Airplane Owner Maintenance

A Maintenance Oriented Podcast For Airplane Owners, Pilots, and Mechanics

Tag: exhaust

249 – An EXHAUST-ing Mooney / Continental Story

January 3, 2025 /

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Today’s episode is about Pat’s Mooney, and how we sealed up some exhaust leaks.

And it’s a fun story because Pat has become a good friend… check out the above photo where he’s showing his airplane to my grandson Spencer 🙂

Spencer and my daughter McKenzie stopped by the shop one day when Pat and I were working on his Mooney 252 (M20K.)

And if you’ve listened to the Airplane Owner Maintenance Podcast, you’ll likely remember that it’s McKenzie’s voice in the podcast intro and outro… thanks McKenzie!

Pat flew his Mooney from Wisconsin to Virginia for his annual inspection, and he hung around for several days to work with me on his airplane… I love airplane owners like Pat!

I love working with the “Pats” of general aviation because they tend to have some or all of the following traits:

  • They love aviation as a whole.
  • They are interested in the maintenance side of things.
  • They want things fixed and working properly.
  • They are easy to work with and fun to be around.
  • They care about people and relationships.

And that pretty well describes Pat, so we got off to a good start on his inspection.

One of the squawks I discovered was 5 of the 6 exhaust flanges had small leaks at the gasket area… we found this while doing a pressure test on the exhaust system. Here’s one of the flanges that was leaking:

This engine is a Continental TSIO-360 and has 2 thin stainless steel gaskets P/N 630365 on each cylinder.

Here are the old gaskets I removed, along with one stud that backed out and had to be replaced with a new one:

I’ve found there is significant confusion out there about how these gaskets should be installed.

One side has a raised area, or a bump on it, and the other side has a recessed, or concave area.

As I’ve researched the internet (sometimes a not-so-good place to get good information,) it seems a fair number of people think these gaskets should be “nested” together for installation.

That is, put both gaskets in the same direction to they fit together, and then install them.

I wanted a definitive answer, so I called Continental.

Vadin was very helpful and explained it to me this way:

“You want to create an air pocket between the two gaskets.”

This means put the concave or recessed side of the two gaskets toward each other and this creates the air pocket.

Then, as you torque the exhaust nuts and squeeze the gaskets together, the bump on the top gasket is up against the cylinder flange, and the bump on the bottom gasket is down against the exhaust riser flange, and in this way you can hopefully seal up any small imperfections on the surfaces and get a perfect (or nearly perfect) seal.

Also, there is another type of gasket that can be installed on this engine… it’s the “blow proof” gasket made my Rapco, P/N RA970.

Here’s the visual difference between the two types of gaskets (the thin ones on the top and the thick, blow proof one on the bottom):

I asked Vadin at Continental about these, and he could not officially endorse them, but he also acknowledged that some people seem to have good success with these thicker gaskets.

So, after discussing the situation with Pat, we decided to go with the thicker, blow proof, RA970 gaskets.

Prior to installing the gaskets, I had carefully sanded all 6 exhaust riser flanges flat and smooth so as to get the best seal possible. Here’s a photo of the exhaust system before sanding the flanges:

I carefully installed the new gaskets, and torqued all the nuts with the studs properly lubed with engine oil.

I was excited to do another pressure test and was confident about the results.

I was sorely disappointed.

Five of the six flanges still had small leaks.

Back to the drawing board.

I texted Pat and notified him that I thought we should try the other type gaskets and see if we could get a better seal.

He agreed.

So, I reluctantly removed the thick RA970 gaskets and installed two each 630365 thin gaskets (properly positioned) on each flange and retorqued everything.

Time for another pressure test.

It wasn’t perfect as I had hoped, but it was very acceptable.

Three of the flanges were perfect with zero leakage.

The other three were nearly perfect with only very small bubbles forming slowly at one side of the flange during the pressure test.

I’m satisfied with this… and as I thought about the whole situation, I suppose you could buy a whole new exhaust system for the engine in hopes of getting a 100% perfect seal, but I don’t think that’s necessary in this situation.

I also realized that if this was my personal airplane, I would feel the same about it, and I would fly my family in it with great confidence.

Be sure to listen to the audio for this episode to hear the whole storyl

And after all that, I’m EXHAUSTED!

But it’s been totally worthwhile, because Pat is such a great guy to work with!

Thanks Pat, and I look forward to returning your airplane to you real soon!

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222 – How an Engine Cylinder Went From 25/80 to 75/80!

May 13, 2023 /

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I inspected another A36 Bonanza recently, and one of the cylinder compressions was too low… lower than the minimum prescribed by Continental using the master orifice tool.

I had two options:

Option One: Remove the cylinder for repair or replacement.

Option Two: Make the exhaust valve seal better and improve the compression result in hopes of saving the cylinder from premature amputation.

I chose Option Two.

It was at least worth a try…

… and the result was stunning!

After lapping the valve in place and installing a new rotocoil, I ran the engine again and rechecked the compression.

It was 75/80!

The lowest cylinder on the engine was now the highest cylinder.

I also lapped the exhaust valve in cylinder #2, and that one improved from 49/80 to 63/80.

If you’d like more info about valve lapping, click here for episode 109.

Another surprise during the inspection was a cracked / leaking exhaust riser.

Here’s a close-up view of the bad area:

Also in this episode, I talked about some other squawks that were repaired during the inspection. Be sure to listen to the audio for all the details.

In Part Two of this episode, I talked about our most recent trip in the King Air. It was quite an adventure navigating some weather situations!

The post “222 – How an Engine Cylinder Went From 25/80 to 75/80!” appeared first at AirplaneOwnerMaintenance.com

199 – A Bulging Exhaust – Change it, or not?

March 11, 2022 /

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I recently inspected a Piper Saratoga, and I found the following condition on the right exhaust collector:

Earlier this week, I sent this photo to my email subscribers and asked if they would change this piece of exhaust if it was on their airplane. I received a huge response about this, with a large range of thoughts and opinions. Thanks to everyone who responded, as it really helped me think through the issue in a much more comprehensive way and I think you’ll find it helpful as well.

I read all the email responses in this episode of the podcast, and listed some lessons for us to learn from this exhaust story.

Today, I removed that exhaust collector and all three of the risers. When I looked on the inside, it became clear to me why it was bulged and deformed. The inside was eroded and thin in the area of the bulging, and I was glad we decided to change it.

I was reminded that when a piece of exhaust shows something like this on the outside, there is likely something happening on the inside as well. Here’s a close-up of the inside:

That’s evidence of many hours of exhaust gases rushing down on this area and going out the muffler.

It was definitely time to change this one. After reading all the responses and thinking about this all week, I’m convinced it’s much better to err on the safe side with exhaust systems.

Dave Ovad provided a link to an accident report where a Beech Debonair crashed because of a muffler failure and subsequent engine fire caused by the exhaust gases. It’s a startling reminder of how important it is to give special attention to exhaust systems. Here’s the link:

http://www.kathrynsreport.com/2019/03/beechcraft-35-a33-debonair-registered.html

Dave, along with at least one or two others, also pointed out that it’s very important to fly with a good quality CO detector, to help prevent carbon monoxide poisoning.

Thanks so much to all of you who contributed to this episode by sharing your thoughts with me!

For more information about exhaust systems and carbon monoxide dangers, check out episode 035:

035 – Airplane Exhaust Systems Tell Stories… Are You Listening?

The post “199 – A Bulging Exhaust – Change it, or not?” appeared first at AirplaneOwnerMaintenance.com

135 – Carl Valeri: Airline Pilot, Piper Pilot, and Aviation Careers Coach

February 9, 2020 / / 0 Comments

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After a successful career in computers early in life, Carl Valeri decided years ago it was time to pursue his passion for aviation. Since that time, he’s been an airline pilot, flight instructor, aviation careers coach, mentor, Piper Cherokee pilot, and many other things.

Carl is well known as the host of two podcasts, the Aviation Careers Podcast, and the Stuck Mic AvCast. You can find him in both of those places:

AviationCareersPodcast.com

StuckMicAvCast.com

Be sure to check out the Scholarships Guide that Carl produces… there are more than $50 MILLION dollars worth of scholarships represented in the guide. Click here to check out the Aerospace Scholarships Guide.

Also, check out Carl’s training courses: Click here to see the options.

And for Instagram, just look for “carlvaleri”

In today’s episode, we talked about all kinds of fascinating things, including:

  • Carl’s background and how he got into aviation.
  • How he was hired years ago as an airline pilot, and furlowed the same year, in 2011.
  • How his struggle served to prepare him for what has become one of his greatest passions… “Helping people move forward with their aviation career.”
  • What the acronym “CAMEL” means to an airline pilot… I had never heard this before, and I thought it was really cool.
  • Carl’s current opportunity to lease and fly a Piper Cherokee… the 12th Cherokee to come off the line years ago.
  • The maintenance issues he’s encountered recently with the Cherokee.

And since this is the Airplane Owner Maintenance podcast, it’s only appropriate that we document this part with some pictures.

ISSUE #1: Smoke in the cockpit! Apparently somebody forgot to tighten an oil line!

The oil made a mess on the cowling. And upon closer examination, the source was identified – the rocker oil return line B-nut had come loose. When the oil dripped down on the hot exhaust, it produced smoke that made its way into the cockpit.

Solution and reminder: Always double check engine fluid lines and hoses, and apply torque putty to the B-nuts.

ISSUE #2: Fuel leak. Carl told us about a leak that showed up under the airplane on the left side. Listen to the episode to hear his advice about how to communicate with your A&P about issues like this.

It turned out the leak was from his “gascolator” or fuel strainer. Here are the parts from this ancient piece of technology… just like you might have seen on your grandpa’s tractor!

In this situation, Carl made the wise decision to upgrade to a “Steve’s Aircraft” gascolator, a much better design with increased reliability and ease of maintenance. Take a look:

ISSUE #3: Exhaust leak. Carl noticed some abnormal discoloration at the cowling seam.

It turned out there was a significant leak at one of the exhaust sleeve transitions in the engine compartment.

This situation is a little different than many Cherokees, since this particular engine was installed with an STC.

ISSUE #4: Electrical problem. With the benefit of 20/20 hindsight, Carl was able to recognize how the airplane had been showing some warning signs of this issue… be sure to listen to the audio to get the details.

What seemed like a complex problem in the beginning, turned out to be a blown fuse.

Sometimes the little things can make a big difference!

In spite of the maintenance challenges, Carl still loves to fly the Cherokee. I think one reason why is because he shares his love for aviation with others:

In telling about his aviation adventures in life, Carl is quick to acknowledge that, “I could never have done any of that without the help of others.” Now, he’s “paying it forward” in so many ways to help those who are coming behind him.

And finally, to finish up with a little humor: “Even an airline pilot who flies jets, recognizes there’s something missing in the following picture!

Carl, thank you very much for pushing all of us to keep moving forward and appropriately pursue our aviation dreams! We appreciate you, and I sure am glad flying still puts a smile on your face!

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