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  #1  
Old 03-03-2017, 10:58 AM
KazooRV-9A KazooRV-9A is offline
 
Join Date: Feb 2016
Location: Kalamazoo, Michigan
Posts: 51
Default Lycoming SB 505B - O-320 Crank

Well the debate begins anew (for me), Lycoming SB 505B...

The (certified) Machine shop reviewed the O-320 crankshaft that I sent, and cannot yellow tag per the SB. They pulled the front plug, machined the paint off, and stated that there is pitting beyond acceptance criteria.

In discussions with them:

-I inquired as to whether they felt it was suitable for Experimental use. They replied that they thought that the SB was essentially over-cautious, and that it would be suitable for flight where certification to the SB, was not required

-They advised against machining the I.D., stating that even if machined, it would not clean up the pits. There would be .009" diametral available, to the max allowable O.D of 1.910", or .0045" radial that could be removed.

-They advised against repainting, stating that they felt the paint could be detrimental to further corrosion, or at lease didn't mitigate further corrosion, once evident.

So the question now becomes, what to do. The options seem to be:

1. Use the crankshaft as-is. Pull the Lycoming I.D. plate and build an engine with an uncertified crank. There are many opinions on this, I've read what I could find on this website, I'm open to a new discussion.
-The engine I have does not have logbooks, but the paperwork I did find showed 11K hours TT in 2001. It was an engine from a school plane, I don't know how much or if it flew after that before the builder purchased it. No bill of sale. Cylinders look OK, I think they'll be able to be overhauled. Cases look OK at Disassy, and I have the accessories. It came with the project I bought from another builder's estate, there was no more info about it,,,
2. Find a used yellow tag crank. Hard to do, very popular, what everyone else needs too. Every crank has a past.....
3. Buy a new crank. Expensive, and would you put one in an eleven thousand hour case?
4. Find another core engine. and hope its crank is certifiable....
5. Buy a new Lycoming engine from Van's. Money as always, is a factor.. I would assuredly have to check with the internal finance dept.
6. Find a used/mid-time engine deal.

The machine shop will finish NDT and dimensional inspections, polish the journals (all were serviceable at oem new dia's.), re-plug the front and return with inspection paperwork only. Cost was reasonable.

I'm evaluating what to do next.

Andy C.











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  #2  
Old 03-03-2017, 12:24 PM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 3,173
Default Run!

With 11,000 hours AND pitting in the crank that goes beyond the SB, my own opinion is that I'd stay as far away from that engine as I could.

Dave
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  #3  
Old 03-03-2017, 01:33 PM
KazooRV-9A KazooRV-9A is offline
 
Join Date: Feb 2016
Location: Kalamazoo, Michigan
Posts: 51
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I was doubting that it would be the original crank, with still having new spec (un-ground) main and rod bearing journal diameters. I was assuming it had been replaced, sometime during the engine's life.

AC
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  #4  
Old 03-03-2017, 01:41 PM
krw5927 krw5927 is offline
 
Join Date: Aug 2010
Location: Wichita, KS
Posts: 1,690
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SB 505B says, "Crankshafts which exhibit the above described pitting on the I.D. may be exchanged for a new crankshaft at a special reduced rate. Contact a Textron Lycoming distributor for this price and to arrange the return of the unserviceable crankshaft."

I'd find out what this reduced rate is...
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  #5  
Old 03-03-2017, 01:49 PM
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johnbright johnbright is offline
 
Join Date: Aug 2010
Location: Newport News, Va
Posts: 81
Default Cylinders

Quote:
Originally Posted by KazooRV-9A View Post
Cylinders look OK...
My mechanic advised against exhaust valves with unknown hours due to possibility of breakage/swallowing.
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  #6  
Old 03-03-2017, 02:56 PM
jrs14855 jrs14855 is offline
 
Join Date: Apr 2008
Location: Lake Havasu City AZ
Posts: 1,984
Default Crank

With all due respect the op asked for advice on crankshaft. What in the world does exhaust valves have to do with this?
Using a non 505 crank with a metal constant speed would cause me some concern. The non 505 causes me ZERO concern with a wood/composite fixed pitch or wood/composite blade constant speed. A metal fixed pitch probably not an issue. The type of blades make a HUGE difference in loads incurred by the crank.
Lycoming has a long history of engineering/manufacturing mistakes where they use questionable service bulletins to reduce their liability.
Lycoming has never solved the problem of crankshaft failures on aerobatic airplanes. The latest greatest special aerobatic cranks fail in as little as 100 hours when used with a metal blade constant speed.
The persistent industry rumor since the original issuance of 505 is there is exactly ONE crank failure world wide on applicable engines that could be blamed on pitting and that was an airplane that lived outside near the salt water.
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  #7  
Old 03-03-2017, 03:06 PM
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az_gila az_gila is online now
 
Join Date: Jan 2005
Location: 57AZ - NW Tucson area
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Exclamation

Quote:
Originally Posted by jrs14855 View Post
With all due respect the op asked for advice on crankshaft. What in the world does exhaust valves have to do with this?
Using a non 505 crank with a metal constant speed would cause me some concern. The non 505 causes me ZERO concern with a wood/composite fixed pitch or wood/composite blade constant speed. A metal fixed pitch probably not an issue. The type of blades make a HUGE difference in loads incurred by the crank.
Lycoming has a long history of engineering/manufacturing mistakes where they use questionable service bulletins to reduce their liability.
Lycoming has never solved the problem of crankshaft failures on aerobatic airplanes. The latest greatest special aerobatic cranks fail in as little as 100 hours when used with a metal blade constant speed.
The persistent industry rumor since the original issuance of 505 is there is exactly ONE crank failure world wide on applicable engines that could be blamed on pitting and that was an airplane that lived outside near the salt water.
The FAA AD mentions quite a few more incidents that the famous UK Piper PA-28 with the O-320-D3G engine -

...In addition, the Federal Aviation Administration (FAA) has confirmed that four other failures in the United States and 10 in foreign countries were due to cracks initiating from corrosion pits in the crankshaft bore on certain Textron Lycoming 320 and 360 reciprocating engines with ratings of 160 horsepower or greater. Of the 10 failures in foreign countries, four resulted in the propeller separating from the aircraft inflight. Three of these four were from 1993 to 1996...

Full AD here -

http://yeeles.com/Reference/AD/Lycoming/98-02-08.pdf
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  #8  
Old 03-03-2017, 04:09 PM
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9GT 9GT is offline
 
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Location: Southern Michigan
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I would scrap it for a new one. Like Kurt said, Lycoming may have reduced pricing for an AD replacement. When I researched this about 7 years ago for my IO-540, a replacement was $6000 for a new crankshaft if it was an AD replacement. I was able to check mine on their website with engine and crankshaft serial number. Mine had already been replaced.
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  #9  
Old 03-03-2017, 04:17 PM
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Vlad Vlad is offline
 
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Location: NJ
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Default

Quote:
Originally Posted by KazooRV-9A View Post

....

5. Buy a new Lycoming engine from Van's. Money as always, is a factor.. I would assuredly have to check with the internal finance dept.

....
Andy check with the chief finance officer. Bribe her, brainwash her if needed. Cut elsewhere (glass, paint etc), delay first flight but get a healthy heart for your RV. You will save a lot of nerves down the road.

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  #10  
Old 03-03-2017, 06:04 PM
Rupester Rupester is offline
 
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Location: Mahomet, Illinois
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Default

FWIW, I second Vlad's advice. A different engine with a known history (or zero time) will be a far better option in the long haul.
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