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:
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:
Chris Saindon, a podcast listener and owner of a Cessna 172G, contacted me with a different, and important perspective that I had completely overlooked.
I recently told of a landing gear light in a Piper Seminole, and how the pilots had done some in-flight troubleshooting when the right gear down light did not illuminate. I’ve often thought in-flight troubleshooting was a great thing, but Chris reminded me that I need to also communicate the danger of in-flight troubleshooting and the potential for pilots to be distracted from flying the airplane. Before we get into the story Chris shared with me in a voice message, I wanted to share a photo of his Cessna 172G:
Nice airplane, Chris!
Now back to the dangers of in-flight troubleshooting…
Years ago, a large passenger jet descended ever-so-slowly and gradually on a dark, moonless night, down to a crash landing in the Everglades where 101 of the 176 passengers and crew were killed.
The cause? A burned out bulb in the nose gear down light, which caused the 3 active crew members to get distracted.
This accident was a huge catalyst for the beginning of CRM (crew resource management) training in the airlines and beyond. If an accident like this could happen to a 29,000 hour captain, it could happen to anyone.
The following video is startling, but totally worth watching… and all of us can learn some valuable lessons from it.
Chris Saindon is uniquely qualified to remind us of the importance of using great caution and wisdom whenever in-flight troubleshooting is required. His experience includes the following:
Retired US Navy Captain
Navy P-3 pilot
Director of aviation safety programs for Navy and Marine aviation
Airline pilot and airline instructor pilot
Owner and pilot of a 1966 Cessna 172G
…AND, Chris is logging time toward getting his A&P!
I’d say Chris qualifies as the “Airplane owner of the week!” Congratulations Chris!
Chris, thank you for making us aware that in-flight troubleshooting is something we should approach with careful consideration to make sure we avoid the dangerous distractions that can happen.
This was what happened recently in a Piper Seneca… and in this episode, we discuss why the alternator quit… it was something I totally was not expecting.
After verifying the field connections (power and ground) were good, and the brushes were nearly perfect, I removed the alternator.
And here is what I found… watch this video:
It was two things, really. First, the nut holding the drive coupling onto the alternator shaft was loose. And second, the drive gear was turning independently of the alternator shaft… not good! The drive coupling is like a clutch that is designed to slip at a preset high torque value in case the alternator seizes.
I had to look closely to really see what had happened… and I discovered the woodruff key that holds the drive coupling securely to the alternator shaft, had completely sheared off, and the remaining portion of the woodruff key was barely visible in the alternator shaft after I removed the drive coupling… check it out:
And, after the woodruff key sheared off, the drive coupling and gear kept turning while the alternator was not turning, and it wore the alternator shaft right down to the shiny surface you see here.
In case you’re not familiar with a woodruff key, here’s what they look like new, and you can buy them at Aircraft Spruce and other places:
The rounded part goes down into a slot in the alternator drive shaft, and the straight part sticks out of the shaft and engages with the drive coupling as you slide the drive coupling down onto the alternator shaft.
Continental has very specific instructions for installing the drive coupling onto the alternator, along with a specific torque value, and very specific instructions for installing the cotter pin.
In this case, we ordered an overhauled alternator (because the shaft was worn and the remaining woodruff key was stuck in the worn shaft,) an overhauled drive coupling (because the slot for the woodruff key was worn,) and a new special nut for the drive coupling (because the old one was worn due to spinning against the gear/drive coupling.)
So, why did this happen? I’m not sure, but I’m guessing the nut was not torqued properly way back when it was installed at engine overhaul about 400 hours ago.
And my next question is, “What about the left engine alternator?” And did the same person install that one? Perhaps we should remove and inspect that one as well.
Here’s another question I’ve been pondering that relates to the title of this episode: “Why did the alternator fail when he put the gear up?”
And here’s my guess: The drive coupling and woodruff key had been wearing over a long period of time, and was barely hanging on, and finally when it was very weak, at the moment the landing gear pump was activated, it caused a momentary surge of amperage draw, just enough to put an increased load on the alternator, and the small bit of remaining woodruff key sheared off completely and the drive gear was free-wheeling at that point, with the alternator shaft remaining still, making it impossible to produce any more electrical power output.
That’s my theory.
And you may wonder, how did the whole thing turn out?
While I would have liked to finish the repair, I was not able to be in the shop the next day, so another A&P installed everything, and the owner took off for a big trip to the South the next day.
If the alternator had to fail, it happened at the perfect time. It was just after a good long 1 hour plus flight to break in a freshly installed repaired cylinder on the left engine, but before the owner blasted off for a long trip in the airplane… amazing.
And that’s another story we covered in this episode… the left engine #3 cylinder had to be changed due to a burning exhaust valve. Check it out:
The compression in this cylinder was 11/80, and then we found the burning exhaust valve with the borescope. This photo was taken after removing the cylinder.
If this valve had been found earlier, perhaps it could have been saved by lapping and installing a new rotocoil, but since it was too far gone with a green edge due to severe burning and wear on the seating area, it had to be removed.
One more interesting thing about this whole scenario is the owner has had some concerning oil analysis reports from both engines recently, and he’s been trying to get to the bottom of it. Hopefully, after repairing the left engine cylinder #3, including a new exhaust valve and valve guide, and no longer having a woodruff key coming apart in the right engine, the oil analysis reports will be much better moving forward… we’ll see.
Here are a few other items we talked about in this episode:
The turbo Cessna 182 RG that’s ready to fly again after a big annual inspection and cam / lifter change in the engine.
A prebuy on a really nice Mooney M20C.
My good friend Dave Ovad and some fuel system work and landing gear work we did on his nice A36 Bonanza. And just to document this, here’s the P/N for the little thin special washers that go on either side of the middle rod end for the nose gear system, at the idler arm connection at the aft end of the nose gear well: 100951CR016YF If you have a Bonanza and you’re going to replace the 3 nose gear rod ends, go ahead and order a couple of these inexpensive washers, because sometimes, they are missing!
Another turbo-normalized Bonanza I’m currently doing an annual inspection on.
Well that’s all for this time… thanks for joining me!
The post “197 – When He Put the Gear Up the Right Alternator Quit” appeared first at AirplaneOwnerMaintenance.com
This fuel injector line must have only been attached finger tight when the fuel injectors were reinstalled after cleaning. The engine ran fine at first, but all of a sudden during one engine run, the #5 EGT took a nose dive, and the #5 CHT immediately started dropping off as well.
The above photo was taken AFTER we discovered what the problem was. I’m guessing the nut was not tight, and it worked itself loose, causing the cylinder to immediately cease firing, since the fuel was no longer being sprayed into the injector nozzle.
Joe hired me to help troubleshoot the situation. We got on a Face Time call, and I asked him to show me the #5 induction pipe and coupling area, and all of a sudden, he noticed the #5 fuel injector line was not attached…
I was sure this was the culprit, and we were both thrilled to have solved the mystery. In our minds, it would be a simple fix, and Joe would be back in the air again.
Not so fast… since the cowling was off, Joe decided to inspect all the cylinders with his borescope. And that’s when he noticed a bigger problem. Joe noticed the exhaust valve in cylinder #2 did not look good, and he sent me some photos.
That is a really bad looking exhaust valve, with three green edges… one at 1 o’clock, one at 4 o’clock and one at 9 o’clock. The edge at 1 o’clock even looks like it has a scalloped edge, a sure sign it is severely worn.
This valve is too far gone, and is not a candidate for lapping in place. The cylinder needs to come off.
Wow, maybe the issue Joe had with the #5 cylinder was a blessing in disguise, since it prompted him to borescope all his cylinders, and that’s when he found the burning exhaust valve in cylinder #2.
Well done Joe! I’m glad you found these issues before they became an inflight emergency.
A borescope is a necessary tool in maintaining piston engine cylinders, and they are surprisingly affordable these days. I recommend the Vividia VA-400 from Oasis Scientific. It’s the one I use. If you’re considering a borescope you may be asking, “Which borescope should I buy?” This is a great question, and I did a podcast episode about it a good while back. It’s episode 115, and you can find it here: “115 – Which Borescope Should I Buy?”
If you decide to buy a Vividia VA-400 (or another model by Oasis Scientific,) you can check it out here:
And remember to use the code “Dean” for a 10 % discount. (This code only works when purchasing from Oasis Scientific, and I appreciate you doing this, because it helps me out as well.)
Ways you can work with me:
Hire me to review your borescope photos.
Hire me to do maintenance records research.
Hire me for one-on-one consulting.
The details and pricing for these services are on the store page of my website:
When an airplane engine is making a small amount of ferrous metal, but the evidence is not totally conclusive, the decision to tear it apart, or not, can be gut-wrenching.
Such was the case for the O-540 engine in a turbo Cessna 182RG I’ve been working on at Classic Aviation LLC.
But after the owners decided to have it torn apart, and I got to see the evidence, I’m convinced they made the right decision.
Take a look at the two worst lifters:
And the corresponding cam lobe for those two lifters:
Here’s a side view of the worn cam lobe:
Now compare to one of the other cam lobes that was NOT worn down:
After seeing the condition of the camshaft and the lifters, I was very pleased with the decision of the airplane’s owners to have the engine torn down and repaired.
This engine was mid-time, and all the cylinders were running fine with good compressions, so it made sense to do this repair as opposed to a full overhaul.
In this episode, we also discussed some squawks from a Cirrus SR22T. I’ve got some photos and even a video for some of these.
Alternator #1 needed to be removed due to brush wear, and the oil seal was leaking… check out the brushes that came out in pieces:
We also had to send the engine driven fuel pump for overhaul… watch a startling video of a BAD fuel leak:
We sent the fuel pump to Mike’s Aircraft Fuel Metering in Tulsa, Oklahoma for overhaul… they do excellent work on fuel system components.
Happy New Year everyone! May God bless you in 2022!
If you’re thinking about buying an airplane, stop right now and listen to this episode, because Adam Sipe can absolutely save you lots of time, money and needless frustration in the process of buying an airplane.
He shared so much valuable wisdom in this episode, and I can’t wait to listen to the whole thing again myself.
… and don’t be fooled by the fact that Adam is only 33 years old… if you listen to the whole episode, you’ll discover his secret (and it’s a secret that applies to all areas of life,) for how he acquired a lifetime of aviation wisdom in such a short time and at such a young age.
Before we go any further, let me tell you a little bit about Adam.
Adam Sipe is the President of Airplane Intel, Inc., a company that helps people buy, maintain, and manage airplanes. He’s an aircraft mechanic with inspection authorization (A&P-IA), commercial pilot, flight instructor, and Embry Riddle graduate. Adam is also a Marine Corps veteran and host of the Airplane Intel Podcast.
Click the following link to read even more about Adam’s aviation journey:
Here are some examples of the “Prebuy Gold” or “Prebuy Wisdom” Adam shared with us in this podcast episode:
“I call a prebuy more of an investigation than an inspection because you’re trying to uncover things that would be outside the normal thinking of an annual or some other scheduled inspection.”
“Missing records can affect the value of the airplane as much as 30%!”
“Sometimes it’s not what the logbooks say, it’s what they don’t say that’s important.”
“Maintenance affects value.”
“In a prebuy scenario, we don’t need to know all the squawks; we need to know the ones that are most important and the most pressing and the most urgent… and the ones that affect value.”
“You’re not replacing a scheduled inspection with the prebuy, and the prebuy is not going to uncover every defect, because it’s just not possible.”
“This is kind of general to the market… the asking prices are extraordinarily too high… in other words, they’re asking far more for the airplane than what it’s worth, and that’s a huge mistake that people go in and offer full price on these airplanes.”
“There’s two points in a transaction on an airplane where you can negotiate (and I encourage folks to negotiate.) One is when you’re making your initial offer. The second time is after the prebuy.”
“Asking prices are too high, and people are over-paying.”
“If there’s a lien on the airplane, that could stop the transaction from happening, and on that note, I recommend people go through an escrow service… a title company that specializes in aircraft transactions, because the reason why that lien didn’t get caught previously is because they didn’t go through escrow.”
“I’ve seen an airplane that was worth maybe $150,000 have a lien on it for $400,000 because someone used it as collateral for something else.”
“I’ve definitely come across missing AD’s and/or overdue AD’s.”
“I highly recommend taking a test flight in the airplane… now, this is where it’s very critical that you’re clearly not the pilot in command; you’re an observer or passenger in the right seat; you let the owner fly the airplane; or someone that’s on the owner’s insurance.”
“The flight test is in my opinion the most important part of the prebuy because that’s where you’re going to learn the most.”
“Hail damage is repairable, but it’s not worth repairing most of the time because it’s just too expensive.”
Wow! Just this list right here has the potential to save you thousands of dollars in your airplane buying process if you put the principles into action.
I highly recommend hiring Adam and his team at Airplane Intel for your next airplane purchase. I’m confident you’ll be glad you did!
Thanks Adam, for joining us for this episode! And thank you for your service in the United States Marine Corps. We appreciate you!
Adam shown next to his F/A-18C Hornet in Beaufort, SC
To learn more about Adam and Airplane Intel, be sure to check out these links:
If you want to read some fun stuff about Adam personally, he was featured earlier this year in the Ocala Magazine, in the series of articles “40 Under 40.” Well done Adam!
And congratulations to Adam and his wife Sarah with the imminent arrival of their first baby, a daughter! Congratulations Adam and Sarah!
That’s a good question, and although I don’t have the full story, we will toss around some possibilities in this episode. Thanks to all of you who responded with some really good guesses about the cause.
I received responses from 33 people after I sent out that email recently! The prevailing guess about the cause had to do with improper magneto timing which then caused the engine to kick back in the reverse direction and break the starter housing. That was my guess as well.
Be sure to listen to the audio to hear about all the responses and ideas.
In a future episode real soon, I’ll be releasing an interview with Adam Sipe from the Airplane Intel Podcast and AirplanePrebuy.com
Adam has a wealth of money-saving, stress-reducing wisdom and knowledge about buying an airplane and conducting prebuy investigations. Be sure to look for this episode real soon.
My good friend, Clark Trobaugh, flew into KSHD this past week, and while he was visiting with his family, I walked over to his airplane on the ramp and noted a few things that needed attention…
Here’s the one that prompted Clark’s brother Scott to send me a text that said, “Thanks for looking out for him. We always knew he had a screw loose and I’m glad you could fix it.” That made me laugh, for sure! These brothers have a lot of fun together.
It turned out the screw was the wrong one… it was a sheet metal screw and should have been a machine screw. Check it out:
And here’s the result after installing the correct screw:
I also discovered a panel chafing under the left horizontal stabilizer:
I removed the panel, cleaned the area, and reinstalled it:
Another item that needed attention was a shielding ground connection on the left alternator… check out this video:
And one more item I took care of for Clark was the left and right elevator trim tab connections… take a look at this:
Since there is a bushing in this location, the bolt should be tightened onto the bushing and the rotation happens around the bushing. I greased the bushing, reinstalled the bolt and nut, and installed a new cotter pin, for both trim tabs.
Here’s how the pieces look when taken apart:
And here’s the end result after reassembly:
Listen to the audio for this episode for more details on these items, as well as a tribute to Clark and Scott’s dad, Larry Trobaugh, who passed away in May of 2020. Larry was a great man, and I think so highly of him and his family.
In this episode, we are talking about two different exhaust valves, both of which showed signs of burning when we looked at them with the borescope.
One valve was in the beginning stages of burning, and the other was too far gone. Scroll down for more info and some photos.
We also talk a bit in this episode about Arthur St. Clair and his P35 Bonanza. I mentioned him in a previous episode, and recently he came back to Classic Aviation so we could borescope his cylinders and exhaust valves. Thankfully, all his valves were in good shape. Here’s a photo from that day:
Now for the two exhaust valves mentioned in the title for this episode…
Here’s a photo of the one that was too far gone, and the cylinder had to be removed and sent out for repair:
Notice the green edge from 11 o’clock to 2 o’clock on the valve… a badly burning area. The valve guide was also very worn, so we sent the cylinder out for repair.
I also cut the old rotocoil apart for this valve and it had a lot of black carbon bits in it, and the internal spring showed the classic flat spot that is many times seen when an exhaust valve has been burning. Here’s the rotocoil:
The other burning exhaust valve on this same engine was only in the beginning stages, and after lapping the valve and installing a new rotocoil and new valve springs, the compression was 72/80 after runup! What a fantastic result! Here’s what that one looked like:
The small area at 12 O’clock on the valve is starting to burn, but it was salvageable by lapping and installing a new rotocoil to ensure proper valve rotation and better sealing capability.
So the moral of the story is, borescope your exhaust valves at regular intervals, like 50 hours, and hopefully you can catch a burning valve before it’s too far gone and has to be removed.
It’s been a long and in-depth annual inspection, along with the extensive list of squawk repairs. But it’s a great airplane, and I’d love to fly it if I had the opportunity!
In today’s podcast, we cover the remaining squawks on this airplane, concluding with scale weighing the aircraft, and sending it back out into the blue skies yesterday!
I’m confident the owner will get many happy and safe hours of flying out of this amazing airplane.
Be sure to check out the store page to learn more about the services I provide. If I can help you in any way, leave me a voice message by clicking the tab over on the right side of the page or send me an email to dean{at}airplaneownermaintenance{dot}com
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