Hi All,

I'm back on the market, looking for a plane here in Anchorage. I've inquired about a couple of aircrafts, but no luck there. I've mostly had some issues finding a plane with a good engine that's going to last me a while. Through this process I've come upon a couple of questions, that I was hoping you BCP brainiacs might be able to help me out with. In addition, if you have any advice at all about what to look out for or what engine related questions I should be asking, I'd love to hear your thoughts.

Scenario 1:
I contacted a fellow regarding an aircraft who was selling it for another guy who had lost his medical, looked like a good deal to me. There were around 600 hours SMOH on it's O-320. Comparing that time to the TBO, I'm thinking that I would have a thousand plus hours I could put on it. I asked the guy if he thought the airplane would need any work on it soon, he was very straight forward with me (which I really appreciated). He mentioned that the owner hadn't flown the plane for more than a few hours a year for the past few years, he noted that this puts the engine at a probable need for a top overhaul. At that point, I'm thinking about all the money and effort that would entail. So, I've decided to back away from that.

I realized that there was a recommended calendar overhaul for these engines, about 12 years and also a time overhaul at 2000 hours. However, I did not realize that the engine needed to be running a certain number of hours for it to still be good.

Questions:
1-1. At a minimum, how many hours should the engine have ran in the past however many months/years for it to still be good (generally speaking)?

1-2. What's the best way to find this out? Will this require me to look at engine logs? Are there ways to visually notice anything like this without tearing down the engine?

2. What types of questions should I be asking owner's in the future regarding the engine?

3. If an engine has low hours, is within that 12 calendar years, and has had regular oil changes, why do I care if it's been sitting for 2 or 3 years in a climate controlled environment?

Scenario 2:
I was looking at another airplane, there was a big ole 0 hours SMOH noted on the post. My initial thought was, "wow I've hit the jackpot". I started asking a few more questions regarding the story of the engine. The owner said that when he bought the plane the jugs were bad, which he had replaced, then found out the cam was bad, so he threw a bunch of money at it to just have it overhauled. He said that he hadn't flown it since the overhaul. I think okay, this probably still isn't a terrible thing, so I asked him who performed the overhaul. I hate to name drop, but he mentioned that Werner Reimers performed the overhaul. He said, "he retired last year, but I think is still around". So I imagine he was the one probably replacing the cam and the jugs as well. Well, little ole' me decided to type in "Werner Reimers overhaul" on Google and low and behold a BCP post pops up. Link to the BCP post: https://backcountrypilot.org/forum/oil-test-6622 Obviously, by the looks of it I probably don't want a newly overhauled engine done by this guy? However, I would think if the dude was that bad then his license would've been taken a way? This all just led me to more questions:

Questions:
1. The guy mentioned he retired last year, which tells me the engine overhaul must've been done over a year ago. So, is this a bad thing, especially if it has 0 hours on it?

2. Should I be staying away from all 0 hour engines, especially as a new owner?


Additional Questions:
1. Are there things I can personally do to test an engine prior to getting a pre-buy inspection done? I couldn't imagine having to pay for pre-buy inspections on these two engines just to find out that they're no good. If it weren't for honest sellers at this point, then I might have been out quite a bit of cash.

2. Are there any other subtle warning signs to look out for?

3. Am I being too cautious or not cautious enough?

4. What other types of questions should I be asking sellers?

Interesting post. I'll answer a couple of the questions a s best I can.
First, yes if it were me, I would not buy and engine overhauled by that guy. Especially if he is now retired and there won't be any warranty.
As far as how many hrs an engine needs to run, that is a loaded question. It really depends on your location. If it's a dry area and climate controlled hangar then it would be fine not running. It also depends on the running. Does it just get fired up and ran for 5 minutes? If so that is terrible for an engine. You need to take it up and fly it for an hr and get it good and warm. Lycoming are a bit more sensitive to corrosion due to cam shaft placement.
I prefer to buy a higher time engine with a price that reflects it, that way I can fly it as long as I'm comfortable with it, then overhaul it and know what I have.

Conitinentals are fairly easy to inspect for corrosion. Which usually shows up on the cam, lifters, and cylinder bores.

I’m not a Lycoming expert but I believe you have to remove cylinders to see the cam and lifters.

I’d rather have a 5 year old engine with 1,000 hrs on it than a 20 year old engine with 200 hrs on it.

You are not being too cautious..... unless you enjoy writing big checks.

To oversimplify it.... if the manufacturer recommends overhaul at 12 years or 2000 hours, somebody thinks 166 hours a year is a good number to start from.

Obviously we don't fly that precisely ... .some fly 100 hours a year, some 300. Either is probably ok.

A couple of hours every other month is not good. Sitting is not good.

If it were me I would pay attention to accessories also. Vacuum pumps, magnetos, spark plugs, batteries, ELT batteries.... most have shorter life expectancies than the engine. They can cause you lots of aggravation and thousands of dollars if every 50 hours one of those times out..... or fails.

I speak from experience.

You’re going to get a lot of advice on this. You asked some good questions.

The search for a good aircraft starts with the search for a good mechanic. Start asking questions and find a good mechanic in your area and then listen to them. Next, be patient.

There’s lots of opinions about things that might happen to an 0-320. Frankly, quality control on NEW cylinders these days seems so bum that an O-320 rebuilt from the factory isn’t “bullet proof” anymore. I took an 0-320 that sat for 10 years from 1000 hrs to TBO in about 3 years with basically no problems. Not because I’m an engine operations expert; that one just worked out. There’s hundreds of stories, good and bad, like this so you can hear anything you want.

The general rule for 0-320s is you don’t want to buy one thats been sitting because different engine parts sit “out” of lubrication and are susceptible to corrosion. I would suggest most GA pilots aren’t flying 100-200 hours per year so I wouldn’t focus on that metric during your screening process; however, the log books do tell a story so get the last 5 years and read them with your new mechanic. Seems like a lot of guys fly about 50-75 hours per year so are their engines junk? I’ve never been able to work that one out. I personally agree that a recent mid time engine is a good engine these days and I wouldn’t walk away from it if the rest of the plane was legit.

No guarantees with any of this stuff and remember a good experienced mechanic is worth their weight in gold.

I would add to the conversation that oil changes according to Lycoming are to be accomplished every 4 months or 25/50 hours depending on filter WHICHEVER COMES FIRST. So many airplanes that fly 50 hours or less per year only get oil changes at annual time, not good. Corrosive acids sit in the oil and need to be removed on a regular basis that is one reason why the 4 month requirement. Infrequent oil changes are common in many airplanes unfortunately and probably are a big contributor to internal rust and corrosion in some engines. Add moisture generated by short flights with the acids in the oil and that is a double whammy. Keep this in mind when considering the purchase of an airplane. Read your engine manuals, change your oil.

Kurt

PS
I dont remember what Continental specifies but it would be worth researching if you have or are considering buying an airplane with a Continental engine.

A good borescope can tell a lot about the condition of the cylinders. Pretty easy to inspect, remove both sparks and insert borescope, have qualified mechanic that knows what he or she is looking at inspect and render an opinion. Inspecting the cam on a 320/360 Lycoming is not that easy. If you remove a cylinder an inspection on part of the cam can be accomplished but not all of the cam. Removing a cylinder for inspection makes some people uncomfortable, you may be able to do this or may not, good thing to discuss with your mechanic and seller. I would be more worried about rusted cam and lifters than cylinders. Although not cheap, cylinders are easy to replace, cams require splitting the case. Generally, these engines rust out before they wear out.

Kurt

Thank you all for the replies so far, getting some good info here. Still looking for some more advice on these subjects if anyone else is out there reading this. In addition, I have another question that I can't see to find a solid answer for. I came upon another plane that I was impressed with, but the engine once again did not seem to be what I'm looking for. It was an O-320 as well, had around 2300 hours SMOH and 500 hours STOH. Okay, so TBO is 2,000 hours for this particular O-320-A2B. From what I understand, the engine must be removed and completely overhauled before or on that 2,000 hour mark. It seems like this engine had the top overhaul done instead of the major overhaul, so does this reset the 2,000 hour TBO? Is this something that I should feel comfortable flying, while also staying legal, for possibly another 1,500 hours? I apologize if this comes across as dumb, I feel out of my depth here.

You can run the engine on "conditions" past the TBO hrs or calendar years.

Ross4289 wrote:Conitinentals are fairly easy to inspect for corrosion. Which usually shows up on the cam, lifters, and cylinder bores.

You can borescope the cylinders easy enough, but checking the cam & lifters requires lifter removal, does it not? This is getting fairly invasive and goes beyond what many sellers would allow. Or is there an easier way?

Thanks.....Ross

Unless you're running an airplane in a Part 135 operation or other commercial scenario, recommended TBO of engines is just that: Recommended. That goes for both calendar and hourly TBO.

So, a 2300 hour engine that's been topped at 1800 hours is perfectly LEGAL to operate, and as noted above, can be operated "on condition".

If I were thinking about buying that plane (and I might, if the plane and price were right) I'd factor in the cost of an overhaul to the selling price. If the seller thinks he/she is going to recover the cost of that top overhaul on a REALLY high time engine.....good luck. That engine might in fact run just fine for another several hundred hours. Or, it may not. One thing to consider when running engines well over TBO is that those bearings are now very old and worn, etc, and running an engine that many hours without overhaul MAY cause excessive wear to VERY expensive engine parts, such as the crankshaft and cam/followers.

Corrosion: As noted above, Lycomings have the cam on top of the crank....the cam and followers tend to dry off after non use. That's an invitation to corrosion, on VERY expensive parts, and as noted, replacing a cam or even re-grinding a cam requires splitting the case.....not cheap. And, if you're splitting the case, you may want to go ahead and have an overhaul done.

Continentals tend to tolerate sitting a little better than Lycomings, but both can corrode cylinder bores. That's not really cheap, but is a LOT easier and cheaper to deal with than camshafts.

So, what is the "trigger" for determining if an engine is a go or no go? Who knows? Look at the logbooks. If it hasn't run at all in six months plus, and it's a Lycoming, or if the dumb shit owner has just cranked it up every few weeks, but not flown it, I'd either plan a camshaft and followers at minimum, or major overhaul and factor that into the purchase price.

Me, if I could find a plane that is otherwise in great shape, but the engine is at or very near TBO, AND, the seller factors that into his selling price....that's the plane I'd buy. Get a good quality overhaul done on your dime, break it in properly yourself, and now you have an engine that you can trust and feel good about.

But, there's everything else in between......as noted, find a good mechanic, make sure you've considered all the factors, and then keep your fingers crossed as you enjoy that airplane. Frankly, these little engines are pretty tough and reliable, so the odds are pretty good that if there's nothing really egregious, your engine will take you many miles and many hours safely.

MTV

I just purchased a 206 with 900 hours since an overhaul in 1980. Had it boroscoped and everything seemed solid, the underwriter at the bank could not get over the fact that TBO was recommended at 12 years. I had appraisers and inspectors explain “on condition”. She still felt very strongly that they would not take a risk with an asset which was in her view in a condition recommended against by Continental.

The only way I could close on the loan was to put money in escrow for a new overall.

pipeliner wrote:

Ross4289 wrote:Conitinentals are fairly easy to inspect for corrosion. Which usually shows up on the cam, lifters, and cylinder bores.

You can borescope the cylinders easy enough, but checking the cam & lifters requires lifter removal, does it not? This is getting fairly invasive and goes beyond what many sellers would allow. Or is there an easier way?

Thanks.....Ross

You do have to pull the lifters on a Continental, but I would consider it pretty non invasive compared to removing cylinders on a Lyc. It takes about 20 minutes per cylinder to pull the rocker cover(s) rocker arm, pushrod, and tube and pull out the lifters and put it back together. There’s no adjustment on the rocker arm involved. Just torque the bolts and bend the tabs.

You are right some sellers might not go for this inspection. Sellers have the upper hand these days!

I was interested in a Maule with a 235hp lyc last fall. The engine was original from 1988 and only had 600 hrs since new. I was concerned about corrosion and wanted to have his mechanic (who I also trust) pull some cylinders and look. That was enough for him to take another similar offer that didn’t involve an inspection.

I ended up with a 185 who’s IO-550 was just IRAN’d by Western Skyways last summer, and couldn’t be happier with the airplane or more confident in the engine

Ross4289 wrote:

pipeliner wrote:

Ross4289 wrote:Conitinentals are fairly easy to inspect for corrosion. Which usually shows up on the cam, lifters, and cylinder bores.

You can borescope the cylinders easy enough, but checking the cam & lifters requires lifter removal, does it not? This is getting fairly invasive and goes beyond what many sellers would allow. Or is there an easier way?

Thanks.....Ross

You do have to pull the lifters on a Continental, but I would consider it pretty non invasive compared to removing cylinders on a Lyc. It takes about 20 minutes per cylinder to pull the rocker cover(s) rocker arm, pushrod, and tube and pull out the lifters and put it back together. There’s no adjustment on the rocker arm involved. Just torque the bolts and bend the tabs.

You are right some sellers might not go for this inspection. Sellers have the upper hand these days!

Thanks - appreciate the confirmation......Ross

Thanks A1 and MTV for the info there on it just being a recommended/conditional TBO, that's good to know. Unfortunately, for my budget, I'm looking for an airplane that I'll be able to get a good amount of hours out of prior to overhauling. Financing isn't the most fun thing in the world. Although, I can definitely see the benefit (if you have the money lying around) to be able to have that option to overhaul a newly purchased plane's engine. I suppose that could be something to think about though, is it even worth it to buy an airplane if you're not willing/able to fork up money for an overhaul at any given time. I'd like to budget for the cost of an overhaul into my hourly expenses of the plane, that I would begin to set aside as I go. I realize it's not a perfect world though. I'm sure it happens all the time where you see owner's having engine troubles, but can't afford to fix it at the time, so the plane ends up sitting for extended amounts of time and deteriorating further.

Borescoping seems like it'd be a good idea for reassurance, are mechanics typically doing this type of thing during pre-buy inspections? With that being said, does anyone have recommendations for good A&P mechanics that also do pre-buys here in Anchorage or surrounding areas? I'd prefer to not have to be like, "hey broski, did you borescope that though?" I guess that also brings up an additional question, should I be watching/assisting the mechanic during a pre-buy and is this typically kosher with them?

I came upon another good looking Super Cub in my area, 85 hours SMOH, but it hadn't been flown in 10 years. However, it was definitely not priced like it was going to need an overhaul. This is the type of thing that makes me wonder if I should be getting pre-buys in scenarios like that though; rather than just writing it off as a no-buy, because I'm already assuming it'll need an overhaul. For the sake of aircrafts, it'd be nice to see more of the older guys selling their planes sooner instead of letting it sit idle for years.

You have to be prepared for an overhaul soon especially if the airplane has been sitting around for any length of time no matter how few hours SMOH, Lycomings more so than Continentals. I bought my Maule with less than 200 SMOH but hadn't flown much in the previous 6-7 years. It has Lycoming O-540 and I knew going in that it may have corrosion. Had two cylinders pulled during the pre-buy first to see if it was worth going further. It looked very clean. Turned that into an annual and bought the plane for a purchase price cheap enough that I could still overhaul the motor and not be upside down in value. I flew it from Anchorage back to Connecticut. Then put another 175 hours or so on it in less than 2 years then started making metal. It ate two cam followers, the cam, cracked one follower bore in the crankcase.