.30-under rod beari...
 
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.30-under rod bearings for 150 Franklin

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ed-reading
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A friend's Franklin 150 has been found to have .30-under rod bearings. They're probably automotive bearings, because the smallest under-size for Franklin is .20-under. What now? Does anyone have a solution, other than buying a crank? Thanks. --Ed

 
Posted : 28/01/2022 9:13 pm
Tim
 Tim
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That crank is junk now. You are going to have to buy a serviceable one. 

It sucks that you have to do that and that some idiot put the engine together that way. This is one of the main reasons Franklin's have a bad name.

 
Posted : 28/01/2022 10:32 pm
Michael
Posts: 280
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Not sure why having  .030 over bearings  is such a big deal. There's no difference between Franklin bearings and automotive bearings. If the crank had to be reground more than .020, what other choice would you have? If you can't figure out how to use "automotive bearings", find a good crank somewhere. 

 
Posted : 29/01/2022 2:23 pm
Tim
 Tim
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@ecos36gmail-com 

It's thinking like this that has given these engines a bad reputation over the years.

 
Posted : 29/01/2022 6:30 pm
Michael
Posts: 280
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@tim 

 It's thinking like this that keeps old Franklin's going. It's crappy cylinders, mags and no oil filter that plague old Franklin engines. If the crank was properly re-ground and the bearings properly fitted, that would be considered a "re-work". Done all the time on old engines.

 
Posted : 29/01/2022 9:18 pm
Tim
 Tim
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No, it's thinking like this that make Stinsons smoking holes in the ground. Crappy mag, cylinders etc... are all the result of this way of thinking, poor maintenance practices and not reading and adhering to the published overhaul/maintenance manuals, service bulletins and AD's. Oil filter kits are readily available for Franklins. So are reputable component and engine overhaulers. That crankshaft was not ground by any aviation shop and I would bet no reference to it is in the logbooks. When a part has exceeded it's service limits, as determined by the manufacturer, it is to be discarded and a new or serviceable part installed. If a new or serviceable part is nonexistent then the owner produced parts section of the regs would be available but you still have to have FAA approval before installing that part and I would bet, that crankshaft has no FAA 337 approval to be ground .030 under.

 
Posted : 29/01/2022 9:50 pm
Wade Modrow Modrow
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@ecos36gmail-com 

Thanks for sharing!

 
Posted : 30/01/2022 7:32 am
ed-reading
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@tim The overhaul that yielded the .30-under bearings was done in 2001, 21 years ago. This is the first time the bottom end has come apart. The overhaul also included recutting the piston ring grooves to accept truck rings. All the work was recorded in the logs. I didn't know the details at the time, and don't know for sure now, because I sold the airplane in 2013 and don't have the logs. The current owner says he will probably buy a used serviceable crank.

 
Posted : 30/01/2022 4:44 pm
Michael
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@ed-reading 

You would think that after going to .030 under during an ovhl, the next time it gets an ovhl it's probably going to need a new crank.  It's kind of a hail mary operation to save a crankshaft.

 I re cut the top ring groove when I went through the Franklin in my Cruisair. With so few good pistons left in the world, this repair is pretty cool. You end up with almost new pistons again.

 
Posted : 30/01/2022 7:54 pm
Wade Modrow Modrow
(@wademodrowoutlook-com)
Posts: 20
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1/8 inch top ring, I've seen this. Works great! 'According to sources'.  Machine shop process and Hastings ring I'm quite sure.

 
Posted : 31/01/2022 12:15 am
Will Ware (Webmaster ISC)
(@stinsono)
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Posted by: @ed-reading

@tim The overhaul that yielded the .30-under bearings was done in 2001, 21 years ago. This is the first time the bottom end has come apart. The overhaul also included recutting the piston ring grooves to accept truck rings. All the work was recorded in the logs. I didn't know the details at the time, and don't know for sure now, because I sold the airplane in 2013 and don't have the logs. The current owner says he will probably buy a used serviceable crank.

I would LUV to see a picture of that logbook entry!

 
Posted : 31/01/2022 5:07 am
Michael
Posts: 280
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@stinsono 

 "Crankshaft reground.  pn12345678 bearings installed."

I have never seen a lot book entry that said much more than that. A yellow tag would be nice but not required because an A&P putting the engine together can take responsibility for everything when it's signed off.  Someone flying part 135 would need to show traceability and would need a yellow tag, but otherwise it would be on the  mechanic signing off the engine for return to service.

Like it or not that's how things have gone on forever. Probably explains why there are so many smoking holes from Stimson's crashing.

 
Posted : 31/01/2022 2:24 pm
ed-reading
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@stinsono The current owner of the airplane tells me the log book says, ”detailed part list on file at [so-and-so] AIRCRAFT under W/O 1725”. The owner of [so-and-so] AIRCRAFT is dead and the business is closed. I would love to see the work order also, but we are at the end of the line here. He's going to buy a crank; he has located three. I wish him good luck. --Ed

 
Posted : 31/01/2022 4:46 pm
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