service limit vs new limit overhaul

[poadeleted21]

What sort of "value" and/or "confidence" do you place on an overhaul that was done to "service limits" as opposed to "new limits"? Looking at log books see they tossed a crank and some other OHed/yellow tagged parts in the engine. Knowing the history of the plane, I can see why they would have done an OH as cheap as possible... Plane slung a rod, then got repoed, bank had to fix it to sell it. Was done by an engine shop though. Not considering buying this plane just wondering what the collective thinks when they see a MOH done this way?

 

[Tom-D]

What sort of "value" and/or "confidence" do you place on an overhaul that was done to "service limits" as opposed to "new limits"? Looking at log books see they tossed a crank and some other OHed/yellow tagged parts in the engine. Knowing the history of the plane, I can see why they would have done an OH as cheap as possible... Plane slung a rod, then got repoed, bank had to fix it to sell it. Was done by an engine shop though. Not considering buying this plane just wondering what the collective thinks when they see a MOH done this way?

read FAR43.2

 

[poadeleted21]

read FAR43.2

OK so there's no difference in the limits if my reading of the FAR is correct, my mistake. Question still stands.
What, if any, "Value" or "Confidence" should one put into an overhaul that has been IRAN vs one where the parts were new? Is a crank that's been ran for 2000 hrs then ground back to limits just as good as a fresh one?

 

[Tom-D]

OK so there's no difference in the limits if my reading of the FAR is correct, my mistake. Question still stands.
What, if any, "Value" or "Confidence" should one put into an overhaul that has been IRAN vs one where the parts were new? Is a crank that's been ran for 2000 hrs then ground back to limits just as good as a fresh one?

Value is in the eye of the buyer. if it meets FAR 43.2 It is good to go.

 

[poadeleted20]

OK so there's no difference in the limits if my reading of the FAR is correct,

It isn't. "Overhaul" does not require taking it to new limits, only "rebuilt" does. "Overhaul" need only take it to the limits specified in the manufacturer's overhaul manual, which may not be the same as new limits, and I believe are usually if not always tighter than "service limits," which are the limits to which a component may be worn before it must be removed from service.

What, if any, "Value" or "Confidence" should one put into an overhaul that has been IRAN vs one where the parts were new? Is a crank that's been ran for 2000 hrs then ground back to limits just as good as a fresh one?

The crank doesn't have to be replaced with a new one in order to call it "rebuilt" if the old crank is still, or can be restored to, new limits. OTOH, there are certain parts which the overhauler may replace with new regardless of the condition of the old parts, e.g., a Lycoming factory "overhaul" always includes new cyinder assemblies even though that is not required by either the FAA or Lycoming's engine overhaul manuals.

At the end of the day, it all comes down to a careful examination of the description of the work to be done provided before the job, and the documentation accompanying the engine back from the shop where the work was done. However, to answer your question as directly as possible, Lycoming charges about a 15% premium for a "rebuilt" engine over an "overhauled" engine, and the fact that the difference is what it is tells you what the market seems to think the difference is worth.

 

[Tom-D]

It isn't. "Overhaul" does not require taking it to new limits, only "rebuilt" does. "Overhaul" need only take it to the limits specified in the manufacturer's overhaul manual, which may not be the same as new limits, and I believe are usually if not always tighter than "service limits," which are the limits to which a component may be worn before it must be removed from service.

The crank doesn't have to be replaced with a new one in order to call it "rebuilt" if the old crank is still, or can be restored to, new limits.

No it can not.. it can only be cut to a undersize, which is below a service limit. If it is still at new measurements, use as it is and make new limits overhaul.

OTOH, there are certain parts which the overhauler may replace with new regardless of the condition of the old parts, e.g., a Lycoming factory "overhaul" always includes new cyinder assemblies even though that is not required by either the FAA or Lycoming's engine overhaul manuals.

At the end of the day, it all comes down to a careful examination of the description of the work to be done provided before the job, and the documentation accompanying the engine back from the shop where the work was done. However, to answer your question as directly as possible, Lycoming charges about a 15% premium for a "rebuilt" engine over an "overhauled" engine, and the fact that the difference is what it is tells you what the market seems to think the difference is worth.

Cylinders can only be enlarged, there is no authorized method to return them to standard size, except chroming, which is not a overhaul manual excepted practice, that is why both major manufacturers use new cylinders on their rebuilt engines.

You should read 43.2 over again, you will note that a REBUILT engine can be at the authorized under size and still be called rebuilt.

A service limit overhaul can't

 

[Velocity173]

I had my engine (IO-320) overhauled to new limits but I really don't think it increased the value of the plane much. I don't think any type of overhaul these days does much for the value of a plane. I've got probably 80 grand into my Glasair but couldn't get 40 for it when I had it for sale. Now I just plan to hold on to it and do small upgrades over time.

 

[Tom-D]

This engine Serial number ______ meets FAR 43.2 as Zero Since Major overhaul, TT 4500, with the following parts replaced.
6 new ECI cylinder kits, 12 new lifter assemblies 1 new cam, all common hardware, gaskets, and seals.
Reassembled using a OEM crankshaft ground to M10 spec, and fitted with a Superior bearings, in a case set reworked by _______ on work order _____ a new carb, alternator, and 2 new Slick Mags Serial number R/H____, L/H_____. and timed to 28 degrees BTDC.
This engine was assembled, tested, and preserved at this facility IAW the ________ overhaul manual dated ____.



Is that a "rebuilt", "Overhauled" engine?
to new standards ?
to service limits ?

 

[poadeleted21]

Photo of what sparked my interest attached. Good as new?

 

[Tom-D]

Photo of what sparked my interest attached. Good as new?

At first I didn't see the overhauled statement, but that's a better sign off than most

 

[gismo]

At first I didn't see the overhauled statement, but that's a better sign off than most

While I wouldn't expect to see this in an "overhaul statement" (i.e. log entry) IMO it's useful/important to get a list by part number/manufacturer for all the major components that were replaced. That way if an AD comes along requiring some action on specific parts (e.g. oil pump gears) you may be able to comply simply by referring to the list if it shows the AD doesn't apply to the part(s) in your engine.

 

[Tom-D]

While I wouldn't expect to see this in an "overhaul statement" (i.e. log entry) IMO it's useful/important to get a list by part number/manufacturer for all the major components that were replaced. That way if an AD comes along requiring some action on specific parts (e.g. oil pump gears) you may be able to comply simply by referring to the list if it shows the AD doesn't apply to the part(s) in your engine.

Part of the aircraft history records should contain the 8030-3 tags or the new perchase records. they do not necessarily need to be in the logbook entry.

 

[gismo]

Part of the aircraft history records should contain the 8030-3 tags or the new perchase records. they do not necessarily need to be in the logbook entry.

I absolutely agree that this doesn't need to be in the logbook, just that said records should be provided to the new owner. AFaIK (you probably know better), there's no FAA requirement that an overhauler must provide this to his customer, just that he determines that the parts that went into the engine were airworthy and getting an 8030-3 form for said parts is a very acceptable method for that. It's my understand that once the overhauler confirms that the parts are airworthy (e.g. they came with a valid 8030) the forms can be held on file or even tossed in the trash.

 

[Tom-D]

I absolutely agree that this doesn't need to be in the logbook, just that said records should be provided to the new owner. AFaIK (you probably know better), there's no FAA requirement that an overhauler must provide this to his customer, just that he determines that the parts that went into the engine were airworthy and getting an 8030-3 form for said parts is a very acceptable method for that. It's my understand that once the overhauler confirms that the parts are airworthy (e.g. they came with a valid 8030) the forms can be held on file or even tossed in the trash.

That's very true, and sadly that happens all to often.

I like to show the owner what they bought.

It's nice to know that the crank and cam sizes before you buy the aircraft.

 

[cirrusmx]

What sort of "value" and/or "confidence" do you place on an overhaul that was done to "service limits" as opposed to "new limits"? Looking at log books see they tossed a crank and some other OHed/yellow tagged parts in the engine. Knowing the history of the plane, I can see why they would have done an OH as cheap as possible... Plane slung a rod, then got repoed, bank had to fix it to sell it. Was done by an engine shop though. Not considering buying this plane just wondering what the collective thinks when they see a MOH done this way?

How much do you value your life? Being cheap in aviation kills. I wouldn't pennypinch on an engine overhaul just to save some dollars. when the engine quits or gives up you will wish you would have paid for a good overhaul. So I would not even bother with those planes with this type of history.

Aviation is, either you can afford it or you can't. Doing it half assed is never smart.

 

[poadeleted21]

How much do you value your life? Being cheap in aviation kills. I wouldn't pennypinch on an engine overhaul just to save some dollars. when the engine quits or gives up you will wish you would have paid for a good overhaul. So I would not even bother with those planes with this type of history.

Aviation is, either you can afford it or you can't. Doing it half assed is never smart.

So, you wouldn't consider the overhaul I posted on an airplane you'd purchase? What would be the problem with it?

 

[Tom-D]

How much do you value your life? Being cheap in aviation kills. I wouldn't pennypinch on an engine overhaul just to save some dollars. when the engine quits or gives up you will wish you would have paid for a good overhaul. So I would not even bother with those planes with this type of history.

Aviation is, either you can afford it or you can't. Doing it half assed is never smart.

You do not have to be "CHEAP" but you can be very frugal with your money. the quality of the overhaul is not money related.

 

[Tom-D]

How much do you value your life? Being cheap in aviation kills. I wouldn't pennypinch on an engine overhaul just to save some dollars. when the engine quits or gives up you will wish you would have paid for a good overhaul. So I would not even bother with those planes with this type of history.

Aviation is, either you can afford it or you can't. Doing it half assed is never smart.

I guess you will never overhaul any engine just buy a new one.

 

[MAKG1]

How much do you value your life? Being cheap in aviation kills. I wouldn't pennypinch on an engine overhaul just to save some dollars. when the engine quits or gives up you will wish you would have paid for a good overhaul. So I would not even bother with those planes with this type of history.

Aviation is, either you can afford it or you can't. Doing it half assed is never smart.

So, you'll assert that overhauled parts fail more often than new? I would dispute that. Brand new parts can be DOA.

A competent overhaul should have the same shelf life as a rebuild. It is not half-assed. Using out-of-limits parts would be half-assed, and probably illegal.

There is nothing wrong with boring a cylinder .010 oversize and using a .010 oversize piston, or grinding a crankpin down by .010 and using a .010 undersize bearing. This is equivalent in operation to a new part. It doesn't have to be cast last week as long as the machine work is done and the mating part matches.

What would be half-assed in a cylinder is not to correct taper, or to reuse a piston that has been flattened by overheat damage.

Many parts, especially piston rings and bearings, don't even work correctly when they are new -- ever -- and their lifetime depends upon good assembly and break-in practices.

 

[Skylane81E]

It isn't. "Overhaul" does not require taking it to new limits, only "rebuilt" does. "Overhaul" need only take it to the limits specified in the manufacturer's overhaul manual, which may not be the same as new limits, and I believe are usually if not always tighter than "service limits," which are the limits to which a component may be worn before it must be removed from service.

The crank doesn't have to be replaced with a new one in order to call it "rebuilt" if the old crank is still, or can be restored to, new limits. OTOH, there are certain parts which the overhauler may replace with new regardless of the condition of the old parts, e.g., a Lycoming factory "overhaul" always includes new cyinder assemblies even though that is not required by either the FAA or Lycoming's engine overhaul manuals.

At the end of the day, it all comes down to a careful examination of the description of the work to be done provided before the job, and the documentation accompanying the engine back from the shop where the work was done. However, to answer your question as directly as possible, Lycoming charges about a 15% premium for a "rebuilt" engine over an "overhauled" engine, and the fact that the difference is what it is tells you what the market seems to think the difference is worth.

Manufacturers or their approved shops may call an engine "rebuilt" Everyone else cannot

 

[Tom-D]

Manufacturers or their approved shops may call an engine "rebuilt" Everyone else cannot

that is not true.

read 43.2

 

[Jaybird180]

 

[Tom-D]

For those who would like to see the difference between new limits and service limits.
see this link, page 114-117

http://www.culvercadet.com/C85_overhaul_manual.pdf

 

[poadeleted21]

Well, to be honest, I'm glad I started... I actually bought the plane in question. Wasn't really even considering it. The only negative is that Airframe log books were lost in the mid 80's but the plane was discounted for that and has immaculate logs since. If cirrusmx thinks I'm about to kill myself, so be it, but he outta see the logs one the planes that I have been looking at that have them all the way back with a factory overhaul for comparison. To put it in perspective this plane has more log book entries in the last 6 months than the one with 400 since a factory rebuild in the last 10 years.

I'll actually post them if anyone is interested. NOTHING in the airframe, propellor or engine log book other than a yearly stamp of annual and a signature, no receipts to back it up other than the mags were rebuilt 5 years ago but not during annual so one can only speculate that they went bad.

 

[Tom-D]

NOTHING in the airframe, propellor or engine log book other than a yearly stamp of annual and a signature, no receipts to back it up other than the mags were rebuilt 5 years ago but not during annual so one can only speculate that they went bad.

how much time was put on the aircraft between annuals?

 

[poadeleted21]

how much time was put on the aircraft between annuals?

Depends on the year, plane was flown on average 10 hours per year for as far back as I saw the logs (10 years). 4 so far this year. Said he never got an invoice because "joe" does his annuals, "joe" is retired and only does his annuals. Said the plane was nice and low maintenance costs, he'd never spent more than $120 on an annual (30hours is what I have budgeted for assuming no issues). An A&P said given how long the logs were neglected (i.e. basically nothing but ELT checks for the past decade) with zero record of anything being done (except a mag overhaul, 2 tires changed out and some ELT checks) in the past 10 years. Figure on a $10,000 annual and be happy with anything less. I walked. The log book entries are literally 13 months apart one right after the other. It was located 5 miles from the beach and had some surface corrosion. I just punted. The engine was past "time" TBO.

If you're interested enough. If you'll PM me your email address, I'll point you to the files. I'm not motivated enough to scale them down, crop and rotate them for posting here. There's a lot of them.

 

[Tom-D]

If you're interested enough.

Not really, just curious.

 

[poadeleted21]

Not really, just curious.

Didn't think so, that's why I didn't go to the trouble.

 

[denverpilot]

How much do you value your life? Being cheap in aviation kills. I wouldn't pennypinch on an engine overhaul just to save some dollars. when the engine quits or gives up you will wish you would have paid for a good overhaul. So I would not even bother with those planes with this type of history.

Aviation is, either you can afford it or you can't. Doing it half assed is never smart.

I hope you never look at the logbooks of most rental/leaseback aircraft. You'll have a heart attack.