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To: flyrotary@lancaironline.net
Date: Sat, 4 Jun 2005 15:13:56 -0700
Subject: Re: [FlyRotary] Re: Rotary risks
Message-ID: <20050604.151405.2820.4.alwick@juno.com>
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From: al p wick <alwick@juno.com>

Good point Dale. Clearly you want to focus on the big risk items. In my
field it's referred to as the 80/20 rule. Meaning 80% of the risk can be
eliminated by addressing only 20% of the items. Just have to figure out
which items are the 20% ones. Lot's of ways to do that.

-al wick

 
On Sat, 4 Jun 2005 11:37:50 -0400 Dale Rogers <dale.r@cox.net> writes:
>    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
> > 
> 
> 
> 
> >>  Homepage:  http://www.flyrotary.com/
> >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
> 
> 


-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