Then again, is this where our inventive efforts would yield the most value, at this time?  So far, it seems that the Mazda CAS is one of the _least_ vulnerable of the engine management components.     So far, the most fragile parts of the system have turned out to be the intake and fuel systems.  So that is where a lot of attention has been, of late.

My $.002 (.02, after 35 years of inflation)

Dale R.                              (___
COZY MkIV-R13B #1254          |----==(___)==----|     Ch's 4, 5, 16 & 23 in progress      o/ | \o


> From: al p wick <alwick@juno.com>
> Date: 2005/06/04 Sat AM 10:43:11 EDT
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Subject: [FlyRotary] Re: Rotary risks
> > First, let's try to get a perspective. > There is no job as creative as that of Design Engineer. This guy is
> making hundreds of decisions. How many inputs do I need, what size
> resistor, how wide should that track be, how do I isolate that from
> vibration, etc etc. It's a very very high risk activity. So easy to
> overlook something. Many of the decisions are arbitrary. You are just
> making your best guess. > > The Japanese produce superior products. When we analyzed their success 30
> years ago, we found they used certain tools in the design and validation
> phase that U.S. designers didn't. One of these is the FMEA (see web
> site). They get a group of engineers together and say" Ok, this is our
> best guess on how it should be designed, what's going to fail?". They go
> thru each characteristic and rate them for risk. Then they find a way to
> prove how far from failure each of those items are.
> For example, they'll say"Ok, the alternator is going to fail. This will
> produce an ac voltage." So then they measure how large the ac voltage can
> get before the device dies. Then they take action if there is not a large
> safety margin, retest. They end up with numbers that measure their safety
> margin.
> > So I would encourage reviewing all the various failure modes of the ECM.
> Deliberately subject it to experiences beyond what it will normally see.
> Unplug each sensor, see how it handles it. Apply heat way beyond normal,
> apply vibrations beyond normal. There are very simple ways to do this. It
> doesn't have to be some long drawn out thing. > > However, statistically, we know if you have true redundancy in this
> particular device, then you get to multiply the probability of failure.
> So if the probability of shut down is 1 time in 1000 hours, since we have
> two with independent probabilities, our odds plummet to 1 time in 1
> million hours. So all you need are two independent circuits. > When in doubt, just take a look at what the auto designers have done.
> They use more than one sensor to measure each characteristic. They
> compare the sensor results to historical data. They instantly recognize
> the sensor is providing false data, then warn you, and use tables or
> other sensor to keep you plugging along. That's why you don't see
> vehicles sitting on the side of the road.
> > Sorry for being so long winded, I have the impression that stuff like
> this haven't been discussed before.
> > > -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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