The International Cessna^® 170 Association

Sometimes damage like this is caused when a cylinder is replaced or an oil leak develops on a part-time engine. Installing a replacement cylinder or attempting to stop an oil leak by re-torqueing through-bolts will overstress the case and lead to a failure.
"Overhauling" an engine in the field can also lead to this if a bearing is not properly placed with it's "tooth" in the case-groove. (This prevents the bearing from rotating within the bearing support.) Unfortunately, an under-torqued assembly may also lead to such a failure as the bearing is never properly pre-loaded or captured. Hydraulic "lock" may also lead to this sort of failure, although it is rare in normally carburetted engines, and usually such things (and similar stresses caused by "back-running" due to preignition or failed impulse couplings) first manifest themselves as failed cylinder heads rather than failed main bearing supports.
But it's always amazing to me how many times seemingly major failures don't always result in catastrophe. These engines will sometimes run all the way to TBO and beyond with this sort of thing and it's discovered during tear-down!

Continental has a service bulletin that details the procedure for replacing cylinders in the field. (Sorry I don't have the number, but it is on their web site.) One of the points they make is that through bolts MUST be torqued on BOTH sides, even if cylinders on only one side are being replaced. If not, the result is broken through bolts or cracked case.

Miles

TCM SB 96-7C issued 6-11-96 and revised 2-08-05. See the MX Library.

gahorn wrote:TCM SB 96-7C issued 6-11-96 and revised 2-08-05. See the MX Library.

Or.....go to http://tcmlink.com/servicebulletins.cfm and see ALL the TCM service bullitens.

lowNslow wrote:...Or.....go to http://tcmlink.com/servicebulletins.cfm and see ALL the TCM service bullitens.

Well....sorta....

Actually that link lists only a few of the most frequently requested bulletins. There are many, many more that have been issued (although most do not apply to our engines.)
In order to view all available, one must be a registered member of TCM's Aviator Services. I am (and so may most folks join).... I usually post the text of those that have special significance for our group in our MX Library.

gahorn wrote: Actually that link lists only a few of the most frequently requested bulletins. There are many, many more that have been issued (although most do not apply to our engines.)

OK true, but if one wants a PDF file saved of MOST of the SBs rather than digging thru the forum....that is were to get them. They have quite a few there that I have not seen on the forum.

MORE WOES.

I chose to use Superior cylinders and from what I am being told Superior has stopped shipping due to some vendor dispute. I was told that they are not going to ship before the end of May so it looks likes I am not going to be flying anytime soon.

Bill Hart wrote:MORE WOES.

I chose to use Superior cylinders and from what I am being told Superior has stopped shipping due to some vendor dispute. I was told that they are not going to ship before the end of May so it looks likes I am not going to be flying anytime soon.

Bill,

Is it too late to cancel your order with Superior? I have yet to hear of anyone who is unhappy with their ECI cylinders. (If there is someone reading this who IS unhappy with ECI, I'm sure we'll hear about it.)

Miles

You are reading my mind Miles.

Bill Hart wrote:You are reading my mind Miles.

I'm originally from Georgia, so we probably think a lot alike.

Miles

Bill, if that's why you think like Miles.....you'd better move! Quick!

Well he is a rocket scientist I just think I am.

Should I be unhappy with no measurable oil usage in the first 14 hours since new ECIs ?

It seems with Superior not shipping that ECI’s are now back ordered as well. This is starting to suck.

Have you considered Genuine TCM? Like every other cylinder mfr they had some early problems but seem to have gotten them corrected.