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I agree for the most part, Al.
I have made it a point to always posted my "incidents" in
hope it will keep someone else from having the same incident. I mean lets
advanced the state-of-the art, if you are going to have an incident - make it a
new one - not one for which we already know the out come. {:>)
However, these postings have sometimes been taken out
of context, misunderstood or misconstrued by others in ways not always
accurate and sometimes in a clear attempt to put down either the
individual, the motor, the technique, etc, - which is not always
pleasing. But, I won't let that
deter me for posting, I feel I have done my part by raising the issue for others
to consider. Sometimes, I find out from others that my incident may
have a possible cause I had not considered.
Clearly, if a list is not encouraging individuals to post
their incidents - no matter how embarrassing it may be (I have a quite a few in
that category) - or otherwise not keeping the discussion professional and in a
"problem solving" mode, then fewer individuals will post - to the detriment of
us all.
Yes, automobile CPUs do have a much greater capability to
do self diagnostics which can be helpful, but at the cost of added complexity
(and you very well know what complexity in software can do {>).
Now, if you have the staff to properly do software on that scale then that's a
different story. I think we will see a limited diagnostic capability
appear in the future - but I certainly couldn't say when.
It still boils down to most of the incidents are not in
the units themselves but in the area (like wiring/ plumbing/ etc) hooking these
things together where most happen. So long as we "roll" our own then that
is going to be an area that will offer the most potential for
incidents.
I don't think taking issue with a posting -if it contains
inaccuracies, or appears out of context, or is intentionally
misconstrued is necessarily defensive - just a matter of setting the record
straight so that others will have a clear and accurate picture of what
happened. Also, lets face it, e mails are certainly lacking as a
communication medium, just too many way to read something - drawing incorrect
inferences that were unintended.
In any case, lets all agree to keep posting our incidents
- it may save someone's bacon.
Best Regards
Ed
----- Original Message -----
Sent: Saturday, June 10, 2006 10:50
AM
Subject: [FlyRotary] Re: Ignition
Failure
I understand that it's totally natural to feel defensive in this
situation. I know you may find this hard to believe, but the goal of the post
is to help others reduce risk. It's not a personal attack. There's no rotary
reference in it anywhere. As far as the readers know it's a piston
engine. But I hope there's at least one person on this list that
sees value of looking at the other causes.
The essence of the post is accurate. Doesn't matter if you are near home
base or not. Ignition failure is very high risk item. An ECU that was better
at self diagnoses would have greatly reduced your risk. On your car, it would
be recognized immediately. Ecu would say "Hey, my cam sensor just went thru
it's normal 50 pulses per revolution with the normal 5 and 8 ms. gaps. But I
didn't get the normal 20 pulses and signal gaps from the crank sensor.
Turn on warning lamp and crank code. Use cam sensor for timing info." You
don't see value in discussing stuff like this? If you guys just used toothed
wheel with pulse gaps, then the ECU could easily self diagnose.
You know what was cool on the other list? Guys came back with
"confessions" of how this parallels a problem they encountered. 2 guys
said, "yeah, I had partial failure, thought it was x, took off only to find it
was y". Then other guys described changes they made to system that totally
eliminated the risk. Some really creative stuff. Then we discussed just how
risky crank sensor really is...we see one ever 1 1/2 to 2 years. Etc. Etc.
Very positive experience that may save someone's life. That's the goal.
Hi Tim,
Isn't it wonderful how stories get twisted around as they
fly from list to list. Obviously this particular twisted story relates to my
recent experience, so let's dilute the fun a little by adding some
truth.
So he was flying along when his engine
started crapping out.
Actually I was in the pattern
at my home field flight testing some minor modifications. The engine began
to run rough above about 4600rpm. Below 4600, which is more than enough to
maintain level flight, it ran perfectly. I circled the field for a few
minutes to try to diagnose the problem by switching redundant coils,
injectors, ECUs, fuel pumps and batteries, checking fuel pressures and
adjusting mixture. Nothing changed so I made a normal landing (at my home
field).
I have the details
correct
You don't
he fired his plane up
after cool down. It sounded ok, so he proceeded to depart. Fortunately he
lucked out again. His engine crapped out on takeoff run. He finally had to
push it off the runway.
Yes, I waited for the engine to cool
down, then (after returning from a business trip a few days later) tried
another runup with no intention of taking off. The runup was normal, so I
did I high speed taxi run on the runway to try to replicate the problem. I
was successful. The problem worsened as I pulled off the runway. This time
max rpm was around 1100. Not enough to propel the plane so, yes. I pushed
the plane 100' back to my hangar.
2) Making
assumptions when diagnosing fault. No doubt this failure could
be
difficult to diagnose. But we all have tendency to jump to
conclusions,
hope for the best, etc. We are all influenced the most
recent
discussions. We are at strange airport and want to get back
home.
No assumptions were made. It was considered a
possibility that the coils might be the problem since similar symptoms had
been experienced by another flyer. Unlike other possible causes, coils take
a while to obtain, so a spare set was ordered while I was out of town IN
CASE they were at issue. This way they would be at hand if needed. As it
happens, they weren't. The decision to order new coils was simply one of
logistics.
4) Using marginal components. If
he wasn't using known marginal coils, he
would not have jumped to that
false conclusion.
The LS1 coils have an excellent reputation,
with only one reported failure on an aircraft of which I'm aware. I have 2
coils per rotor with switching to defeat each set in turn during runup. The
engine runs well with either set switched off.
While we're
speaking of assumptions, making them in third hand reports of a fault and
subsequent fix, while entertaining, is totally counterproductive with
respect to learning from others mistakes.
The truth is that the
rotary has two crank angle sensors, and ran smoothly with what may have been
an intermittent fault on one sensor. The RTV was, in fact, used to seal the
end of the connector and was well away from the soldered connection. I
suspect either a bad solder joint or insufficient strain relief as the
probable causes.
John Slade
PS Feel free to post "The rest of
the story" back to wherever the rumor mongers lurk
Timothy Peters
wrote:
All,
I'm going to risk the wrath of the anti-cross
posters and post here what I read on one of the Fly Subaru
lists. I was hoping someone else here might have caught it and
raised the issue with the group, but I haven't seen anything yet.
(Although I do run perpetually 2 days behind.) It was weighing too
heavily on my mind to let it pass.
It may help to know that I have not made a
final decision about what type of engine I am going to use, so I monitor
several different mailing lists... John Slade has told me I don't
even need to worry about an engine until I get an airframe
built... or even decide which airframe to build. ;-)
I'm primarily looking at the Cozy IV and
the design changes I'm considering involve engine type. I will
be deciding on an engine before building.
So far I'm thinking Bruce T. built
13B turbo-equalized with RWS redrive and EC2. (I'm also
kicking around a H6 turbo Subie engine).
But this raises a question about fault
tolerance, specifically how non-OEM engine controllers handle such things
as a failed crank sensor.
I did get irritated with the rounds of self
congratulatory rhetoric and Darwin jokes that passed back and forth after
this post. One following post even boasted that, unlike this silly
bloke, he used bullet proof GM coils. To his credit, the original
poster did return that the suspected failed coils were GM
coils.
Well, time to separate the facts from the hot
air... where do we stand with sensor faults and how do they affect
the RWS controller verses an OEM controller?
Couple weeks ago one of the
guys had ignition failure on his conversion.
There were
so many contributing causes, so much to be learned by his
experience.
Fortunately he and his plane survived, although we should all
pretend
it didn't turn out so well.
I've been harping a few years now on
the need for the custom ignition
systems to handle sensor faults
better. This failure would have been
lower risk if he had such a
system. So he was flying along when his
engine started crapping out.
Wisely he took precautionary landing.
Recently there were newsgroup
discussions about a certain brand of coil
giving out from heat. So he
assumed that was what he was experiencing. If
I have the details
correct, he fired his plane up after cool down. It
sounded ok, so he
proceeded to depart. Fortunately he lucked out again.
His engine
crapped out on takeoff run. He finally had to push it off
the
runway.
The direct cause? He lost his crank sensor. The wire
connector was
corroded. Reportedly he adapted OEM plug to the sensor
and used RTV as a
strain relief. I never knew this but I'm told RTV
cures using a chemical
that can corrode electrical contacts. Coupled
with the fact that he flies
in corrosive part of country (humid
Florida).
So here are all the causes. I attach significance to
them all. Many of
them we are all vulnerable to.
1) Custom
wiring of critical component using unproven method (RTV). He
had good
intentions, but inadvertently caused a problem. This is very
common
failure scenario. All custom work is high risk.
2) Making
assumptions when diagnosing fault. No doubt this failure could
be
difficult to diagnose. But we all have tendency to jump to
conclusions,
hope for the best, etc. We are all influenced the most
recent
discussions. We are at strange airport and want to get back
home.
3) Use of unintelligent custom ignition system. Your car in
this scenario
would have immediately turned on the check engine light
and the code for
"bad crank sensor" would be sent. This ignition system
boasts dual
computer and all that, yet is vulnerable to crank sensor. I
sure want to
encourage these suppliers to improve fault handling.
4) Using marginal components. If he wasn't using known marginal
coils, he
would not have jumped to that false conclusion.
5) No
discussion of contributing causes. We don't learn from these
situations
if we don't pursue the other causes.
-----
Original Message -----
Sent:
Monday, June 05, 2006 9:22 PM
Subject:
[FlyRotary] Re: Shoe Goo Research, Was Re: Protecting splices
DAMHIKT.
>
>
OK, I give up.
What does it mean? :)
Don't Ask Me How
I Know This
Pretty soon,
"acronym" will be an official language, without any words
:-)
BTW, a belated
congrats to Jason on his first flight, Joe on his continued testing, and
a big thanks to John for getting the hell out of my state
:-)
Cheers,
Rusty (Kolb on
Ebay as I type)
--
Homepage: http://www.flyrotary.com/
Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/
-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
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