Today's Message Index:
----------------------
1. 01:25 AM - Re: Engine/avionics shutdown procedure (Stephen Morrey)
2. 11:52 AM - Re: Engine/avionics shutdown procedure (Yak Pilot)
3. 12:55 PM - Re: Engine/avionics shutdown procedure (doug sapp)
4. 12:55 PM - Re: Engine/avionics shutdown procedure (Yak Pilot)
5. 01:13 PM - Re: Engine/avionics shutdown procedure (Didier Blouzard)
6. 03:22 PM - Re: Engine/avionics shutdown procedure (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E)
7. 07:40 PM - Re: Engine/avionics shutdown procedure (Eric Wobschall)
Message 1
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| Subject: | Re: Engine/avionics shutdown procedure |
On a yak during low idle the generator light will go on indicating
the generator is not operating (or at least not charging to some
level) when the rpm is low. Should I assume that stress to the
avionics can also happen just during idle when the generator cycles on
and off as indicated by the generator light or is the light just an
indication of the level of output of the generator and hence the same
effect as seen in shut down is not likely? steve
On Sun, Sep 26, 2010 at 6:28 PM, Bitterlich, Mark G CIV Det Cherry
Point, MALS-14 64E <mark.bitterlich@navy.mil> wrote:
>
> Dave, That is a very good point. Again, I must caution anyone reading this that
I have never worked on a CJ, though I am aware that they have two types of
control systems for the generator.
>
> I believe there is a solid state controller and also a older more traditional
style controller. Whatever. Let's just cut to the chase. It would be much smarter
to turn off your avionics before killing the mags (engine) if you have anything
in there worth worrying about.
>
> Why? Because on any engine that has a generator, when you kill the mags, the
generator stops turning. As it slows down, the generator voltage will drop below
the battery voltage. When this happens, current stops flowing from the generator
to the battery, and instead flows from the battery to the generator. This
is called "Reverse Current". In all aircraft with real generators, there is
some device that is in there to prevent this.
>
> Or at least... normally the way it works is that as current STARTS flowing from
the battery to the generator, There is usually some kind of "set point" where
this relay operates and then DISCONNECTS the generator from the aircrafts electrical
bus.
>
> Here is the problem. If your battery is not in just TIP TOP condition... which
by the way, many of our batteries are not... because we fail to CHECK THEM PROPERLY.....
what will happen is that when the engine starts slowing down to a
stop after you kill the mags, reverse current will start to flow. If your batteries
are not up to snuff, then the battery output voltage will drop as the
current going to the generator increases.
>
> Hopefully, eventually the current will rise high enough to where the reverse
current RELAY operates and then disconnects the generator. However, that does
not HAVE to happen right away when it should. If the batteries are WEAK, then
this chain of events will happen much more SLOWYLY. And that is a bad bad thing,
because then your battery voltage will drop way down below 24 volts and maybe
as low as 14-16 VDC. Avionics systems really don't like voltage spikes like
this. Going down, or going up They just don't like that kind of thing. Will it
cause instant failure of your avionics? NO. Is it asking for a failure? YES.
Shut off your avionics before killing the engine is the smart thing to do, regardless
of what any check list currently says.
>
> Mark Bitterlich
>
> p.s. I do not bother to follow my own advice, but then I check my batteries carefully
all the time, and I also am only powering one Russian radio. But, I really
should, and if I had any Avionics that cost more than a few hundred, I would
be religious about it.
>
> ________________________________
>
> From: owner-yak-list-server@matronics.com on behalf of KingCJ6@aol.com
> Sent: Sun 9/26/2010 5:58 PM
> To: yak-list@matronics.com
> Subject: Yak-List: Engine/avionics shutdown procedure
>
>
> Most Nanchang checklists specify shutting the engine down with mags prior to
shutting off the electric switches which power all of the avionics. All traditional
GA checklists I've seen specify turning off the avionics master (or individual
components) prior to shutting down the engine to presumably prevent damage
from a potential power spike. Any technical reason for the Nanchang to be
different?
>
>
> Dave
>
>
Message 2
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| Subject: | Re: Engine/avionics shutdown procedure |
I use those same batteries in my UTVA-66 and they work extremely well. Yes, a
pair of them are very heavy, but they ought to work extrememly well. I use the
battery charger you are looking at on them and it works perfectly. Suggest
installing the temp sensor and also making a way to connect the charger easily
after flight.
Mark
--- On Mon, 9/27/10, Walter Lannon <wlannon@persona.ca> wrote:
> From: Walter Lannon <wlannon@persona.ca>
> Subject: Re: Yak-List: Engine/avionics shutdown procedure
> To: yak-list@matronics.com
> Date: Monday, September 27, 2010, 10:59 PM
> Walter Lannon <wlannon@persona.ca>
>
> Thanks mark;
>
> Thats the one I will get.
> Don't have my batteries yet but leaning toward the
> Panasonic LC-X1228P (2
> ea.) which is valve regulated lead acid.
> I used these in my last CJ restoration, at the customers's
> request and they
> are still going strong after at least 8 years. They are a
> bit heavy at 24 lb
> ea. (and pricey) but fit nicely into the CJ battery box.
> This time it's my CJ so I would really appreciate your
> thoughts on the
> battery.
>
> Cheers;
> Walt
> ----- Original Message -----
> From: "Bitterlich, Mark G CIV Det Cherry Point, MALS-14
> 64E"
> <mark.bitterlich@navy.mil>
> To: <yak-list@matronics.com>
> Sent: Monday, September 27, 2010 6:20 PM
> Subject: RE: Yak-List: Engine/avionics shutdown procedure
>
>
> CIV Det Cherry Point,
> > MALS-14 64E" <mark.bitterlich@navy.mil>
> >
> > On second thought, to be absolutely sure you will be
> happy, get this one.
> >
> > http://www.thebatteryminder.com/24vs2aircraftbatteryminder-p-79.html
> >
> >
> >
> >
> >
> > Mark
> >
> >
> >
> >
> >
> >
> > ________________________________
> >
> > From: owner-yak-list-server@matronics.com
> on behalf of Walter Lannon
> > Sent: Mon 9/27/2010 12:41 AM
> > To: yak-list@matronics.com
> > Subject: Re: Yak-List: Engine/avionics shutdown
> procedure
> >
> >
> >
> <wlannon@persona.ca>
> >
> > Thanks Mark;
> >
> > Great information. Do you have a recommendation for
> which Battery- Minder
> > to
> > get?
> >
> > Walt
> > ----- Original Message -----
> > From: "Bitterlich, Mark G CIV Det Cherry Point,
> MALS-14 64E"
> > <mark.bitterlich@navy.mil>
> > To: <yak-list@matronics.com>
> > Sent: Sunday, September 26, 2010 8:04 PM
> > Subject: RE: Yak-List: Engine/avionics shutdown
> procedure
> >
> >
> Mark G CIV Det Cherry Point,
> >> MALS-14 64E" <mark.bitterlich@navy.mil>
> >>
> >> Steve, that is yet another good question.
> Most of us these days are
> >> using gell cell batteries so checking the specific
> gravity of the
> >> electrolyte is just not do-able.
> >>
> >> So, another method is easy and very simple but it
> is not something you
> >> can
> >> tape to a calibration table per se.
> >>
> >> Batteries that are in "good shape" (a very loose
> term) will hold their
> >> voltage for awhile when you put a load on
> them. If you notice, most of
> >> those gell cells we stick in there have an
> amp/hour rating. What this
> >> means is that you can draw that number of amps
> continuously for one hour.
> >> You can do some math with this and interpolate
> accordingly. You can get
> >> pretty fancy with this if you want to.
> >>
> >> But the plain and simple method is pretty straight
> forward. Most YAK's
> >> and I believe CJ's, have a voltage and amp meter
> built into the aircraft.
> >> Turn on the electrical master. BEFORE you go
> flying. Look at the
> >> voltage. It should be around 24 volts or so,
> maybe as high as 25. If it
> >> down around 22 vdc, your eyebrows should start
> going up in alarm. At
> >> this
> >> point, start turning on anything that draws a lot
> of current. Landing
> >> lights would be good. So is Pitot
> Heat. Radios, no.As you turn this
> >> stuff on, look at that battery voltage. Is
> it HOLDING? Or is it
> >> dropping
> >> like a stone?If you had 22-23
> VDC and you turn on Pitot Heat and it
> >> drops to 20 vdc... HMMM!!!If you
> then turn on a landing light.... and
> >> it drops to 16-18 volts OR LESS, then it is time
> to replace the
> >> batteries.
> >> A much better way is to put a good digital meter
> on the battery terminals
> >> themselves when you do this by the way and read
> the voltage with that.
> >>
> >> Do not check them and come back and say: HEY, ONE
> IS 12 VOLTS AND ONE IS
> >> 6
> >> VOLTS, SO I AM ONLY GOING TO REPLACE
> ONE!!!Yeah, that will work, but
> >> it
> >> it is penny wise and dollar foolish. You
> want all the cells in the two
> >> 12
> >> volt batteries that you connect in series to get
> 24 volts to be BALANCED.
> >> If they are NOT balanced, then the current to
> charge the WEAK cells has
> >> to
> >> flow through the GOOD cells to charge the weak
> ones. This ends up
> >> over-charging the GOOD cells and causing them to
> vent gas. Which makes
> >> them go bad. Quickly.
> >>
> >> SO ... try to replace them in PAIRS.
> >>
> >> I don't want to sound like an advertisement, but I
> really am impressed
> >> with Battery-Minder battery chargers. They
> not only have a temp. sensor
> >> that keeps from overheating charging batteries,
> but also, after the
> >> batteries are charged, they put a 3 Mhz blast
> pulse into the batteries
> >> that works to turn battery sulfate off the plates
> and put it back into
> >> solution, or.... "gell" that extends the life of
> the battery PLUS they
> >> check the status of the battery
> automatically. They are not cheap.
> >> But.... They are worth every cent in my
> opinion.I own THREE of them.
> >>
> >> The YAK and CJ's aircraft for the most part do not
> use electrical
> >> starters
> >> (Some rare models excepted). An electrical
> starter is a quick test for a
> >> battery.I.E. Think of your
> car when it gets cold. Bad battery? You
> >> don't start, so you replace it. We do not
> have that huge electrical draw
> >> that the car starter represents... so our
> batteries kind of go bad in a
> >> sneaky way. Leading to issues with the
> reverse current relay.
> >>
> >> Just had a nice person with a YAK-18T that this
> just happened to. Hope
> >> this explains what is happening, and how to keep
> an eye out for it.
> >>
> >> Mark
> >>
> >>
> >> ________________________________
> >>
> >> From: owner-yak-list-server@matronics.com
> on behalf of Steven Johnson
> >> Sent: Sun 9/26/2010 8:18 PM
> >> To: yak-list@matronics.com
> >> Subject: RE: Yak-List: Engine/avionics shutdown
> procedure
> >>
> >>
> >>
> Johnson" <sajdds@comcast.net>
> >>
> >> Mark, how does one check the batteries properly?
> >>
> >> Steve Johnson
> >> Yak 52 N9900X 0B5
> >> 413 522-1130 Cell
> >> -----Original Message-----
> >> From: owner-yak-list-server@matronics.com
> >> [mailto:owner-yak-list-server@matronics.com]
> On Behalf Of Bitterlich,
> >> Mark
> >> G
> >> CIV Det Cherry Point, MALS-14 64E
> >> Sent: Sunday, September 26, 2010 6:29 PM
> >> To: yak-list@matronics.com
> >> Subject: RE: Yak-List: Engine/avionics shutdown
> procedure
> >>
> Mark G CIV Det Cherry
> >> --> Point, MALS-14 64E" <mark.bitterlich@navy.mil>
> >>
> >> Dave, That is a very good point.
> Again, I must caution anyone reading
> >> this
> >> that I have never worked on a CJ, though I am
> aware that they have two
> >> types
> >> of control systems for the generator.
> >>
> >> I believe there is a solid state controller and
> also a older more
> >> traditional style controller.
> Whatever. Let's just cut to the chase.
> >> It
> >> would be much smarter to turn off your avionics
> before killing the mags
> >> (engine) if you have anything in there worth
> worrying about.
> >>
> >> Why? Because on any engine that has a
> generator, when you kill the mags,
> >> the generator stops turning. As it slows
> down, the generator voltage
> >> will
> >> drop below the battery voltage. When this
> happens, current stops flowing
> >> from the generator to the battery, and instead
> flows from the battery to
> >> the
> >> generator. This is called "Reverse
> Current". In all aircraft with real
> >> generators, there is some device that is in there
> to prevent this.
> >>
> >> Or at least... normally the way it works is that
> as current STARTS
> >> flowing
> >> from the battery to the generator, There is
> usually some kind of "set
> >> point" where this relay operates and then
> DISCONNECTS the generator from
> >> the
> >> aircrafts electrical bus.
> >>
> >> Here is the problem. If your battery is not
> in just TIP TOP condition...
> >> which by the way, many of our batteries are not...
> because we fail to
> >> CHECK
> >> THEM PROPERLY..... what will happen is that
> when the engine starts
> >> slowing
> >> down to a stop after you kill the mags, reverse
> current will start to
> >> flow.
> >> If your batteries are not up to snuff, then the
> battery output voltage
> >> will
> >> drop as the current going to the generator
> increases.
> >>
> >> Hopefully, eventually the current will rise high
> enough to where the
> >> reverse
> >> current RELAY operates and then disconnects the
> generator. However, that
> >> does not HAVE to happen right away when it
> should. If the batteries are
> >> WEAK, then this chain of events will happen much
> more SLOWYLY. And that
> >> is
> >> a bad bad thing, because then your battery voltage
> will drop way down
> >> below
> >> 24 volts and maybe as low as 14-16 VDC.
> Avionics systems really don't
> >> like
> >> voltage spikes like this. Going down, or
> going up They just don't like
> >> that kind of thing. Will it cause instant failure
> of your avionics? NO.
> >> Is
> >> it asking for a failure?
> YES.Shut off your avionics before killing
>
> >> the
> >> engine is the smart thing to do, regardless of
> what any check list
> >> currently
> >> says.
> >>
> >> Mark Bitterlich
> >>
> >> p.s. I do not bother to follow my own
> advice, but then I check my
> >> batteries
> >> carefully all the time, and I also am only
> powering one Russian radio.
> >> But,
> >> I really should, and if I had any Avionics that
> cost more than a few
> >> hundred, I would be religious about it.
> >>
> >> ________________________________
> >>
> >> From: owner-yak-list-server@matronics.com
> on behalf of KingCJ6@aol.com
> >> Sent: Sun 9/26/2010 5:58 PM
> >> To: yak-list@matronics.com
> >> Subject: Yak-List: Engine/avionics shutdown
> procedure
> >>
> >>
> >>
> >> Most Nanchang checklists specify shutting the
> engine down with mags prior
> >> to
> >> shutting off the electric switches which power all
> of the avionics. All
> >> traditional GA checklists I've seen specify
> turning off the avionics
> >> master
> >> (or individual components) prior to shutting down
> the engine to
> >> presumably
> >> prevent damage from a potential power spike.
> Any technical reason for
> >> the
> >> Nanchang to be different?
> >>
> >>
> >>
> >> Dave
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
>
>
> Forum -
> FAQ,
> - MATRONICS WEB FORUMS -
> List Contribution Web Site -
> -Matt
> Dralle, List Admin.
>
>
>
>
Message 3
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| Subject: | Re: Engine/avionics shutdown procedure |
Mark,
I have been using the dry cell batteries for a few years now and like them,
will the same "minder" work for the dry cell as the gel or led acid
batteries?
Doug
On Mon, Sep 27, 2010 at 6:08 PM, Bitterlich, Mark G CIV Det Cherry Point,
MALS-14 64E <mark.bitterlich@navy.mil> wrote:
> MALS-14 64E" <mark.bitterlich@navy.mil>
>
> For 24 volt systems, I recommend one of two.
>
> For those that want to just plug it in and walk away, this one:
> http://www.thebatteryminder.com/24vs3aircraftbatteryminder-p-83.html
>
> For those that want more manual control, then this one:
> http://www.thebatteryminder.com/24vs2aircraftbatteryminder-p-79.html
>
> Both are good. Both cost around $180.
>
> There are other models for 220 volt applications for overseas. Just check
> the web site.
>
> I use other models for 12 volt automobile systems. I love these things.
> They really work. But, you need to form your own opinion. That said, I
> can walk around the airport at New Bern these days and see them ALL over the
> place. There are really not battery "chargers" per se. They are battery
> MAINTAINERS. You leave them plugged into the battery on your aircraft 24/7.
> I have actually made an external cannon plug on my airplanes so that I can
> just plug them in and walk away after flying. I don't like to influence
> others on what to buy commercially. I do not like to put my name to things
> like that. But... Walt... I would never steer you wrong Sir, and I think
> you will REALLY like these things. If not.., I can always use another one.
> If you are not happy with it, call me up and I will buy it from you at full
> price.
>
> Mark
>
>
> ________________________________
>
> From: owner-yak-list-server@matronics.com on behalf of Walter Lannon
> Sent: Mon 9/27/2010 12:41 AM
> : yak-list@matronics.com
> Subject: Re: Yak-List: Engine/avionics shutdown procedure
>
>
>
> Thanks Mark;
>
> Great information. Do you have a recommendation for which Battery- Minder
> to
> get?
>
> Walt
> ----- Original Message -----
> From: "Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E"
> <mark.bitterlich@navy.mil>
> To: <yak-list@matronics.com>
> Sent: Sunday, September 26, 2010 8:04 PM
> Subject: RE: Yak-List: Engine/avionics shutdown procedure
>
>
> > MALS-14 64E" <mark.bitterlich@navy.mil>
> >
> > Steve, that is yet another good question. Most of us these days are
> > using gell cell batteries so checking the specific gravity of the
> > electrolyte is just not do-able.
> >
> > So, another method is easy and very simple but it is not something you
> can
> > tape to a calibration table per se.
> >
> > Batteries that are in "good shape" (a very loose term) will hold their
> > voltage for awhile when you put a load on them. If you notice, most of
> > those gell cells we stick in there have an amp/hour rating. What this
> > means is that you can draw that number of amps continuously for one hour.
> > You can do some math with this and interpolate accordingly. You can get
> > pretty fancy with this if you want to.
> >
> > But the plain and simple method is pretty straight forward. Most YAK's
> > and I believe CJ's, have a voltage and amp meter built into the aircraft.
> > Turn on the electrical master. BEFORE you go flying. Look at the
> > voltage. It should be around 24 volts or so, maybe as high as 25. If it
> > down around 22 vdc, your eyebrows should start going up in alarm. At
> this
> > point, start turning on anything that draws a lot of current. Landing
> > lights would be good. So is Pitot Heat. Radios, no. As you turn this
> > stuff on, look at that battery voltage. Is it HOLDING? Or is it
> dropping
> > like a stone? If you had 22-23 VDC and you turn on Pitot Heat and it
> > drops to 20 vdc... HMMM!!! If you then turn on a landing light.... and
> > it drops to 16-18 volts OR LESS, then it is time to replace the
> batteries.
> > A much better way is to put a good digital meter on the battery terminals
> > themselves when you do this by the way and read the voltage with that.
> >
> > Do not check them and come back and say: HEY, ONE IS 12 VOLTS AND ONE IS
> 6
> > VOLTS, SO I AM ONLY GOING TO REPLACE ONE!!! Yeah, that will work, but
> it
> > it is penny wise and dollar foolish. You want all the cells in the two
> 12
> > volt batteries that you connect in series to get 24 volts to be BALANCED.
> > If they are NOT balanced, then the current to charge the WEAK cells has
> to
> > flow through the GOOD cells to charge the weak ones. This ends up
> > over-charging the GOOD cells and causing them to vent gas. Which makes
> > them go bad. Quickly.
> >
> > SO ... try to replace them in PAIRS.
> >
> > I don't want to sound like an advertisement, but I really am impressed
> > with Battery-Minder battery chargers. They not only have a temp. sensor
> > that keeps from overheating charging batteries, but also, after the
> > batteries are charged, they put a 3 Mhz blast pulse into the batteries
> > that works to turn battery sulfate off the plates and put it back into
> > solution, or.... "gell" that extends the life of the battery PLUS they
> > check the status of the battery automatically. They are not cheap.
> > But.... They are worth every cent in my opinion. I own THREE of them.
> >
> > The YAK and CJ's aircraft for the most part do not use electrical
> starters
> > (Some rare models excepted). An electrical starter is a quick test for a
> > battery. I.E. Think of your car when it gets cold. Bad battery? You
> > don't start, so you replace it. We do not have that huge electrical draw
> > that the car starter represents... so our batteries kind of go bad in a
> > sneaky way. Leading to issues with the reverse current relay.
> >
> > Just had a nice person with a YAK-18T that this just happened to. Hope
> > this explains what is happening, and how to keep an eye out for it.
> >
> > Mark
> >
> >
> > ________________________________
> >
> > From: owner-yak-list-server@matronics.com on behalf of Steven Johnson
> > Sent: Sun 9/26/2010 8:18 PM
> > To: yak-list@matronics.com
> > Subject: RE: Yak-List: Engine/avionics shutdown procedure
> >
> >
> >
> >
> > Mark, how does one check the batteries properly?
> >
> > Steve Johnson
> > Yak 52 N9900X 0B5
> > 413 522-1130 Cell
> > -----Original Message-----
> > From: owner-yak-list-server@matronics.com
> > [mailto:owner-yak-list-server@matronics.com] On Behalf Of Bitterlich,
> Mark
> > G
> > CIV Det Cherry Point, MALS-14 64E
> > Sent: Sunday, September 26, 2010 6:29 PM
> > To: yak-list@matronics.com
> > Subject: RE: Yak-List: Engine/avionics shutdown procedure
> >
> > --> Point, MALS-14 64E" <mark.bitterlich@navy.mil>
> >
> > Dave, That is a very good point. Again, I must caution anyone reading
> > this
> > that I have never worked on a CJ, though I am aware that they have two
> > types
> > of control systems for the generator.
> >
> > I believe there is a solid state controller and also a older more
> > traditional style controller. Whatever. Let's just cut to the chase.
> It
> > would be much smarter to turn off your avionics before killing the mags
> > (engine) if you have anything in there worth worrying about.
> >
> > Why? Because on any engine that has a generator, when you kill the mags,
> > the generator stops turning. As it slows down, the generator voltage
> will
> > drop below the battery voltage. When this happens, current stops flowing
> > from the generator to the battery, and instead flows from the battery to
> > the
> > generator. This is called "Reverse Current". In all aircraft with real
> > generators, there is some device that is in there to prevent this.
> >
> > Or at least... normally the way it works is that as current STARTS
> flowing
> > from the battery to the generator, There is usually some kind of "set
> > point" where this relay operates and then DISCONNECTS the generator from
> > the
> > aircrafts electrical bus.
> >
> > Here is the problem. If your battery is not in just TIP TOP condition...
> > which by the way, many of our batteries are not... because we fail to
> > CHECK
> > THEM PROPERLY..... what will happen is that when the engine starts
> > slowing
> > down to a stop after you kill the mags, reverse current will start to
> > flow.
> > If your batteries are not up to snuff, then the battery output voltage
> > will
> > drop as the current going to the generator increases.
> >
> > Hopefully, eventually the current will rise high enough to where the
> > reverse
> > current RELAY operates and then disconnects the generator. However, that
> > does not HAVE to happen right away when it should. If the batteries are
> > WEAK, then this chain of events will happen much more SLOWYLY. And that
> > is
> > a bad bad thing, because then your battery voltage will drop way down
> > below
> > 24 volts and maybe as low as 14-16 VDC. Avionics systems really don't
> > like
> > voltage spikes like this. Going down, or going up They just don't like
> > that kind of thing. Will it cause instant failure of your avionics? NO.
> > Is
> > it asking for a failure? YES. Shut off your avionics before killing
> the
> > engine is the smart thing to do, regardless of what any check list
> > currently
> > says.
> >
> > Mark Bitterlich
> >
> > p.s. I do not bother to follow my own advice, but then I check my
> > batteries
> > carefully all the time, and I also am only powering one Russian radio.
> > But,
> > I really should, and if I had any Avionics that cost more than a few
> > hundred, I would be religious about it.
> >
> > ________________________________
> >
> > From: owner-yak-list-server@matronics.com on behalf of KingCJ6@aol.com
> > Sent: Sun 9/26/2010 5:58 PM
> > To: yak-list@matronics.com
> > Subject: Yak-List: Engine/avionics shutdown procedure
> >
> >
> >
> > Most Nanchang checklists specify shutting the engine down with mags prior
> > to
> > shutting off the electric switches which power all of the avionics. All
> > traditional GA checklists I've seen specify turning off the avionics
> > master
> > (or individual components) prior to shutting down the engine to
> presumably
> > prevent damage from a potential power spike. Any technical reason for
> the
> > Nanchang to be different?
> >
> >
> >
> > Dave
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
>
>
Message 4
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| Subject: | Re: Engine/avionics shutdown procedure |
You are again correct.
If everything is working absolutely perfectly and your batteries have good capacity,
when the engine is brought down to idle, the generator output will go below
28 volts, reverse current will start to flow, the reverse current relay will
sense this and the main generator contactor will disengage and the generator
will no longer be connected to the aircraft electrical system. So in reality
... this does not happen as you shut down the mags, it actually should happen
when you bring the power back to idle.
Again, if everything is working perfectly at this point, if you shut off the engine
with the mag switch, at this point the generator is already disconnected
and there should be no load change or voltage surge to the avionics.
This may sound contrary to what I was saying before, but I tried to cover it in
the other explanation.
A gent with a YAK-18T recently had an issue where his generator light did not come
on all the time at idle. When he killed the engine with the mags, it then
DID come on as the engine came to a stop. In this case, the gent had weak batteries.
When he brought the engine down to idle, the batteries were so weak
that they could not provide enough reverse current to cause the reverse current
relay to do it's job. The result was that the main contactor for the aircraft
stayed closed, and kept the generator connected to the aircraft electrical
bus.
During this period of time, main bus electrical voltage sagged down to between
12 and 14 volts. Eventually the generator came to a stop and there was enough
current to cause the reverse current relay to open, thus disengaging the main
contactor to the generator, and the load went away and battery voltage jumped
back up to 20 volts or so.
This is the kind of nonsense I was trying to talk about.
However, if your aircraft battery is in good shape and every part in the aircraft
is working properly, you should not see a really large voltage spike as the
generator comes on and off line. Basically, if everything is working just perfectly,
the generator will be connected to the aircraft electrical bus when it's
output is a few volts above that of the battery. There will be a minor 2-3
volt jump in battery voltage as the thing connects, but that is usually not
something to worry about.
When the engine RPM is lowered and the generator voltage drops, current flow will
increase going back to the generator. This is where if your batteries are
not working right that you will run into trouble.
In the end, I just think it is a good idea to get any expensive avionics turned
off as soon as possible to avoid any kind of voltage spikes or lags. But as
I said, if you keep your batteries in perfect working order and you have a good
reverse current relay ... all should be well.
Mark
--- On Tue, 9/28/10, Stephen Morrey <stephenmorrey@gmail.com> wrote:
> From: Stephen Morrey <stephenmorrey@gmail.com>
> Subject: Re: Yak-List: Engine/avionics shutdown procedure
> To: yak-list@matronics.com
> Date: Tuesday, September 28, 2010, 4:16 AM
> Stephen Morrey <stephenmorrey@gmail.com>
>
> On a yak during low idle the generator light will go
> on indicating
> the generator is not operating (or at least not charging to
> some
> level) when the rpm is low. Should I assume
> that stress to the
> avionics can also happen just during idle when the
> generator cycles on
> and off as indicated by the generator light or is the light
> just an
> indication of the level of output of the generator and
> hence the same
> effect as seen in shut down is not likely? steve
>
> On Sun, Sep 26, 2010 at 6:28 PM, Bitterlich, Mark G CIV Det
> Cherry
> Point, MALS-14 64E <mark.bitterlich@navy.mil>
> wrote:
> CIV Det Cherry Point, MALS-14 64E" <mark.bitterlich@navy.mil>
> >
> > Dave, That is a very good point. Again, I must
> caution anyone reading this that I have never worked on a
> CJ, though I am aware that they have two types of control
> systems for the generator.
> >
> > I believe there is a solid state controller and also a
> older more traditional style controller. Whatever. Let's
> just cut to the chase. It would be much smarter to turn
> off your avionics before killing the mags (engine) if you
> have anything in there worth worrying about.
> >
> > Why? Because on any engine that has a generator,
> when you kill the mags, the generator stops turning. As it
> slows down, the generator voltage will drop below the
> battery voltage. When this happens, current stops flowing
> from the generator to the battery, and instead flows from
> the battery to the generator. This is called "Reverse
> Current". In all aircraft with real generators, there is
> some device that is in there to prevent this.
> >
> > Or at least... normally the way it works is that as
> current STARTS flowing from the battery to the generator,
> There is usually some kind of "set point" where this relay
> operates and then DISCONNECTS the generator from the
> aircrafts electrical bus.
> >
> > Here is the problem. If your battery is not in just
> TIP TOP condition... which by the way, many of our batteries
> are not... because we fail to CHECK THEM PROPERLY.....
> what will happen is that when the engine starts slowing
> down to a stop after you kill the mags, reverse current will
> start to flow. If your batteries are not up to snuff,
> then the battery output voltage will drop as the current
> going to the generator increases.
> >
> > Hopefully, eventually the current will rise high
> enough to where the reverse current RELAY operates and then
> disconnects the generator. However, that does not HAVE to
> happen right away when it should. If the batteries are
> WEAK, then this chain of events will happen much more
> SLOWYLY. And that is a bad bad thing, because then your
> battery voltage will drop way down below 24 volts and maybe
> as low as 14-16 VDC. Avionics systems really don't like
> voltage spikes like this. Going down, or going up They
> just don't like that kind of thing. Will it cause instant
> failure of your avionics? NO. Is it asking for a
> failure? YES. Shut off your avionics before killing the
> engine is the smart thing to do, regardless of what any
> check list currently says.
> >
> > Mark Bitterlich
> >
> > p.s. I do not bother to follow my own advice, but
> then I check my batteries carefully all the time, and I also
> am only powering one Russian radio. But, I really should,
> and if I had any Avionics that cost more than a few hundred,
> I would be religious about it.
> >
> > ________________________________
> >
> > From: owner-yak-list-server@matronics.com
> on behalf of KingCJ6@aol.com
> > Sent: Sun 9/26/2010 5:58 PM
> > To: yak-list@matronics.com
> > Subject: Yak-List: Engine/avionics shutdown procedure
> >
> >
> >
> > Most Nanchang checklists specify shutting the engine
> down with mags prior to shutting off the electric switches
> which power all of the avionics. All traditional GA
> checklists I've seen specify turning off the avionics master
> (or individual components) prior to shutting down the engine
> to presumably prevent damage from a potential power spike.
> Any technical reason for the Nanchang to be different?
> >
> >
> >
> > Dave
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
>
>
> Forum -
> FAQ,
> - MATRONICS WEB FORUMS -
> List Contribution Web Site -
> -Matt
> Dralle, List Admin.
>
>
>
>
Message 5
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| Subject: | Re: Engine/avionics shutdown procedure |
Hi gents,
for my point of view, it doesn't do anything bad to turn off all the
unnecessary electrical loads after landing and that's just what I do.
When landing the engine is at low boost but not low RPM. I imagine that's
why we don't have the generator lamp coming on. After landing, I turn off
all unnecessary electrical consumers like the gyros and the converter, the
radio and transponder and all the rest.
The only switches that are staying on are the five first : Battery,
Generator, Ignition, Motor and landing instruments.
The rest is off as soon as the speed is controlled or just after having
vacated the airstrip.
I would enjoy any comments concerning this...way of doing.....is it good or
bad for the system..???
Thanks a lot and fly safe
Didier
2010/9/28 Yak Pilot <yakplt@yahoo.com>
>
> You are again correct.
>
> If everything is working absolutely perfectly and your batteries have good
> capacity, when the engine is brought down to idle, the generator output will
> go below 28 volts, reverse current will start to flow, the reverse current
> relay will sense this and the main generator contactor will disengage and
> the generator will no longer be connected to the aircraft electrical system.
> So in reality ... this does not happen as you shut down the mags, it
> actually should happen when you bring the power back to idle.
>
> Again, if everything is working perfectly at this point, if you shut off
> the engine with the mag switch, at this point the generator is already
> disconnected and there should be no load change or voltage surge to the
> avionics.
>
> This may sound contrary to what I was saying before, but I tried to cover
> it in the other explanation.
>
> A gent with a YAK-18T recently had an issue where his generator light did
> not come on all the time at idle. When he killed the engine with the mags,
> it then DID come on as the engine came to a stop. In this case, the gent
> had weak batteries. When he brought the engine down to idle, the batteries
> were so weak that they could not provide enough reverse current to cause the
> reverse current relay to do it's job. The result was that the main
> contactor for the aircraft stayed closed, and kept the generator connected
> to the aircraft electrical bus.
>
> During this period of time, main bus electrical voltage sagged down to
> between 12 and 14 volts. Eventually the generator came to a stop and there
> was enough current to cause the reverse current relay to open, thus
> disengaging the main contactor to the generator, and the load went away and
> battery voltage jumped back up to 20 volts or so.
>
> This is the kind of nonsense I was trying to talk about.
>
> However, if your aircraft battery is in good shape and every part in the
> aircraft is working properly, you should not see a really large voltage
> spike as the generator comes on and off line. Basically, if everything is
> working just perfectly, the generator will be connected to the aircraft
> electrical bus when it's output is a few volts above that of the battery.
> There will be a minor 2-3 volt jump in battery voltage as the thing
> connects, but that is usually not something to worry about.
>
> When the engine RPM is lowered and the generator voltage drops, current
> flow will increase going back to the generator. This is where if your
> batteries are not working right that you will run into trouble.
>
> In the end, I just think it is a good idea to get any expensive avionics
> turned off as soon as possible to avoid any kind of voltage spikes or lags.
> But as I said, if you keep your batteries in perfect working order and you
> have a good reverse current relay ... all should be well.
>
> Mark
>
>
> --- On Tue, 9/28/10, Stephen Morrey <stephenmorrey@gmail.com> wrote:
>
> > From: Stephen Morrey <stephenmorrey@gmail.com>
> > Subject: Re: Yak-List: Engine/avionics shutdown procedure
> > To: yak-list@matronics.com
> > Date: Tuesday, September 28, 2010, 4:16 AM
> > Stephen Morrey <stephenmorrey@gmail.com>
> >
> > On a yak during low idle the generator light will go
> > on indicating
> > the generator is not operating (or at least not charging to
> > some
> > level) when the rpm is low. Should I assume
> > that stress to the
> > avionics can also happen just during idle when the
> > generator cycles on
> > and off as indicated by the generator light or is the light
> > just an
> > indication of the level of output of the generator and
> > hence the same
> > effect as seen in shut down is not likely? steve
> >
> > On Sun, Sep 26, 2010 at 6:28 PM, Bitterlich, Mark G CIV Det
> > Cherry
> > Point, MALS-14 64E <mark.bitterlich@navy.mil>
> > wrote:
> > CIV Det Cherry Point, MALS-14 64E" <mark.bitterlich@navy.mil>
> > >
> > > Dave, That is a very good point. Again, I must
> > caution anyone reading this that I have never worked on a
> > CJ, though I am aware that they have two types of control
> > systems for the generator.
> > >
> > > I believe there is a solid state controller and also a
> > older more traditional style controller. Whatever. Let's
> > just cut to the chase. It would be much smarter to turn
> > off your avionics before killing the mags (engine) if you
> > have anything in there worth worrying about.
> > >
> > > Why? Because on any engine that has a generator,
> > when you kill the mags, the generator stops turning. As it
> > slows down, the generator voltage will drop below the
> > battery voltage. When this happens, current stops flowing
> > from the generator to the battery, and instead flows from
> > the battery to the generator. This is called "Reverse
> > Current". In all aircraft with real generators, there is
> > some device that is in there to prevent this.
> > >
> > > Or at least... normally the way it works is that as
> > current STARTS flowing from the battery to the generator,
> > There is usually some kind of "set point" where this relay
> > operates and then DISCONNECTS the generator from the
> > aircrafts electrical bus.
> > >
> > > Here is the problem. If your battery is not in just
> > TIP TOP condition... which by the way, many of our batteries
> > are not... because we fail to CHECK THEM PROPERLY.....
> > what will happen is that when the engine starts slowing
> > down to a stop after you kill the mags, reverse current will
> > start to flow. If your batteries are not up to snuff,
> > then the battery output voltage will drop as the current
> > going to the generator increases.
> > >
> > > Hopefully, eventually the current will rise high
> > enough to where the reverse current RELAY operates and then
> > disconnects the generator. However, that does not HAVE to
> > happen right away when it should. If the batteries are
> > WEAK, then this chain of events will happen much more
> > SLOWYLY. And that is a bad bad thing, because then your
> > battery voltage will drop way down below 24 volts and maybe
> > as low as 14-16 VDC. Avionics systems really don't like
> > voltage spikes like this. Going down, or going up They
> > just don't like that kind of thing. Will it cause instant
> > failure of your avionics? NO. Is it asking for a
> > failure? YES. Shut off your avionics before killing the
> > engine is the smart thing to do, regardless of what any
> > check list currently says.
> > >
> > > Mark Bitterlich
> > >
> > > p.s. I do not bother to follow my own advice, but
> > then I check my batteries carefully all the time, and I also
> > am only powering one Russian radio. But, I really should,
> > and if I had any Avionics that cost more than a few hundred,
> > I would be religious about it.
> > >
> > > ________________________________
> > >
> > > From: owner-yak-list-server@matronics.com
> > on behalf of KingCJ6@aol.com
> > > Sent: Sun 9/26/2010 5:58 PM
> > > To: yak-list@matronics.com
> > > Subject: Yak-List: Engine/avionics shutdown procedure
> > >
> > >
> > >
> > > Most Nanchang checklists specify shutting the engine
> > down with mags prior to shutting off the electric switches
> > which power all of the avionics. All traditional GA
> > checklists I've seen specify turning off the avionics master
> > (or individual components) prior to shutting down the engine
> > to presumably prevent damage from a potential power spike.
> > Any technical reason for the Nanchang to be different?
> > >
> > >
> > >
> > > Dave
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
> >
> > Forum -
> > FAQ,
> > - MATRONICS WEB FORUMS -
> > List Contribution Web Site -
> > -Matt
> > Dralle, List Admin.
> >
> >
> >
> >
>
>
--
Didier BLOUZARD
didier.blouzard@gmail.com
0624243672
Message 6
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| Subject: | Engine/avionics shutdown procedure |
Doug,
Honestly, you caught me competely off guard. I have no idea what a "dry cell"
battery is, and thus I really can not answer your question. Could you give me
a make and model number please?
Mark
________________________________
From: owner-yak-list-server@matronics.com on behalf of doug sapp
Sent: Tue 9/28/2010 2:51 PM
Subject: Re: Yak-List: Engine/avionics shutdown procedure
Mark,
I have been using the dry cell batteries for a few years now and like them, will
the same "minder" work for the dry cell as the gel or led acid batteries?
Doug
On Mon, Sep 27, 2010 at 6:08 PM, Bitterlich, Mark G CIV Det Cherry Point, MALS-14
64E <mark.bitterlich@navy.mil> wrote:
For 24 volt systems, I recommend one of two.
For those that want to just plug it in and walk away, this one:
http://www.thebatteryminder.com/24vs3aircraftbatteryminder-p-83.html
For those that want more manual control, then this one:
http://www.thebatteryminder.com/24vs2aircraftbatteryminder-p-79.html
Both are good. Both cost around $180.
There are other models for 220 volt applications for overseas. Just check the
web site.
I use other models for 12 volt automobile systems. I love these things. They
really work. But, you need to form your own opinion. That said, I can walk
around the airport at New Bern these days and see them ALL over the place. There
are really not battery "chargers" per se. They are battery MAINTAINERS.
You leave them plugged into the battery on your aircraft 24/7. I have actually
made an external cannon plug on my airplanes so that I can just plug them in
and walk away after flying. I don't like to influence others on what to buy
commercially. I do not like to put my name to things like that. But... Walt...
I would never steer you wrong Sir, and I think you will REALLY like these
things. If not.., I can always use another one. If you are not happy with it,
call me up and I will buy it from you at full price.
Mark
________________________________
From: owner-yak-list-server@matronics.com on behalf of Walter Lannon
Sent: Mon 9/27/2010 12:41 AM
: yak-list@matronics.com
Subject: Re: Yak-List: Engine/avionics shutdown procedure
Thanks Mark;
Great information. Do you have a recommendation for which Battery- Minder to
get?
Walt
----- Original Message -----
From: "Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E"
<mark.bitterlich@navy.mil>
To: <yak-list@matronics.com>
Sent: Sunday, September 26, 2010 8:04 PM
Subject: RE: Yak-List: Engine/avionics shutdown procedure
> MALS-14 64E" <mark.bitterlich@navy.mil>
>
> Steve, that is yet another good question. Most of us these days are
> using gell cell batteries so checking the specific gravity of the
> electrolyte is just not do-able.
>
> So, another method is easy and very simple but it is not something you can
> tape to a calibration table per se.
>
> Batteries that are in "good shape" (a very loose term) will hold their
> voltage for awhile when you put a load on them. If you notice, most of
> those gell cells we stick in there have an amp/hour rating. What this
> means is that you can draw that number of amps continuously for one hour.
> You can do some math with this and interpolate accordingly. You can get
> pretty fancy with this if you want to.
>
> But the plain and simple method is pretty straight forward. Most YAK's
> and I believe CJ's, have a voltage and amp meter built into the aircraft.
> Turn on the electrical master. BEFORE you go flying. Look at the
> voltage. It should be around 24 volts or so, maybe as high as 25. If it
> down around 22 vdc, your eyebrows should start going up in alarm. At this
> point, start turning on anything that draws a lot of current. Landing
> lights would be good. So is Pitot Heat. Radios, no. As you turn this
> stuff on, look at that battery voltage. Is it HOLDING? Or is it dropping
> like a stone? If you had 22-23 VDC and you turn on Pitot Heat and it
> drops to 20 vdc... HMMM!!! If you then turn on a landing light.... and
> it drops to 16-18 volts OR LESS, then it is time to replace the batteries.
> A much better way is to put a good digital meter on the battery terminals
> themselves when you do this by the way and read the voltage with that.
>
> Do not check them and come back and say: HEY, ONE IS 12 VOLTS AND ONE IS 6
> VOLTS, SO I AM ONLY GOING TO REPLACE ONE!!! Yeah, that will work, but it
> it is penny wise and dollar foolish. You want all the cells in the two 12
> volt batteries that you connect in series to get 24 volts to be BALANCED.
> If they are NOT balanced, then the current to charge the WEAK cells has to
> flow through the GOOD cells to charge the weak ones. This ends up
> over-charging the GOOD cells and causing them to vent gas. Which makes
> them go bad. Quickly.
>
> SO ... try to replace them in PAIRS.
>
> I don't want to sound like an advertisement, but I really am impressed
> with Battery-Minder battery chargers. They not only have a temp. sensor
> that keeps from overheating charging batteries, but also, after the
> batteries are charged, they put a 3 Mhz blast pulse into the batteries
> that works to turn battery sulfate off the plates and put it back into
> solution, or.... "gell" that extends the life of the battery PLUS they
> check the status of the battery automatically. They are not cheap.
> But.... They are worth every cent in my opinion. I own THREE of them.
>
> The YAK and CJ's aircraft for the most part do not use electrical starters
> (Some rare models excepted). An electrical starter is a quick test for a
> battery. I.E. Think of your car when it gets cold. Bad battery? You
> don't start, so you replace it. We do not have that huge electrical draw
> that the car starter represents... so our batteries kind of go bad in a
> sneaky way. Leading to issues with the reverse current relay.
>
> Just had a nice person with a YAK-18T that this just happened to. Hope
> this explains what is happening, and how to keep an eye out for it.
>
> Mark
>
>
> ________________________________
>
> From: owner-yak-list-server@matronics.com on behalf of Steven Johnson
> Sent: Sun 9/26/2010 8:18 PM
> To: yak-list@matronics.com
> Subject: RE: Yak-List: Engine/avionics shutdown procedure
>
>
>
>
> Mark, how does one check the batteries properly?
>
> Steve Johnson
> Yak 52 N9900X 0B5
> 413 522-1130 Cell
> -----Original Message-----
> From: owner-yak-list-server@matronics.com
> [mailto:owner-yak-list-server@matronics.com] On Behalf Of Bitterlich, Mark
> G
> CIV Det Cherry Point, MALS-14 64E
> Sent: Sunday, September 26, 2010 6:29 PM
> To: yak-list@matronics.com
> Subject: RE: Yak-List: Engine/avionics shutdown procedure
>
> --> Point, MALS-14 64E" <mark.bitterlich@navy.mil>
>
> Dave, That is a very good point. Again, I must caution anyone reading
> this
> that I have never worked on a CJ, though I am aware that they have two
> types
> of control systems for the generator.
>
> I believe there is a solid state controller and also a older more
> traditional style controller. Whatever. Let's just cut to the chase. It
> would be much smarter to turn off your avionics before killing the mags
> (engine) if you have anything in there worth worrying about.
>
> Why? Because on any engine that has a generator, when you kill the mags,
> the generator stops turning. As it slows down, the generator voltage will
> drop below the battery voltage. When this happens, current stops flowing
> from the generator to the battery, and instead flows from the battery to
> the
> generator. This is called "Reverse Current". In all aircraft with real
> generators, there is some device that is in there to prevent this.
>
> Or at least... normally the way it works is that as current STARTS flowing
> from the battery to the generator, There is usually some kind of "set
> point" where this relay operates and then DISCONNECTS the generator from
> the
> aircrafts electrical bus.
>
> Here is the problem. If your battery is not in just TIP TOP condition...
> which by the way, many of our batteries are not... because we fail to
> CHECK
> THEM PROPERLY..... what will happen is that when the engine starts
> slowing
> down to a stop after you kill the mags, reverse current will start to
> flow.
> If your batteries are not up to snuff, then the battery output voltage
> will
> drop as the current going to the generator increases.
>
> Hopefully, eventually the current will rise high enough to where the
> reverse
> current RELAY operates and then disconnects the generator. However, that
> does not HAVE to happen right away when it should. If the batteries are
> WEAK, then this chain of events will happen much more SLOWYLY. And that
> is
> a bad bad thing, because then your battery voltage will drop way down
> below
> 24 volts and maybe as low as 14-16 VDC. Avionics systems really don't
> like
> voltage spikes like this. Going down, or going up They just don't like
> that kind of thing. Will it cause instant failure of your avionics? NO.
> Is
> it asking for a failure? YES. Shut off your avionics before killing the
> engine is the smart thing to do, regardless of what any check list
> currently
> says.
>
> Mark Bitterlich
>
> p.s. I do not bother to follow my own advice, but then I check my
> batteries
> carefully all the time, and I also am only powering one Russian radio.
> But,
> I really should, and if I had any Avionics that cost more than a few
> hundred, I would be religious about it.
>
> ________________________________
>
> From: owner-yak-list-server@matronics.com on behalf of KingCJ6@aol.com
> Sent: Sun 9/26/2010 5:58 PM
> To: yak-list@matronics.com
> Subject: Yak-List: Engine/avionics shutdown procedure
>
>
>
> Most Nanchang checklists specify shutting the engine down with mags prior
> to
> shutting off the electric switches which power all of the avionics. All
> traditional GA checklists I've seen specify turning off the avionics
> master
> (or individual components) prior to shutting down the engine to presumably
> prevent damage from a potential power spike. Any technical reason for the
> Nanchang to be different?
>
>
>
> Dave
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
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| Subject: | Re: Engine/avionics shutdown procedure |
For what it's worth, the procedure I use (discussing electrical only):
I have a pretty much stock Yak-52. The only two electrical additions
are a transponder and a hard-wire for a Garmin 696. They are both
wired right to the master switch
with in-line fuses.
I always leave the engine instrument switch on, as I pretty much
always need those any time the master is on.
I check mags off, usually on both cockpits. Before I charge the system
side (left side primer on the 52), I turn on the master so I can see
if fuel pressure is building. Then I turn master back off and do
whatever priming (if any) I'm going to do before entering the cockpit.
I turn the rear cockpit mags to 1+2. After strapping in, I turn the
master on again, and my GPS off (which turned on when I turned on the
master). Then generator and ignition. After start, I check instruments
and then turn on all (left panel) switches and press the gyro button
(OK, so that's not electric). GPS on, transponder on via the standby
button (will go to ALT on takeoff, which I think is a cool feature).
(Fly)
When I am shutting down, I run it up to 70%, and while that's going
on, I shut off all left panel switches, then GPS and transponder. Then
retard to 40% for a second or so, then fully retarded, then mags off,
then master-generator-ignition off.
Re-check switches before leaving hangar.
On Sep 28, 2010, at 4:10 PM, Didier Blouzard wrote:
> Hi gents,
>
> for my point of view, it doesn't do anything bad to turn off all the
> unnecessary electrical loads after landing and that's just what I do.
> When landing the engine is at low boost but not low RPM. I imagine
> that's why we don't have the generator lamp coming on. After
> landing, I turn off all unnecessary electrical consumers like the
> gyros and the converter, the radio and transponder and all the rest.
> The only switches that are staying on are the five first : Battery,
> Generator, Ignition, Motor and landing instruments.
> The rest is off as soon as the speed is controlled or just after
> having vacated the airstrip.
>
> I would enjoy any comments concerning this...way of doing.....is it
> good or bad for the system..???
>
> Thanks a lot and fly safe
>
> Didier
>
>
> 2010/9/28 Yak Pilot <yakplt@yahoo.com>
>
> You are again correct.
>
> If everything is working absolutely perfectly and your batteries
> have good capacity, when the engine is brought down to idle, the
> generator output will go below 28 volts, reverse current will start
> to flow, the reverse current relay will sense this and the main
> generator contactor will disengage and the generator will no longer
> be connected to the aircraft electrical system. So in reality ...
> this does not happen as you shut down the mags, it actually should
> happen when you bring the power back to idle.
>
> Again, if everything is working perfectly at this point, if you shut
> off the engine with the mag switch, at this point the generator is
> already disconnected and there should be no load change or voltage
> surge to the avionics.
>
> This may sound contrary to what I was saying before, but I tried to
> cover it in the other explanation.
>
> A gent with a YAK-18T recently had an issue where his generator
> light did not come on all the time at idle. When he killed the
> engine with the mags, it then DID come on as the engine came to a
> stop. In this case, the gent had weak batteries. When he brought
> the engine down to idle, the batteries were so weak that they could
> not provide enough reverse current to cause the reverse current
> relay to do it's job. The result was that the main contactor for
> the aircraft stayed closed, and kept the generator connected to the
> aircraft electrical bus.
>
> During this period of time, main bus electrical voltage sagged down
> to between 12 and 14 volts. Eventually the generator came to a stop
> and there was enough current to cause the reverse current relay to
> open, thus disengaging the main contactor to the generator, and the
> load went away and battery voltage jumped back up to 20 volts or so.
>
> This is the kind of nonsense I was trying to talk about.
>
> However, if your aircraft battery is in good shape and every part in
> the aircraft is working properly, you should not see a really large
> voltage spike as the generator comes on and off line. Basically, if
> everything is working just perfectly, the generator will be
> connected to the aircraft electrical bus when it's output is a few
> volts above that of the battery. There will be a minor 2-3 volt
> jump in battery voltage as the thing connects, but that is usually
> not something to worry about.
>
> When the engine RPM is lowered and the generator voltage drops,
> current flow will increase going back to the generator. This is
> where if your batteries are not working right that you will run into
> trouble.
>
> In the end, I just think it is a good idea to get any expensive
> avionics turned off as soon as possible to avoid any kind of voltage
> spikes or lags. But as I said, if you keep your batteries in
> perfect working order and you have a good reverse current relay ...
> all should be well.
>
> Mark
>
>
> --- On Tue, 9/28/10, Stephen Morrey <stephenmorrey@gmail.com> wrote:
>
> > From: Stephen Morrey <stephenmorrey@gmail.com>
> > Subject: Re: Yak-List: Engine/avionics shutdown procedure
> > To: yak-list@matronics.com
> > Date: Tuesday, September 28, 2010, 4:16 AM
> > Stephen Morrey <stephenmorrey@gmail.com>
> >
> > On a yak during low idle the generator light will go
> > on indicating
> > the generator is not operating (or at least not charging to
> > some
> > level) when the rpm is low. Should I assume
> > that stress to the
> > avionics can also happen just during idle when the
> > generator cycles on
> > and off as indicated by the generator light or is the light
> > just an
> > indication of the level of output of the generator and
> > hence the same
> > effect as seen in shut down is not likely? steve
> >
> > On Sun, Sep 26, 2010 at 6:28 PM, Bitterlich, Mark G CIV Det
> > Cherry
> > Point, MALS-14 64E <mark.bitterlich@navy.mil>
> > wrote:
> > CIV Det Cherry Point, MALS-14 64E" <mark.bitterlich@navy.mil>
> > >
> > > Dave, That is a very good point. Again, I must
> > caution anyone reading this that I have never worked on a
> > CJ, though I am aware that they have two types of control
> > systems for the generator.
> > >
> > > I believe there is a solid state controller and also a
> > older more traditional style controller. Whatever. Let's
> > just cut to the chase. It would be much smarter to turn
> > off your avionics before killing the mags (engine) if you
> > have anything in there worth worrying about.
> > >
> > > Why? Because on any engine that has a generator,
> > when you kill the mags, the generator stops turning. As it
> > slows down, the generator voltage will drop below the
> > battery voltage. When this happens, current stops flowing
> > from the generator to the battery, and instead flows from
> > the battery to the generator. This is called "Reverse
> > Current". In all aircraft with real generators, there is
> > some device that is in there to prevent this.
> > >
> > > Or at least... normally the way it works is that as
> > current STARTS flowing from the battery to the generator,
> > There is usually some kind of "set point" where this relay
> > operates and then DISCONNECTS the generator from the
> > aircrafts electrical bus.
> > >
> > > Here is the problem. If your battery is not in just
> > TIP TOP condition... which by the way, many of our batteries
> > are not... because we fail to CHECK THEM PROPERLY.....
> > what will happen is that when the engine starts slowing
> > down to a stop after you kill the mags, reverse current will
> > start to flow. If your batteries are not up to snuff,
> > then the battery output voltage will drop as the current
> > going to the generator increases.
> > >
> > > Hopefully, eventually the current will rise high
> > enough to where the reverse current RELAY operates and then
> > disconnects the generator. However, that does not HAVE to
> > happen right away when it should. If the batteries are
> > WEAK, then this chain of events will happen much more
> > SLOWYLY. And that is a bad bad thing, because then your
> > battery voltage will drop way down below 24 volts and maybe
> > as low as 14-16 VDC. Avionics systems really don't like
> > voltage spikes like this. Going down, or going up They
> > just don't like that kind of thing. Will it cause instant
> > failure of your avionics? NO. Is it asking for a
> > failure? YES. Shut off your avionics before killing the
> > engine is the smart thing to do, regardless of what any
> > check list currently says.
> > >
> > > Mark Bitterlich
> > >
> > > p.s. I do not bother to follow my own advice, but
> > then I check my batteries carefully all the time, and I also
> > am only powering one Russian radio. But, I really should,
> > and if I had any Avionics that cost more than a few hundred,
> > I would be religious about it.
> > >
> > > ________________________________
> > >
> > > From: owner-yak-list-server@matronics.com
> > on behalf of KingCJ6@aol.com
> > > Sent: Sun 9/26/2010 5:58 PM
> > > To: yak-list@matronics.com
> > > Subject: Yak-List: Engine/avionics shutdown procedure
> > >
> > >
> > >
> > > Most Nanchang checklists specify shutting the engine
> > down with mags prior to shutting off the electric switches
> > which power all of the avionics. All traditional GA
> > checklists I've seen specify turning off the avionics master
> > (or individual components) prior to shutting down the engine
> > to presumably prevent damage from a potential power spike.
> > Any technical reason for the Nanchang to be different?
> > >
> > >
> > >
> > > Dave
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
> >
> > Forum -
> > FAQ,
> > - MATRONICS WEB FORUMS -
> > List Contribution Web Site -
> > -Matt
> > Dralle, List Admin.
> >
> >
> >
> >
>
>
> ==========
> rget="_blank">http://www.matronics.com/Navigator?Yak-List
> ==========
> http://forums.matronics.com
> ==========
> le, List Admin.
> ="_blank">http://www.matronics.com/contribution
> ==========
>
>
> --
> Didier BLOUZARD
> didier.blouzard@gmail.com
> 0624243672
>
>
Eric D. Wobschall
Buffalo Skyline
Buffalo-Lancaster Airport (KBQR):
4343 Walden Avenue
Lancaster, NY 14086
Office:
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