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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