Would a well documented small shop overhaul or field overhaul be a problem to you. Would it be substantially of less value than a big shop or factory overhaul as long as it is done to the same standards?

shorton wrote:Would a well documented small shop overhaul or field overhaul be a problem to you. Would it be substantially of less value than a big shop or factory overhaul as long as it is done to the same standards?

My old Super Cub had a "paper overhaul" when I bought it. Turned out to be junk. My mechanic's recommendation was to see if I could talk one of the local mechanics into overhauling it for me. He had a great reputation, and he was gracious enough to overhaul my engine. He had one caveat: If he said a part needed to be replaced with new, there would be no argument.

He rebuilt that engine, and it was a real hot rod, and totally reliable. That was one of the best engines I've ever run.

I'd do it again in a heartbeat, assuming I had good recommendations on the particular mechanic.

MTV

Curious who that was Mike. I had a “small shop/local guy” overhaul in one of my 185’s, incredible engine! Local Anchorage guy. If I remember correctly his name is Werner Reimer.

Back to the OP question, the best overhaul in my opinion is a small shop somewhere, finding that shop and convincing a buyer is the challenge. Name overhauls may be better from a resale standpoint.

Kurt

Overhauling an aircraft engine is not hard, but there are many little "gotchas" and knowledge only learned from experience.

A small shop can do an awesome job, and in fact might even give the engine more attention than one of the larger engine shops. There's a right way to do it — but also lots of opportunities to cut corners for a dishonest mechanic. Avoid that guy. Usually only reputation can make that determination. Or having a shrewd advocate who can verify for you how the shop accomplishes their overhauls.

There's also the fact that many of the tools to do it correctly, like the NDI stuff, might not be at a small shop. They're going to have to farm out the inspections. It may factor into the price.

Specify that you want new parts or overhauled serviceable parts — don't leave it up to them.

I really enjoyed rebuilding my 540 myself, it was a great education under a very experienced mechanic. Even though it's experimental, I saved all my receipts for new parts, inspection and overhaul services of parts, and all the yellow tags, and the checklist of Lycoming mandatory items. If I ever have to sell it, this will be my case for a field overhaul done properly.

I think an overhaul by a "name brand" shop might be a selling point...
but that doesn't mean that it's a better engine.
I do think that a guy is probably better off going with a shop that specializes in doing engine overhauls,
vs a jack-of-all-trades airplane shop.
I'd rather have my engine OH'd by someone who does one a week, vs one a year.

You can surmise a lot about the quality of the overhaul by the quality of the paperwork that comes with it. When I overhaul an engine myself I put together a small binder to keep the work and paperwork organized. Make sure all the SB's and AD's referenced are put in the binder with all the receipts for things I farm out like machine work, NDI, parts etc...

Overhauling these engines is actually quite simple and the manuals for the most part are very thorough. I go over and above a little bit with my overhauls with balancing, I balance and match each piston/rod/pin/ring combo, then have the crank/flywheel assembly dynamically balanced and micro polished before I put it in the case. Its interesting even some simple things aren't mentioned in the overhaul manuals and surely skipped by overhaul shops like paralleling connecting rod bushings. Finally I assemble the case/crank/cam and rods on the crank one time with the old hardware and plastigauge to verify clearances before final assembly.

There's a big name overhaul shop in very hot water at the moment with a bunch of customers and facing a possible class action. I had previously really thought highly of this shop until seeing some very shoddy work come out of it in the past two years or so. We're talking re-using corroded/pitted through studs, and claiming they were replaced with new kind of stuff.

G44 wrote:Curious who that was Mike. I had a “small shop/local guy” overhaul in one of my 185’s, incredible engine! Local Anchorage guy. If I remember correctly his name is Werner Reimer.

Back to the OP question, the best overhaul in my opinion is a small shop somewhere, finding that shop and convincing a buyer is the challenge. Name overhauls may be better from a resale standpoint.

Kurt

Kurt,

It was Bob Desrochers. Bob passed away in 2016. His obituary included this quote: "It was said that if you flew a plane with an engine built by Bob Desrochers you flew with confidence."

Amen, and tailwinds, Bob....

MTV

Not all the employees who work at the big 145 stations are certified many of them are low paid laborers (they're "supervised" by certified guys); what you're paying for is the companies processes (e.g. AS9110 compliance) and the name/reputation that company has. More than likely a good small shop with a competent mechanic who takes pride in his work will pay closer attention on assembly than the average underpaid worker at the big repair station. The difference is the worker at the big repair station normally has a QA inspector check the work and they're supposed to ensure everyone follows process and is "trained".

I've worked in Big Aero for 20 years and my experience in GA is only a tiny fraction of that; but the guys I worked with at a small FBO I'd trust flying behind something they worked on more than some guys I've worked with on the Space Shuttle (had a guy building External Tank parts that was completely illiterate; his work was actually ok though it was the laziness and corner cutting of others that'd really make your jaw drop).

As Newbizor pointed out a recip is pretty simple and straightforward to assemble. As long as everything has had the proper NDT done where required, and proper machining a good mechanic should be able to assemble it and have it last just as long as if Penn Yan had done it.

When times comes for me to have my 470 overhauled,
I plan on having an engine specialty shop do it.
IMHO it makes sense to have someone do it who does several engines a month,
as opposed to someone who does maybe one or two a year.
In my experience, the small GA shop guy is also more likely to have interruptions & distractions,
with people coming in needing flat tires fixed, oleos pumped up, etc.

hotrod180 wrote:When times comes for me to have my 470 overhauled,
I plan on having an engine specialty shop do it.
IMHO it makes sense to have someone do it who does several engines a month,
as opposed to someone who does maybe one or two a year.
In my experience, the small GA shop guy is also more likely to have interruptions & distractions,
with people coming in needing flat tires fixed, oleos pumped up, etc.

Yep, hire those unlicensed, barely trained dudes to assemble your engine, rather than that one licensed and experienced guy who takes pride in his or her engines,...

Here’s an interesting tidbit: When I attended Lycoming Piston Engine Service School (well worth the time and cost BTW) part of the program was a tour of the factory.

The tour started at the loading dock, wher new engines are shipped out and used engines come in for overhaul. Prominently featured on that dock is a huge hydraulic press. While we were there, a worker was “receiving” an engine for overhaul. First thing he did was remove all cylinder assemblies, including pistons, stack them in that press, and pushed the button......six cylinder barrels promptly became scrap.

Lycoming uses ONLY new cylinder assemblies on ALL engines, even overhauls. I asked why. The response was “Consider all the heat cycles a cylinder goes through in a tbo cycle. Now consider what all those cycles do to the microscopic structure of those cylinder heads. Is it any wonder so many engines have cracked cylinder heads?”.

MTV

Thank you people for your insightful and helpful comments. When I overhauled my last engine I was able to get ALL specs within "new" limits. I had to dig through some extra parts to get just what I wanted. My biggest hassle was indeed, to package and ship out all the parts for testing. While I had the engine open I didn't work on anything else, I had cleaned the shop and prepped like I was going to paint. Dust control and so on, then I kept every thing in a clean room for assembly. I ran that engine for about 150 hrs and it was just great.
Anyone with other ideas I would like to hear them.
Thanks

A couple of mechanics I know who build engines say they lock the shop door while building and follow a strict check list to eliminate distractions and miss items. Seems like a great way to operate!


Kurt

mtv wrote:

hotrod180 wrote:When times comes for me to have my 470 overhauled,
I plan on having an engine specialty shop do it.......

Yep, hire those unlicensed, barely trained dudes to assemble your engine, rather than that one licensed and experienced guy who takes pride in his or her engines,......

1) Without knowing which "engine specialty shop" I might be referring to, (not the Continental factory BTW),
you're making a big assumption that it will be "unlicensed barely trained dudes" working on it.
It just might happen to be a one-man shop.

2) If you expect to have others respect your comments & opinions, you should reciprocate.
IMHO leading off with a simple "I disagree" followed by why is a more appropriate response than sarcasm.

One of the most challenging aspects I discovered in overhauling was the AD and SB tracking and compliance.

The tools available to make this easy, at least that I know of, are pay to use.

Also, the Lycoming overhaul manual was written by an engineer in a dark office somewhere, with the sole objective being to figure out how to make one manual cover 947 different models. It takes a little practice to use. Looking for torque values? Good luck. You choose between the standard stated values or read a big wordy paragraph to get the special value. Trying to click the gears? Wrap you head around that graphic, and make sure it's the right one first.

Looking up parts, cross referencing, deciding between factory, ECI, or Superior...all good times. Lots of time spent at the computer sorting out the information and ordering stuff.

A guy definitely needs time to concentrate without being distracted.

hotrod180 wrote:

mtv wrote:

hotrod180 wrote:When times comes for me to have my 470 overhauled,
I plan on having an engine specialty shop do it.......

Yep, hire those unlicensed, barely trained dudes to assemble your engine, rather than that one licensed and experienced guy who takes pride in his or her engines,......

1) Without knowing which "engine specialty shop" I might be referring to, (not the Continental factory BTW),
you're making a big assumption that it will be "unlicensed barely trained dudes" working on it.
It just might happen to be a one-man shop.

2) If you expect to have others respect your comments & opinions, you should reciprocate.
IMHO leading off with a simple "I disagree" followed by why is a more appropriate response than sarcasm.

Sorry, my point was a "specialty shop" or two have recently come under scrutiny for turning out some real junk engines.

As noted above, a "Shop" may (and many do) have unlicensed workers working "under the supervision of" a licensed mechanic. Sometimes that works, others.....maybe not.

If I were going to have an engine overhauled, I'd look for a VERY small shop, or a one man operation who has a good track record and lots of references. Too expensive a program to screw up.

And, as always, that's an opinion, and we all know about those, I certainly hope....

MTV

G44 wrote:A couple of mechanics I know who build engines say they lock the shop door while building and follow a strict check list to eliminate distractions and miss items. Seems like a great way to operate!


Kurt

A checklist and NO interruption is definitely a MUST!!!
I like a second set of eyes to look things over as well. If you stare at things long enough, you can see right past them sometimes.
Zzz... the AD's and SB's are a killer on some engines!! Try overhauling the Lycoming TIO-541 engines on a Beechcraft Duke....lots of SB's and a few really important ones that are easily missed!
I know when I worked in the overhaul shop, we got a lot sharper on specific engines by doing a bunch of them...specializing. I worked every position in the shop and on all the engines from Pratts to Wrights, but I was most comfortable on the Pratts after having done a bunch in a row. I do know, out of about 10 mechanics, there were only 3 of us with licenses, but there were some that had been doing overhauls for a lot of years that had no license, and I learned a LOT from them!!!!
John

hardtailjohn wrote:.... I know when I worked in the overhaul shop, we got a lot sharper on specific engines by doing a bunch of them,
specializing. ..... I do know, out of about 10 mechanics, there were only 3 of us with licenses, but there were some that had been doing overhauls for a lot of years that had no license, and I learned a LOT from them!!!!

Specializing was what I was talking about.
Good point about the unlicensed engine guys,
thanks for pointing that out John.