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TOPIC: Distorted firewall in 182. Is replacement a MUST?

Distorted firewall in 182. Is replacement a MUST? 1 month 1 week ago #1160

  • Kent Dellenbusch
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Thank you Paul!
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Distorted firewall in 182. Is replacement a MUST? 1 month 1 week ago #1156

  • Alan
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Thanks, Paul. Great info!
Knowing what I do today, if I had owned the airplane when this incident happened I would have ask for the additional structural bracing (and paid for it myself). But I'm not going to have it done now. I don't fly rough fields or training operations and I don't have insurance concerns. (By coincidence, my insurance company rep happened to be in my area so he saw it in person.)
The firewall sheet is not buckled, wrinkled, creased, or otherwise damaged but it is also not perfectly flat. This does not concern me because any damage to the structure was repaired -- all affected bulkheads, stiffeners, doublers were replaced.
I did get a preliminary estimate from Beegles. (They did not look at it in person.) To replace the firewall sheet and add two stiffeners is 156 hours labor. It's something I may do some day, if there is a need for other repairs. But to tear into it now is too much risk for too little benefit.
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Distorted firewall in 182. Is replacement a MUST? 1 month 1 week ago #1155

  • Paul Gryko
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SK182-44C should be done when that part of the aircraft is opened up and easily accessible. IE it should have been done when the firewall was initially repaired regardless if the insurance was paying for it or not. In today's world, SL SE71-5 would be viewed as justification to deny a insurance claim if you were found to have used "Rough Field and/or training operations". Since this information is available to the owners and mechanics and required for sign off using a aircraft KNOWING there is a potential for damage may not be in compliance with some regulatory information.

Without getting into the nitty gritty of it, I have attached the section from the manuals. (You can sign up at Textron and get all the latest stuff you need for your plane.)
You can see in black and white what your mechanic is saying, how the previous repair should have been completed etc. There are other structural repairs available to some service centres that may be 3rd party. The beef up I was referring to is one of these done by STC. I was going to attach it but for some reason it wont upload.

Ultimately it should be at the minimum "Addressed". If you need a second opinion, take it to someone like Beegles in Colorado that 1)specialises these sorts of things and 2) really doesn't need any "make work" projects.
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Distorted firewall in 182. Is replacement a MUST? 1 month 1 week ago #1154

  • Alan
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Just to close this off...

After consulting many experts and conducting my own research, I've concluded that my prior mechanic's proposal to replace the firewall skin is too risky. I've chosen not to do this, and have engaged a new mechanic (IA) who agrees with my assessment.

As the owner/operator, it is my responsibility to maintain the aircraft in an airworthy condition. While I respect the professional opinion of the mechanic who says the firewall is unairworthy, I disagree. (This is somewhat analogous to if my doctor told me I have cancer; I would seek a second opinion. The second doctor may agree or may not. Either way, it's my body and I will choose the treatment.)

In this case, my new mechanic examined it, then contacted the FAA at my FSDO, and sent them pictures. The FAA agrees, as does almost everyone else, that the firewall is fine. A quote from AOPA resonated with me: "There are mechanics who are pragmatic, and there are those that want to do a $12,000 annual every year."

The other decision factor was this: Replacing the firewall "skin" is a major repair in any sense of the word. There are many things that could go wrong and remain undetected until failure. My plane's 'tunnel structure' was replaced 10 years ago. It, and the existing firewall, has had hundreds of hours of successful flight testing. The risk/benefit ratio of replacing the firewall now is simply too high.

P.S. I am aware of Service Kit SK182-44C for firewall and tunnel reinforcement. If I ever do need the firewall repaired I will apply this. But for now, "if it ain't broke, ...".
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Distorted firewall in 182. Is replacement a MUST? 1 month 3 weeks ago #1140

  • Paul Gryko
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Alan,
You can add reinforcement kit to that firewall to strengthen it up. The firewall skin is a skin but the combined stringers, and structure DOES make is structural. On the 182 Float Plane, the float struts are attached to the lower firewall. The landing load is then transferred through the Float Style mount to the upper firewall and structure. Then depending on the actual kit tie rods connect that load to the wing spar.

The biggest concern is is that the nose gear is attached to the 'tunnel structure' and if it came loose or was not attached properly the next incident may not take as much of a hard landing as you think.

Most people don't realise how bent the firewall is until they either 1) Measure the firewall dimensions from one point to the other 3 engine mount bolt holes 2) try and install a float style mount. The stock mount has some give but over time you risk cracking the tube at the aft gussets. The problem can be made worse buy a up-rated engine, 3 bladed prop while using the little rubber mounts that were in the firewall initially.

PG
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Distorted firewall in 182. Is replacement a MUST? 3 months 3 days ago #1041

  • Alan
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Thank you both for your reply! You're both saying what I suspected, but I'm not a mechanic. Unfortunately, my mechanic doesn't agree so I will either need to shell out $20k to fix it or find another mechanic. Thanks again!
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