Controlling heat damage PA 32R-301T

[dpilot_citation]

We are currently overhauling our TIO-540-SAID. And through out this process we have been trying to repair heat damaged areas. IE: Firewall, Engine Mount and Turbo brackets. All of the coatings I have looked into are good to about 400 degrees, but the areas around the exhaust and the turbo obviously gets much hotter.

Has anyone ever used ceramic coatings say on the engine mount? I talked to our local FSDO guy and he said they leave coatings up to the local A& P. But that he saw no problems as long as the coatings didn’t change the weight or the size, of the mount. These ceramic coatings are good to 1600 – 2000 degree range depending on who you talk to. Some have been tested to over 2400 degrees.

This seems like a good solution to an ongoing problem of heat damaged engine mounts on high horsepower aircraft. I have been trying to find a down side but as of yet…none.


They can also coat the exhaust pipe inside and out. This reduces the radiated heat by 50% or more. There are other benefits besides heat reduction, they claim a longer life out of the exhaust system. It reduces the thermal expansion and corrosion giving a much longer life. Some claim 10 times longer.

The only downside I can find to ceramic coating the exhaust is the reparability of the pipes. You would have to bead blast the finish away inside and out. If you where not able to get all the coating off repairs may not be possible because of contamination to the welds.

Has anyone done one or the other? If so what were your results?

I welcome any and all thoughts and comments.

Thanks….Dpilot_Citation

 

[USMCmech]

What sort of "heat damage" are you refering to? Unless you have an exaust leak (particularly near the turbo) there shouldn't be any heat damage at all. That's what the exaust pipe is for, to carry those hot exaust gases out of the engine compartment.


Coating the exaust pipes with ceramic is widely done in cars with headers, and sounds like a good idea for airplanes. However I'm not sure if it will be a legal modification in a certified aircraft (might be a good idea to try in an experimantal).

Rotorway helicopters (a kit) has the builder wrap the exaust pipes, coat them with a high temp paint, and heat treat the whole thing. Much like some dragsters or sprint cars. However that is the only aircraft where I have seen this done.

 

[SabreFlyR]

What sort of "heat damage" are you refering to? Unless you have an exaust leak (particularly near the turbo) there shouldn't be any heat damage at all. That's what the exaust pipe is for, to carry those hot exaust gases out of the engine compartment.


Coating the exaust pipes with ceramic is widely done in cars with headers, and sounds like a good idea for airplanes. However I'm not sure if it will be a legal modification in a certified aircraft (might be a good idea to try in an experimantal).

Rotorway helicopters (a kit) has the builder wrap the exaust pipes, coat them with a high temp paint, and heat treat the whole thing. Much like some dragsters or sprint cars. However that is the only aircraft where I have seen this done.

This particular installation is well known for cooking everything on the turbo side, seen it on several different planes over the years. If your not familiar with it you have to see it to believe how tight and in close proximity the engine mount and firewall is to the turbo and exhaust tailpipe.

 

[dpilot_citation]

Sabreflyr you are correct, it gets extremely hot and it is very tight on the right rear side of the engine. It Cooks the finish off the engine mount on the right side and also the upper left side of the mount, where the crossover pipe travels across to the turbo. The turbo support brackets also cook on the ends at the attachment to the turbo. When the engine mount heats up the paint will burn up in the first few hours of operation, leaving a place for corrosion to start.

The ceramic coatings I’m referring to supposedly reduce the radiated heat from the pipes and turbo, forcing the heat out through the exhaust. They all claim a 50 % or better reduction in radiated heat (these claims are backed up by independent studies). These coatings are good to 1800 degrees..

I spoke to one of the Maintenance guys at our local FSDO and he had no problem with any type of coatings we used as long as it did not change the weight or the size of the piece. If we used the ceramic coatings on the exhaust and reduced ambient temperature by 50% then a high heat powder coat on the mount should last the life of the engine (good to 1000 degrees).

The other benefit I can see is a longer life on Mags and wiring, starter and alternator. Also it would reduce the heat in the engine compartment allowing the engine to run cooler, extending the life of the cylinders.

Thoughts please!

Dpilot_Citation

http://www.nicindustries.com/sectionindex.asp?sectionid=8

http://coatings.lewinc.org/aircraft/index.asp

 

[PBRstreetgang]

Sabreflyr you are correct, it gets extremely hot and it is very tight on the right rear side of the engine. It Cooks the finish off the engine mount on the right side and also the upper left side of the mount, where the crossover pipe travels across to the turbo. The turbo support brackets also cook on the ends at the attachment to the turbo. When the engine mount heats up the paint will burn up in the first few hours of operation, leaving a place for corrosion to start.

The ceramic coatings I’m referring to supposedly reduce the radiated heat from the pipes and turbo, forcing the heat out through the exhaust. They all claim a 50 % or better reduction in radiated heat (these claims are backed up by independent studies). These coatings are good to 1800 degrees..

I spoke to one of the Maintenance guys at our local FSDO and he had no problem with any type of coatings we used as long as it did not change the weight or the size of the piece. If we used the ceramic coatings on the exhaust and reduced ambient temperature by 50% then a high heat powder coat on the mount should last the life of the engine (good to 1000 degrees).

The other benefit I can see is a longer life on Mags and wiring, starter and alternator. Also it would reduce the heat in the engine compartment allowing the engine to run cooler, extending the life of the cylinders.

Thoughts please!

Dpilot_Citation

http://www.nicindustries.com/sectionindex.asp?sectionid=8

http://coatings.lewinc.org/aircraft/index.asp

Hey,
The A/C maint manual will list all approved paints and coverage requirments. Any deviation from these processes will require a 337 and FSDO approval. Once you try to get a Fed to buy off on the process that deviates from the maint manual is where it gets interesting. Remember the insurance policy that you carry usuall states in the first paragraph or so "The owner/operator shall keep the aircraft in an airworthy condition" Airworthiness is a combination of condition and conformity, local FSDO variation will be vast and inconsistent. If you have an accident, the ensuing court trial will be detailed, and efforts will be to detect any deviation from the main manual, and assigning blame to such. Engine mounts and exhaust systems are a very dicy areas to be experimenting with processes. That is why any repairs to an engine mount is a "Major" repair requiring a 337. If you are going to go to the trouble to fix this problem, try to fabricate some stainless steel heat deflectors with stand off from the mount tubing, a small amount of air gap does wonders and the stainless has a poor coefficient of heat transfer. Any maint fed would have alot less issue with this type of removable mod and be quicker to buy off on it.
Good luck
PBR

 

[dpilot_citation]

I understand the 337 requirement, the mount was just totally rebuilt and sent back with a 8310. There were 6 braces which had to be replaced due to corrosion caused by heat damage.

Since some turbine wheels are coated with ceramics it just seemed like a viable fix for an ongoing problem. I don’t see the harm in trying to improve a bad situation, the coatings on the parts would be1-2 mil thick and don’t see that as additional weight or changing the intent.

If you have an accident, the ensuing court trial will be detailed, and efforts will be to detect any deviation from the main manual, and assigning blame to such.

If I made every decision in life based on what a attorney could drag up, I would stay locked in a vault. I’m not at all concerned about a lawsuit over a coating as long as it improves a bad situation.

Keep the thoughts coming…

Dpilot_Citation

 

[PBRstreetgang]

I understand the 337 requirement, the mount was just totally rebuilt and sent back with a 8310. There were 6 braces which had to be replaced due to corrosion caused by heat damage.

Since some turbine wheels are coated with ceramics it just seemed like a viable fix for an ongoing problem. I don’t see the harm in trying to improve a bad situation, the coatings on the parts would be1-2 mil thick and don’t see that as additional weight or changing the intent.



If I made every decision in life based on what a attorney could drag up, I would stay locked in a vault. I’m not at all concerned about a lawsuit over a coating as long as it improves a bad situation.

Keep the thoughts coming…

Dpilot_Citation

Well,
Its like this, the manufacturer decides what parts and processes are acceptable. I does not matter what you think or don't think, The Piper manual specifies the acceptable processes allowed for servicing their product. Alright since you are going to have a non FAA approved process applied to the motor mount, how do you know that the chemicals will not cause embrittlment in the weld area zones due to the high temps that the tubing and the unapproved materials you applied? Are you an aeronautical engineer? do you have your DER status? Everybody wants to take a WAG and say it should be ok, well if that unapproved process causes the engine mount to fail with the ensuing potential tragedy, the person who installed the engine mount will be left holding the bag of flaming poo. The overhaul shop will state that the engine mount went out repaired as per the overhaul manual. This is not some turbine wheels that are coated by the manufacturer, this an engine mount who's integrity is so essential that all repairs are deemed major! You asked, this would be the answer the FAA legal office would give you, you want another opinion, ask PIPER Mfg. if they will buy off on the above process, if they will, ask for it in writing and coat away with the knowledge that the manufacturer approves. Aircraft maintenence is fairly simple when the manual is followed, all guess work is eliminated, remember if you cannot support the process with APPROVED or ACCEPTABLE information you are working on your own without a net.
Read the Piper maintence manual and you will find all the info you will need to maintain a safe and legal/airworthy a/c
PBR