Hey Britt, thanks for your thoughts!

You where wondering about the “sequence” of the demise of a burned valve: What fails first, the valve, or the guide John Schwaner, on page 81 of the Skyranch Engineering Manual, writes: “Most of the heat conducted from the head of the Lycoming exhaust valve goes out through the valve stem into the cylinder head fins.” The guide is in this heat path.

To support this conclusion further, Mike Busch, in his article entitled Exhaust Valve Failures, Part 2: Preventing Failures By Early Detection, states: “We’ve seen that exhaust valve failure is usually caused by accelerated valve guide wear.” He then relates to a personal observation of nickel content in engine oil analysis which was followed by the demise of the corresponding valve in his Cessna 310. The valve guide is the source of the nickel alloy. He presents chronologic evidence in support of his statement.

Thanks for another podcast. Please, keep ’em coming. We want to know how to think like the pros.

Britt,
Roping the cylinder is a very interesting idea for ferrying a 4 engine aircraft… makes sense to keep the inop engine from turning during flight.
As far as “roping the cylinder” during compression testing, I’ve never heard of that. During compression testing, we need the cylinder at top center on the compression stroke. When it’s perfectly at top center, it usually does not take a lot of effort to keep the prop from turning. But as we rotate the prop back and forth on either side of top center, that’s when it takes a lot of pressure, and deserves much caution. If we put a rope in the cylinder, it would not let us position the piston at top center, so I don’t think that would work. The bottom line is we always need to use great caution while performing a compression test. Thanks for your post here… it’s a very interesting idea to think about!

“Roping the cylinder” is a technique routinely employed during 3-engine ferry of 4-engine reciprocating powered aircraft to secure inoperative piston engines. The rotation of which could cause the propeller to come out of it’s feathered position, and run away.

I greatly enjoy your podcasts and thank you for making your wealth of knowledge available to our aviation community.

Hi Bill! The new borescope is the same model… the VA-400. They’ve designed a better resolution camera for it, but it’s still the same model number. I think you can still get 10% off with Oasis Scientific if you use my code “Dean.” https://www.oasisscientific.com/store/p314/Vividia_AbleScope_VA-400_Rigid_USB_Borescope_Endoscope_with_180_Degree_Articulating_8.5mm_%280.33%22%29_Diameter_Probe_and_LED_Lights.html

Thanks Allen… I’ll send you an email and check in. You’ve got me curious about that engine now.

If the engine quits when you select one mag, it’s usually either a bad mag, or a worn P-lead wire that is shorting to ground somewhere, often near the magneto. You might be able to do some troubleshooting by swapping the P-leads left and right. Let me know how it turns out.

Good info Scott… thanks!

where are the mags typically ground faulted I am having this problem, engine quits on right mag

Yes, this is the new one… and the photo resolution is quite a bit better than the previous version. I used my new one recently and was very impressed with the quality compared to my old one. If you buy it from Oasis, use the code “Dean” for 10% off.

Hey Troy! Yes, that’s the new version of the VA-400. I tried my new one out today, and I was surprised at how much better the resolution and sharpness of the color was. If you decide to buy one, I think it’s a good investment. Also, if you use the code “DEAN” when you buy from Oasis Scientific, you can get 10% off, and you’ll also be supporting the podcast as well. Thank you Troy!

https://www.oasisscientific.com/vividia-va-400-rigid-usb-articulating-borescope-videoscope-inspection-camera.html

Thanks,
Troy

Thanks Glen! I appreciate the tip!

I look forward to your podcasts and particularly enjoyed the recent strut servicing discussion as we own a Cherokee 140 that has three struts to service.

I wanted to mention an interesting thread on the Piper owners blog that I thought you might be interested in. https://www.piperforum.com/threads/bicycle-strut-pump.22737/

Thanks again for all you do to keep us flying,

-Glen

We arrived at the airplane a little after 1 pm. We assessed the situation, uncowled the engine, drained oil removed bottom spark plugs and oil suction screen, checked out the farm field, towed the airplane up to a level area, and removed the wings. Probably had them off by around 7 pm. So it’s hard to say exactly how long for wing removal alone. The local farmers were super helpful in draining the fuel and supporting the wings as we removed them. The biggest difficulty was removing the wing attachment bolts.

Thanks Peter!
I do not know of a good A&P in the Chicago area. Sorry.

If you select R mag and the engine dies, it would seem the R mag is bad. Or, the P-leads could be swapped and the L mag is bad. You could also swap the P-leads and see what happens. Which mag did you replace Did it work at all after replacement Let me know.

Your welcome! Do some research for a good used one, or ask around in the forums and Facebook groups.

Travis, that’s very interesting indeed… thanks!

John, thanks so much for sharing that story. I’ll pass it along!

Thanks Don! This is great information, and I appreciate you sharing it.

Smoke machine!

https://mooneyspace.com/topic/34821-n2652w-will-have-a-new-home/page/10/#comments

Ck the YouTube videos…

Kent, thanks for your thoughts! That’s very interesting about the belly pod and the CO numbers.

As far as the T-34, it might be worth looking at the engine shock mounts, but I have no idea who does the maintenance on it. Good observation on your part!

Thanks for your thoughts John! That’s good information.

Joe,
I use the Airbox device with my iPhone. I’m not sure about the details of using it with an Android phone. We have also used the borescope with an Android tablet, so that is also an option, and you don’t need the Airbox device for that. If you need to speak with someone about using the borescope with your Android phone, send me an email to dean@airplaneownermaintenance.com and I can put you in touch with Courtland at the company that sells the borescope. Thanks,Dean

However the WIFI image app does not work. The screen remains black.
There is an error: “The system detected the last exception to quit. Do you want to send a report and need to connect to the Internet#8221;
I have provided the default permissions for the app to access smartphone’s storage.
I am using a motorola Moto G5 Plus, with Android 8.1.0.

The borescope camera works, when I plugged it into a computer and installed “vividia_ablescope_viewer_setup.exe” But I purchased the AirBox for the mobility and convenience of connecting to a smart phone.

After removing the belly pod, the number sots at zero at all times. I found that interesting.

On another note Dean, looking at the General’s T-34, notice the misalignment of the spinner and cowling Is this an indication of new rubber dampers needed on the motor mount or is this a misaligned cowl or even a bent motor mount?

Keep up the great work!

We had about a dozen other aircraft all on Slick mags and with about 4,000 hours per year never had any problems* with them either (and they were a breeze to work on compared to the Bendix duals.) (That is until Champion bought the line and cut manufacturing corners, which I understand that they have now worked out.)

This statement is a bit of a ‘math trick’. Accidents due to mag failures are rare. If 1/10 of one percent of accidents are due to mags of all sorts, and that rises to 1/5 of one percent when only dual mags are considered, it is both fair and true to say that “there is very little difference”. After all, it has risen only a fraction of a percent, right And, I’m sure that most crashes of dual mag equipped aircraft are still “pilot error”. If a dual mag equipped Pa31 looses an engine because the mag fell out, and that guy crashes, even that is pilot error. I say that because most dual mag aircraft I’ve dealt with happen to be Navajos. Regardless, redundancy and tolerance for mechanic error are reduced, and in the above scenario, the risk has doubled…while also being “a slight increase”. Redundancy is good in aviation.

Diego, thanks for your question! Go to AirplaneOwnerMaintenance.com/115 That episode is called “Which borescope should I buy#8221; There are two links there for the Vividia Ablescope VA-400. One is for the borescope alone, and the other is for the wifi bundle which includes an adapter for using it with your iPhone or iPad. Also, if you use the code “Dean” at checkout, you’ll receive a 10% discount. Let me know if you have any other questions.

It’s not difficult to remove the rotocoil if you have the right tools and you’ve done it before. The first time it’s best to do this with someone who is familiar.

thank you

Diego – From Uruguay SA

Thanks Natalie! I appreciate your thoughts… and I certainly remember reading your article in the AOPA Pilot magazine about “imposter syndrome.” Well done… I’m sure that was an encouraging message for a lot of people… I know it was for me!

Thanks Steven! That’s a very good point… thanks for sharing it!

While looking on Aircraft Spruce & Specialty to find out more about the SCAT, SCEET, CAT and CEET hoses, I noted the following under their Aeroduct SCEET Ducting listing (https://www.aircraftspruce.com/catalog/appages/thermoid-ad-sceet.php):

“Not recommended for handling liquids or highly abrasive materials, or for negative pressure applications. ”

[Note that this warning is not present on the other brands of SCEET that they sell.]

This makes sense as any delamination will likely cause a collapse with negative pressure. The induction system is under negative pressure, so this is an important consideration. Production aircraft with approved parts probably will not use SCEET, but this is an important consideration for E-AB aircraft!!!

Thought this is important to pass along.

Thank you Scott… I certainly appreciate all you’ve done for the GA community as well!

Thank you Jim! The additive is called Granville Strut Seal. You can find it here: https://www.aircraftspruce.com/catalog/pnpages/06-13300.php

I absolutely love listening to your Podcast. Keep up the great work. Quick question: I believe I heard you talking about an additive you use to fix a leaking strut. I believe you said you add it to the strut and it swells up he O rings. My friend has a leaky strut on his champ and I thought of the stuff you mentioned, but I can’t remember the name of the stuff. Could you please send me the information of that additive.

Thanks,

Jim

You’re welcome… thanks for your thoughts David!

Awesome!

Hi Bob,
It might be good to verify the P-leads are attached to their correct magneto… sometimes P-leads get swapped, and this can really cause some troubleshooting confusion. After verifying P-leads are in their correct location, I would do some testing on that left P-lead wire, with it disconnected from the magneto… With the ignition switch off, there should be continuity to ground, from the P-lead wire terminal… while watching an ohm meter, wiggle the wire around and see if resistance goes up… maybe there’s a broken wire inside the insulation. I wish I was there to look at it for you! Keep us posted how it turns out.

Excellent discussion on how to troubleshoot a magneto. I have a 2020 Cirrus SR22T that at 40 hours flight time developed a right hot magneto. With the switch on RIGHT position there was no rpm drop and when moved to the OFF position the engine continued to run. This problem was intermittent in nature. The P-Lead wiring was thought to be fine and it was recommended that the LEFT magneto be replaced which it was. Everything worked fine for about 4 flight hours and then the same issue developed with no rpm drop in the right position and the engine continues to run in the OFF position. This issue is always present. It is going back into the shop next week. Any thoughts as to cause and next steps?

Thanks for your story Kent! I’m glad you were able to land safely!

I’ve heard bits and pieces about the plans for the 737, but I’m really not sure what it will be used for. Time will tell!

So yeah, I agree with hour assessment, Dean. Love the podcast!

Absolutely, you’re welcome!

Yes sir, a small punch and some light taps with a small hammer should drive the locking pins in just fine. Let me know how it turns out. Also, here’s a short simple video I found to be really helpful as well: https://www.youtube.com/watch?v=XyCTh23Z6o0

Sometimes they can be difficult, for sure! Remove the fuel cap and use the opening to try to pull the tank forward. If this does not work, you might try placing the end of a piece of 2×4 wood on the back edge of the tank, and hit the other end of the 2×4 with a rubber mallet to try to dislodge the tank. Do this in multiple locations on both the top and bottom, and hopefully the tank will come loose. Hope that helps.

Hey Doug!
Thanks for your feedback…good things to think about, and I appreciate your input. As far as a plane with a stuck valve, I might be cautious to fly that plane again until the guide is reamed, since I wouldn’t know when it might stick again. But that’s a great point, you can probably use the rope trick to “unstick” the valve.

Many of the big Continentals have RPM limitations associated with crankshaft harmonics, so be aware with STCed engine upgrades.

Final note, many episodes ago you referenced a stuck valve on a Ercoupe, this is all to common on small continentals. You can use the same cylinder rope trick that you use to lap valves to pop that valve down and get the plane back home so you can ream the guide, no need to be stranded. Aggressive leaning and auto gas seem to help prevent future occurrences.

Thank you Fax! Yes, Jim’s list and other info is available on his website at http://www.rst-engr.com/annual/
Just scroll down and click on “annual policies” for the 4 page document I referred to in the podcast.

That’s a good point Ken. Thanks for pointing it out.

Thanks Mario! Maybe it will work out sometime!

Hi Ramon,
I agree there should be no oil inside the mag. Perhaps it needs a new oil seal on in the drive end of the magneto.
As far as the stumble and the fuel system, that’s hard to say what’s going on there… one thing you might do, is pressurize the induction system with a small amount of air pressure and check for induction leaks with soapy water… check the intake gaskets and the other end of the intake pipes… the couplings if you have that type, or the orings if you have that type. Let me know how things turn out.

Mark,
If there’s air in the line, it is important to purge the air out of the line so you have it filled with oil. This will give the most accurate reading.

If you purge the air out, and still have no oil pressure, definitely find out why… let me know what you find.
Dean

thanks Mark

Don, is it necessary to purge the oil pressure line to the gauge in order to get it to read correctly I was flying when I noticed ZERO oil pressure. Made it back to my runway. The pump is pulling oil out of the oil pan but I don’t have a reading on my new mechanical gauge install outside the cabin for checking function.

thanks Mark

Thanks Keith!
That’s a really great idea… I really would like to do something with that one soon.

Thanks John! You are one of two people so far who have let me know about the mistake I made in this episode, and I appreciate that. I modified the audio and went back to that 20:38 location and added a “wrong answer” sound effect, along with some commentary to clear up the mistake. Thanks for taking the time to respond and to share some info to help us think through the mag switch positions and what they mean. Well done!

If I got it correct, the ignition switch’s job is to “ground” and “un ground” the P-Leads in order to disable and enable the Mag(s) it is connected to; in other words, a grounded P-Lead turns OFF a Mag. Double negatives – or in computers/electronics, “negative logic” – is easy to mix up…

This leads to a table like the following

Key OFF – RMag P-Lead grounded LMag P-Lead grounded
Key RIGHT – RMag P-Lead NOT grounded LMag P-Lead grounded
Key LEFT – RMag P-Lead grounded LMag P-Lead NOT grounded
Key BOTH – RMag P-Lead NOT grounded LMag P-Lead NOT grounded

… which is the same as
Key RMag LMag
OFF OFF OFF
RIGHT ON OFF
LEFT OFF ON
BOTH ON ON

With me so far?

The confusion is that you correctly said @5:23 that “cutting the P-Lead turns the magneto ON”, yet at 20:38 you get it backwards and say “cutting a P-Lead on a magneto has the same effect as turning the ignition switch OFF”. I think you meant “… turning the ignition key ON”, since the ignition switch would then be UNABLE to ground the P-Lead and turn the magneto OFF, leading to a hot mag…

(I love your podcast – I’m a computer guy, and not a pilot, but enjoy living the flying life vicariously thru you and others…)

Thank you Chris! Excellent information… and yes, I hope we can meet in person one day.

Regarding this Podcast 116: It really bothered me that a CFI could look at a JPI engine monitor showing rapidly falling EGT on Cyl.#1 when on the R mag during a preflight mag check and to summarize that it “…seems like the mag” was the issue. And then, to be honest, I was disappointed when YOU had to trace the wire from the right mag to cylinder #1 in order to figure out if it was the top or bottom plug.
I have the luxury of maintaining a single aircraft over the past thirty years/2600 hrs, and know for certain that if Cyl. #1 drops out on a right mag check that I can go directly to the upper plug, as the right mag fires the upper right and lower left plugs on my Continental O-470. And, I certainly know that it would not be a mag issue. I perform in-flight mag checks on every flight I take as this gives a better reflection of overall ignition system health than 1700RPM on the ramp.

Secondly, when the Apache had fouled BOTH plugs on one cylinder it made me wonder how many highly abnormal mag checks and asymmetrical preflight and in-flight JPI indications that pilot had experienced before you got your hands on it. You might be doing that client a favor by instilling in him that he is responsible for the airworthiness of his aircraft and that a deeper understanding of his engine monitor might save his engine some day, if not his life. He needs a little time with the Owners Manual.

In addition, please let your listeners know that they can go to: https://www.aopa.org/training-and-safety/air-safety-institute/valve-safety and download Adrian Eichhorn’s ‘Green Means Stop/Burnt Pizzas are OK’ poster. It has nine excellent photos of exhaust valves taken through a borescope. I have my poster laminated on my hangar wall.

I’m looking forward to meeting you someday at your hangar or at a Airventure Forum.

Thanks Justin… I enjoyed the time with you guys!

Keep up the great work on these podcasts, look forward to each one!

Regards,
Justin Rodes, formerly with Shenandoah Aviators N4156J

Thanks Rick, for your thoughts. Locktite might help… good idea. I still like to put a screwdriver on them at the annual… it doesn’t take long, and is good insurance.

I’ve been in industrial maintenance for over 25 years. What your thoughts on thread locking fluids like locktite or thread lock for lower temp applications (Stuff breaks down in higher heat applications) Might be a good solution to prevent having to retorque rocker arm covers.

Yes, reskinning is replacing the entire surface. If the maintenance manual gives info for replacing a large section instead of the whole skin, then that’s certainly an option… it depends on the manufacturer… some allow this, and some do not.

Thanks Joe. I sent you another email with the borescoping guide attached. Thanks. Let me know if it works.

Thanks
Joe

Hello David! Great to hear from someone in Peru!

Todd,
You’re welcome! And thank you for your thoughts. As far as payments or donations for the podcast, I’ve been looking into that, but don’t have it set up yet. Thanks so much for your interest in the podcast.

Thanks,
Todd Ramsey
Greenville, SC
N5504R
C-172F

Thank you Don. I appreciate your honest feedback. And yes, I might have made a wrong assumption that an A&P did that job. That may not have been the case at all. Thanks again for your thoughts.

I am not an A&P but was wondering if the A&P did the work or did the owner do it himself Like you I have a hard time believing an A&P would do that bad of a job

Thanks David! Maybe I’ll see you at Oshkosh next year!

Thanks Bob! I hope to see you soon!

I have a hat just like it, wore it everyday at Airventure!

Sorry I missed your presentation, I was volunteering in the SPA booth..

Thanks Brian! Yep, the hat is definitely a good sun blocker!

Ramon,

That is frustrating for sure.

Is Zephyr also sending replacement capacitors, or just the mag When we send dual mags to Kevin at Aircraft Ignition Services in Texas, he wants to also check the capacitors. I’m not sure a standard ohm check is adequate for those. I’d recommend calling Kevin and talking with him about your situation.

Also, take a real close look at your P-leads. I’ve seen cases where the wire insulation cracks near the attachment to the magneto, and causes the P-lead to short out to ground. Sometimes this can be an intermittent problem… very frustrating.

Let me know how it turns out. Here’s Kevin’s number: 903-378-7205 http://aircraftignitionservices.com/contact-us/

Dean

So on my 1977 Piper Lance with the Bendix dual mag, I am again having a mag problem. The engine has 12 hours on it since overhaul by Zephyr Aircraft Engines. After a flawless 3 hour flight and topping the tanks, the engine started easily but on taxi to take off, the engine was extremely rough, surging and finally quit even though changing tanks, adding fuel boost, changing mixture had no effect. We immediately went to maintenance hangar and checked: fuel injector nozzles, spark plugs, wires, external timing, air filter and all checked OK. Another run up showed same problem although full RPM could be achieved with minimal roughness. Zephyr then recommended checking the mag since the second runup showed the engine ran well on the left mag while the right mag was intermittently rough.
Externally, the mag looked normal although internal exam showed the right points seemed more pitted than the left. The right capacitor showed 13 ohms resistance while the left capacitor was zero. After cleaning up the right cap connections, the resistance fell to zero. Engine was runup and it ran normally on both, left and right mags.
This is the second time a newly overhauled mag on a newly overhauled dual mag engine has caused near catastrophe. Fifteen years ago, the right capacitor burned out at 5 hours in flight and the right points burned severely causing failure but the left magneto ran well. The only indication was the expected increase in EGT running on one mag. Installing a new cap on the right mag fixed the problem. Ironically a few weeks later (1999) an AD came out telling of a bad batch of capacitors and they needed to be removed. Overhauler at that time was Teledyne and they sent another OVH magneto as I was stranded away from home. That mag ran flawlessly for 500 hours until I had it sent away for inspection; no unusual anomalies found.
So now my Lance is AOG while Zephyr Aircraft is sending another overhauled magneto for replacement. Let me say at this point that Zephyr Aircraft has been outstandingly supportive of my predicament even though they could deny any warranty based on hours. Incidentally, the magneto was overhauled by Quality Aircraft Accessories, another facility with a great reputation.
I agree with Dean: I am not a fan of the dual mag and considered changing to two separate magnetos during the recent engine overhaul but that would have entailed another~ $10K on top of a $33K overhaul plus a bunch of STC paperwork. But such as it is.
Going to 2019 AirVenture last week, I visited booths for magnetos looking for an STCed electronic dual mag. SureFly does not have one, ElectroAir has one in development, and I’m not sure what E-Mag has on their R & D bench. So I guess I’m stuck with another overhauled D3000 magneto. Maybe the included maintenance manual will have a preflight chant to the patron saint of magnetos for better reliability. And I’ll rely on Lycoming SI 1508C for correct installation.
Anyone else have other ideas or suggestions, please post them.

Thanks Pete! It was great to meet you guys, and I loved seeing the Champ that day. By all means, stop in and see me if you’re down this way again.

P.S. Save a Little Debbie cream pie for me!

Thanks,

Pete B.

The other thing I like about is boroscope is it has a wide field of focus. I have one of the $50 specials and it can only focus up to less than an inch.

If one strut is more than 5″ then it would make sense to let a little pressure out. Also, sometimes the seals inside the strut get old and hard, and the strut does not move freely up and down. In this case, it might help to install new seals in the bottom of the strut, and service with fresh hydraulic fluid and nitrogen.

You can certainly help with the process, but this task will need to be supervised and signed off by an A&P. It’s a good experience, to be a part of it.

You are right. I did forget to mention that very important detail. Thanks for pointing that out, and also for the excellent recommendation of using garden mats.

Another item I use to spread my weight in the plane is to use small gardening mats. They are cheap, thick and spread the weight around. https://www.lowes.com/pd/AWP-HP-Yellow-23-in-x-11-5-in-Foam-Kneeling-Pad/50331647

Also, have you ever thought of offering Patreon as a way to get some income for all this great work I would certainly support you.

Thanks Michael. I’d suggest you contact “The Prebuy Guys,” Don Sebastian and Adam Sipe. Go to airplaneprebuy.com and click the “contact us” tab at the top right. From there you can either leave them a message, or call one of them… both of their phone numbers are there. I wish you well in your airplane purchase!