dealing with, so with the new version banjo hose end, there will be increased clearance all around. We've gotten the drawings completed, and just waiting on the pre=production samples to get here for checking.

Tom and Steve
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Tom Swearengen, TS Flightlines LLC
Teflon Hose Assemblies for Experimentals
Proud Vendor for RV1, Donator to VAF
RV7 Tail Kit Completed, Fuse started-Pay as I go Plan
Ridgeland, SC
www.tsflightlines.com
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  #3  
Old 11-02-2018, 08:26 PM
Harvey rv12 Harvey rv12 is offline
 
Join Date: Apr 2015
Location: Olympia WA
Posts: 155
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Jim;
I had the same issue when I bought my 12. The fitting was making contact with the muffler body. I thought the friction would rub through the fitting and dump all my motor oil while inflight. After asking around here on VAF, I left with the same feeling, "that's the way it is". I saw that Rotax uses the same banjo fitting on the stock engine. I installed it on my aircraft and have been happy since!.
I think you are right that there may be some dimensional errors/stackup with the muffler system.
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RV-12, bought flying
Hoskins Field, 44T
Olympia WA

the bitterness of poor quality
lingers long after the cheap
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  #4  
Old 11-02-2018, 09:12 PM
Aircraft Specialty Aircraft Specialty is offline
 
Join Date: Jan 2012
Location: Oconomowoc, WI
Posts: 359
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Quote:
Originally Posted by Harvey rv12 View Post
Jim;
I had the same issue when I bought my 12. The fitting was making contact with the muffler body. I thought the friction would rub through the fitting and dump all my motor oil while inflight. After asking around here on VAF, I left with the same feeling, "that's the way it is". I saw that Rotax uses the same banjo fitting on the stock engine. I installed it on my aircraft and have been happy since!.
I think you are right that there may be some dimensional errors/stackup with the muffler system.
For those of you that know us at Aircraft Specialty/TSFlightlines, "That's the way it is" is NOT our mantra. We love working with other builders/owners to try to build a better mousetrap. On my dad's RV-12 the 90 degree fitting does not make contact with the muffler body, but it is close.

We worked with Jim to test fit the Stock Rotax Banjo fitting, and it is definitely a huge clearance improvement over the 90 degree fitting on the bottom of the engine. However, as Tom mentioned, we are also working on our own proprietary banjo fitting that will function directly as one of the Teflon hose ends. This will eliminate the -8 AN nut on the end of the hose which still has a pretty tight clearance on the bottom of the engine casting.

For those of you who are looking at this option, the new Banjo fitting will not be in production and tested for approximately a year, and will provide no substantial benefit over utilizing the current banjo fitting and AN setup. It will be a slightly more compact solution with more clearance on the engine case, but muffler clearance will remain the same.

Thanks again to Jim for helping us to verify this installation. We have said it many times, but really really appreciate the help of the RV community to help us in our product ideas, development and testing.

If anyone has any questions on the RV-12 oil kit we offer, or the different options available, please feel free to reach out to us.

Take care,
Steve
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Last edited by Aircraft Specialty : 11-02-2018 at 09:16 PM.
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