CTSW: 2006 vs. 2007

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Re: CTSW: 2006 vs. 2007

Postby drseti » Tue Dec 26, 2017 12:21 pm

Wm.Ince wrote:Was that a chronic failure? If not, and it was considered an isolated incident, aren't you kind of painting ("red flagging") with a very wide brush?


Not an isolated case, Bill, just the first one with which I had personal experience. But it is common enough that it was mentioned in my biennial Rotax Heavy Maintenance course a year ago as a known problem. And, when my former students mentioned their problem to Lockwood, they were asked the crankcase s/n and then told Lockwood knew all about the failure mode. So, it appears not all that uncommon (although it's true that many of the early engines did make it to 2500 hours or beyond).
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Re: CTSW: 2006 vs. 2007

Postby drseti » Tue Dec 26, 2017 12:30 pm

Wm.Ince wrote:IMO, a "red flag" advisory, from a pre-buy surveyer, is synonymous to a "do not buy" alert.


No, a red flag is a "proceed with extreme caution" in my use. Perhaps a better term (from my SCCA days) would have been yellow flag. The conditions for "walk away from it" were covered in my prebuy EAA webinar a couple of years ago.

Is that a fair assessment for all those engines with a 1500 hour TBO? If it is, then the FAA should have stepped in, long ago, with specific corrective action.


Actually, some of those earliest 912s were 1200 TBO or even less.

These are not certified engines, Bill, so I can think of nothing short of a string of fatal accidents (like the Zenith main spar issue) that would cause the FAA to step in.
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Re: CTSW: 2006 vs. 2007

Postby drseti » Tue Dec 26, 2017 12:39 pm

3Dreaming wrote:Wasn't it more like 2010 or 2011 that 2000 hour TBO became standard with new engines?


The service bulletin allowing an upgrade to 2000 TBO came out in about the second quarter of 2010. It only applied to crank case s/n above 06.0010, and required modification of the oil pressure regulator valve by replacing the pressure spring and cap with a newer design. It was a simple, under $100 upgrade, so AFAIK every eligible engine was modded. As soon as the new spring and cap became available, the factory started using them, so anything manufactured after mid-2010 should have been 2000 TBO. The service bulletin listed which engines already were, by s/n.
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Re: CTSW: 2006 vs. 2007

Postby TimTaylor » Tue Dec 26, 2017 1:45 pm

I think whether or not a red flag should be raised depends on your perspective. If you own one, then no. If you might buy one, then yes. If nothing else, you would want to factor in any potential risk into your price negotiations.
Commercial Pilot Airplane Single & Multiengine Land; Instrument Airplane; Sport Endorsement Airplane Single Engine Sea; Flight Instructor Airplane Single And Multiengine; Ground Instructor Advanced Instrument

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Re: CTSW: 2006 vs. 2007

Postby Wm.Ince » Tue Dec 26, 2017 2:51 pm

drseti wrote:The service bulletin allowing an upgrade to 2000 TBO came out in about the second quarter of 2010. It only applied to crank case s/n above 06.0010, and required modification of the oil pressure regulator valve by replacing the pressure spring and cap with a newer design. It was a simple, under $100 upgrade, so AFAIK every eligible engine was modded. As soon as the new spring and cap became available, the factory started using them, so anything manufactured after mid-2010 should have been 2000 TBO. The service bulletin listed which engines already were, by s/n.

. . . a red flag is a "proceed with extreme caution" in my use. Perhaps a better term (from my SCCA days) would have been yellow flag. The conditions for "walk away from it" were covered in my prebuy EAA webinar a couple of years ago.

Actually, some of those earliest 912s were 1200 TBO or even less.

These are not certified engines, Bill, so I can think of nothing short of a string of fatal accidents (like the Zenith main spar issue) that would cause the FAA to step in.

Not an isolated case, Bill, just the first one with which I had personal experience. But it is common enough that it was mentioned in my biennial Rotax Heavy Maintenance course a year ago as a known problem. And, when my former students mentioned their problem to Lockwood, they were asked the crankcase s/n and then told Lockwood knew all about the failure mode. So, it appears not all that uncommon (although it's true that many of the early engines did make it to 2500 hours or beyond).

Thank you Paul, for further clarifying.
So, to the best of your knowledge and understanding, what was the underlying cause (in addition to what 3Dreaming mentioned above) and what was the recommended corrective action?
Bill Ince
CTSW
Retired Heavy Equipment Operator

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Re: CTSW: 2006 vs. 2007

Postby drseti » Tue Dec 26, 2017 3:10 pm

I think the root cause of the original flaw was the design of the crankshaft half through bolts. When properly torqued, they still allowed some movement of the case halves, resulting in some oil leakage. When owners or mechanics observed oil seeping out at the joining line, they simply increased the torque on the bolts, causing warpage until the main bearing to crankshaft journal clearance was compromised. As I understand it, the failure mode was crankshaft journal wear, followed by bearings spinning and seizing. (If anyone else has further info on this defect, please feel free to chime in.) In any case, the new crankshaft design incorporates a completely different through-bolt design and torquing sequence, if I recall correctly.
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof H Paul Shuch
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Re: CTSW: 2006 vs. 2007

Postby drseti » Tue Dec 26, 2017 3:13 pm

I think the person best able to respond knowledgeably to this question is Eric Tucker, of Rotax Flying Club. Eric, if you're lurking here, please elaborate for us all.
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof H Paul Shuch
PhD CFII DPE LSRM-A/GL/WS/PPC iRMT
AvSport LLC, KLHV
fly@AvSport.org
AvSport.org
facebook.com/SportFlying
SportPilotExaminer.US


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