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Hobbs wiring

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ronburnett(at)charter.net
Guest

Posted: Wed Mar 08, 2017 7:52 pm Post subject: Hobbs wiring

Although I have this engine time on my GRT EIS I would like to have this already installed additional system on my RV-6A which has a zero time rebuilt Lycoming.



I have a master key and start button which I believe should be spliced into the starter switch from the lamp, which being red when engine isn't running will also serve as a reminder to shut it off after the flight.



Then I should wire from the Hobbs meter to my fuse panel.  Could someone please confirm for my pace of mind?



Thanks,



RonBurnett



May you have the Lord's blessings today!

Sent from my iPad

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user9253

Joined: 28 Mar 2008
Posts: 1921
Location: Riley TWP Michigan

Posted: Thu Mar 09, 2017 5:55 am Post subject: Re: Hobbs wiring

You are on the right track if my interpretation of your post is correct.  But I can not say for sure until seeing a complete schematic of your proposed circuit including the master switch and battery contactor.  A picture is worth a thousand words.

_________________
Joe Gores

millner(at)me.com
Guest

Posted: Thu Mar 09, 2017 8:51 am Post subject: Hobbs wiring

Ron, starter switch is not wired to Hobbs meter.



Paul



Sent from my iPhone



 	  Quote: 	
		   On Mar 8, 2017, at 7:49 PM, Ron Burnett <ronburnett(at)charter.net> wrote:

 

 Although I have this engine time on my GRT EIS I would like to have this already installed additional system on my RV-6A which has a zero time rebuilt Lycoming.

 

 I have a master key and start button which I believe should be spliced into the starter switch from the lamp, which being red when engine isn't running will also serve as a reminder to shut it off after the flight.

 

 Then I should wire from the Hobbs meter to my fuse panel.  Could someone please confirm for my pace of mind?

 

 Thanks,

 

 RonBurnett

 

 <D7891D3F-0CEE-4F2F-8694-E4BFA25E7C3F.JPG>

 

 

 

 May you have the Lord's blessings today!

 Sent from my iPad

ronburnett(at)charter.net
Guest

Posted: Sat Mar 11, 2017 5:12 am Post subject: Hobbs wiring

Joe,



Don't have picture so will try to describe.  I have converted from a Subaru back to a Lycoming, so I have a keyed master switch and EFII ignition.  The whole system comes alive with the key, but has a switch that bypasses all if necessary.



Trying to tie in a Hobbs bought and in panel but never hooked up before.  Now I have the oil pressure activated switch teed into the VDO oil pressure sender for the GRT EIS.



Thanks,



Ron Burnett



May you have the Lord's blessings today!

Sent from my iPad



 	  Quote: 	
		   On Mar 9, 2017, at 7:55 AM, user9253 <fransew(at)gmail.com> wrote:

 

 

 

 You are on the right track if my interpretation of your post is correct.  But I can not say for sure until seeing a complete schematic of your proposed circuit including the master switch and battery contactor.  A picture is worth a thousand words.

 

 --------

 Joe Gores

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=467106#467106

Kellym

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

Posted: Sat Mar 11, 2017 5:30 am Post subject: Hobbs wiring

What might be the advantage of a hobbs in a plane that cannot be used 

for hire? Just curious.

Seems like tach would be more than sufficient.

A hobbs will accelerate when maintenance is required, make the aircraft 

look higher time than it really is, etc. Not to mention the extra 

complexity and potential failure points.

Certainly your choice to do if you want one.



On 3/11/2017 6:09 AM, Ron Burnett wrote:

 	  Quote: 	
		   



 Joe,



 Don't have picture so will try to describe.  I have converted from a Subaru back to a Lycoming, so I have a keyed master switch and EFII ignition.  The whole system comes alive with the key, but has a switch that bypasses all if necessary.



 Trying to tie in a Hobbs bought and in panel but never hooked up before.  Now I have the oil pressure activated switch teed into the VDO oil pressure sender for the GRT EIS.



 Thanks,



 Ron Burnett

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

user9253

Joined: 28 Mar 2008
Posts: 1921
Location: Riley TWP Michigan

Posted: Sat Mar 11, 2017 6:39 am Post subject: Re: Hobbs wiring

Ron,

It doesn't matter where the 12 volt supply comes from

as long as it goes on and off with the battery contactor.

Just connect 12 volts to the hobbs meter and to the

indicator light as pictured in your original post.

This advice is based on the assumption that the switch

in your picture is an oil pressure switch.

_________________
Joe Gores

alec(at)alecmyers.com
Guest

Posted: Sat Mar 11, 2017 7:33 am Post subject: Hobbs wiring

Most TC aircraft Hobbes meters don't get switched via the battery master. Too easy to hide time by flying with the master off.



 	  Quote: 	
		   On Mar 11, 2017, at 9:39 AM, user9253 <fransew(at)gmail.com> wrote:

 

 

 

 Ron,

 It doesn't matter where the 12 volt supply comes from as long as it goes on and off with the battery contactor.  Just connect 12 volts to the hobbs meter and to the indicator light as pictured in your original post.  This advice is based on the assumption that the switch in your picture is an oil pressure switch.

 

 --------

 Joe Gores

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=467166#467166

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Mar 11, 2017 9:10 am Post subject: Hobbs wiring

At 09:31 AM 3/11/2017, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: Alec Myers <alec(at)alecmyers.com>



 Most TC aircraft Hobbes meters don't get switched via the battery master. Too easy to hide time by flying with the master off.

 	


   Correct. Most folks are unaware of the fact that

   tens of thousands of Cessnas had an always hot

   battery bus right at the battery contactor. It

   feed two fuses . . . one for the Hobbs meter controlled

   through an oil pressure switch . . . the other for

   the electric clock.



   If one would like to add a low oil pressure warning

   light, then the hobbs feeder needs to drive from

   a controlled source. In OBAM aircraft a good alternative

   feed is the e-bus.



   Now the low oil pressure light (and perhaps warning buzzer)

   serves four functions. It monitors oil pressure, it controls

   the Hobbs meter to measure ENGINE RUN time, it gives warning

   at shut down that both the DC master and E-Bus alternate

   feed switches are open.



   See . . .



  http://tinyurl.com/zlpjzuc



   If you have an engine fitted with a PM alternator

   (a la Rotax or SD-8 standby) one COULD fabricate a

   circuit to watch for the existence of AC voltage

   on the alternator winding and use this signal to

   control the Hobbs and offer warnings for DC power

   shutdown . . . you just wouldn't have oil pressure

   warning.



 

 

   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Mar 11, 2017 9:16 am Post subject: Hobbs wiring

At 11:07 AM 3/11/2017, you wrote:

  	  Quote: 	
		  At 09:31 AM 3/11/2017, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: Alec Myers <alec(at)alecmyers.com>



 Most TC aircraft Hobbes meters don't get switched via the battery master. Too easy to hide time by flying with the master off. 	


   Correct. Most folks are unaware of the fact that

   tens of thousands of Cessnas had an always hot

   battery bus right at the battery contactor. It

   feed two fuses . . . one for the Hobbs meter controlled

   through an oil pressure switch . . . the other for

   the electric clock 	


  Hmmm . . . not always two fuses . . . seems the 1976

  C-172 drove the Hobbs and clock from the same fuse



 [img]cid:7.1.0.9.0.20170311111312.055a9338(at)aeroelectric.com.0[/img] 



 



 

   Bob . . .

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ronburnett(at)charter.net
Guest

Posted: Sat Mar 11, 2017 2:14 pm Post subject: Hobbs wiring

My only tach is provided by the EIS. 

I do not have an engine tach.

Thanks.

Ron Burnett

May you have the Lord's blessings today!

Sent from my iPad

 	  Quote: 	
		   On Mar 11, 2017, at 7:28 AM, Kelly McMullen <kellym(at)aviating.com> wrote:

 What might be the advantage of a hobbs in a plane that cannot be used for hire? Just curious.

 Seems like tach would be more than sufficient.

 A hobbs will accelerate when maintenance is required, make the aircraft look higher time than it really is, etc. Not to mention the extra complexity and potential failure points.

 Certainly your choice to do if you want one.

> On 3/11/2017 6:09 AM, Ron Burnett wrote:

> 

> 

> Joe,

> 

> Don't have picture so will try to describe.  I have converted from a Subaru back to a Lycoming, so I have a keyed master switch and EFII ignition.  The whole system comes alive with the key, but has a switch that bypasses all if necessary.

> 

> Trying to tie in a Hobbs bought and in panel but never hooked up before.  Now I have the oil pressure activated switch teed into the VDO oil pressure sender for the GRT EIS.

> 

> Thanks,

> 

> Ron Burnett

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