Field Overhaul?

[AdamZ]

I was chatting with a client today who is also a pilot and has owned a few planes including a baron and Tiger and I think a couple of others. We were looking at some planes on one of the plane for sale sites and I commented that it seemed like all of the Tigers and Cardinals listed for the most part had run out engines and were priced a bit high given the engine times.

We had the discussion about is or isn't TBO just a number etc. He commented that he has had no issues taking engines beyond TBO and that his over hauls cost significantly less because he got Field Overhauls at a shop that he really likes somewhere down in VA. Apparently the shop only does engines so they seem to be the P in A&P.

He says they repair and replace based on condition and need and the cost is significantly less and they do great work.

So it got me thinking, Is there anything wrong with getting a field overhaul? I mean if your not intending on selling the plane or if you buy a plane at or near TBO you can get a plane priced for a runout engine ( which may be running fine) and get a field overhaul of the engine and see significant savings??

Is there something inherently problematic with a Field Overhaul as opposed to sending it to a shop like Mattituck or is like anything else in life that if you have someone who knows what they are doing and takes pride in their work you should be fine but ya just have to watch out for Bubba with a wrench?

 

[poadeleted20]

Is there anything wrong with getting a field overhaul?

It's all about the quality of that shop. Get referrals and recommendations. As you said, "...if you have someone who knows what they are doing and takes pride in their work you should be fine but ya just have to watch out for Bubba with a wrench." Two smaller shops known for taking pride in their work are Charlie Melot's Zephyr Engines and Bill Scott's Precision Engine.
http://precisionengine.home.mindspring.com/
http://www.zephyrengines.com/

 

[Tom-D]

So it got me thinking, Is there anything wrong with getting a field overhaul?

I hope not, because all overhauls done by anyone except the factory or their representatives are "FIELD OVERHAULS"

a guide is, if the Time since new is ZERO, its a factory overhaul, if the time since new continues it is a field overhaul, if the entry in the engine log says time since overhaul its a field overhaul.

Read FAR 43.2 for the proper terms for the entry of the overhaul.

I do as many do, I disassemble, clean, measure, and replace only the parts required to meet the term "rebuilt".or the ones on the required replacement list.
I send my cases to Chuck Ney, my cranks to aircraft services. I give a labor discount when the owner will buy new cylinders.

Lycoming removes a major portion of the field overhauler's discretion by placing a list of mandatory parts to be replaced in the overhaul manual.

 

[Tom-D]

It's all about the quality of that shop.

Not really Ron, we are all required to follow the overhaul manual.

any other method of overhauling is a major alteration.

 

[Capt. Geoffrey Thorpe]

One data point.

Back in the '70s the C-85 in the old man's airplane swallowed the generator drive. It got overhauled locally. Very locally - the old man did it with A&P supervision and sign off.

Last year I tracked down the current owner. According to him, he is still flying on that overhaul. Dunno how many hours.

The airplane has been repainted since then.

 

[AdamZ]

I hope not, because all overhauls done by anyone except the factory or their representatives are "FIELD OVERHAULS"

a guide is, if the Time since new is ZERO, its a factory overhaul, if the time since new continues it is a field overhaul, if the entry in the engine log says time since overhaul its a field overhaul.

Read FAR 43.2 for the proper terms for the entry of the overhaul.

I do as many do, I disassemble, clean, measure, and replace only the parts required to meet the term "rebuilt".or the ones on the required replacement list.
I send my cases to Chuck Ney, my cranks to aircraft services. I give a labor discount when the owner will buy new cylinders.

Lycoming removes a major portion of the field overhauler's discretion by placing a list of mandatory parts to be replaced in the overhaul manual.

Thanks Tom, I do get confused about the terminology, I perhaps incorrectly understood sending the engine back to say Lycoming as a factory reman and sending it somewhere like Mattituck or Pen Yan a as rebuilt because I thought that they replaced and repaired to factory new tolerances and a Field Overhaul as just repair and replace as needed.

In essences I thought there to be three levels of engine "Overhaul" is that incorrect?

 

[dmccormack]

Adam, I don't think you'd want Bubba Widawrench changing your tires, so you're not going to ask him to do an OH, either.

That said, you can save MANY $$ assisting with the OH. I sure did!!

I did lots of work away from the shop, including fabricating some simple parts (gaskets, etc), cleaning and refinishing various parts, and shopping for parts (for example, one gasket was quoted at $24 each for 16. I found a shop that had 12 for $14. I bought the balance at the higher price).

When I could I stopped by the shop and assisted with engine removal and hanging, etc...

PLUS you learn about aircraft engines. All very good things.

 

[TMetzinger]

Adam,

From a regulatory standpoint, I thinik engines only come in three flavors:
Factory-New
Factory-Remanufactured
Field Overhauled.

The ones with "Factory" in the name come with 0-time logbooks.


Now, from a MARKETING/VALUE standpoint, there are all sorts of different options within the "Field Overhaul" category.

Above and beyond the minimum required to qualify as an overhaul, you can have a shop put in all new parts. Or you can have the engine blueprinted and balanced where the parts are held to very tight tolerances. The value of these "above and beyond" services is all in the eye of the purchaser.

I've flown behind a blueprinted/balanced engine in a Mooney, and I will admit it was VERY smooth compared to an identical factory-reman engine in the same model plane. Obviously the owner thought the smoothness was worth the price.

 

[poadeleted20]

Not really Ron, we are all required to follow the overhaul manual.

any other method of overhauling is a major alteration.

Yes, really, just as some pilots are better than others because they are more conscientious and detail oriented. It's not only what you do, it's how you do it.

 

[dell30rb]

Yes, really, just as some pilots are better than others because they are more conscientious and detail oriented. It's not only what you do, it's how you do it.

Right - O a shop may replace and measure everything as specified in the manual, but one shop might spread everything out on a dirty workbench, while the other takes the time to make sure everything is squeaky clean.

 

[Tom-D]

Yes, really, just as some pilots are better than others because they are more conscientious and detail oriented. It's not only what you do, it's how you do it.

What that amounts to is some folks don't follow the manual. It is very detailed.

 

[weirdjim]

What that amounts to is some folks don't follow the manual. It is very detailed.

The devil with most field overhauls is that some of them specify a particular make and model of run-in fixture with this or that model of club prop. If you don't happen to have that particular setup, you can't follow the manufacturer's overhaul instructions.

Thankful to merciful heavens the o/h manual on my bird's O-470 has one sentence that is a lifesaver ... "The airframe may be used as a suitable test stand".

Jim

 

[Tom-D]

Thanks Tom, I do get confused about the terminology, I perhaps incorrectly understood sending the engine back to say Lycoming as a factory reman and sending it somewhere like Mattituck or Pen Yan a as rebuilt because I thought that they replaced and repaired to factory new tolerances and a Field Overhaul as just repair and replace as needed.

In essences I thought there to be three levels of engine "Overhaul" is that incorrect?

The overhaul manual gives us a list of tolerances that can be used in overhauling the engine, this list gives 2 sizes new and service limit, a new limit is a size that is within the tolerance of manufacturing a new part, the service limit is a part that is considered good enough to make the next TBO of the engine.
the term of Rebuilt is given as :
c. Rebuilt engine. A used engine that has been completely disassembled, inspected, repaired as necessary, reassembled, tested, and approved in the same manner and to the same tolerances and limits as a new engine with either new or used parts. However, all parts used in it must conform to the production drawing tolerances and limits for new parts or be of approved oversized or undersized dimensions for a new engine. Refer to part 91.421, Rebuilt engine maintenance records.

Advertising and factory hype has confused many folks as to what rebuilt actually means. Manufacturers can approve over and under sizes that can used in their rebuilt engines, Field overhaulers such as myself, and another A&Ps can not. So when we sign it off as rebuilt you get an engine that was "Rebuilt" to new standards, when we do not use the term "rebuilt" the engine has a part that meets service limits standards.

 

[Anthony]

Always think of your Exit Strategy. I would not buy, nor pay nearly as much for a "Field Overhaul" unless it was done by an ENGINE OVERHAUL SHOP like Charlie Merlot's or Bill Scott's, as Ron referenced. These are experience shops that specialize in engine overhauls, and have to be viewed differently from your average maintenance shop.

Anything else is a crap shoot, and will be reflected in the sale price of the aircraft. Don't think you'll never sell, because stuff happens.

 

[Tom-D]

Adam,

From a regulatory standpoint, I thinik engines only come in three flavors:
Factory-New
Factory-Remanufactured
Field Overhauled.

The ones with "Factory" in the name come with 0-time logbooks.


Now, from a MARKETING/VALUE standpoint, there are all sorts of different options within the "Field Overhaul" category.

Above and beyond the minimum required to qualify as an overhaul, you can have a shop put in all new parts. Or you can have the engine blueprinted and balanced where the parts are held to very tight tolerances. The value of these "above and beyond" services is all in the eye of the purchaser.

I've flown behind a blueprinted/balanced engine in a Mooney, and I will admit it was VERY smooth compared to an identical factory-reman engine in the same model plane. Obviously the owner thought the smoothness was worth the price.

any time a part is modified by resizing its weight, is a major modification of the engine, so blue printing is already done by the part manufacturer, and balancing is not allowed in the field.

read FAR 43-A

 

[Tom-D]

Adam,

From a regulatory standpoint, I thinik engines only come in three flavors:
Factory-New
Factory-Remanufactured
Field Overhauled.

The ones with "Factory" in the name come with 0-time logbooks.


Now, from a MARKETING/VALUE standpoint, there are all sorts of different options within the "Field Overhaul" category.

Above and beyond the minimum required to qualify as an overhaul, you can have a shop put in all new parts. Or you can have the engine blueprinted and balanced where the parts are held to very tight tolerances. The value of these "above and beyond" services is all in the eye of the purchaser.

I've flown behind a blueprinted/balanced engine in a Mooney, and I will admit it was VERY smooth compared to an identical factory-reman engine in the same model plane. Obviously the owner thought the smoothness was worth the price.

any time a part is modified by resizing its weight, is a major modification of the engine, so blue printing is already done by the part manufacturer, and balancing is not allowed in the field.

read FAR 43-A
(ii) Changes to the engine by replacing aircraft engine structural parts with parts not supplied by the original manufacturer or parts not specifically approved by the Administrator.

 

[Tom-D]

The devil with most field overhauls is that some of them specify a particular make and model of run-in fixture with this or that model of club prop. If you don't happen to have that particular setup, you can't follow the manufacturer's overhaul instructions.

Thankful to merciful heavens the o/h manual on my bird's O-470 has one sentence that is a lifesaver ... "The airframe may be used as a suitable test stand".

Jim

You still need the equipment ( think test club) and instrumentation required by Continental service bulletin.

 

[Tom-D]

Always think of your Exit Strategy. I would not buy, nor pay nearly as much for a "Field Overhaul" unless it was done by an ENGINE OVERHAUL SHOP like Charlie Merlot's or Bill Scott's, as Ron referenced. These are experience shops that specialize in engine overhauls, and have to be viewed differently from your average maintenance shop.

Anything else is a crap shoot, and will be reflected in the sale price of the aircraft. Don't think you'll never sell, because stuff happens.

Ask any of those shops if they will overhaul a Warner, Jacobs, or any other round or obsolete engine?

I guess that's why you don't own a Beech stagger wing or a Spartan executive.

 

[TMetzinger]

any time a part is modified by resizing its weight, is a major modification of the engine, so blue printing is already done by the part manufacturer, and balancing is not allowed in the field.

read FAR 43-A

Didn't say they modified it. I said they used tighter tolerances.

So let's say that Lycoming ships 100 connecting rods, all within manufacturer tolerances.

Your "basic" rebuild may include rods taken at random.

Your "balanced" rebuild would have the rods chosen to match each other as closely as possible weight-wise from the stock on hand. Or as they come in they get thrown into sets for similar weights.

Example:
Let's say that the 100 Lycoming con rods have weights that vary by 5 grams between the heaviest and the lightest, and let's say that when you graph the weights they show a classic bell curve.

Let's further say that you need four con rods for your engine.

In a basic rebuild you might end up with four rods at random, which may include the heaviest and the lightest in the set.

In a balanced rebuild they'll take four rods as close as possible (probably in sequence along the curve) in weight to each other.

No modifying anything, just selecting part for maximum similarity.

And I have no opinion on what value someone might get from such an effort. That's strictly an opinion in the eye of the purchaser.

 

[Skylane81E]

Always think of your Exit Strategy. I would not buy, nor pay nearly as much for a "Field Overhaul" unless it was done by an ENGINE OVERHAUL SHOP like Charlie Merlot's or Bill Scott's, as Ron referenced. These are experience shops that specialize in engine overhauls, and have to be viewed differently from your average maintenance shop.

Anything else is a crap shoot, and will be reflected in the sale price of the aircraft. Don't think you'll never sell, because stuff happens.

This isn't too far off, but has no real standing on the actual quality of the work. Known shops are seen as offering O/Hs that are worth more than if some A&PIA like myself did it. The interesting fact is that if someone like me does the overhaul much of the critical stuff (NDT and machining specificly) will probably have been done by that big name shop as I don't have to tools to do that in house so I must farm it out.

You get what you pay for from a resale stand point, and the big guy can probably offer a better warranty than I could due to deeper pockets but as Tom said if I follow the book it will come out to be a to-spec engine just like anyone else's.

 

[jhausch]

Don't miss this sentence from the OP

He says they repair and replace based on condition and need and the cost is significantly less and they do great work.

It may not be an overhaul at all, but rather an IRAN. I'd think about my flying, the time of day, and the terrain over which I fly and I think I'd be OK with that if I trusted the shop.

Considering this sentence:

I mean if your not intending on selling the plane

I'd add - "now IRAN makes even more sense"

However, I'd also recognize that once it's time to sell, the price would reflect this.

One more thing: I'd want to buy the plane with the financial wherewithal to be ready to hang a new engine on it if I had to. (call it my "Lawn-Ornament-Prevention" fund)

 

[Tom-D]

Didn't say they modified it. I said they used tighter tolerances.

So let's say that Lycoming ships 100 connecting rods, all within manufacturer tolerances.

Your "basic" rebuild may include rods taken at random.

Your "balanced" rebuild would have the rods chosen to match each other as closely as possible weight-wise from the stock on hand. Or as they come in they get thrown into sets for similar weights.

Example:
Let's say that the 100 Lycoming con rods have weights that vary by 5 grams between the heaviest and the lightest, and let's say that when you graph the weights they show a classic bell curve.

Let's further say that you need four con rods for your engine.

In a basic rebuild you might end up with four rods at random, which may include the heaviest and the lightest in the set.

In a balanced rebuild they'll take four rods as close as possible (probably in sequence along the curve) in weight to each other.

No modifying anything, just selecting part for maximum similarity.

And I have no opinion on what value someone might get from such an effort. That's strictly an opinion in the eye of the purchaser.

Name 1 supplier that will go thru their inventory and select parts like that.

and you can't alter the parts in the field, the manufacturer must hold the weight to the standard in the prints. So it is impracticable to think it can or will make a difference.

 

[TMetzinger]

Name 1 supplier that will go thru their inventory and select parts like that.

and you can't alter the parts in the field, the manufacturer must hold the weight to the standard in the prints. So it is impracticable to think it can or will make a difference.

http://www.victor-aviation.com/nav.shtml?reciprocating.shtml

I believe Flying or AOPA did an article on this in the late 80s or early 90s.

 

[Skylane81E]

The little(er) shop that just did the cylinders for the o320 I'm working on sent me new pistons, all identical in weight.

 

[Tom-D]

The little(er) shop that just did the cylinders for the o320 I'm working on sent me new pistons, all identical in weight.

I've never found a difference in piston weights either, I have found a difference between rod lengths, when the machine shops rebore the large end of a rod they will grind a couple thousands off the mating surfaces and rehone the bore. after a few reworks they become different lengths.

It's minor but I'm anal about stuff that places my house at risk.

 

[dmccormack]

Ask any of those shops if they will overhaul a Warner, Jacobs, or any other round or obsolete engine?

I guess that's why you don't own a Beech stagger wing or a Spartan executive.

...or a Lycoming O-145

I'm glad I have an A&P I can trust who can maintain my engine. I'll take that over a "name" that does lots of magazine ads...

 

[Skylane81E]

I've never found a difference in piston weights either, I have found a difference between rod lengths, when the machine shops rebore the large end of a rod they will grind a couple thousands off the mating surfaces and rehone the bore. after a few reworks they become different lengths.

It's minor but I'm anal about stuff that places my house at risk.

And there is why I'm not doing overhauls outside of the school or my plane.

 

[Tom-D]

And there is why I'm not doing overhauls outside of the school or my plane.

I don't overhaul for the general public either, I support my friends that know I have nothing they want.

I do have engines in Part 135 service that transport the public on flight see operations by they are running out soon and will go to Charley when and if the aircraft aren't sold first.
I have only done 1 Lycoming recently for a very good friend that salvaged a 0-360 from a cub that he had built, that crashed in the alaskan bush. Lycoming would not except it as a core, so we saved the data tag and rebuilt it, using the cylinders that Charley rebuilt. He knew he had bought it new and the TT was 900+ that is the only time I will use used cylinders. ( a known TT)

 

[Skylane81E]

Well I'm still waiting on the NDT of my first mill to get a full overhaul that will be on a school 172.

I plan on an IRAN of my planes engine in the near future and am half looking for a core engine so I can get a jump start.

Other than that, well I really don't even work on anything outside the repair station.

 

[Dan Thomas]

The ones with "Factory" in the name come with 0-time logbooks.

Not quite. From the Lycoming Flyer we see this:

Lycoming Factory Overhauls are built to (within) service limits and are time-continued engines in the logbook.

Lycoming Zero-Time Rebuilts must meet new drawing specifications.
Since Lycoming designed and built your original engine, only Lycoming has the ability to rebuild this engine to “new-quality” specifications and tolerances. Any reused part used on a Zero-Time Rebuilt must also meet new part specifications.

(Reference http://www.lycoming.com/support/tips-advice/key-reprints/pdfs/Key FAQ.pdf )

The many engines I bought from Lycoming were all "Factory Overhauls" and were not zero-timed. Most had several thousand hours noted in the documentation. There were a couple, though, that were brand-new first-run engines taken off the new assembly line and sold as overhauls, probably because they had too few useable cores to overhaul. When I was in the air brake remanufaturing business we sometimes had to do that: buy new units and sell them as exchanges and make less money just to get cores to keep the business moving. When that happens, core charges go way up.

Dan

 

[somorris]

I personally have no problem with field overhauls is they are done by someone (like Tom) that takes pride in their work and knows what they are doing. Check around before you buy.

 

[TMetzinger]

Not quite. From the Lycoming Flyer we see this:

Lycoming Factory Overhauls are built to (within) service limits and are time-continued engines in the logbook.

Lycoming Zero-Time Rebuilts must meet new drawing specifications.
Since Lycoming designed and built your original engine, only Lycoming has the ability to rebuild this engine to “new-quality” specifications and tolerances. Any reused part used on a Zero-Time Rebuilt must also meet new part specifications.

(Reference http://www.lycoming.com/support/tips-advice/key-reprints/pdfs/Key FAQ.pdf )

The many engines I bought from Lycoming were all "Factory Overhauls" and were not zero-timed. Most had several thousand hours noted in the documentation. There were a couple, though, that were brand-new first-run engines taken off the new assembly line and sold as overhauls, probably because they had too few useable cores to overhaul. When I was in the air brake remanufaturing business we sometimes had to do that: buy new units and sell them as exchanges and make less money just to get cores to keep the business moving. When that happens, core charges go way up.

Dan

True, I didn't mean to imply that "factory" meant zero time. Just that the two in my list - factory reman and factory new, did mean zero time.

 

[Ted]

What has been said here is pretty much accurate. For the record, when it comes time to overhaul the engines in the 310, we will probably be going for a field overhaul from a reputable engine shop.

I'm with the camp of people who say that there is a variable quality of field overhaul. An engine shop that performs the field overhaul properly and actually gives you a 0 SMOH (not to be confused with 0 SNEW, only a factory can do that) will probably typically give you a good engine. But, there are minor differences, even among the engine shops that are doing things to the letter.

For example, the IO-520-Es in the 310 were Continental remans done about 15 years ago, and have the heavy cases. One engine shop I spoke with, when asked about whether I'd get back a heavy case, said "It depends on what we have" and wouldn't just overhaul my engine with my case. Well, that translated to me as "We'll take your heavy cases for ourselves and give you light cases." Don't know if it's true or not, but I didn't like the vibe I got there.

Additionally, let's say that I wanted to get the IO-540-C4B5s in my Aztec overhauled. They are the narrow-deck cases with flat tappets. It is perfectly legal for me to overhaul them as-is and just use them, and there's nothing wrong with them. Lycoming, however, has updated those engines with wide-deck cases and roller tappets. If I wanted to get an engine with those features, my best bet is to just send it in for a Lycoming reman, because I'll get it back that way automatically.

There are variations in weights of certain components. Connecting rods are the main ones. There are also variations in clearances of certain parts (such as valve clearances). There is an acceptable range, as allowed by the type certificate of the engine. They are allowed because it was determined somehow that that range produced roughly the same result (close enough for the range of outputs the engine can be certified to). Tim is correct as far as the method - rods are not altered, ones just taken from the same weight range all from stock.

I wouldn't hesitate to get a field overhaul on a good engine from a reputable shop or A&P who took pride in his/her work. I'd want it to be someone/place who does these regularly. I would also keep in mind that, were I shopping for a plane, I would reduce the value of an aircraft that had a field overhaul done by "Random A&P" vs. one done by the factory or one of the more well-known shops.

So, as with most things in aviation, "it depends."