Dear Duncan
These figures are most helpful - brings the whole scene into perspective.
I think that the 1:500000 sounds about right for a whole system integrated
by one manufacturer eg. a Ford engine in a Ford car with a wiring loom by
Ford. With your knowledge and the TLC you will lavish on your aircraft
would will probably do better.
Now consider a Company who wants to put the engine into production and send
it to all corners of the world to the kit plane market where the generic
engine will be installed on dozens of different airframes by all sorts of
different builders who all think that they know best and probably want to
customise looms etc. Even with well documented installation guidelines etc
I think that the likely outcome will be failure rates 10 or 100 times higher
than your the 1:500000 that we might agree is applicable to (non-duplicated)
car systems. To stay out of court the manufacturer will either need control
of the whole system eg a Toyota engine/plane (we almost saw one) or will
want do build in mechanical back-up or electrical redundancy channels. The
cost of this compared to carbs is going to be much higher. .......it won't
be a business proposition for the likes of Rotax. Don't forget, carbs are
very simple cheap devices which work rather well.
I think that the first mechanical gasoline injection system to hit cost
targets will win. Anyone else agree with me?
Regards............MARK WILKSCH
PS: Thanks for your stimulating response.
-----Original Message-----
From: ami mcfadyean <ami@mcfadyean.freeserve.co.uk>
<milesm@avnet.co.uk>; europa@avnet.co.uk <europa@avnet.co.uk>
Date: Thursday, August 26, 1999 09:48
Subject: Re: Flying: Fuel consumption in 'Classic' with Rotax
912.
>NTSB Figures:
>Over a 5-year period in the early 90`s there were 93 accidents in the US
>attributable to magneto failure. Annual piston airtime in the States is
>about 20,000,000 hours per year. Some simple sums tells you that the
failure
>rate of what must be mostly twin mag. systems is 1 in 1,000,000 (the same
as
>your figure for dropping dead at the controls!). This doesn`t include all
>the other probable failures which didn`t end with an accident.
>
>Bosch Figures (published in an SAE paper):
>Beyond the stage where infant mortality is at a high rate, the failure rate
>of the electronics alone is about 1in 5,000,000 hours. Electronics win.
>However, (also from Bosch figures) 90% of all SYSTEM failures are caused by
>something other than the electronics (eg wiring (mostly),
>transducers,actuators etc). On that basis, whole-system failure rate comes
>down to 1 in 500,000. Magnetos win.
>These figures probably include a large number of units which were killed by
>"maintenance" (ie non-operational failures) stated by the aftermarket
>companies as being the largest cause of returns on electronic units.
>
>The risk we face in the UK of dying in a GA accident is 1 in 150,000hours
>flown (based on what I surmise from GASIL figures; someone please correct
me
>if they know different). So, that level of risk is presumably acceptable to
>all of us who choose to go flying, although CAA are always making efforts
to
>reduce this (pun intended). 1 in 500,000 would therefore seem to be of an
>acceptable order of magnitude, especially if one is not guaranteed to die
>during such an occurrence.
>
>Duncan McFadyean
>
>-----Original Message-----in the
From: Wilksch Airmotive <mark@wilksch.com>
><milesm@avnet.co.uk>; europa@avnet.co.uk <europa@avnet.co.uk>
>Date: Wednesday, August 25, 1999 11:01 PM
>Subject: Re: Flying: Fuel consumption in 'Classic' with Rotax
>912.
>
>
>>Dear wiggly-amps technofiles
>>
>>Re EFI for GA:
>>
>>I would assert that the failure rate of the whole system ie black box,
>>looms, power source etc is significantly worse than duel mag systems. The
>>duel mag always wins because it is positively checked at every flight so
we
>>have a dual system with a relatively low MTBF requirement.
>>
>>Since we can't compete with the dual mag system we need to ask what is the
>>real reliability requirement. A good benchmark is the probability that
the
>>pilot will spontaneously drop dead at the controls. My friends in the
CAA
>>tell that this is about 1 in 1000000 per flying hour. My anecdotal
>>experience with cars with black boxes tells me that EFI is not that
>>reliable, particularly if subjected to a relatively low level of TLC.
>>
>>Making an EFI duel channel with genuine redundancy is not so easy as it
>>first appears (as we found at Cosworth). In any case times sequential
>>injection is completely unnecessary for an aircraft engine which spends
>most
>>of its life running pseudo-steady state.
>>
>>This whole area is under continuing discussion within a working group in
>the
>>JAA so clearer (and I believe sensible) guidelines will emerge. We then
>>need viable technical solutions to emerge!
>>
>>Regards......MARK WILKSCH
>>
>>
>>-----Original Message-----
>From: ami mcfadyean <ami@mcfadyean.freeserve.co.uk>
>><milesm@avnet.co.uk>; europa@avnet.co.uk <europa@avnet.co.uk>
>>Date: Wednesday, August 25, 1999 06:06
>>Subject: Re: Flying: Fuel consumption in 'Classic' with Rotax
>>912.
>>
>>
>>>OK, OK,so mechanically injected 2-stroke charged diesels are superior to
>>>everything else!! but the failure rate of modern automotive FI
electronics
>>>compares favourably with the rate at which TWIN magneto failures kill and
>>>injure people in the US.
>>>Just to put things in perspective.
>>>
>>>However the reliability of the wiring is another matter. I agree that in
>>>this respect some car based solutions are less than ideal.
>>>
>>> Bosch, nevertheless (the manufacturer of the K and subsequent electronic
>>>systems) consider the latter to be more reliable. Maybe they have an axe
>to
>>>grind (and they don`t make the wiring).
>>>.
>>>
>>>Duncan McFadyean
>>>
>>>-----Original Message-----
>>From: Wilksch Airmotive <mark@wilksch.com>
>>><europa@avnet.co.uk>
>>>Date: Monday, August 23, 1999 9:49 PM
>>>Subject: Re: Flying: Fuel consumption in 'Classic' with
Rotax
>>>912.
>>>
>>>
>>>>Dear Miles
>>>>
>>>>
>>>>I have a better way of doing it. Pure machanical with electronic
>>trimming.
>>>>
>>>>There is no use in messing about with car based solutions. The only one
>>>>which will succeed in the long run is one designed to do the right job
>for
>>>>aviation - no
>>>>compromises. I would love to get one up and running on a 912! My
>>>>solution will also work on 200,000 Lycontinentals.
>>>>
>>>>Development cost is the problem - will Nigel help us with the budget?
>>How
>>>>many orders can you get me?
>>>>
>>>>I can show you some of the components next time we meet - you will be
>>>>impressed!
>>>>
>>>>Regards...........MARK WILKSCH
>>>>
>>>>
>>>>
>>>>
>>>>-----Original Message-----
>>>From: Miles McCallum <milesm@avnet.co.uk>
>>>>Date: Monday, August 23, 1999 11:55
>>>>Subject: Re: Flying: Fuel consumption in 'Classic' with
>Rotax
>>>>912.
>>>>
>>>>
>>>>>Carbs.. CV carbs... I don't want carbs at all: I want fuel injection.
>>>Nigel
>>>>>has the kit (not Rotax - they won't do it) but he won't get around to
it
>>>>>until enough people show an interest......
>>>>>
>>>>>M
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>
>>
>
>
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