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airframe grounding

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Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Wed Dec 29, 2010 3:39 am Post subject: airframe grounding

I don't like that practice....I feel the engine mount bolts should do  

JUST that, with nothing else between the bolt and the mount/airframe.  

Running the wires directly to the battery or to where the ground  

cable connects to the engine is a better procedure, in my estimation.



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062

Sensenich 62"x 55.5 Wood (winter) until the Prince prop arrives

Electroair direct-fire ignition system

Rotec TBI-40 injection

Status: flying...1074 hrs (since 3-27-2006)

do not archive



On Dec 28, 2010, at 6:35 PM, bob noffs wrote:



 	  Quote: 	
		   hi all, i was visiting a friend who bought a ''second hand  

 ''kitfox. i noticed that on at least 2 engine mount to airframe  

 bolts there was an elect. ring terminal on the bolt . terminals  

 were to ground all to the battrey. is this recommended/accepted  

 practice with engine mount bolts?

     bob noffs

 ============================================================

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Wed Dec 29, 2010 6:57 am Post subject: airframe grounding

Maybe I ought to give a reason for why I feel as I do...if the  

terminal that you are putting under a bolt/nut is copper, it stands  

to reason that the copper is soft, and under vibration will squash,  

and this leaves the bolt/nut with less tension than when first  

installed. Maybe if the bolt/nut were topped off with the terminal  

and then another nut that holds the terminal in place would be  

acceptable. Has anybody thought of looking in AC43.13 to see the  

"acceptable methods"?



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062

Sensenich 62"x 55.5 Wood (winter) until the Prince prop arrives

Electroair direct-fire ignition system

Rotec TBI-40 injection

Status: flying...1074 hrs (since 3-27-2006)



On Dec 29, 2010, at 6:37 AM, Lynn Matteson wrote:



 	  Quote: 	
		   



 I don't like that practice....I feel the engine mount bolts should  

 do JUST that, with nothing else between the bolt and the mount/ 

 airframe. Running the wires directly to the battery or to where the  

 ground cable connects to the engine is a better procedure, in my  

 estimation.



 Lynn Matteson

 Kitfox IV Speedster, taildragger

 Jabiru 2200, #2062

 Sensenich 62"x 55.5 Wood (winter) until the Prince prop arrives

 Electroair direct-fire ignition system

 Rotec TBI-40 injection

 Status: flying...1074 hrs (since 3-27-2006)

 do not archive



 On Dec 28, 2010, at 6:35 PM, bob noffs wrote:



> hi all, i was visiting a friend who bought a ''second hand  

> ''kitfox. i noticed that on at least 2 engine mount to airframe  

> bolts there was an elect. ring terminal on the bolt . terminals  

> were to ground all to the battrey. is this recommended/accepted  

> practice with engine mount bolts?

>     bob noffs

> ============================================================

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

KITFOXZ(at)aol.com
Guest

Posted: Wed Dec 29, 2010 8:14 am Post subject: airframe grounding

As an avionics technician I have to say that you should always strive  to make electrical connections clean, dry, tight and separate from any other  mechanical purpose.  Any engine/airframe bolt or fastener should be for  that mechanical purpose only and not shared as an electrical connection.

 If four engine bolts hold the engine to the engine mount, that should be  their only purpose.  A separate grounding bolt should be connected to the  engine block for the purpose of connecting a grounding ring terminal.  This  grounding connection is, among other things, the electrical current path  for the negative side of the battery/starter circuit.  -A high current  connection.  You want it to be infallible. 

 The theory is that an engine mount bolt is there to hold the engine to  it's mount.  It is a "working" bolt.  It is doing an important job of  flexing and holding a working member of the aircraft.  Although small, this  working (flexing) will eventually cause undue wear and tear (corrosion) at the  electrical connection if it is a shared connection.

 While I am preaching:  Additional strain relief of electrical  connections is desirable too.  You don't want to allow your precious engine  block grounding wire ring terminal to be tugged on and flexed while in  use.  Secure the ring terminal to it's engine block bolt and then  protect it from ever seeing any mechanical loads by securing the cable to the  engine block via wire tie downs, etc.

 John

 Columbus, Ohio

 Outback, 912S, building   

  In a message dated 12/29/2010 9:58:31 A.M. Eastern Standard Time,  lynnmatt(at)jps.net writes:

  	  Quote: 	
		  -->    Kitfox-List message posted by: Lynn Matteson    <lynnmatt(at)jps.net>

Maybe I ought to give a reason for why I feel    as I do...if the  

terminal that you are putting under a bolt/nut is    copper, it stands  

to reason that the copper is soft, and under    vibration will squash,  

and this leaves the bolt/nut with less    tension than when first  

installed. Maybe if the bolt/nut were topped    off with the terminal  

and then another nut that holds the terminal    in place would be  

acceptable. Has anybody thought of looking in    AC43.13 to see the  

"acceptable methods"?

Lynn    Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200,    #2062

Sensenich 62"x 55.5 Wood (winter) until the Prince prop    arrives

Electroair direct-fire ignition system

Rotec TBI-40    injection

Status: flying...1074 hrs (since 3-27-2006)

On Dec 29,    2010, at 6:37 AM, Lynn Matteson wrote:

 	  Quote: 	
		   --> Kitfox-List message    posted by: Lynn Matteson <lynnmatt(at)jps.net>

 I don't like    that practice....I feel the engine mount bolts should  

 do JUST    that, with nothing else between the bolt and the mount/ 

 airframe.    Running the wires directly to the battery or to where the  

    ground cable connects to the engine is a better procedure, in my     

 estimation.

 Lynn Matteson

 Kitfox IV    Speedster, taildragger

 Jabiru 2200, #2062

 Sensenich 62"x 55.5    Wood (winter) until the Prince prop arrives

 Electroair direct-fire    ignition system

 Rotec TBI-40 injection

 Status: flying...1074    hrs (since 3-27-2006)

 do not    archive

 On Dec 28, 2010, at    6:35 PM, bob noffs wrote:

> hi all, i was visiting a friend    who bought a ''second hand  

> ''kitfox. i noticed that on at    least 2 engine mount to airframe  

> bolts there was an elect.    ring terminal on the bolt . terminals  

> were to ground all to    the battrey. is this recommended/accepted  

> practice with    engine mount bolts?

>     bob noffs

>    ============================================================

&g========================;  nbsp;             (And Get Some AWESOME FREE     to find   Gifts       ilder's  ELP  b  k you for  p;                        -Matt Dralle,    List  ========================   the  ties  Day  ================================================               - MATRONICS WEB FORUMS  ==================================================

  [quote][b]

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Wed Dec 29, 2010 5:12 pm Post subject: airframe grounding

I'm in agreement with Lynn on this one...  I think the jumper (Ground braid)

should connect the base of the engine to a solid ground buss on the frame

not to an engine mount where possible electrically induced corrosion can

become an issue.



Noel



--

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Wed Dec 29, 2010 5:23 pm Post subject: airframe grounding

Lynn: the copper in the ring against the 4130 steel of the washer and bolts

is a good place for dissimilar metal corrosion to start...  I never

considered the softness of the ring mostly because it is backed by the

rubber elastometric mounting pads which are even softer. I should have

considered that to.



Noel



--

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Wed Dec 29, 2010 5:34 pm Post subject: airframe grounding

Having received my share of slices from unfinished nylon ties under the cowls of aircraft I am left with two words.  Cora Seal... learn how to use it!

Noel

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of KITFOXZ(at)aol.com

Sent: December 29, 2010 12:40 PM

To: kitfox-list(at)matronics.com

Subject: Re: airframe grounding

As an avionics technician I have to say that you should always strive to make electrical connections clean, dry, tight and separate from any other mechanical purpose.  Any engine/airframe bolt or fastener should be for that mechanical purpose only and not shared as an electrical connection.

If four engine bolts hold the engine to the engine mount, that should be their only purpose.  A separate grounding bolt should be connected to the engine block for the purpose of connecting a grounding ring terminal.  This grounding connection is, among other things, the electrical current path for the negative side of the battery/starter circuit.  -A high current connection.  You want it to be infallible. 

The theory is that an engine mount bolt is there to hold the engine to it's mount.  It is a "working" bolt.  It is doing an important job of flexing and holding a working member of the aircraft.  Although small, this working (flexing) will eventually cause undue wear and tear (corrosion) at the electrical connection if it is a shared connection.

While I am preaching:  Additional strain relief of electrical connections is desirable too.  You don't want to allow your precious engine block grounding wire ring terminal to be tugged on and flexed while in use.  Secure the ring terminal to it's engine block bolt and then protect it from ever seeing any mechanical loads by securing the cable to the engine block via wire tie downs, etc.

John

Columbus, Ohio

Outback, 912S, building   

In a message dated 12/29/2010 9:58:31 A.M. Eastern Standard Time, lynnmatt(at)jps.net writes:

 	  Quote: 	

--> Kitfox-List message posted by: Lynn Matteson <lynnmatt(at)jps.net>

Maybe I ought to give a reason for why I feel as I do...if the  

terminal that you are putting under a bolt/nut is copper, it stands  

to reason that the copper is soft, and under vibration will squash,  

and this leaves the bolt/nut with less tension than when first  

installed. Maybe if the bolt/nut were topped off with the terminal  

and then another nut that holds the terminal in place would be  

acceptable. Has anybody thought of looking in AC43.13 to see the  

"acceptable methods"?

Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062

Sensenich 62"x 55.5 Wood (winter) until the Prince prop arrives

Electroair direct-fire ignition system

Rotec TBI-40 injection

Status: flying...1074 hrs (since 3-27-2006)

On Dec 29, 2010, at 6:37 AM, Lynn Matteson wrote:

 	  Quote: 	
		   --> Kitfox-List message posted by: Lynn Matteson <lynnmatt(at)jps.net>

 I don't like that practice....I feel the engine mount bolts should  

 do JUST that, with nothing else between the bolt and the mount/ 

 airframe. Running the wires directly to the battery or to where the  

 ground cable connects to the engine is a better procedure, in my  

 estimation.

 Lynn Matteson

 Kitfox IV Speedster, taildragger

 Jabiru 2200, #2062

 Sensenich 62"x 55.5 Wood (winter) until the Prince prop arrives

 Electroair direct-fire ignition system

 Rotec TBI-40 injection

 Status: flying...1074 hrs (since 3-27-2006)

 do not archive

 On Dec 28, 2010, at 6:35 PM, bob noffs wrote:

> hi all, i was visiting a friend who bought a ''second hand  

> ''kitfox. i noticed that on at least 2 engine mount to airframe  

> bolts there was an elect. ring terminal on the bolt . terminals  

> were to ground all to the battrey. is this recommended/accepted  

> practice with engine mount bolts?

>     bob noffs

> ==========

&g========================; nbsp;          (And Get Some AWESOME FREE to find Gifts    ilder's ELP b k you for p;                     -Matt Dralle, List ======================== the ties Day =======================              - MATRONICS WEB FORUMS 

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_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

WurlyBird

Joined: 16 May 2008
Posts: 207
Location: North Pole, Alaska

Posted: Mon May 02, 2011 7:27 am Post subject: Re: airframe grounding

I am gonna drag up this old post since I am swapping out engines and have decided to desire the whole plane in the process. My plane also has the motor mount bolts operating as a ground and I would like to remedy this.  So what is the best method?  I am thinking it would be good to get a bus that could be connected to the battery and the engine block with wires and the bus or grounding block could then be mounted behind the instrument panel.  Should the airframe also be connected to this? Where is a good place for airframe attachment if so?  Thanks for any input.

_________________
James
Kitfox 3 / 582 / 70" IVO 2 blade GA
50 hrs on the 582 swapping for HKS 700E and Avid Cowl.

Vic Baker

Joined: 11 Jan 2006
Posts: 71
Location: Carson City, Nevada

Posted: Mon May 02, 2011 8:25 am Post subject: airframe grounding

James,



Good question.  Unwanted ground loops will cause radio noise.  Here's what I 

did:



On the engine mount,  the one that bolts to the firewall and airframe, there 

is a tab intended for ground connection.  I connected the engine case (#6 

AWG), the battery neg terminal (#6 AWG) and  the "ground" bus bar that is 

located behind the panel (2 each #14 AWG) to this point.



All ground returns from the aircraft electrical equipment connect to the 

"ground" bus bar.



The result is that there is no current flow in the airframe itself.  My 

radio is noise free.



One exception,  the transponder and transceiver antennas do connect to the 

airframe.  (easier than making an isolated ground plane for each)



Hope this makes sense.

Vic





Vic Baker

S7 912S Warp

Carson City, Nv

---

_________________
Vic Baker
Series 7
Carson City, Nevada

Guy Buchanan

Joined: 16 Jul 2006
Posts: 1204
Location: Ramona, CA

Posted: Mon May 02, 2011 12:57 pm Post subject: airframe grounding

On 5/2/2011 8:27 AM, WurlyBird wrote:

 	  Quote: 	
		   Should the airframe also be connected to this? Where is a good place for airframe attachment if so?  Thanks for any input.

    

I have this 3/8" brass bolt that goes through the firewall, location 
	


irrelevant. On the engine side I have a braid strap that connects it to 

the engine. On the passenger side it goes through a brass 

"forest-of-tabs" ground bus I got from B&C specialty products. The 

battery negative connects to the passenger side of the bolt. All powered 

items are grounded at this bus. Nothing goes through the airframe. Audio 

grounds are to a separate bus near the audio stack, which is then 

grounded to the firewall bus. This helps isolate the communications 

grounds from power.



Guy Buchanan

Ramona, CA

Kitfox IV-1200 / 592-C / Warp 3cs / 500 hrs. and grounded

_________________
Guy Buchanan
Deceased K-IV 1200
A glider pilot too.

lcfitt(at)sbcglobal.net
Guest

Posted: Mon May 02, 2011 5:12 pm Post subject: airframe grounding

This is an interesting question.  I am working on a Model IV and a Series V 

with 7 FWF.  I understand the theory regarding no current flow through the 

airframe, but the V has capacitance fuel level senders which recommend two 

grounds.  One to the negative buss and one to a "local ground".    I did the 

IV a bit different  from Vic's method which is the factory design for the 7 

by running the negative battery cable straight to the engine - no extra 

connections and no loss possibility.  Then a length of braid runs to an adel 

clamp connecting to the ignition module grounds.  The buss ground runs from 

the battery to the negative buss bar.  As of yet I have not decided how to 

ground the fuselage.



Lowell



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

From: "Vic Baker" <vr_baker(at)nvbell.net>

Sent: Monday, May 02, 2011 9:22 AM

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

Subject: Re: Re: airframe grounding



[quote] 



 James,



 Good question.  Unwanted ground loops will cause radio noise.  Here's what 

 I did:



 On the engine mount,  the one that bolts to the firewall and airframe, 

 there is a tab intended for ground connection.  I connected the engine 

 case (#6 AWG), the battery neg terminal (#6 AWG) and  the "ground" bus bar 

 that is located behind the panel (2 each #14 AWG) to this point.



 All ground returns from the aircraft electrical equipment connect to the 

 "ground" bus bar.



 The result is that there is no current flow in the airframe itself.  My 

 radio is noise free.



 One exception,  the transponder and transceiver antennas do connect to the 

 airframe.  (easier than making an isolated ground plane for each)



 Hope this makes sense.

 Vic





 Vic Baker

 S7 912S Warp

 Carson City, Nv

 ---

WurlyBird

Joined: 16 May 2008
Posts: 207
Location: North Pole, Alaska

Posted: Mon May 02, 2011 6:00 pm Post subject: Re: airframe grounding

Well I talked to Jerry at GreenSky Adventures who is the one setting up my HKS and he is going to add a dedicated tab to the engine mount to be used as a common ground. So this point will connect to the battery (-), the engine ground and will connect to a (-) bus behind the panel.  I am happy with this idea.  



Concerning HKS engines I highly recomend dealing with Jerry. He is great to work with. And very patient which is good because I have been bugging him about this engine idea for almost a year.

_________________
James
Kitfox 3 / 582 / 70" IVO 2 blade GA
50 hrs on the 582 swapping for HKS 700E and Avid Cowl.

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