Received-SPF: pass
 receiver=logan.com; client-ip=64.136.30.75; envelope-from=alwick@juno.com
To: flyrotary@lancaironline.net
Date: Mon, 6 Jun 2005 12:23:53 -0700
Subject: Re: [FlyRotary] Re: EC2 problems - solved / rotary risks
Message-ID: <20050606.130311.2568.26.alwick@juno.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
From: al p wick <alwick@juno.com>

You are right. The low failure rate of your CAS is important to consider.
But don't forget, risk also includes "What happens if it fails?". Loss of
CAS for you guys is highly significant. Engine shutoff. So all of those
causes are priority ones. 

Since you are using a low volume ECM, actually I'd be pretty quick to
consider redundancy there. Low volume meaning very high odds of design
oversights. Two ECM boards with separate inputs and outputs is my
inclination. 

You are right also, only with dual ECM's or some other of independent
backup, would you accomplish "dramatic" risk reduction.

I'm not a big believer in jumping to redundancy alternative. It depends
on the circumstances. Custom design, complex device, critical to
propulsion, will shut off if sensor fails.

Please notice, I say "I'd be quick to consider", "my inclination". Wishy
washy words like that show that I'm not sure.

-al


On Tue, 7 Jun 2005 01:31:40 +0800 david mccandless <daval@iprimus.com.au>
writes:
> Hi Al,
> I fail to see how installing another CAS will 'dramatically' reduce 
> 
> risk of all ECM causes.
> 
>   We have already said we have no history of failure of the CAS, how 
> can 
> installing another CAS (with no history of failure), 'dramatically' 
> 
> reduce the risk of failure?
> 
> And how can installing another CAS have any influence on "the risk 
> of 
> all ECM causes" ?
> 
> I also have great respect for redundant systems, but I cannot see 
> your 
> logic in this one. It is the 'dramatic reduction' that troubles me.  
>  
> BR, Dave McC
> 
> 
> On 06/06/2005, at 9:57 PM, al p wick wrote:
> >
> >  
> > Regarding CAS risk. It's not just crank angle sensor that is the 
> risk 
> > item. Going to redundancy with the CAS will dramatically reduce 
> risk 
> > of all ECM causes. Like this connector risk. I'm not always 
> proponent 
> > of redundancy, but with my limited info on this item, I SUSPECT 
> it's 
> > significant, positive step.
> >
> > -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
> 


-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