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From: "Ian Dewhirst" <ianddsl@magma.ca>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: RE: [FlyRotary] Re: EC2 problems - solved / rotary risks
Date: Mon, 6 Jun 2005 12:03:15 -0400
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Auto makers often mount their ECUs in trays that extend past the connector,
the connector is attached to the ECU and then the cable is secured to the
tray a couple of inches downstream of the connector.  Critical harness
connections will often be stabilized with a "splint" that bridges the
connector and ties the harnesses together while immobilizing the connector
housings.  They do use crimped connectors but that is likely a production
issue, Dale makes a good point about focusing force of movement.  Auto
makers put a lot of effort into connector design, typically an ECU connector
will be positively sealed with a rubber O ring in the connector body.

Ian

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On
Behalf Of Dale Rogers
Sent: Monday, June 06, 2005 11:40 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: EC2 problems - solved / rotary risks


John,

   I suspect what Al W. was getting at, is that every
connector which is put together in the same way as the
troublesome one is now *suspect*.  If you _are_ using one
on a flight critical system, you'll want to inspect it and
verify its integrity under some reasonable level of motion.

   As a semi-aside, this sort of thing is why I really don't
care for soldered cable connections.  I work in the computer
industry as a field engineer, and soldered connections are
rare except inside a chassis where the wires are well-
secured against motion.  Soldering a stranded wire connection
focuses all the force of motion onto the point at which the
solder no longer binds the strands together.  There is a
reason why the connector industry can get more money for
crimp connectors than for the solder type.  They're worth
the extra cost.

My $.002,
Dale R.


> From: "John Slade" <sladerj@bellsouth.net>
> Date: 2005/06/06 Mon AM 10:49:51 EDT
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Subject: [FlyRotary] Re: EC2 problems - solved / rotary risks
>
> Thanks, Al.
> After a slightly bad start, this is starting to get very informative and
> interesting. Please keep it coming.
>
> In the case of the wire/connector, I'm not really worried about it because
> it'd not an engine out thing, just a loss of communication with the engine
> monitor.
>
> I like the "best asset is that I know I'm an idiot" theory.
> It works well for me because Rusty keeps reinforcing it. :)
> John
>
>   -----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> 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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