Flying Friday: the one where I didn’t fly to the Bahamas

Some of you may remember two previous articles here: one about dispatch reliability and one about piston engines. If you like, you can consider this one to be titled “on aircraft piston engines, part 3”

One of the best reasons to buy an airplane is to use it to go places. In my case, a big part of the reason for buying a twin was so I could comfortably fly over water, mountains, and other places where a single-engine plane might leave me as an involuntary glider pilot. Not long after I bought Carmen, I started roughing out plans to fly to the Bahamas with Erica, since neither of us had been and there are many out-islands with small airports to visit. Unfortunately, then I made a critical mistake.

See, what had happened was…

The American Bonanza Society is the largest national club for owners of Beech aircraft, including Barons. I could go on for pages about how valuable their magazine and tech support forums have been, but I’ll ask that you take it as stipulated. One of the services they offer is the ABS service clinic, a comprehensive review of an airplane hosted by a master mechanic with long Beech experience. For another post, I’ll talk about the details, but for now, let me just say I was blown away by how much Wayne Whittington taught me in a 90-minute exploration of the guts of my airplane. One of the bonus services included in the clinic is a borescope inspection, performed by a technician from Continental Motors, the company that makes the engines.. This inspection is conceptually simple: you pull out a spark plug, stick a borescope inside, take some pictures, and then examine them looking for signs of badness. These signs might indicate damaged, sticking, or fouled intake and/or exhaust valves, corrosion, space aliens, rude graffiti, and so on. There’s lots of lore concerning how to interpret these pictures and signs. In my case, the examination found this:

This is a thing you do not want to see in your engine

“What is that?” you ask. Well, to the inspector, it looked like a crack in the plating of the cylinder barrel. That brown discoloration is a little unusual but not in itself a bad sign, but a crack in the plating is bad because it might allow part of the plating to break loose and go ricocheting around the engine. Armed with that picture, I ordered a replacement cylinder and made plans to take the plane up to Winchester to let Jon Foote work on it.

A quick digression. Continental makes engines, including the IO-470-L engines on this plane. But these particular engines were built by a gentleman named Bill Cunningham at PowerMasters. He used stock Continental parts to start with but added some other, better parts along the way, including Millenium cylinders from Superior Air Parts. See, one design feature of most piston aircraft engines is that the cylinders aren’t cast into a single block– they bolt on individually and can thus be repaired or replaced individually.

Anyway, I emailed Bill, who said that he hadn’t seen a similar defect and that he would definitely replace the cylinder. For fun, I decided to ask Superior, the cylinder manufacturer, if they wanted to have a look at the cylinder once it was pulled. The gentleman I spoke to there, who owns their QA team and has been manufacturing parts for aircraft engines for nearly 40 years, said he definitely would like to see it and that he definitely wouldn’t fly the cylinder in that condition.

Instead of going to Winchester, I had the cylinder diverted from Winchester to Decatur and dropped the plane off at the local shop. This caused a double-barreled delay: first UPS took a solid week to change the delivery address on the cylinder, then the shop, which is shorthanded just like every other aviation shop on this blessed blue planet, had to fit me into their complicated schedule. I begrudgingly booked tickets on Delta to Nassau. (More on that later.)

The truth is revealed

Finally, the day before we were supposed to leave, the mechanic called. “I pulled that cylinder,” he said. “That’s not a crack or a scratch; it’s just a tooling mark.”

Silence.

“Wait,” I said. “You mean that there’s nothing wrong with it?”

“Nope,” he said cheerfully. “Want me to put it back on?”

Reader, I did want that very much. But in the interest of aviation safety, I decided to put the new cylinder on instead. These engines have been around a while, and I didn’t see the value in putting the old one back on when I already had a new one handy. There’s a degree of risk any time you remove a cylinder, but that ship had already sailed, so overall it was less risky to put the new one on instead, especially because I did want the manufacturer to check out that beauty mark.

Then we went to the Bahamas. Amazing trip, about which more another day. I was a little sad each time I saw the empty apron at Staniel Cay, where my Baron would have fit perfectly, but that didn’t diminish my enjoyment of the trip. What most certainly did diminish it was when Delta cancelled our return flight, then booked us onto another flight that got us home about 1am on Monday morning, 6 hours later than scheduled.

Anyway. later that same Monday morning I texted the mechanic. One of the bushings on the rocker arm for that cylinder was worn and needed to be replaced, so they were waiting on a part which was hopefully going to arrive “early this week.” By the time I got to the airport about 1130 to drop off some oil filters so they could change the oil, the new part had arrived and was installed. By Tuesday afternoon, they’d done a thorough ground run and leak check, and it was time for me to go fly it.

Breaking it in

A brand-new cylinder has to be broken in. The piston rings and the cylinder lining will of course rub against each other; at a microscopic level, you want there to be a nice cross-hatched pattern that allows some oil to lubricate the cylinder-ring interface. so the goal of the break-in procedure is to accelerate this process so that the rings form a tight seal against the cylinder wall. It’s important to keep the cylinder temperature high, but not too high. Superior has a detailed procedure for this, which I followed religiously.

(You might wonder why you don’t have to break in car engines. Fair question– which this article about cylinder finishes helps answer. tl;dr the car engine already has the right finish machined in from the start.)

I flew a break-in flight, following Superior’s recommendation to the letter, in the form of a big triangle: Decatur to Monroe County (KY) to Clarksville (TN), ending up at Thom Duncan Avionics in Fayetteville. They put in a new Avidyne IFD440, which was an adventure in itself, and then I flew home again.

What I learned

I still would much rather have flown myself to the Bahamas, and I hate having spent money replacing a part that, by all appearances, was still serviceable. However, when the guy who built the engine and the engine manufacturer and the cylinder manufacturer all say “I wouldn’t fly that” I am certainly not going to argue with them. I’d make the same decision again today if faced with the same facts. Insh’allah, this cylinder will last for many more years.

The old cylinder has gone back to the factory for inspection. When they’re done with it, I plan to have them overhaul it so I can keep it as a spare; lead times on new factory cylinders can be 4+ months so it’ll be good to have an extra on hand. No word on them quite yet what’s wrong with it.

In the meantime

A postscript: as I mentioned, I finally did make it to Thom Duncan Avionics for a bit of an upgrade. We replaced one of the two ancient Garmin GNS430Ws with a shiny Avidyne IFD440, the smaller sibling of the IFD540 that did so well for me in 706. We had a weird problem where the display and bezel lights of. the IFD would blink off and back on, but the unit worked fine on the bench. After a bunch of trial and error, we determined that was because the cross-fill setting that allows automatic sync of flight planning data between the two GPS units wasn’t working. If you have two Garmin units, or two Avidyne units, great. If you have one of each, you can’t do the sync (which isn’t unexpected) but you’ll get the blinking (which was unexpected, and is also undocumented in the Avidyne install manual).

The combined stack: IFD on the top, then the GNS430, then the GTX345 transponder

One of the drawbacks of the 440 is that its screen is smaller, but Avidyne has a very clever solution for this: the IFD100 iPad app, which you can think of like a remote desktop session for your IFD. I found that putting ForeFlight and the IFD100 app side-by-side on my iPad mini worked wonderfully well. As you can see below, there’s a lot of information available. I can use the IFD100 app to have a completely independent view of the data that the in-panel GPS has while still looking at charts, airport info, and so on in ForeFlight.

Because the iPad mini is mounted on a RAM mount on the yoke arm, I can easily flip it 90º. If I want to use both apps together, I put it in landscape mode; if I’m just using ForeFlight (as when I’m briefing and preparing an approach and want to see all the plates), then portrait mode.

I put the new configuration to the test by flying down to Auburn to pick Matt up for his birthday, then flying to Atlanta to go have a bison burger at Ted’s, and then back. It works better than I expected, and it’s making me rethink my original plan to put the larger IFD540 in the panel– I can save quite a bit by keeping the 440 and using the iPad display instead.

In our next episode: what’s a Stormscope, and why would you want one? Stay tuned!

2 Comments

Filed under aviation

2 responses to “Flying Friday: the one where I didn’t fly to the Bahamas

  1. I’m interested to find out what the factory says about that mark. Love following your airplane adventures. If you’re ever in the area and stop at Spirit of St. Louis (KSUS), lunch/dinner is on me. 🙂

    • robichaux

      Thanks, Scott! I will definitely look you up next time I’m in your part of the world.

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