Question for Paul McBride, the General Aviation News engines expert: I have a Lycoming O-320-E2A that was converted to 160 horsepower by STC at last overhaul installed on my Osprey 2 amphibian. I have been flying it every summer for the past 24 years. The engine has just under 5,000 hours since new and 975 hours since overhaul. I store the engine during the winter months with Aeroshell 2F and Camguard, as well as desiccant plugs. I do oil samples at every oil change and borescope the cylinders. The engine has been operating perfectly with no problems.
I want to get the engine overhauled. Not because of any operating problems, but because it has been 35 years since overhaul. After contacting overhaul shops I find that due to the work force shortage, overhaul times are now in the six to eight month or more time frame. I don’t want to stop flying to overhaul an engine where the only problem is that it has been 35 years since it was last overhauled.
So my thought is to get another 160-hp engine that I can either buy new or used and get it overhauled. Then when that is ready just swap it with my engine. That way I can continue flying in the mean time. Looking at Lycoming document SSP-204 it appears that maybe the O-320-D2A, or D2G might work. But I don’t know.
The other option would be to find another -E2A and have it overhauled and converted to 160 horsepower. But they seem to be hard to find right now. Looking at SSP-204, it says that the -E2D is similar to my engine, but has an O-235 main bearing. What does that mean? Is the O-235 main bearing better or worse than what the E2A has? Could that engine be converted to 160 horsepower?
The carburetor on any replacement engine has to be in the exact location as the -E2A in order to work on my Osprey 2. The throttle and mixture cables reach the engine by going through the top of the cabin. The tunnel that the throttle/mixture cables go through is very small. The Osprey 2 is tightly cowled, so the replacement engine would have to be the same dimensions.
A new engine ordered today is 900 days out, from what I am told, so that doesn’t seem like a good option. And I’m not sure any new engine will work on my Osprey 2.
Sorry for so many questions, but I thought you would be the one to ask.
Thank you,
William J Wuorinen
Paul’s Answer
First of all, let me compliment you on your beautiful Osprey 2, and I’ll do my best to answer your questions regarding what path to take regarding the engine.
I am not familiar with the STC that you mentioned, but do know there are several good conversions out there. If my calculations are correct, it looks like you’ve averaged about 27 hours per year since the overhaul 35 years ago. That’s amazing, but it also is a cause for concern, which you pointed out.
My biggest concern is the potential for internal corrosion, as you might expect. You mentioned that you do an oil analysis at every oil change and borescope the cylinders. I compliment you on doing that. However, you didn’t mention what the results were from either one, which leads me to believe that you aren’t seeing any contamination in the oil samples. I must admit that it does come as a surprise, but it does throw a positive light on your maintenance procedures, so keep up the good work.
Since you borescope all of the cylinders and did not mention anything about indications of corrosion, that leads me to believe that you must have chrome-plated cylinders. This, of course, is a plus for an aircraft that spends most of its life on the water.
So, now let’s see what we can do about the next step when it comes to engines. You’ve done your homework and know about the O-320-E2D, and we don’t need to go any further regarding that model because it cannot be converted to 160 hp because of the front main bearing configuration. This model was built for a specific application requiring a lower manufacturing cost. Your idea of using an O-320-D2A or O-320-D2G is a good one that should work, providing you can find one.
William, I’m going to be honest and tell you that I am shocked where our industry finds itself these days regarding engine and parts replacement lead times. As you have probably learned by now, the availability of good used engines is virtually non-existent, so if you stumble on one, you’d better buy it. However, be sure you know what you’re getting because what might appear as a good deal may end up costing you more than you would expect, especially if the crankcase is cracked or the crankshaft cannot be made serviceable.
Honestly speaking, I think what you are intending to do has merit but having all the planets line up will be difficult at best. I admire your forward thinking but will admit it’s going to be a real challenge. You may want to consider reviewing the overall maintenance and operating performance of your engine and consider operating it one more summer. That would give you enough time to arrange for another engine, whether it be new or overhauled.
I’m an old A&PIA and pilot. While you have concerns, primarily based on manufactures “recommendations” of tbo there is an another option. Go in and look and replace the only parts (rubber seals) that are really affected by calendar age. I’m with Mike Bush and the old WWII study that implies that taking things apart often induces more failure than what the preventive maint would result in if left to a longer interval. Pull the #2 cylinder and look inside. You can see the cam, lifters and shiny parts. If you really want you could pull all four. Hone and lap the valves and put in new base seals and push rod rubbers and correctly reassemble and go for another 35 years. As long as scopes and oil samples don’t show metal deterioration metal doesn’t just fail because it’s been wrapped in 2F and surrounded by winter weather. It ain’t broke. Prove it to yourself so your brain trusts it and go fly.
Nice to see a well reasoned query, and nicer still to read an equally well seasoned answer.
Mr. McBride would you for us minions out here PLEASE write an in-depth article detailing the what, why, how for of our aviation engine- engine parts situation?
I think most of us would like to understand really where we are and why.
Holding an a&e lic. from 1973 (though long unused professionally) one has a very hard time understanding the lack of spare parts let alone the OUTRAGEOUS lead time for new engine delivery.
Please do consider writing and posting such an article. Of course one understands that in a missive of such scope that it will do no useful good with a “scorched earth” blame game, (we all have dragons we’d love to see publicly impaled), rather though a straight dope telling of where we really are today captive. The situation and the box it came in. Years ago one could ring up Dick Scheffner .. alas.
If it were me I would rather fly an engine with 975 SMOH, running perfectly well, oil sampled, borescoped, and maintained, than a brand new, or brand new overhauled engine. The devil you know. To just keep flying it I would also have no lost flying seasons, and more cash. Thats a win-win-win.