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