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nuckollsr(at)cox.net
Guest

Posted: Tue Aug 01, 2006 8:59 pm Post subject: STC for standby generator on a

Talk to B&C. The Mooney's were the first TC'd aircraft to get the

SD-20 style alternator on a production aircraft. I'm certain that by

now MANY Mooney owners have installed this system on older airplanes

under a one-time field approval (Form 337 or perhaps the limited

applicability STC). If anyone knows, they'd be the first to ask,

then go to Mooney Type Clubs.



Bob . . .



At 02:11 PM 7/31/2006 -0500, you wrote:



 	  Quote: 	
		  



What do you mean it would cost a fortune?  Whom would I be paying money 

to, and for what?



Dave Morris



At 09:48 PM 7/30/2006, you wrote:

>

>

>AFAIK, no one has STC'd a standby alternator for early Mooneys. The only 

>place to put one would be on the vacuum pump pad. Unless one has been 

>STC'd for the O-360, you would spend a fortune getting it approved.





--

No virus found in this incoming message.



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Checked by AVG Anti-Virus.


	




        Bob . . .

      ---------------------------------------------------------

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

      ---------------------------------------------------------

Kellym

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

Posted: Wed Aug 02, 2006 4:57 am Post subject: STC for standby generator on a

I've been on the Mooney email list for the last 8 years. No mention of 

anyone retrofitting a standby alternator that I recall, on anything but 

the late model planes as a replacement for the standby vacuum pump on 

late models. The earlier models would require approval for removal of 

the vacuum pump and installation of a dual electric system.



Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   

 <nuckollsr(at)cox.net>

 

 Talk to B&C. The Mooney's were the first TC'd aircraft to get the

 SD-20 style alternator on a production aircraft. I'm certain that by

 now MANY Mooney owners have installed this system on older airplanes

 under a one-time field approval (Form 337 or perhaps the limited

 applicability STC). If anyone knows, they'd be the first to ask,

 then go to Mooney Type Clubs.

 

 Bob . . .

 

 At 02:11 PM 7/31/2006 -0500, you wrote:

 

> 

> <N6030X(at)DaveMorris.com>

>

> What do you mean it would cost a fortune?  Whom would I be paying 

> money to, and for what?

>

> Dave Morris

>

> At 09:48 PM 7/30/2006, you wrote:

>> 

>> <kellym(at)aviating.com>

>>

>> AFAIK, no one has STC'd a standby alternator for early Mooneys. The 

>> only place to put one would be on the vacuum pump pad. Unless one has 

>> been STC'd for the O-360, you would spend a fortune getting it approved.

>

>

> -- 

> No virus found in this incoming message.

>

> -- incoming mail is certified Virus Free.

> Checked by AVG Anti-Virus.

 

 

        Bob . . .

 

 

      ---------------------------------------------------------

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

      ---------------------------------------------------------

 

 

 

 

 http://www.matronics.com/Navigator?AeroElectric-List

 http://wiki.matronics.com

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

oldbob(at)BeechOwners.com
Guest

Posted: Wed Aug 02, 2006 5:29 am Post subject: STC for standby generator on a

Good Morning Kelly,



Are you sure about having to get "approval" to remove

that vacuum pump? I agree that you need approval to

add the standby alternator, (Though B&C may already

have it STC'd) but on the Bonanza, all that is

required is a log book entry that the pump and

associated plumbing was removed.



You might check the Mooney TCDSs to see if the pump is

listed as required or as optional equipment.  If it is

not listed as required, get rid of it!



Happy Skies,



Old Bob

AKA

Bob Siegfried

Stearman N3977A



--- Kelly McMullen <kellym(at)aviating.com> wrote:



 	  Quote: 	
		   

 McMullen <kellym(at)aviating.com>

 

 I've been on the Mooney email list for the last 8

 years. No mention of 

 anyone retrofitting a standby alternator that I

 recall, on anything but 

 the late model planes as a replacement for the

 standby vacuum pump on 

 late models. The earlier models would require

 approval for removal of 

 the vacuum pump and installation of a dual electric

 system.

 

 Robert L. Nuckolls, III wrote:

 > 

 L. Nuckolls, III" 

 > <nuckollsr(at)cox.net>

 > 

 > Talk to B&C. The Mooney's were the first TC'd

 aircraft to get the

 > SD-20 style alternator on a production aircraft.

 I'm certain that by

 > now MANY Mooney owners have installed this system

 on older airplanes

 > under a one-time field approval (Form 337 or

 perhaps the limited

 > applicability STC). If anyone knows, they'd be the

 first to ask,

 > then go to Mooney Type Clubs.

 > 

 > Bob . . .

 > 

 > At 02:11 PM 7/31/2006 -0500, you wrote:

 > 

 >> 

 N6030X 

 >> <N6030X(at)DaveMorris.com>

 >>

 >> What do you mean it would cost a fortune?  Whom

 would I be paying 

 >> money to, and for what?

 >>

 >> Dave Morris

 >>

 >> At 09:48 PM 7/30/2006, you wrote:

 >>> 

 McMullen 

 >>> <kellym(at)aviating.com>

 >>>

 >>> AFAIK, no one has STC'd a standby alternator for

 early Mooneys. The 

 >>> only place to put one would be on the vacuum

 pump pad. Unless one has 

 >>> been STC'd for the O-360, you would spend a

 fortune getting it approved.

 >>

 >>

 >>

 >>

 >>

 >>

 >>

 >>

 >>

 >>

 >>

 >>

 >>

 >>

 >> -- 

 >> No virus found in this incoming message.

 >>

 >>

 >>

 >>

 >>

 >> -- incoming mail is certified Virus Free.

 >> Checked by AVG Anti-Virus.

 > 

 > 

 >        Bob . . .

 > 

 > 

 >     



---------------------------------------------------------
	


 	  Quote: 	
		   >      < What is so wonderful about scientific

 truth...is that >

 >      < the authority which determines whether

 there can be   >

 >      < debate or not does not reside in some

 fraternity of   >

 >      < scientists; nor is it divine. The authority

 rests     >

 >      < with experiment.                           

           >

 >      <                            --Lawrence M.

 Krauss       >

 >     



---------------------------------------------------------
	


 	  Quote: 	
		   > 

 > 

 > 

 > 

 >

 http://www.matronics.com/Navigator?AeroElectric-List

 > http://wiki.matronics.com

 > 

 > 

 > 

 > 

 > 

 > 

 > 

 > 

 

 

 



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 Admin.

Kellym

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

Posted: Wed Aug 02, 2006 10:50 am Post subject: STC for standby generator on a

Bob, I couldn't tell you about the pre-1965 models, but on the '65-75  

models it was required to operate the wing leveler, which was  

standard, not optional, equipment. I suspect that it would be  

questionable on the later 4-cyl Lycoming models because they were all  

sold as IFR certified, with standard IFR equipment.

AFAIK, the Porsche powered model was the 1st Mooney to be all  

electric, and probably the only model until the GX series with G1000  

panels came out.

I still think it is a whole lot simpler to install an electric AI like  

Sporty's, either as additional instrument, or as replacement for T&B,  

than to screw with changing whole systems in a certified plane. Both  

easier and cheaper.



Quoting OldBob Siegfried <oldbob(at)BeechOwners.com>:



 	  Quote: 	
		   

 <oldbob(at)beechowners.com>



 Good Morning Kelly,



 Are you sure about having to get "approval" to remove

 that vacuum pump? I agree that you need approval to

 add the standby alternator, (Though B&C may already

 have it STC'd) but on the Bonanza, all that is

 required is a log book entry that the pump and

 associated plumbing was removed.



 You might check the Mooney TCDSs to see if the pump is

 listed as required or as optional equipment.  If it is

 not listed as required, get rid of it!



 Happy Skies,



 Old Bob

 AKA

 Bob Siegfried

 Stearman N3977A



 --- Kelly McMullen <kellym(at)aviating.com> wrote:



> 

> McMullen <kellym(at)aviating.com>

>

> I've been on the Mooney email list for the last 8

> years. No mention of

> anyone retrofitting a standby alternator that I

> recall, on anything but

> the late model planes as a replacement for the

> standby vacuum pump on

> late models. The earlier models would require

> approval for removal of

> the vacuum pump and installation of a dual electric

> system.

>

> Robert L. Nuckolls, III wrote:

> > 

> L. Nuckolls, III"

> > <nuckollsr(at)cox.net>

> >

> > Talk to B&C. The Mooney's were the first TC'd

> aircraft to get the

> > SD-20 style alternator on a production aircraft.

> I'm certain that by

> > now MANY Mooney owners have installed this system

> on older airplanes

> > under a one-time field approval (Form 337 or

> perhaps the limited

> > applicability STC). If anyone knows, they'd be the

> first to ask,

> > then go to Mooney Type Clubs.

> >

> > Bob . . .

> >

> > At 02:11 PM 7/31/2006 -0500, you wrote:

> >

> >> 

> N6030X

> >> <N6030X(at)DaveMorris.com>

> >>

> >> What do you mean it would cost a fortune?  Whom

> would I be paying

> >> money to, and for what?

> >>

> >> Dave Morris

> >>

> >> At 09:48 PM 7/30/2006, you wrote:

> >>> 

> McMullen

> >>> <kellym(at)aviating.com>

> >>>

> >>> AFAIK, no one has STC'd a standby alternator for

> early Mooneys. The

> >>> only place to put one would be on the vacuum

> pump pad. Unless one has

> >>> been STC'd for the O-360, you would spend a

> fortune getting it approved.

> >>

> >>

> >>

> >>

> >>

> >>

> >>

> >>

> >>

> >>

> >>

> >>

> >>

> >>

> >> --

> >> No virus found in this incoming message.

> >>

> >>

> >>

> >>

> >>

> >> -- incoming mail is certified Virus Free.

> >> Checked by AVG Anti-Virus.

> >

> >

> >        Bob . . .

> >

> >

> >

>

 ---------------------------------------------------------

> >      < What is so wonderful about scientific

> truth...is that >

> >      < the authority which determines whether

> there can be   >

> >      < debate or not does not reside in some

> fraternity of   >

> >      < scientists; nor is it divine. The authority

> rests     >

> >      < with experiment.

>           >

> >      <                            --Lawrence M.

> Krauss       >

> >

>

 ---------------------------------------------------------

> >

> >

> >

> >

> >

> http://www.matronics.com/Navigator?AeroElectric-List

> > http://wiki.matronics.com

> >

> >

> >

> >

> >

> >

> >

> >

>

>

> browse

> Subscriptions page,

> FAQ,

> http://www.matronics.com/Navigator?AeroElectric-List

> Admin.

>

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

Bill Denton

Joined: 10 Jan 2006
Posts: 97
Location: Chicago, IL USA

Posted: Wed Aug 02, 2006 11:17 am Post subject: STC for standby generator on a

Would it be possible to just put in an electric AI and DG, and leave the

vacuum system in place, but not connected to anything?



--

N6030X(at)DaveMorris.com
Guest

Posted: Wed Aug 02, 2006 11:43 am Post subject: STC for standby generator on a

The downside to that is that you've got an all-electric airplane 

then, with no vacuum backup, and only the battery to save you in the 

event of an alternator failure.  That's what I was hoping the backup 

alternator would solve.  Although maybe a second battery would be 

easier to manage.



Dave Morris



At 02:13 PM 8/2/2006, you wrote:

[quote]



Would it be possible to just put in an electric AI and DG, and leave the

vacuum system in place, but not connected to anything?



--

ornerycuss2001(at)yahoo.c
Guest

Posted: Wed Aug 02, 2006 12:55 pm Post subject: STC for standby generator on a

Here's a link to the FAA's site for Type Certificate Data Sheets if anyone wants to do the research:

  

  http://www.airweb.faa.gov/REGULATORY_AND_GUIDANCE_LIBRARY/RGMAKEMODEL.NSF/MAINFRAMENETSCAPE4X?OpenFrameSet

  

  Greg

  

  

  

  



Dave N6030X <N6030X(at)DaveMorris.com> wrote:[quote]  --> AeroElectric-List message posted by: Dave N6030X 



The downside to that is that you've got an all-electric airplane 

then, with no vacuum backup, and only the battery to save you in the 

event of an alternator failure.  That's what I was hoping the backup 

alternator would solve.  Although maybe a second battery would be 

easier to manage.



Dave Morris



At 02:13 PM 8/2/2006, you wrote:

[quote]--> AeroElectric-List message posted by: "Bill Denton" 



Would it be possible to just put in an electric AI and DG, and leave the

vacuum system in place, but not connected to anything?



--

brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Wed Aug 02, 2006 1:32 pm Post subject: STC for standby generator on a

On Aug 2, 2006, at 3:39 PM, Dave N6030X wrote:



 	  Quote: 	
		   

 <N6030X(at)DaveMorris.com>



 The downside to that is that you've got an all-electric airplane  

 then, with no vacuum backup, and only the battery to save you in  

 the event of an alternator failure.  That's what I was hoping the  

 backup alternator would solve.  Although maybe a second battery  

 would be easier to manage.


	


The problem with vacuum power is that, if you lose your vacuum  

source, all your vacuum-driven devices go away. Providing backup  

power for your vacuum devices is a challenge. Also, your vacuum  

system has several single-points of failure, among them:



1. vacuum pump,

2. vacuum lines,

3. vacuum regulator.



If any of those fail you lose your vacuum system.



If you have a properly designed electrical system you will have no  

single point of failure for electrical power. If the alternator fails  

your battery will continue to power your instruments. If you are  

worried about that, install a dynamo or alternator on the vacuum pump  

pad and now you have three power sources for your gyro instruments,  

i.e. alternator, backup alternator, and then battery if both  

alternators fail. And not only will that power your gyros but it will  

provide backup power for other electrical devices, like navigational  

instruments and radios.



And as for wiring, if your vacuum hose to one gyro fails you will  

lose the vacuum to the other gyro(s). If the wire fails to one gyro,  

the others run just fine.



We could go on and on here but there is just no way to make a system  

that uses vacuum-powered gyros as reliable as a system that uses  

electrically-powered gyros.



Brian Lloyd                         361 Catterline Way

brian-yak AT lloyd DOT com          Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry

_________________
Brian Lloyd
brian-yak at lloyd dot com
+1.916.367.2131 (voice) +1.270.912.0788 (fax)

I fly because it releases my mind from the tyranny of petty things . . .
- Antoine de Saint-Exupery

brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Wed Aug 02, 2006 1:36 pm Post subject: STC for standby generator on a

On Aug 2, 2006, at 3:13 PM, Bill Denton wrote:



 	  Quote: 	
		   

 <bdenton(at)bdenton.com>



 Would it be possible to just put in an electric AI and DG, and  

 leave the

 vacuum system in place, but not connected to anything?


	


We can talk about the details but let's look at the spirit of the  

thing. The FAA wants to see that there are two power sources for the  

gyros so that no single failure will cause all the gyros to stop  

working at once.



Since it is a type certified airplane, you are going to want FAA buy- 

in. They are going to want to see the following:



1. no single point of failure;

2. a second source of power (battery probably OK, second alternator  

better);

3. justification for a claim that a failure to one gyro will not  

affect the others.



Keep that in mind when crafting a system to put in your TC aircraft.



Brian Lloyd                         361 Catterline Way

brian-yak AT lloyd DOT com          Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry

Bill Denton

Joined: 10 Jan 2006
Posts: 97
Location: Chicago, IL USA

Posted: Wed Aug 02, 2006 1:55 pm Post subject: STC for standby generator on a

I was thinking more of staying in compliance with the Type Certificate...



--

oldbob(at)BeechOwners.com
Guest

Posted: Wed Aug 02, 2006 2:24 pm Post subject: STC for standby generator on a

Good Evening Bill, Brian and All,



I note that Brian has stated that the FAA would like

us to have redundancy of power for our instruments

used for inflight reference.



It is true that they are requiring redundancy for

newly certificated flying machines and for anyone who

wants to replace a turn coordinator or turn and bank

with an attitude gyro, but the basic FARs do NOT

require that we have any redundancy at all for our

older certificated flying machines.



It is up to us to decide just how much risk we wish to

take. 



We can still fly with only one engine, one alternator,

one radio, one pilot and one power source for our

instruments!



The choice of redundant systems is up to us.



I think that is the way it should be and I do not feel

that the FAA's recent foray into mandating redundancy

has improved safety at all. 



Once they designate what we must have for redundancy

of flight instruments, how much longer will it be

before they try to tell us under what conditions we

can fly single pilot? How long will it take them to

require an autopilot? When will they decide we need

two engines at night or over water?



All of those ideas have merit, but statistics do not

support the need.



Back to the FAA ideas of redundancy.



By the time they decide something meets their

interpretation of redundancy, there are many forms of

redundancy available that are far superior to the

devices finally approved by the FEDs. The beauty of

the way it was is that we had almost as much

flexibility to evaluate risk for our certificated

airplanes as do those folks who build and fly OBAM

aircraft.



Lets not add difficulties beyond those that the FAA

has already foisted upon us.



Happy Skies,



Old Bob

Stearman N3977A



--- Bill Denton <bdenton(at)bdenton.com> wrote:



[quote] 

 Denton" <bdenton(at)bdenton.com>

 

 I was thinking more of staying in compliance with

 the Type Certificate...

 

 --

N6030X(at)DaveMorris.com
Guest

Posted: Wed Aug 02, 2006 2:41 pm Post subject: STC for standby generator on a

Thanks to all of you who have commented, some 

also privately.  I'm just a rebel who spends most of his time outside the box.

Dave Morris

At 04:35 PM 8/2/2006, you wrote:

 	  Quote: 	

On Aug 2, 2006, at 3:13 PM, Bill Denton wrote:

>

><bdenton(at)bdenton.com>

>

>Would it be possible to just put in an electric AI and DG, and

>leave the

>vacuum system in place, but not connected to anything?

We can talk about the details but let's look at the spirit of the

thing. The FAA wants to see that there are two power sources for the

gyros so that no single failure will cause all the gyros to stop

working at once.

Since it is a type certified airplane, you are 

going to want FAA buy- in. They are going to want to see the following:

1. no single point of failure;

2. a second source of power (battery probably OK, second alternator

better);

3. justification for a claim that a failure to one gyro will not

affect the others.

Keep that in mind when crafting a system to put in your TC aircraft.

Brian Lloyd                         361 Catterline Way

brian-yak AT lloyd DOT com          Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)

I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry

brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Wed Aug 02, 2006 2:43 pm Post subject: STC for standby generator on a

On Aug 2, 2006, at 5:52 PM, Bill Denton wrote:



 	  Quote: 	
		   

 <bdenton(at)bdenton.com>



 I was thinking more of staying in compliance with the Type  

 Certificate...


	


Old Bob made a good point. Many of these aircraft were certified  

without gyro instruments and the regs covering IFR instrumentation  

are pretty loose. You should be able to drop in an electric AI.



But the points I made were correct. The FAA (and you if you aren't  

stupid) want to see that there is no way that all your gyros can fail  

at the same time. They want to not have to bother with yet more  

"wrecked airplane, dead pilot, dead passengers, new lawsuit" paperwork.



So rather than argue the number of angels needed to keep your vacuum  

pump running, talk to the FSDO and get started on a 337 for a well- 

designed electrical source for your all-electric gyros. There are  

still some not-stupids at the FAA who will help you do what you want.



So just remember, the goal is a system that is more reliable and will  

be less likely to fail when you need it most. And if it does fail, it  

fails softly, i.e. without the wholesale loss of big chunks of your  

gyro panel.



So don't argue, think. This is not rocket science. This is common  

sense. If you can really show the FAA guys (the smart ones - work on  

finding the smart ones) that you have a better way, they will  

probably go along with you and grant their blessings.



And a Mooney that has the old vacuum-powered wing leveler will  

probably have to keep that vacuum-powered wing leveler as it was  

specifically part of the TC. But that doesn't preclude making things  

better for everything else.



Heck, my 1960 Comanche has an e-bus with a second battery. There were  

no hassles getting that approved. Work on it.



Brian Lloyd                         361 Catterline Way

brian-yak AT lloyd DOT com          Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry

Kellym

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

Posted: Wed Aug 02, 2006 3:00 pm Post subject: STC for standby generator on a

You ASSUME two totally separate electrical systems available to each  

gyro, which is a physical impossiblity, and that the battery will be  

available if that fails. Each master switch you have is a single point  

of failure, as well as the relay it operates. Any place one system  

interconnects with the other is also a single point of failure that  

can take out both systems. Smoke from the electrical system will have  

you killing all electrics. Now where are you??? Turn system back on  

and risk cockpit fire? I don't think so. Truly independent...AI on one  

system, DG and TC on the other? You still lose pitch if that side fails.

Vacuum regulators fail about 0.5 times in the life of an airframe.  

About the most reliable mechanical device on the airframe. Hoses, if  

they are replaced with the pump never fail. Pumps are your only real  

point of failure. If you equip the aircraft with one vacuum and one  

electric AI you will have far better redundancy and reliability than  

all electric.

Quoting Brian Lloyd <brian-yak(at)lloyd.com>:



 	  Quote: 	
		   We could go on and on here but there is just no way to make a system

 that uses vacuum-powered gyros as reliable as a system that uses

 electrically-powered gyros.

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

Bill Denton

Joined: 10 Jan 2006
Posts: 97
Location: Chicago, IL USA

Posted: Wed Aug 02, 2006 3:20 pm Post subject: STC for standby generator on a

Again allow me to point out that the Sporty's and the Mid-Continent "backup" attitude indicators have an internal battery backup; they can operate without any ship's power whatsoever.



And while they were originally designed for backup purposes, couldn't they also be used in place of the primary attitude indicators in cases where an electric unit is permitted?



--

brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Wed Aug 02, 2006 3:51 pm Post subject: STC for standby generator on a

On Aug 2, 2006, at 6:58 PM, Kelly McMullen wrote:

 	  Quote: 	

 <kellym(at)aviating.com>

 You ASSUME two totally separate electrical systems available to  

 each gyro, which is a physical impossiblity, and that the battery  

 will be available if that fails. Each master switch you have is a  

 single point of failure, as well as the relay it operates. Any  

 place one system interconnects with the other is also a single  

 point of failure that can take out both systems. Smoke from the  

 electrical system will have you killing all electrics. Now where  

 are you??? Turn system back on and risk cockpit fire? I don't think  

 so. Truly independent...AI on one system, DG and TC on the other?  

 You still lose pitch if that side fails.

 Vacuum regulators fail about 0.5 times in the life of an airframe.  

 About the most reliable mechanical device on the airframe. Hoses,  

 if they are replaced with the pump never fail. Pumps are your only  

 real point of failure. If you equip the aircraft with one vacuum  

 and one electric AI you will have far better redundancy and  

 reliability than all electric.

 Quoting Brian Lloyd <brian-yak(at)lloyd.com>:

> We could go on and on here but there is just no way to make a system

> that uses vacuum-powered gyros as reliable as a system that uses

> electrically-powered gyros.

I see we have reached an impasse. Clearly you have not worked with  

electrical systems nor have you read Bob's book.

But I will address your point about switches. Yes if the battery  

master switch fails and/or the battery contactor fails, you lose the  

main bus. That is why there is a second path from the battery to your  

e-bus which drives your gyros. You can feed the e-bus from either the  

main bus or the battery directly. You would now need a chain of  

failures to cause your gyros to go away.

The e-bus is simplicity itself. In my Comanche it started out as an  

avionics bus but became the e-bus by virtue of adding a second  

battery, a separate charging path from primary battery to backup  

battery, a separate path from backup battery to e-bus, and separate  

circuits from e-bus to each load, each with its own current limiter.  

It even has a backup switch to connect to the e-bus to the main bus  

should the main switch fail. (I didn't want to add that but the FAA  

wanted it and it was cheaper and faster to add it than to argue.  

What's the cost of one switch and two wires.) A failure of a single  

circuit causes that current limiter to open and protect the wiring  

for that circuit without taking out everything else. The only common  

point is the e-bus itself and that was just a piece of bus bar. I  

trust a piece of bus bar a lot more than I trust a vacuum pump.

As a suggestion, perhaps you ought to look at the current crop of  

airlines plying our skies. I think that, no matter how hard you look,  

you won't find a single vacuum pump or air-driven gyro in the lot.  

That might suggest something to you.

But you are sold on having a vacuum pump. More power to you. I have  

owned many, many airplanes and my experience is that the vacuum pump  

and its related components were less reliable than electrical  

systems. That is my experience. When I finish restoring my Nanchang  

CJ6A there will be no air-powered gyros in it. When I build my F1  

Rocket there will be no vacuum pumps and no air-powered gyros. I am  

willing to bet my life on an all-electric panel in hard IFR. You  

should do what makes you most comfortable.

Brian Lloyd                         361 Catterline Way

brian-yak AT lloyd DOT com          Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)

I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry

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