speedy11(at)aol.com
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 Posted: Fri Nov 28, 2014 5:13 pm Post subject: AeroElectric-List Digest: 13 Msgs - 11/27/14 |
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For Christ's sake, Does anyone have an answer to his question?
For his own reasons, Justin wants two lightweight, lithium batteries on his aircraft.
His question was not give me your advice on that decision - his question was can you help me with how to incorporate Paisley's Bus Manager and two lithium batteries into the Rotax wiring system?
He also didn't ask for advice on whether a lithium battery is the best choice given the price vs risk mitigation so I doubt he is interested in a sermon on that subject.
Is there anyone on the list who can provide Justin with information on how to accomplish what HE wants to do?
Stan Sutterfield
Port Orange, FL
Do Not Archive
| Quote: | | Quote: | Nothing that we do in aviation, experimental aviation especially, is without
risk.
It is merely a game of acceptable risk. For me, having 2 independent and
completely redundant electronic ignition units provides an acceptable level of
risk. This is because there isnt a single point of failure in the system.
I feel that the benefit of having both electronic units is the added performance
of an adaptable timing curve and a much hotter spark. Others, such as yourself,
feel comfortable with one electronic unit and one magneto. Both are correct
because the system meets the designers acceptable amount of risk and both
for different reasons.
Cheers
Justin
| Quote: | On Nov 27, 2014, at 12:15 PM, Kelly McMullen <kellym(at)aviating.com (kellym(at)aviating.com)> wrote:
Well, I had two electronic ignitions stone cold fail in Alaska. One at 40
below. |
The other in summer, but just as inconvenient. You don't hear about the failures
much because they just pull over to roadside and call a tow truck. Typically
when they fail it is a hard failure, not just rough running like a mag on
its way out. I may install electronic in place of one mag, but definitely not
two.
| Quote: |
On 11/27/2014 2:04 PM, Justin Jones wrote:
>
> I also fly in Alaska. I agree that a battery failure isnt as likely as a
starter |
failure, but if having two batteries on the aircraft is an acceptable risk
mitigation step for him, then he is justified having the extra battery. I
will have two alternators. One gear driven and one belt driven. I will also
carry
a battery jump starter pack and a solar cell that is capable of charging
it when I plan on spending any time in the bush. I understand the added weight
of the pack, however after using it just a single time, it will have been worth
it. If my starter does die and the battery still has at least 6 volts (EFII
system minimum), the ignition and injection systems will still operate, making
hand propping much easier than a healthy magneto. I will still need enough
voltage to excite the alternator for continued 12v operation. One pass of the
flywheel magnets past the crank trigger should start the engine.
| Quote: | >
> I disagree with the statement that electronic ignition adds risk. There are
many reasons. |
| Quote: | >
> 1st reason is the massive amount of time electric ignition has been in
operation. |
Nearly every vehicle manufactured since the mid 70s has electronic ignition,
meaning there are MANY MANY more hours of operation on electronic ignition
units than magnetos. They have been proven VERY reliable and need very little
maintenance.
| Quote: | >
> 2nd reason is there are solid state units that require no moving parts (crank
trigger systems). It is true that there are different electric systems out |
there, however they all run on the same principal. There are also redundant
systems
available that can keep the engine running in the extremely unlikely event
that one fails. Choose the one that is satisfactory to you and go with it.
| Quote: | >
> 3rd reason that electronic ignition doesnt add risk is the complexity and
unreliability |
of magnetos. They have moving parts that wear. They have TBOs on
them because they are known to wear and malfunction. They are heavy, expensive,
and do not provide the same amount of energy that an electronic ignition does.
I have personally had 3 magneto failures. Thankfully both have never quit
on me at once. A good friend in a Maule M4 just had one fail last week.
| Quote: | >
> 4th reason is the correct 12v system architecture that electronic ignition
requires |
is very reliable. The Z-diagrams that Bob has authored have the capability
to mitigate most risk involved with the 12v system. I have personally chosen
to go with a dual alternator system. I will carry small light solar panels
that can recharge a battery in a matter of days.
| Quote: | >
> There is a good compromise out there. Look at the G3i ignition system. It
adds an MSD electronic ignition box and runs it through the magneto (if you feel |
that you MUST have the unreliable mags). If the MSD box fails or if the battery
dies, the magnetos will still act like magnetos.
| Quote: | >
> The thing to keep in mind regardless of how many batteries that you have on
the aircraft is watching your battery health. If your battery or batteries show |
any sign of ill health, replace them. Dont push it. Batteries seldom fail
overnight. Some people even replace them every annual.
| Quote: | >
> I feel that a properly installed and maintained redundant electronic ignition
system will actually REDUCE the risk that the legacy magneto systems offer. |
| Quote: | >
> Respectfully,
>
> Justin
>
>
>> On Nov 27, 2014, at 11:10 AM, Kelly McMullen <kellym(at)aviating.com (kellym(at)aviating.com)> wrote:
>>
>>
>> Well, having flown for 20 yrs in Alaska, I would take starter motor failure
as a higher risk than battery failure. Adding electronic ignition to a plane |
in that environment IMHO adds risk over a dead simple pair of magnetos. Most
of time there is a means to hand prop if lack of battery presents itself.
Needing
electrons to fire the ignition as well as crank the engine creates more
potential
risk.
| Quote: | >>
>> On 11/27/2014 12:32 PM, Ken Ryan wrote:
>>> An argument can be made both for and against the second battery. I have
considered |
both and determined that in my case the extra battery is justified. Your
points are nevertheless well taken.
| Quote: | >>>
>>> On Nov 27, 2014 10:54 AM, "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)
<mailto:nuckolls.bob(at)aeroelectric.com ([email]nuckolls.bob(at)aeroelectric.com?[/email])>> wrote: |
| Quote: | >>>
>>> At 10:58 AM 11/27/2014, you wrote:
>>>> Being in Alaska, many landings are remote, off airport. The
>>>> engine must start. If it doesn't the only option is to trigger
>>>> search and rescue. Two batteries mitigates the risk of the engine
>>>> not starting 150 miles from the nearest civilization.
>>>
>>> Okay, how often has the 'unavailable battery' syndrome
>>> presented itself . . . and what was root cause for the
>>> failure?
>>>
>>> A battery can and should be the single most reliable
>>> source of energy on your airplane. This presumes, of
>>> course, that you give it the same level of attention
>>> to airworthiness that is bestowed upon fuel, oil, tires,
>>> continuity of flight controls, fuel filters and sumps,
>>> prop blade nicks, etc. etc.
>>>
>>> Batteries tend to be the oft neglected step-child
>>> of flight systems. The predominant public perception
>>> of battery consumerism is to run it until it wont
>>> crank the engine any more . . . Walmart sells
>>> a gizillion batteries every year that are replaced
>>> in response to that same symptom.
>>>
>>> Some years ago I corresponded with a Cessna 206
>>> floatplane owner in S. America who was wanting to add a
>>> second battery to his ship. We pondered useful volume
>>> to exploit for several exchanges of e-mails. We
>>> finally decided that inside one of the floats was
>>> the best location. The battery could be positioned
>>> right on C.G. and it occupied volume that had
>>> no other purpose.
>>>
>>> After we had corresponded a few times, he agreed
>>> that his REAL worry was for loss of a battery contactor.
>>> He conceded that in the grand scheme of things,
>>> battery maintenance was not a big adder to cost-of-
>>> ownership, his big worry was for loss of battery
>>> contactor that would make the battery unavailable.
>>>
>>> I suggested then than he add a piece of welding cable
>>> to run from downstream side of battery contactor to
>>> the battery box (accessible while standing on a
>>> float). Should preflight testing before tossing
>>> the mooring lines showed that the battery contactor was
>>> "iffy", he could make a manual connection to the
>>> battery (+) terminal with the short jumper.
>>>
>>> He decided that was a much less expensive, lighter
>>> and lower cost plan-C for dealing with a failed
>>> battery contactor. We also discussed simply carrying
>>> a spare contactor and tools . . . but that didn't
>>> cover the potential loss of wiring and/or battery
>>> master switch. So he opted for the jumper-cable
>>> and a pair of pliers.
>>>
>>> The point to ponder is how best to accommodate or
>>> modify a system that is a direct descendant from
>>> systems common to garden tractors: PM alternator,
>>> simple rectifier/regulator and a lead acid battery.
>>>
>>> It seems that the elegant design goal is to craft
>>> a combination of architecture, preventive maintenance\
>>> and operating procedures that accommodates low risk failures
>>> -OR- drives specific failure rates down to insignificance.
>>>
>>> I believe this can be achieved without adding the
>>> weight, cost or complexity of burdening a
>>> garden-tractor-style electrical system with
>>> concepts holy-watered by the FAA and embraced
>>> by Boeing and Airbus.
>>>
>>> This requires a simple but thorough thought
>>> process that goes through the steps of considering
>>> EVERY part of your electrical system from crimped
>>> terminals to alternators and batteries.
>>>
>>> How can this part fail?
>>>
>>> Is failure pre-flight detectable?
>>>
>>> If it fails in flight, how will I know about
>>> it?
>>>
>>> How would in-flight failure affect comfortable
>>> termination of flight?
>>>
>>> What are the lowest cost, lightest weight,
>>> simplest mitigations for the failure?
>>>
>>> Due diligence to Failure Mode Effects Analysis
>>> (FMEA) offers the short-path to the simpler,
>>> lightest weight, lowest cost, lowest risk
>>> (elegant) design easily understood and managed by the
>>> cognizant pilot.
>>>
>>> Bob . . . |
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