Carb line leaking fuel

H. Paul Shuch is a Light Sport Repairman with Maintenance ratings for airplanes, gliders, weight shift control, and powered parachutes, as well as an independent Rotax Maintenance Technician at the Heavy Maintenance level. He holds a PhD in Air Transportation Engineering from the University of California, and serves as Director of Maintenance for AvSport of Lock Haven.

Moderator: drseti

User avatar
drseti
Posts: 5901
Joined: Sat Nov 28, 2009 6:42 pm
Location: Lock Haven PA
Contact:

Re: Carb line leaking fuel

Postby drseti » Wed Sep 26, 2018 8:44 pm

You'll also need an oetiker clamp tool to install them.
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof H Paul Shuch
PhD CFII DPE LSRM-A/GL/WS/PPC iRMT
AvSport LLC, KLHV
fly@AvSport.org
AvSport.org
facebook.com/SportFlying
SportPilotExaminer.US

Warmi
Posts: 656
Joined: Sun Oct 16, 2016 5:35 pm
Location: Frankfort, IL

Re: Carb line leaking fuel

Postby Warmi » Wed Sep 26, 2018 9:08 pm

Yep, got everything + the end tape: http://www.americanfiresleeve.com/fires ... r-now.html

Learning new stuff every day - thanks again.
Flying Sting S4 ( N184WA ) out of Illinois

User avatar
FastEddieB
Posts: 2510
Joined: Wed Jan 07, 2009 9:33 pm
Location: Mineral Bluff, GA

Re: Carb line leaking fuel

Postby FastEddieB » Thu Sep 27, 2018 4:56 am

This is the kind iuse,available at any auto parts store:

Image

Maybe not as elegant a Oetikers, but get the job done.
Fast Eddie B.
Sky Arrow 600 E-LSA • N467SA
CFI, CFII, CFIME
FastEddieB@mac.com

Warmi
Posts: 656
Joined: Sun Oct 16, 2016 5:35 pm
Location: Frankfort, IL

Re: Carb line leaking fuel

Postby Warmi » Thu Sep 27, 2018 7:40 am

Thanks

in this case Oetiker clamps are actually pretty cheap ( ~60 cents), even at the Leading Edge store :-) - which is pretty rare since just about everything there is rather expensive ( comparatively speaking )
Flying Sting S4 ( N184WA ) out of Illinois

3Dreaming
Posts: 2418
Joined: Sun Jan 10, 2010 6:13 pm
Location: noble, IL USA

Re: Carb line leaking fuel

Postby 3Dreaming » Thu Sep 27, 2018 9:01 am

Most of the airplanes I deal with either have the stainless fuel line or the Rotax Teflon line. With the carb connection it is something that will have to be disconnected from time to time for carb maintenance. I think I would prefer a screw type fuel injection clamp so I could remove the hose from the fitting, instead of having to remove the banjo bolt to remove the carb. The only problem with the screw type clamp is that it makes it harder to cleanly finish the end of the firesleeve.

User avatar
ShawnM
Posts: 350
Joined: Sat Nov 11, 2017 9:59 pm
Location: Clearwater, FL / KZPH

Re: Carb line leaking fuel

Postby ShawnM » Thu Sep 27, 2018 10:25 am

Warmi wrote:Thanks

in this case Oetiker clamps are actually pretty cheap ( ~60 cents), even at the Leading Edge store :-) - which is pretty rare since just about everything there is rather expensive ( comparatively speaking )


Yes, but the special tool needed to clamp that .60¢ clamp is about $35 or more for a good one. Using the clamp that Eddie posted, which is also what I use, uses a screwdriver or nut driver and everyone has one of those laying around. The smooth clamp like Eddie posted is a fuel injected hose clamp and has great clamping pressure all the way around the hose. Those crappy, serrated, screw style clamps dont. I buy the "Breeze" brand made in the US.

User avatar
MrMorden
Posts: 1975
Joined: Fri Aug 17, 2012 7:28 am
Location: Athens, GA

Re: Carb line leaking fuel

Postby MrMorden » Thu Sep 27, 2018 11:37 am

I always use Oetikers for fuel lines where I can. They literally *can't* loosen over time or due to vibration or something bumping them. The clamp tool is totally worth having if it means not leaking fuel in flight and potentially burning to death. Just IMO.
Andy Walker
Athens, GA
Sport Pilot ASEL, LSRI
2007 Flight Design CTSW E-LSA

Warmi
Posts: 656
Joined: Sun Oct 16, 2016 5:35 pm
Location: Frankfort, IL

Re: Carb line leaking fuel

Postby Warmi » Thu Sep 27, 2018 12:29 pm

MrMorden wrote:I always use Oetikers for fuel lines where I can. They literally *can't* loosen over time or due to vibration or something bumping them. The clamp tool is totally worth having if it means not leaking fuel in flight and potentially burning to death. Just IMO.


You were actually right it was a clamp after all.

It can get loose over time and in my case it is pretty much gone and the hose just freely rotates around the fitting.

https://youtu.be/APpDykQnUDY
Flying Sting S4 ( N184WA ) out of Illinois

3Dreaming
Posts: 2418
Joined: Sun Jan 10, 2010 6:13 pm
Location: noble, IL USA

Re: Carb line leaking fuel

Postby 3Dreaming » Thu Sep 27, 2018 4:23 pm

MrMorden wrote:I always use Oetikers for fuel lines where I can. They literally *can't* loosen over time or due to vibration or something bumping them. The clamp tool is totally worth having if it means not leaking fuel in flight and potentially burning to death. Just IMO.


I also use Oetikers most of the time, but there are places I like these better. https://www.wurthusa.com/Service-and-Re ... /p/0540139 This is the brand Flight Design uses, or at least they used to. It is a very high quality clamp. Depending on the clamp location I sometimes swap the slotted screw out for a hex head screw. I have never experienced these loosening up.

Personally I would not use a cheap clamp like Eddie posted a picture of.

User avatar
ShawnM
Posts: 350
Joined: Sat Nov 11, 2017 9:59 pm
Location: Clearwater, FL / KZPH

Re: Carb line leaking fuel

Postby ShawnM » Thu Sep 27, 2018 5:35 pm

I also have never had one loosen up, ever. I always put torque seal on them so at a quick glance I could see if anything moved. The fuel injected style clamps are great clamps and not one has ever come loose. The fuel injected ones all have a hex bolt, slotted head so you can get a good grip on it and tighten it with a nut driver.

Warmi
Posts: 656
Joined: Sun Oct 16, 2016 5:35 pm
Location: Frankfort, IL

Re: Carb line leaking fuel

Postby Warmi » Sun Sep 30, 2018 2:27 pm

drseti wrote:
Warmi wrote:do you know which clamp would be suitable for the carb fuel hose ?


I've always been partial to the Oetiker clamps. Sometimes called "stainless steel ear clamps":

https://www.leadingedgeairfoils.com/stainless-ear-clamp-15-32-to-37-64.html


I think the proper size is this one :
https://www.leadingedgeairfoils.com/sta ... 35-64.html

The hose is 12 mm so I will need smaller size when closed
Flying Sting S4 ( N184WA ) out of Illinois

Warmi
Posts: 656
Joined: Sun Oct 16, 2016 5:35 pm
Location: Frankfort, IL

Re: Carb line leaking fuel

Postby Warmi » Sun Sep 30, 2018 3:15 pm

Btw , the reason it started leaking is because the mechanic messed up installation of the clamp during 5 year rubber replacement - it was different diameter than the one on the other side ( which is as tight as it should be ) , it was different type and also it looks like it was clamped and then reclamped.

I am actually quite pissed off - this is some serious shit , we could have easily ended up with one carb completely being cut off and/or in-flight fire , at the very least with an off airport landing due to only one carb working ( which I presume would result in the degree of vibration which would necessitate shutting down the engine )

PS.
This was actually quite progressive failure - just before we started disconnecting the hose it got even worse ...
https://youtu.be/kDW1AOBs3VE
Last edited by Warmi on Sun Sep 30, 2018 4:06 pm, edited 1 time in total.
Flying Sting S4 ( N184WA ) out of Illinois

User avatar
ShawnM
Posts: 350
Joined: Sat Nov 11, 2017 9:59 pm
Location: Clearwater, FL / KZPH

Re: Carb line leaking fuel

Postby ShawnM » Sun Sep 30, 2018 3:28 pm

As for sizing on the Oetiker clamps, if you look at the other side that is done properly the size is stamped in the side of the clamp. Just match it up so they'll be he same.

Certainly alarming to hear what has happened and that it wasn't checked before OR after it was clamped.

Warmi
Posts: 656
Joined: Sun Oct 16, 2016 5:35 pm
Location: Frankfort, IL

Re: Carb line leaking fuel

Postby Warmi » Sun Sep 30, 2018 3:45 pm

Yeah, I got it under control now :-)

The 5 year rubber was done just a few months after I bought the plane - back then I had no idea even what to look for , beyond the basic pre-flight of the plane..

Since then I went to the Rotax maintenance class and step by step getting to the point where I can fix or at least recognize potential issues before they become a major problem - ultimately, as they say "if you want to get it done right - do it yourself " - of course, within reasonable limits, but there is definitely some truth to that - it is my ass riding up there after all :D
Flying Sting S4 ( N184WA ) out of Illinois

roger lee
Posts: 751
Joined: Tue Dec 08, 2009 11:47 am
Location: Tucson, Az. Ryan Airfield (KRYN)

Re: Carb line leaking fuel

Postby roger lee » Mon Oct 01, 2018 10:05 am

Oetiker and fuel injection screw clamp like the one in the previous post are both considered band clamps and are good choices for fuel hose.
Do not use the Ace hardware serrated worm drive clamps on oil and fuel hose. Usually for 1/4: hose I use 13.3 or 13.5mm and 5/16" I use 14.5 or 14.7mm Oetiker. Some different fuel hoses have slightly different OD sizes. I usually use fuel injection clamps on oil hose. The choice is yours.
Roger Lee
Tucson, Az.
LSRM-A, Rotax Instructor & Rotax IRC
(520) 574-1080 (Home) Try Home First.
(520) 349-7056 (Cell)


Return to “Ask The Mechanic”

Who is online

Users browsing this forum: No registered users and 4 guests