What kind of signal is on the CAS line? Could it go through a relay safely?
I'm thinking backup sensor here...
On Sep 13, 2011 12:33 PM, "Al Wick" <
alwick@juno.com> wrote:
> <An open CAS would cause instant shutdown
>
> The Oem guys have such a brilliant solution for this. They know from
history that sensors occasionally fail. So they plan on it. Every revolution
they count the number of pulses they saw from the CAS. So normally they see 16
pulses, with 2 breaks. The toothed wheel is missing teeth at two different
spots. One area missing 3 teeth, one missing 4 teeth. So when they see TDC,
they say "Hey, how'd the sensor do last revolution? Did we get 16 total
pulses? Did we see both a 3 tooth break and a 4 tooth break? No? Ok, then
let's use the backup sensor and turn on the fault lamp.
>
> They
also measure the integrity of the backup sensor. Pretty simple really, it's
just software calculations. Comparing to history. The other cool thing, once
you develop this logic, you have it forever. Every future pilot has a ton of
extra safety if he needs it. They do this with all critical sensors. Oh, yeah.
The other cool thing is that the engine takes longer to start. So the user
doesn't just get fault light, they also get poor starting feedback. It's just
so brilliant.
>
> There's another important lesson here: The
KISS concept. So often true, but every once in a while it's a big mistake. Not
a good idea to blindly adopt a philosophy. Depends on the details. Two CAS
sensors are much safer if you compare readings to history, make a decision.
>
> -al wick
>
>
> ----- Original Message
-----
> From: Tracy
> To: Rotary motors in aircraft
>
Sent: Saturday, September 10, 2011 7:09 AM
> Subject: [FlyRotary] Re:
The good news and the bad news......
>
>
> I agree that it
sounds like electrons Bobby. An open CAS would cause instant shutdown but I've
never heard of a Mazda CAS going bad. Have had reports of bad Subaru CAS's.
>
>
> BTW, apologies for the confusion about your fuel
system. I was confusing you with Sam Hoskins who also had a recent power
failure. His sounded like fuel system problem but no further word from
him.
>
>
> Tracy Crook
>
> Sent from my
iPad
>
> On Sep 3, 2011, at 9:08 AM, "Bobby J. Hughes" <
bhughes@qnsi.net> wrote:
>
>
> What was the system voltage during run up? At what voltage
does the EC2 shutdown? Not a likely candidate.
>
>
> What
happens when the CAS circuit goes open? Does the EC2 stop firing?
>
>
> Will a exhaust blockage of ?% stop the engine completely?
Steve's testing showed a partial blockage has a major effect on power. Bill's
muffler had to be full of crud for that much to end up back in the engine. If
the HP2 lower cone was partly intact and came loose then a major blockage is
very possible. It would trap all the little pieces that had been collecting in
the muffler. My first HP had large chunks of cone still intact along with all
the little pieces. My second HP seemed more intact when my incident occurred.
Meaning less large chunks appeared to be loose but plenty of the small crud.
The outlet cone was loose but more intact. I had hoped that moving the second
muffler to the belly would extend it's life but it didn't. In fact it may be
more dangerous since the small pieces can't be discharged as easily. My under
cowl muffler was mounted at a downward angle. Belly mount is almost flat.
>
>
> I agree Ed that electrons seem to be the most
logical cause but may be impossible to validate.
>
>
>
>
> Bobby
>
>
>
>
>
>
>
>
> Sent from my iPad
>
> On Sep 3, 2011,
at 10:20 AM, "Ed Anderson" <
eanderson@carolina.rr.com>
wrote:
>
>
> We still don't know (and may never),the
causes, but Sam's and Bills incidents based on initial information would
appear to me to be two different causes.
>
> Sam's engine kept
running - although sputtering and producing no power - this to me sounds like
a fuel related problem (possibly vapor lock, possibly something else - could
be muffler blockage). Bill's on the other hand quit suddenly and without any
warning - that to me sounds more like an electrical problem - either the
firing pulses to the injector stopped or the spark stopped.
>
>
If I were Bill, I would use the EC2's diagnostic modes to check out each
circuit - if one doesn't check out then that is probably the answer. If both
check OK then more head scratching.
>
> Ed
>
>
> From: Bobby J. Hughes
> Sent: Saturday, September 03, 2011
9:43 AM
> To: Rotary motors in aircraft
> Subject: [FlyRotary]
Re: The good news and the bad news......
>
>
>
Bill,
>
>
> I'm sorry to here about the damage but glad
you weren't injured. I don't know at what percentage of exhaust blockage the
engine would stop running. Also no reports on the condition of Sam's HP2
muffler. Three aircraft experiencing very similar problems this year is too
many. If you have leading / trailing plugs and primary / secondary injectors
on separate power feeds then it should have kept running. That leaves fuel
delivery (vapor lock), CAS circuit, Controller power, A side computer issue or
muffler? I believe Sam did switch controllers during his incident. I didn't
and had plenty of time to do so. It's now the second item in my emergency
flow.
>
>
> One common item can be eliminated be removing
any muffler that has packing. Especially Hushpower 2 since they are common to
all three incidents. I'm assuming Sam's muffler also had loose internals.
>
>
> Bobby
>
>
>
>
>
>
>
>
>
>
> Sent from my
iPad
>
> On Sep 2, 2011, at 11:54 PM, "Bill Eslick" <
wgeslick@gmail.com> wrote:
>
>
> I have been holding up reporting this until all the facts
are in, but that might never happen, so here we go.
>
>
>
Good news: No injuries.
>
> Bad news: I have some work to
do.
>
> Photos at:
http://www.tiny9.com/u/2101>
> On August 16th at 10 AM, I lined up for takeoff at my home airport
(3600' paved) into a 5 knot headwind. I had just finished changing the oil and
filter and plugs. Run-up was fine, so off I went. Approximately mid-field, and
a couple of hundred feet in the air, it suddenly and without any warning
became very silent.
>
> Hit the big switch which puts direct
battery power to everything engine, but no noise. No more time. At this point
flying the machine becomes THE priority. Dropped the nose and was amazed to
see a little bit of runway under the nose! I had fully expected to land in
trees, houses or the river, so I dove what seemed like straight down to
capture as much runway as possible while (somehow) holding the electric flap
switch long enough to get full flaps (noticed this later). Pulled probably my
best round-out ever - no bounce. Brakes to max and tail up for weight. I think
my sub-concious put it all the way on the nose to try to prevent going through
the fence and down the hill. Wheel skid starts about 200 feet from the
stopping point. Skid marks from the wheel pants, cowling and prop run about
the last 50 feet. It stopped nose down just off the end. The tail was still
over pavement. Pushed the slider canopy UPHILL, stepped out and down. Noticed
that I was not even scared by the whole event. Interesting. Never even
considered trying to turn around. Pre-thinking that non-option apparently paid
off.
>
> More good news. No FAA or NTSB as it was a
non-reportable incident. Didn't even bend the gear legs. Also, my neighbor
crashed in a Challenger about 10 minutes earlier at the city airport about 10
miles away. The police and rescue types were headed that way (they had
injuries) and were not interested in my minor mishap.
>
> As for
the engine. When we got it back to the hangar, the prop would turn only
haltingly. You could feel grinding going on inside. First try at turning had
it come up hard and stop. More fooling with it and it gradually came looser
and would turn. Really looked like something came loose in there. Pulled a
plug from each rotor and did a compression test. Rotor 1 was 80-80-80. Rotor 2
was 2-2-2. More proof that something had come loose. With that evidence, the
insurance company allowed me to remove the engine for inspection. What I found
was a pile of ground up ceramic junk. All the seals were still fine. Lots of
time went in to finding where that stuff came from. Went through every inch of
the induction system. Finally Jason Hutchison (my other on-airport rotary guy)
broke the code. While the RV was standing on it's nose, this crap from my
burned-out Hushpower II ran back up the manifold and in the exhaust port. That
is what was grinding. Crap. Now the entire thing is off the firewall including
the engine mount. All the wiring is disconnected (did not find anything loose
or missing). I spent the morning looking under the panel for any loose or
broken wiring, but found none. When I get the EC-2 out, Jason wants to plug it
into his plane and we'll do the plugs and injectors test. If that checks out,
Tracy, it is coming to you for a good look. I don't know what else to check.
The engine quit just like somebody reached over and turned off the ignition.
No stumble, no hiccup, just instant silence. I honestly do not know if the
prop was turning or not. I suspect not, due to the silence and the fact that
one blade is untouched.
>
> As you can see from the photos, there
was something going on with Rotor 1. Wear is apparent down stream from the
plug holes and all 3 apex seals are starting to chip in the center. There is
quite a lot of carbon also on the rotors after 170 hours.
>
>
Going forward, I have decided to look at resale value for if/when my RV-12
days arrive. This means putting a (gasp) IO-360 on it. The rotary has given me
a safe 10-year run (til now, of course), so I have no regrets, but this is an
opportunity to make some changes, and parts are already on the way. I will
still be hanging out at the engine tent at S-n-F and wherever else gatherings
happen. Hope to be flying by the first of next year....
>
> I'm
sure some of you will have suggestions about what might have gone wrong, and I
welcome any kind of speculation, but bear in mind I am just looking at a pile
of parts and wires at this point. Both fuel pumps were on, tanks were over
half full, crank angle sensor worked fine.
>
> Guess it's obvious
that I now have a RD-1A, EC-2, EFI Monitor (Ed's), Felix 68/72 and Props Inc
68/72 wood props and LOTS of engine parts (my whole 14-year stash) available!
And priced to sell!
>
> Bill Eslick
> RV-6 13B/NA EC-2
RD-1A
> 750 Hours
>
>
>
>