Breather tube extension?

D

Diana

New member
We will be recovering our 1977 7GCAA in a month. Someone suggested that we install a breather tube extension and run it to the back of the airplane. Does anyone have any experience with installing these? Would an STC be necessary? Thanks.

Diana
Citabria 4216Y
 
Diana,
I dont think adding an extension to the vent would be helpful. If the problem is oil on the belly I would invest in a good oil seperator. If you decide to install the extension use rigid tube not flexible hose. Any sag in the hose will act as a check valve when the low point fills with fluid.
I would check with your IA about documentation. My opion would be that it is a minor alteration. Good luck on your rebuild.
Paul
 
I would be careful about adding any extension to the breather line as they can ice up in cold weather (if you're in that kind of a climate) and cause a buildup in pressure sufficient to blow out engine seals. That's the reason they're usually kept inside the cowl (to prevent icing). Also, under the right conditions, the tube hanging out in the air can cause a venturi effect and actually pull oil from the crankcase. That being said, I have a short one on my Champ, but I take it off in cold weather. It doesn't seem to pull oil out, but I might just be luckywith the location.
 
Suggest you look at Pitts and other aerobatic aircraft as they have
the tube run out the tail. As far as ice is concerned it requires the same hole to prevent from freezing. It will require a form 337 to your FSDO
Rod
 
Thanks all, for your input. Looks like we'll be installing one (with a whistle hole) and run it out to the tail.
 
Diana,
I am interested in doing the same, could you email me the instructions, or link to what you found? and of course how did it work?

hermh@fencespecialists.com

thanks.
Herm
 
This is an interesting subject and as I see form the date an old one. I did a search for breathers because I have a 73 Decathlon with the breather that exits the fuselage at the tail. The tube is flexible and I do not remember seeing a whistle hole anywhere in the engine compartment. Even if there was a hole in the engine compartment I doubt it would melt any ice that forms in the tail section. After any extended inverted flight oil does flow out the tube and continues to drain after shut down. It is noce to not have the oil on the belly but I am told the newer Decathalons do not have this tube. Is there a service letter addressing this issue? Is there something I should be doing if planning to fly during below freezing temperatiures?
Ken
 
Hi Ken, the purpose of the whistle hole is to allow the crankcase pressures to be released so as not to blow the crankshaft seal, its not to melt the ice that may form. Generally the whistle hole is in the rubber hose that connects the breather tube to the engine or is located about 6" up from the bottom of the breather tube inside the cowl.
 
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