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COWL Burning from Exhaust Pipe

J

jackking123

Well Known Member
Patron
RV-12iS front right pipe comes too close to the lower engine cowl, NACA scoop and burned the paint. The owner repaired cowl, and put a little tiny bit of regular heat wrap and some metal. It still blistered the paint. Helping him I loosened the pipes up and shifted pipes a little more to aircraft left, it made a small difference, a little. However we got better thicker *black wrap, extending it above and below further. (*Black exhaust pipe wrap, "black titanium" or lava rock-based versions, features a carbon fiber-like appearance or is coated to enhance durability and heat resistance.)

Already on that same forward right pipe is a metal heat shields held on with hose clamp below the problem area, to keep heat off plumbing. I used that heat shield hose clamp to terminate the heat wrap at the bottom. It looks good. The paint is still blistered damaged, he has yet to repair that. If he takes cowl off and repairs it, I am not sure what will happen... Yet to fly it since modification.

ANY TIPS...
 
jackking123 said:
RV-12iS front right pipe comes too close to the lower engine cowl, NACA scoop and burned the paint. The owner repaired cowl, and put a little tiny bit of regular heat wrap and some metal. It still blistered the paint. Helping him I loosened the pipes up and shifted pipes a little more to aircraft left, it made a small difference, a little. However we got better thicker *black wrap, extending it above and below further. (*Black exhaust pipe wrap, "black titanium" or lava rock-based versions, features a carbon fiber-like appearance or is coated to enhance durability and heat resistance.)

Already on that same forward right pipe is a metal heat shields held on with hose clamp below the problem area, to keep heat off plumbing. I used that heat shield hose clamp to terminate the heat wrap at the bottom. It looks good. The paint is still blistered damaged, he has yet to repair that. If he takes cowl off and repairs it, I am not sure what will happen... Yet to fly it since modification.

ANY TIPS...
Click to expand...
Does the area where the damage is occurring have the specified aluminum heat shield material applied to the cowl?

Shielding the cowl from the radiant heat energy will get much better results than applying a wrap to the pipe ( which induces a high probability of pipe failure in the future).
 
rvbuilder2002 said:
Does the area where the damage is occurring have the specified aluminum heat shield material applied to the cowl?

Shielding the cowl from the radiant heat energy will get much better results than applying a wrap to the pipe ( which induces a high probability of pipe failure in the future).
Click to expand...

Yes and no. The first time he burned it, early on in the first hour of flight he left it. Then he repaired the cowl, did a very minimal pipe wrap. He burned it again. I got involved. I applied several layers of aluminum metal tape with adhesive back. This thick aluminum adhesive tape is NOT the good stuff good for reflecting and some radiant heat. The paint is still damaged. As I said pipe was also re-wrapped with better material. However he needs (suggestions requested):

Thermo-Tec Thermo Shield Adhesive Backed Composite Tap​
Aluminized Heat Barrier is made up of woven silica with a flexible aluminized finish.​
Flyboy heat shield matt (I bought this for my RV-7)​

Right now it is flying burned paint, the metal tape I put on, and pipe wrapped. The burn is in the bottom ramp of the NACA scoop. Besides suggesting he bond on high quality heat mat to cowl, I suggested he paint the bottom of the NACA scoop flat black, heat resistant paint. It might not look as nice as base paint scheme, but better than burnt paint. He may elect to repaint again and see how it goes (after getting good heat matt bonded to cowl.

I am sure it is safe, and fiberglass is holding up fine. However not until he repaints it will he know if the paint can hold up with the added heat protection. It's his plane and I can only suggest and encourage.
 
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