Cowling blister

[glenn reynolds]

The right Hand lower cowling developed a dim size blister yesterday. Any idea?

 

[kortopates]

I assume adjacent to the exhaust? You'll have to examine the cowling from the inside to assess the extent of the damage. You may find dry, soft, fiberglass material which will likely require a fiberglass repair and then to be protected with some heat shield material to prevent a re-occurrence.

[N201MKTurbo]

You may find that the fiberglass is fine but the paint is blistered. Usually more of a cosmetic issue than a structural issue, but you will have to evaluate that.

I use header wrap tape glued on with high temp RTV as an insulator.

There is a place on my plane where the exhaust is less than 1/4 inch from the cowl. Wish it didn't but it does. The fiberglass gets discolored but seems to retain its strength. 

[jetdriven]

I have this stuff on parts of my cowl that are next to the exhaust. It hasn't changed in 2 years and it stopped the cooking of the fiberglass.  When I rebuilt the cowl I replaced substantial parts of it due to the exhaust heat ruining the resin. Like all of if between the cowl flaps and large portions where the exhaust risers get close 

 

Thermo-Tec 13575 12" X 24" Adhesive Backed Heat Barrier https://www.amazon.com/dp/B00029KC2K/ref=cm_sw_r_cp_api_XRstzbMP8MA9F

[kortopates]

I used the same Thermo-Tec adhesive backed material right on the cowling adjacent to my Turbo, which gets so hot it glows cherry red, and Thermo-Tec material has been working great for years.

[Harry Wightman]

Similar thing happened to me recently. If the lower exhaust clamp is not rotated to the correct position it gets very close to (touching) the small exhaust outlet fibreglass cowling section. Rotating the clamp eliminates the problem but needs to be watched after any exhaust work.

[carusoam]

Harry are you flying an O as well?

Gathering details for things to keep an eye on for my O...

Best regards,

-a-

[Harry Wightman]

Just now, carusoam said:

Harry are you flying an O as well?

Gathering details for things to keep an eye on for my O...

Best regards,

-a-

Yes, A 1998 O. Judging by the previous repairs to the exhaust sub-cowl I suspect its not uncommon. I'll be watching for it in future, this time it put a hole in the fibreglass. I've rotated the clamp & put a small section of metal tape over the repaired fibreglass section.

[N201MKTurbo]

21 hours ago, jetdriven said:

I have this stuff on parts of my cowl that are next to the exhaust. It hasn't changed in 2 years and it stopped the cooking of the fiberglass.  When I rebuilt the cowl I replaced substantial parts of it due to the exhaust heat ruining the resin. Like all of if between the cowl flaps and large portions where the exhaust risers get close 

 

Thermo-Tec 13575 12" X 24" Adhesive Backed Heat Barrier https://www.amazon.com/dp/B00029KC2K/ref=cm_sw_r_cp_api_XRstzbMP8MA9F

I'll have to give it a try. Looks like the right stuff.

[Hank]

36 minutes ago, N201MKTurbo said:

I'll have to give it a try. Looks like the right stuff.

That looks like what's under the bed of my truck, above the muffler. Should work well.

I'd put some down by the turbo as well as along the exhaust (if you have one).

[N201MKTurbo]

1 hour ago, Hank said:

That looks like what's under the bed of my truck, above the muffler. Should work well.

I'd put some down by the turbo as well as along the exhaust (if you have one).

The turbo is not close to the cowl, but one of the exhaust pipes almost rubs on the cowl.

[markejackson02]

I bought a square foot of heat shield from Aircraft Spruce and used contact cement to glue it in place in the cowl where the exhaust is about 1" from the cowl.  No problems since.