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A possible suggestion

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mark.bitterlich(at)navy.m
Guest

Posted: Wed Mar 14, 2007 2:03 pm Post subject: A possible suggestion

Lately I have become pretty deeply involved in Yak electrical issues.

One part of the Yak (and other Russian aircraft)in the overall design

seems to have a pretty significant failure rate, and also is difficult

to impossible to replace, with the current "if you can find one" price

being around $650 each.  This is the DNP-200A "Combined Device" detailed

in my White Paper posted several weeks ago.  



I may indeed have become "overly sensitive" to this issue and my

up-coming suggestion may indeed be over-kill.  I will leave that up to

each persons individual judgment or even open debate for that matter.  



That said, I personally am going to modify my operating habits a little

bit.  Namely, I am going to start my engine from now on with the

generator switch in the OFF position.  I am going to LEAVE if off for

all taxi operations.  I am ONLY going to turn it on when performing the

pre-take-off run up, and of course I will then leave it on for the rest

of the flight.  



After landing, I will turn the generator switch off immediately and

leave it off even past engine shut-down.  



Why am I doing this?  



Because every single time you increase engine RPM to about 40% or so,

the generator comes on right?  No... Not really.  The generator is on as

soon as you start the engine.  The generator VOLTAGE only gets high

enough around 40% or so and then the DNP-200A contactor relay closes and

generator power is fed to the bus.  Reduce engine speed back to idle,

and what happens?  REVERSE current flows TO the generator and the

DNP-200A contactor OPENS (at least we hope it will) and generator power

is REMOVED from the aircraft bus and the generator LIGHT comes on.  



Consider if you will how many times this happens from when you first

start until you are ready to take off.  



Reducing the amount of times this happens will extend the life of the

DNP-200A Combined Assy.  



Is it worth taking such a step in order to extend the life of this part?

You be the judge.  



Mark Bitterlich 

N50YK

david(at)mcgirt.net
Guest

Posted: Wed Mar 14, 2007 3:41 pm Post subject: A possible suggestion

Mark,



 Very good points, I just finished REPLACING my regulator and alternator in

my TW - purely due to a DOS error... ( Dumbass Owner Syndrome )



My batteries we low, and instead of pulling and charging, I started up, and

let them charge off the alternator at low RPM.. thus burning up a 50 AMP

Alternator and regulator...  That would have worked ( although, still not

the right was to go about it.. )  if I would have waited to after takeoff,

at high RPM, thus getting the full capability of the Alternator..



  After owning up to my error to the Manufacturer, they also asked if I was

starting and shutting down with the Alternator on, and HIGHLY recommended

turn it off during these low RPM areas.. as you suggested..



I know Gen's and Alternator are not the same, but the practice should help

all..



Just my $750 worth of experience.. that is a lot of gas money wasted.. 



David

--

dsavarese(at)elmore.rr.co
Guest

Posted: Wed Mar 14, 2007 3:53 pm Post subject: A possible suggestion

Mark,

I like your suggestion and plan on implementing that procedure beginning 

with the next time I fly.  Thanks for taking the time to "educate" our 

group.

Dennis



---

mark.bitterlich(at)navy.m
Guest

Posted: Wed Mar 14, 2007 4:07 pm Post subject: A possible suggestion

Thanks David for sharing your experience.   When I went through my own

electrical nightmare, I came close to just bagging the whole mess and

going the "American way", namely by converting to the exact same system

you have in your TW.  There is no question that it is the 'cat's meow'.

Then I started to think about it and wondered if there was any

circumstance where you could blow that really beautiful but very

expensive Alternator!  Hmmm, thanks for THAT education!   I then decided

to sweat some more and see if I could figure out what really was wrong

with my Russian system.  At least with it, the parts are cheap....

EXCEPT for that dang DNP-200A thing.  So, bottom line is that any way

you look at it, you're damned if you do, and damned if you don't.  



By the way, sooner or later all of our readers here are going to

experience the "DNP-200 syndrome".  I am thinking about going into

business repairing them...   



Dennis.... Thanks for your comments as well.  The way I look at it, it

can't hurt anything, and if your batteries go dead that fast, it's

better to know that sooner than later as well!  



Mark

 



--

drc(at)wscare.com
Guest

Posted: Wed Mar 14, 2007 6:54 pm Post subject: A possible suggestion

Exact same experience in mine with the same advice from the  

manufacturer.  We have been starting on air (or battery electric  

start) then not turning on alternator until run up.  Shutting down  

the alternator when turning off the runway.. so far so good.



Herb

On Mar 14, 2007, at 6:40 PM, David McGirt wrote:



[quote] 



 Mark,



  Very good points, I just finished REPLACING my regulator and  

 alternator in

 my TW - purely due to a DOS error... ( Dumbass Owner Syndrome )



 My batteries we low, and instead of pulling and charging, I started  

 up, and

 let them charge off the alternator at low RPM.. thus burning up a  

 50 AMP

 Alternator and regulator...  That would have worked ( although,  

 still not

 the right was to go about it.. )  if I would have waited to after  

 takeoff,

 at high RPM, thus getting the full capability of the Alternator..



   After owning up to my error to the Manufacturer, they also asked  

 if I was

 starting and shutting down with the Alternator on, and HIGHLY  

 recommended

 turn it off during these low RPM areas.. as you suggested..



 I know Gen's and Alternator are not the same, but the practice  

 should help

 all..



 Just my $750 worth of experience.. that is a lot of gas money wasted..



 David

 --

viperdoc(at)mindspring.co
Guest

Posted: Wed Mar 14, 2007 7:51 pm Post subject: A possible suggestion

Hey, I'm having the BMP 200 issue as this thread unravels. I agree with the

idea whole heartedly. That reverse current thing is real. To high a voltage

and the 50 fuse to the battery fries too. Will be doing a voltage check on

the generator side of the DNP 200 tomorrow to see what else is or is not

working after that failure. Hopefully it is just the DNP 200A. That cost

just about as much as Dave's B&C Alternator/ regulator by itself. And to

think it all started with flickering indicator lights and volt meter only

to fully crap out within 24 hours.

Doc

[quote] [Original Message]

 From: Herb Coussons <drc(at)wscare.com>

 To: <yak-list(at)matronics.com>

 Date: 3/14/2007 10:00:03 PM

 Subject: Re: A possible suggestion



 



 Exact same experience in mine with the same advice from the  

 manufacturer.  We have been starting on air (or battery electric  

 start) then not turning on alternator until run up.  Shutting down  

 the alternator when turning off the runway.. so far so good.



 Herb

 On Mar 14, 2007, at 6:40 PM, David McGirt wrote:



 > 

 >

 > Mark,

 >

 >  Very good points, I just finished REPLACING my regulator and  

 > alternator in

 > my TW - purely due to a DOS error... ( Dumbass Owner Syndrome )

 >

 > My batteries we low, and instead of pulling and charging, I started  

 > up, and

 > let them charge off the alternator at low RPM.. thus burning up a  

 > 50 AMP

 > Alternator and regulator...  That would have worked ( although,  

 > still not

 > the right was to go about it.. )  if I would have waited to after  

 > takeoff,

 > at high RPM, thus getting the full capability of the Alternator..

 >

 >   After owning up to my error to the Manufacturer, they also asked  

 > if I was

 > starting and shutting down with the Alternator on, and HIGHLY  

 > recommended

 > turn it off during these low RPM areas.. as you suggested..

 >

 > I know Gen's and Alternator are not the same, but the practice  

 > should help

 > all..

 >

 > Just my $750 worth of experience.. that is a lot of gas money wasted..

 >

 > David

 >

 >

 > --

jan.mevis(at)informavia.b
Guest

Posted: Wed Mar 14, 2007 9:54 pm Post subject: A possible suggestion

This seems to be a very good suggestion. I always switched on the generator

AFTER the start, but it certainly is not too bad an idea to wait with the

generator until applying full power. Thanks, Mark!



Jan Mevis



--

pa3arw(at)euronet.nl
Guest

Posted: Thu Mar 15, 2007 12:06 am Post subject: A possible suggestion

Mark,

It's a dc-generator, so a high current diode ( e.g. from an old ac car

generator) helps as well from preventing reverse current. The only thing is,

you loose 0,5v over the diode....but I'm sure we can live with that...

Hans

-----Oorspronkelijk bericht-----

Van: owner-yak-list-server(at)matronics.com

[mailto:owner-yak-list-server(at)matronics.com] Namens Roger Kemp

Verzonden: donderdag 15 maart 2007 4:51

Aan: yak-list(at)matronics.com

Onderwerp: Re: A possible suggestion

Hey, I'm having the BMP 200 issue as this thread unravels. I agree with the

idea whole heartedly. That reverse current thing is real. To high a voltage

and the 50 fuse to the battery fries too. Will be doing a voltage check on

the generator side of the DNP 200 tomorrow to see what else is or is not

working after that failure. Hopefully it is just the DNP 200A. That cost

just about as much as Dave's B&C Alternator/ regulator by itself. And to

think it all started with flickering indicator lights and volt meter only

to fully crap out within 24 hours.

Doc

[quote] [Original Message]

 From: Herb Coussons <drc(at)wscare.com>

 To: <yak-list(at)matronics.com>

 Date: 3/14/2007 10:00:03 PM

 Subject: Re: A possible suggestion

 Exact same experience in mine with the same advice from the  

 manufacturer.  We have been starting on air (or battery electric  

 start) then not turning on alternator until run up.  Shutting down  

 the alternator when turning off the runway.. so far so good.

 Herb

 On Mar 14, 2007, at 6:40 PM, David McGirt wrote:

 > 

 >

 > Mark,

 >

 >  Very good points, I just finished REPLACING my regulator and  

 > alternator in

 > my TW - purely due to a DOS error... ( Dumbass Owner Syndrome )

 >

 > My batteries we low, and instead of pulling and charging, I started  

 > up, and

 > let them charge off the alternator at low RPM.. thus burning up a  

 > 50 AMP

 > Alternator and regulator...  That would have worked ( although,  

 > still not

 > the right was to go about it.. )  if I would have waited to after  

 > takeoff,

 > at high RPM, thus getting the full capability of the Alternator..

 >

 >   After owning up to my error to the Manufacturer, they also asked  

 > if I was

 > starting and shutting down with the Alternator on, and HIGHLY  

 > recommended

 > turn it off during these low RPM areas.. as you suggested..

 >

 > I know Gen's and Alternator are not the same, but the practice  

 > should help

 > all..

 >

 > Just my $750 worth of experience.. that is a lot of gas money wasted..

 >

 > David

 >

 >

 > --

Mozam

Joined: 24 Nov 2006
Posts: 85

Posted: Thu Mar 15, 2007 4:14 am Post subject: A possible suggestion

 	  Quote: 	
		  >>>From: "David McGirt" <david(at)mcgirt.net>  

Subject: RE: A possible suggestion  
	


   

   

Mark,  

   

 Very good points, I just finished REPLACING my regulator and alternator in my TW - purely due to a DOS error... ( Dumbass Owner Syndrome )  

   

My batteries we low, and instead of pulling and charging, I started up, and let them charge off the alternator at low RPM.. thus burning up a 50 AMP Alternator and regulator...  That would have worked ( although, still not the right was to go about it.. )  if I would have waited to after takeoff, at high RPM, thus getting the full capability of the Alternator..  

   

  After owning up to my error to the Manufacturer, they also asked if I was starting and shutting down with the Alternator on, and HIGHLY recommended turn it off during these low RPM areas.. as you suggested..<<<<  

   

   

Dave,  

   

Been there, done that, got the T-shirt.  DO NOT try to charge low batteries with the alternator in our TW’s.  

   

Also, besides the vastly improved CG, this is another good reason to move the batteries up in front of the oil cooler.  They are VERY easy to access for charging.  You don’t even have to remove them.  Just pop several fasteners, the batteries swing down, and connect the charger.  Piece of cake!  

   

I have one question about turning on the alternator just prior to takeoff, and I admit I am an electrical moron.  Is there any concern that your first indication of a bad electrical problem (like an electrical fire) will be during, or just after takeoff?  

   

Cheers,  

Steve Dalton  

   

       [quote][b]

Rob Rowe

Joined: 10 Jan 2006
Posts: 124
Location: Berkshire, UK

Posted: Thu Mar 15, 2007 5:42 am Post subject: Re: A possible suggestion

A few other related thoughts ... regardless of whether you have the generator on OR off while taxying;



The PAG-1 & PT200 inverters take c.20 Amps DC power ... over half a kilowatt of power from your battery!



So if the generator is offline (of its own volition or has been turned off) it's a good idea to keep the invertors off too, as this helps prevent your batteries from getting hammered. If you've strobes fitted these can also be quite power hungry.



Secondary benefit of taxying with inverters off (especially on rough surfaces) is that the gyros are consequently de-powered, this saves a lot of wear & tear on their delicate bearings (gather this is common practice in Russia ... 2nd hand info from someone who had instruction from Azat Zaydullin).



Might be good practice to have the generator on-line for the power checks, as before commiting aviation it would be good to know that;

- the DC power system will regulate at high RPM

- the generator will disconnect at low RPM

- the gyros have had time to spool up (think a minimum of 2 minutes is specified), assuming you've just turned the invertors on too



After clearing the active on landing I add the following to the stop / brakes on / identify & operate flap lever / fully open oil & air cowls regime.

- shed unnecessary electrical loads (strobes / ADF / slaved DI / PAG-1 / PT200)

If you want to turn the generator off too, this is a good time to add it to your check list.



Cheers, Rob R

mark.bitterlich(at)navy.m
Guest

Posted: Thu Mar 15, 2007 12:37 pm Post subject: A possible suggestion

That is in fact true, and is a perfectly sound suggestion.  



Where you are going with this is basically engineering a simple and

total replacement for the DNP-200.  I have been thinking along the exact

same lines.  To cover any voltage spikes, I was thinking that the

reverse voltage spec on the diode should be at least double (if not even

more) the supply voltage, and probably rated for between 50 and 75 amps.

Such devices are not CHEAP, but they are obtainable. Car alternator

diodes?  Are they rated high enough current?  Maybe even use two in

parallel for safety?  Couple that with a good main line 28 VDC 100 amp

contactor (or less maybe), and you could then easily adapt that right

into the rest of the existing Russian designed circuitry.  



Thanks Hans.  Great thought.  



Mark Bitterlich

 



--

rogerbyak(at)yahoo.com
Guest

Posted: Fri Mar 16, 2007 7:11 pm Post subject: A possible suggestion

Is there any specific operating procedure in the Pilots Manual concerning this practice? 

  This is well "beyond me" and my understanding of the systems, but why has it been a common practice to tie wire the generator switch in the closed position on CJ's delivered by some west coasters?; with some advice that if the switch were opened, it would result in failure of the generator?  rb



"Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E" <mark.bitterlich(at)navy.mil> wrote:

  [quote]--> Yak-List message posted by: "Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E" 



Thanks David for sharing your experience. When I went through my own

electrical nightmare, I came close to just bagging the whole mess and

going the "American way", namely by converting to the exact same system

you have in  your TW. There is no question that it is the 'cat's meow'.

Then I started to think about it and wondered if there was any

circumstance where you could blow that really beautiful but very

expensive Alternator! Hmmm, thanks for THAT education! I then decided

to sweat some more and see if I could figure out what really was wrong

with my Russian system. At least with it, the parts are cheap....

EXCEPT for that dang DNP-200A thing. So, bottom line is that any way

you look at it, you're damned if you do, and damned if you don't. 



By the way, sooner or later all of our readers here are going to

experience the "DNP-200 syndrome". I am thinking about going into

business repairing them...  



Dennis.... Thanks for your comments as well. The way I look at it, it

can't hurt anything, and if your batteries go dead that fast, it's

better to know that sooner than later as well! 



Mark

-----Original  Message-----

From: owner-yak-list-server(at)matronics.com

[mailto:owner-yak-list-server(at)matronics.com] On Behalf Of David McGirt

Sent: Wednesday, March 14, 2007 19:40

To: yak-list(at)matronics.com

Subject: RE: A possible suggestion



--> Yak-List message posted by: "David McGirt" 



Mark,



Very good points, I just finished REPLACING my regulator and alternator

in my TW - purely due to a DOS error... ( Dumbass Owner Syndrome )



My batteries we low, and instead of pulling and charging, I started up,

and let them charge off the alternator at low RPM.. thus burning up a 50

AMP Alternator and regulator... That would have worked ( although,

still not the right was to go about it.. ) if I would have waited to

after takeoff, at high RPM, thus getting the full capability of the

Alternator..



After owning up to my error to the Manufacturer, they also asked if I

was starting and shutting down  with the Alternator on, and HIGHLY

recommended turn it off during these low RPM areas.. as you suggested..



I know Gen's and Alternator are not the same, but the practice should

help all..



Just my $750 worth of experience.. that is a lot of gas money wasted.. 



David

--

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