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Touchy!

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Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Fri Nov 28, 2014 6:25 pm Post subject: Touchy!

For any question or problem there are a number of ways to skin the cat, 

including it may not be a problem at all.

To object to folks questioning whether he needs to do what he wants is 

just as valid a discussion and learning point as assuming he has 

correctly parsed his situation, already knows the best solution and just 

needs to know how to implement it.

If the best solution was so obvious, he would also know how to 

implement. When you start incorporating the latest of everything, like 

lithium batteries, electronic ignition, etc. you are on what is called 

the bleeding edge for a reason.

Others like Bob and some of the rest of us have been around GA planes 

for 30-40 years or more, worked our way through risk mitigation in a lot 

of different environments and know what last century products work, and 

what doesn't.

Some of us just don't agree on the reliability of various items. I for 

one have personal experience with dual electronic mag failure which 

pushes me towards having one conventional mag, but others see that 

differently, even though there are some of the same differences between 

auto alternators and auto ignition that change their reliability when 

used in aircraft.

On 11/28/2014 6:11 PM, speedy11(at)aol.com wrote:

[quote] 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



     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

     > On Nov 27, 2014, at 12:15 PM, Kelly McMullen <kellym(at)aviating.com  <mailto: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.

     >

     > 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.

     >>

     >> I disagree with the statement that electronic ignition adds risk.  There are

     many reasons.

     >>

     >> 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.

     >>

     >> 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.

     >>

     >> 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.

     >>

     >> 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.

     >>

     >> 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.

     >>

     >> 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.

     >>

     >> I feel that a properly installed and maintained redundant electronic ignition

     system will actually REDUCE the risk that the legacy magneto systems offer.

     >>

     >> Respectfully,

     >>

     >> Justin

     >>

     >>

     >>> On Nov 27, 2014, at 11:10 AM, Kelly McMullen <kellym(at)aviating.com  <mailto: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.

     >>>

     >>> 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.

     >>>>

     >>>> On Nov 27, 2014 10:54 AM, "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com  <mailto:nuckolls.bob(at)aeroelectric.com>  

     <mailto:nuckolls.bob(at)aeroelectric.com  <mailto:nuckolls.bob(at)aeroelectric.com?>>> wrote:

     >>>>

     >>>>    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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_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Nov 30, 2014 9:26 am Post subject: Touchy!

At 20:22 2014-11-28, you wrote:

 	  Quote: 	
		  



For any question or problem there are a number of ways to skin the 

cat, including it may not be a problem at all.

To object to folks questioning whether he needs to do what he wants 

is just as valid a discussion and learning point as assuming he has 

correctly parsed his situation, already knows the best solution and 

just needs to know how to implement it.


	


    Exactly. There's another important component to this

    discussion. The List is not just a place to ask, "what's

    2 + 3 and where do I buy some 3's?"  It's a classroom

    where about 1400 individuals watch the proceedings and

    take away buckets of simple-ideas along with a few

    recipes for their utilization.



    Whether we're cooking stuff up on the stove, writing

    software, or configuring an electrical system, the

    elegant solution will be elusive unless the 'chef'

    understands exactly how all the ingredients behave

    as individual components and then in combination with

    each other.



    In this class room environment there is, and should

    be, a high probability that any questioner may be

    asked to stand up in front of the class and defend

    his/her recipe for success. My bosses called this

    process preliminary, critical, and qualification

    design review. A means by which ideas could oscillate between

    any constellation of extremes as collegial argument

    deduces the elegant, lowest risk way to meet customer

    design goals.



    There is a risk that some questioner will feel picked

    on or belittled. I'm probably as guilty as

    any for not always making sure that the questioner

    understands this process along with his own, important

    role in this sharing of knowledge.



    Mr. Ryan has states some ideas and goals and he

    has been asked to share his supporting thought processes.

    Of course, nobody will be insulted or even disappointed

    if he declines. At the same time, everyone

    interested in the conversation may harvest and

    exploit any number of simple-ideas supported with

    examples of how they fit together.



   Bob . . .

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