Happy 4th and Muffler Tip Question

[M Towsley]

Happy 4th to everyone on this side of the pond, and a great weekend to those on the other side.

While flying back from a fly-in this morning apparently my exhaust tip decided to depart, (appears from rust and thin metal). It broke off about even with the bottom of the heat muff.

I have a spare, used, exhaust but what a PITA to replace the system. Has anyone, (after checking to see if the rest of the exhaust is viable), welded on a new tip while on the airplane? If so, what did you use? Thanks in advance!

[Robert Lees]

Re: Happy 4th and Muffler Tip Question

Thanks for the kind sentiment, Marty, and we were glad to see the back of y'all 235+ years ago! Even more so now that "General Lee" is losing it's Confederate Flag on the roof...how I used to enjoy the Dukes of Hazard (well...Daisy, actually )

I have (in the past) screwed on a chrome automotive extension to get the exhaust gases out of the lower cowl. I fear that this type of "repair" might not be according to approved data in the US (we operate our Taylorcraft here in the UK under a non-certified system, similar to the Canadian "Owner Maintenance" programme.

I think you will have to do the decent thing and get it sorted properly to stay legal in the US. And no, don't weld it on the airframe.

Interestingly, I contract a few days a week to a certified shop here in the UK and by rote we remove exhausts every annual for pressure testing.

It keeps the exhaust in tip-top condition, satisfies the requirement for a cabin heat pressure test (same as you guys) and prevents the exhaust studs/nuts from corroding solid or pulling out of the head. All for an hours labour and 4 new gaskets & lockwashers.

Rob

[Hank Jarrett]

Re: Happy 4th and Muffler Tip Question

That would make a FANTASTIC video next time! MANY people who don't have Stainless exhausts ignore the 25 hr inspection of the exhaust and I don't know of anyone who has been able to remove an exhaust and replace it in an hour! We want to watch your technique....even if it takes SEVERAL hours!

Hank

[Pearson]

Re: Happy 4th and Muffler Tip Question

Before you go to very much trouble doing a repair, I suggest you THOROGHLY inspect the rest of the exhaust. Check it by hooking a vacuum cleaner hose connected to the exhaust of the vacuum, so that it blows instead of sucks. I use a Craftsman shop vac at each annual. The hose is a perfect fit. If yours doesn't fit well you may have to use some duct tape. Mix up some soapy water and brush it on the exhaust pipes. If you see ANY bubbles, you might want to do some poking with an awl to make sure the metal isn't rusted so thin it is beyond repair. I would hate to see you go to the trouble of welding an extension on and then find out the rest of the exhaust was also rusted out.

[magman]

Re: Happy 4th and Muffler Tip Question

I AGREE with Pearson BIG-TIME!

I personally use a Leaf Blower.

It will show up cracks undetectable by Vis alone.

One find was on a T-Craft with a spiral crack about 400 degrees

around the Pressure Can.

No removal needed.

Plugs IN helps.

[astjp2]

Re: Happy 4th and Muffler Tip Question

Hank, what requirement is the 25 hour inspection due? was that the Piper AD one? Tim

That would make a FANTASTIC video next time! MANY people who don't have Stainless exhausts ignore the 25 hr inspection of the exhaust and I don't know of anyone who has been able to remove an exhaust and replace it in an hour! We want to watch your technique....even if it takes SEVERAL hours!

Hank

[Hank Jarrett]

Re: Happy 4th and Muffler Tip Question

It is in some of the OLD paperwork on my Taylorcraft. The inspection seems to have just fallen off the "T" records, but sure makes sense, especially considering the number of perforated exhaust systems I have seen. Neither I nor my IA could find any current requirement, but the tag saying to do it is on LOTS of the old Taylorcraft heat muffs.
The real solution is to use SS exhaust systems.

Hank

[labe0202]

Re: Happy 4th and Muffler Tip Question

It is in some of the OLD paperwork on my Taylorcraft. The inspection seems to have just fallen off the "T" records, but sure makes sense, especially considering the number of perforated exhaust systems I have seen. Neither I nor my IA could find any current requirement, but the tag saying to do it is on LOTS of the old Taylorcraft heat muffs.
The real solution is to use SS exhaust systems.

Hank

I remember seeing a placard saying as much on the heat muff on mine too.

[M Towsley]

Re: Happy 4th and Muffler Tip Question

Tim,

On the original muffs there used to be a placard attached that advised to remove the muff and inspect the exhaust. Current-built muffs don't have that.

[astjp2]

Re: Happy 4th and Muffler Tip Question

Yes, but I have to look at regulatory requirements. Continental/Lycoming says that if you prop touches a blade of grass, its an engine stoppage, and requires a full overhaul. FAA says that you inspect (dial indicator/check the crank) and if its in spec, fly it. Bendix and Slick says that 500 hours/5 years requires a tear down of the mags, how many of you have pulled mags in 5 years and only 150 hours if you only fly 30 hours a year? It is required to inspect annually and at 100 hours if you fly for hire. If you don't trust your exhaust enough to fly for a year, would you not change it to something you trust until the next annual?

something else to think about:
Just because the FAA expects the aircraft to be airworthy at the time the inspection is dated, does not mean that some frivolous lawyer wont sue you for something that you as a mechanic did 5 years ago....

[M Towsley]

Re: Happy 4th and Muffler Tip Question

I think we are getting off of the subject, (I think).

The exhaust gets inspected at annual, I usually don't get that much flying in per year. It will get inspected again once I pull the cowl and the muffs.

So either way, repair or replace, I will need to pull the engine/mount and see how it looks. If the exhaust outlet can be repaired, any thoughts?

If I have to put my used spare exhaust on are there any thoughts on exhaust gaskets? I cannot remember the preference on those. I know there is a reason for one over the other. Thanks.

[magman]

Re: Happy 4th and Muffler Tip Question

CO Detectors are the cheapest Life Insurance you can buy.

Even the little dot can save your life.

btw- Hitting a blade of grass is is NOT a Sudden Stoppage

& if it was it's still not an Overhaul.

[Hank Jarrett]

Re: Happy 4th and Muffler Tip Question

I have seen a WHOLE LOT of exhausts with a new pipe welded on that you couldn't tell unless you pulled the heat muff off (which is fine by me). If it isn't leaking and your IA will sign it off I see NO problem. It is another one of those things where I do what is SAFE first and what is legally required by the FAA second. If what I do exceeds the requirement, fine and dandy. IF I think the FAA is full of "soft brown and smelly", well, I hold my nose and do it anyway. If they want me to do something I think is UN-safe, then we have a problem, but it is the IA who makes the next to last call. I make the LAST call when I think something isn't right anyway and then I just don't fly her until I am convinced.

Hank

The FAA can't MAKE you fly, but they can stop you. I have no safety concerns with a properly welded exhaust, but I won't be signing it off.

[Mark Julicher]

Re: Happy 4th and Muffler Tip Question

It is not too difficult to weld a new tip onto an exhaust. It can be done in place, but it is safer and easier to weld if the exhaust stack is on the bench. If you have the conical stand-off that holds the lower heat muff in place, then you must consider how you are going to slip that conical piece back on -- in other words, the weld must be flat enough to allow the stand-off to slide up the down-pipe.
You may have to remove six or more inches of the original pipe to get to some metal that is sound enough to take a weld.

[Robert Lees]

Exhaust gaskets

....<snip>

If I have to put my used spare exhaust on are there any thoughts on exhaust gaskets? I cannot remember the preference on those. I know there is a reason for one over the other. Thanks....</snip>

Marty, I always use the spiral wound gaskets. RA627429 (Aircraft Spruce P/No 08-05229). For an A65, one or two of them need grinding a little bit on the outside edge to get them past the intake elbow. I can't recall which cylinders require this, but it's little more than a few licks with a file.

They are more expensive than the pressed-steel ones, but are better quality and seal better.

Just my opinion.

If you do remove the exhaust, make sure the flanges are flat. Old thinner flanges can warp, and that could lead to exhaust gas leakage, whatever gaskets are used.

Rob