On the other hand when I had my shop I found that the biggest cause of belt failure was belt tensioner bearing seizing up usually after the first belt was replaced(even though the tensioner felt free the sealed bearings had dried up) In my opinion the tensioner(s) should be replaced at the same tine as the belt(s) . One that sticks to mind was a Peugeot MY16 twin cam, the customer didn't go for the $100.00 + tensioner , 4000km later had $3000.00 rebuild (valve to piston contact at high rpm). It's pretty hard to have redundancy on timing belts, I like the odds with a rotary!!
Georges B.
 
/-------Original Message-------/
 
/*From:*/ Rotary motors in aircraft <mailto:flyrotary@lancaironline.net>
/*Date:*/ 06/06/05 08:50:33
/*To:*/ Rotary motors in aircraft <mailto:flyrotary@lancaironline.net>
/*Subject:*/ [FlyRotary] Re: EC2 problems - solved / rotary risks
 
Hi Al,
 
The timing belt risk on your Subaru may be lower then you think, in my experience timing belt failures occur at engine start 9 times out of 10.  Most Japanese manufacturers recommend a replacement interval of about 70,000 miles, if the oil seals are replaced at the same time and the belt is re-tensioned after the first heat cycle you should be quite safe.  Ian
 
(Convinced that you are NOT flying the highest risk aircraft ever made ;-)
-----Original Message-----
*From:* Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]*On Behalf Of *al p wick
*Sent:* Monday, June 06, 2005 9:58 AM
*To:* Rotary motors in aircraft
*Subject:* [FlyRotary] Re: EC2 problems - solved / rotary risks

When we are pursuing a problem like Johns, we are eager to find the cause. It's a great relief when we do. We say "Eureka!". We did it! We did it! This sense of relief is a root cause for failure. We are so eager to get the problem off our back, that we don't take the next step....
Yes, I know you firmly believe this connector was the problem. But if you can force yourself to pretend it WASN'T, then you can do this:
Is the cause logical? Like is that really the wire that causes that effect? If I remove that wire, does it have the same effect? What if I have two things causing the same thing? By pretending that really wasn't the cause, then you will do some more testing, looking around. Looking for similar connector issues, stuff like that.
 
Now I have to admit, this really does sound like he found the cause. But I've seen this scenario so often. So you use the disciplines I suggest to reduce your risk. Logical cause? Can I make it recur?
Repeat after me: "Al Wick is an idiot". "Al will jump to conclusions". If you believe that, then you start finding ways to prove your theory with facts instead of just accepting your first conclusion. My best asset is that I know I'm an idiot.
 
Yeah, yeah, I know, you guys already knew I was.
 
We had a perfect example of this on Cozy list couple weeks ago. Subaru engine slipped 2 teeth on timing belt. Would no longer start. Keith talked to expert and the guy said:"You know, the engine normally is never rotated backwards. But you've been pushing your new prop backwards recently (installing new prop). I think you relaxed the belt tensioner when going backwards and caused it to skip tooth." So Keith said" Yes, all of that's true. That has to be it."
 
But then one of the guys looked into it, guess what? The direction the belt slipped is the opposite of that theory. That could not have caused it.
The lesson? Prove all aspects of the theory are logical. Prove that all the various facts support the theory. Find a way to convert your theory to facts!
 
Oh, by the way, if you look at my analysis of my engine risks....you will notice that timing belt is the highest risk item on this engine. So we have exposed another root cause for his problem. He didn't focus on the leading cause for all engine failures. When we reviewed some facts he had, we found conclusive evidence he had loose belt from day one! It was installed wrong.
 
Regarding CAS risk. It's not just crank angle sensor that is the risk item. Going to redundancy with the CAS will dramatically reduce risk of all ECM causes. Like this connector risk. I'm not always proponent of redundancy, but with my limited info on this item, I SUSPECT it's significant, positive step.

-al wick
Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on engine/airframe from Portland, Oregon
Prop construct, Subaru install, Risk assessment, Glass panel design info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
 
 
 
On Sun, 5 Jun 2005 21:44:00 -0400 "Tracy Crook" <lors01@msn.com <mailto:lors01@msn.com>> writes:
*Ahh..  Music to my ears John : )*
** *And this brings up the subject of risk (rotary & otherwise) that Al W. (and every other builder I know) is concerned with.  I agree with Al W. that getting to the major causes of failures is a (hell, THE) key issue.  That is why I have not spent much time on the crank angle sensor single point failure question.  I have never seen or heard of a confirmed Mazda 13B CAS failure.  Can it happen?  Of course.  I am in the process of developing a dual CAS for the Renesis CAS but it is not a 'front burner' project.*
** *I'm reading between the lines of Al's posts but it seems that he is emphasizing the importance of leaving the engine as un-touched as possible.  I once wrote an article for Light Plane World (EAA's ultralight magazine back in the late 80's) and advocated the same thing after noting that many Rotax failures  occurred soon after the owner opened up the engine for maintenance.  Decarboning the piston ring grooves was important but many builders were causing more problems than they fixed when they went inside so I recommended some products and procedures that would do the job without opening the engine.  *
** * That was the basic gist anyway but I eventually decided this was not a reasonable approach for builders who planned on installing an alternative engine in 200 mph category airplanes.  There were simply far too many areas where things could go wrong in this process.  The root cause of the problems had to be identified.   One of the names I gave to the cause is a term I recently used on this list - Shopcraft (or lack of).   This referred to the ability to identify the quality or suitability of virtually everything that goes into the plane.  Yes, I know this is a generality of the highest order but if we are to get to the root cause of failures in the field of alternative aircraft engines, this level of abstraction is required.  *
** *It has been suggested that a collection of 'best practices' might be a solution.  This may help but it is not a solution.  There is an unlimited number of potential problem areas so a list of them could never be compiled.   So, how do you learn to recognize what is or is not a 'good thing'?   I'm getting so frustrated just trying to describe the problem that there may not be a solution, at least not one that can be spelled out in something like an email message.   Damn, now I can't even criticize Al W. for not spelling it out. *
** *The best I can do for now is to emphasize two things.  Pay attention to every detail and admit to yourself when you don't have the ability to execute something well.   Another version of these rules was given to me long ago:*
** *1.  Rules are for those who are not smart enough to make up their own.  (Author unknown)*
*2.  A man's got to know his own limitations.  (Dirty Harry)*
*3.  Always follow BOTH rules 1 & 2.*
** *Small details like the problem of soldering thermocouple wire to a connector that Al Gietzen mentioned can be critically important.  He was able to recognize the problem (he made a lousy solder joint) and devise a solution (acid flux) even though it violated one of the cardinal rules of electrical wiring.  He recognized that too and took the steps necessary to achieve satisfactory results (knowing when to make up his own rules).*
** *Out of time, I'll stop blathering now.*
** *Tracy  *
 
*Subject:* [FlyRotary] EC2 problems - solved

Tracy and others.
Following more than 12 months of battling with EC2 issues I'm pretty sure it's Eureka day!
After rewiring and testing for almost 4 weeks I plugged the EC2 in last night, and got exactly the same symptoms as before. NOP flashing indicating no communication. I took the EC2 to Buly's plane and tried it in his installation. Same NOP, so I was thinking I'd fried it again. Before sending it back yet again I decided to install it my plane one more time and see if there was a spark.
 
To my amazement it worked. No NOP, and I could bring up the EC2 data. The only thing that changed overnight was that I moved the cable to unplug it. I climbed in the back and found that I could make the NOP flash, or stop flashing, by moving the cable. I haven't taken the connector apart yet, but I'm expecting to find a broken wire inside the insulation, probably near a solder joint at the pin. Whenever I bent the connector outward for testing it made contact. When I bent it back to plug it in, contact was lost.
 
Bingo!
John
 
Just guessing, but maybe the new EC2 can't communicate with a pre-autotune EM2 like Buly's. ???
 
 




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