Propeller shaft SB

Hi Brett

I would not worry.  The only way your older engine would be affected is if the propshaft was replaced in the past 2 years.  The SB states the problem is one related to a batch of shafts that may have a machining issue.  The surface of the machined area they are worried about may lead to premature wear or bearing failure.  

To find the location of the propshaft serial use your parts manual, IPC.  Look for the drawing at the beginning of the related chapter on the gearbox and you can see a picture of the parts with XXX on any serialized part.  This is showing you where to find the serial of that part.  I have attached one from the 912ULS iPC as a reference.  It shows that as long as you can see the flange from the backside of the propshaft you should find it.  The number will be laser engraved on the inside of the flange.  You do not have to remove the prop but may have to remove a cowling or anything else that is restricting your view of that area.  

Cheers

I had the same reaction as Brett. Where is the 2 year limit text? SBs 074-078 seem to be cut and paste in terms of formatting and raise the same question. Although my engine SN is not in the range, the wording says 'condition_A OR condition_B' and condition_B can be difficult to confirm (e.g. stator part # and serial # or prop shaft p/n, s/n). An explicit cut-off date in this second condition would be useful for those with an older engine where the part in question has never been replaced; the questionable parts have a known manufacturing date after all.

hi David...consider a spare part installed on a 10 year old engine, it happens.  In that case you must confirm that the new prop shaft installed is not within the spare part serial numbers listed. (condition B)  We also must consider that engine supply for kits might not see someone check this SB for many months.  (condition A, new engine never repaired) 

Condition A is engine serial.  Condition B does not apply if you have never changed the prop shaft for a new one.  if you maintain a logbook according the EASA and FAA standards you will record the serial of the part removed and the part installed.  Your logbook should give you the data for any replaced part inside like the stator.  The prop shaft serial can be seen on the back of the prop flange.  

Cheers

Absolutely! I agree with the single exception that nowhere do the SB's explicitly state that if the component in question (prop shaft, stator etc) has not been replaced AND the engine SN is not in the list then the SB didn't apply.

Part of my post did say that these parts hadn't been replaced on my 2009 engine; which means though that for completeness I should check the p/n, s/n of what is installed based on the plain a or b statement in the SB (since I have no knowledge of when these rogue parts were manufactured) -- so, yes, I checked the logbooks anyway to confirm that they hadn't been replaced and then *assumed* based on engine sn that the SB was likely not applicable.

Regards,

David

hi David

I have been a pilot since 1991.  I have been a mechanic and worked on aircraft much longer than that.  If the serial number is not on the list and the engine has no listed work regarding the said part common sense says it does not apply.  If people do not maintain a logbook you can't assume anything and need to check.  The normal practice is if there is no work listed then it did not happen.  The engine produced in 2009 would not be involved since the part in this case, the prop shaft, was a limited run (batch) that was identified and much newer.  (the first 2 digits are the year produced)   The machining was suspect on some areas and they take the number of serials they believe are possible problems and add to the top and bottom of the range to capture them all.  This is standard aviation practice.  

Personally I don't know of any other way they could do this.  The verbiage of how the put together an SB is to comply with the regulators requirements for such releases.  If we can see the serial, as in the case of the prop shaft, then this is easy to check.  On engines where the serial is hidden you can only rely on your logbook for what was installed if that part was ever changed.  This would be the case of the stator as you noted. 

Cheers