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Firewall Hot-Side Enclosure

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email(at)jaredyates.com
Guest

Posted: Fri Aug 13, 2010 1:10 pm Post subject: Firewall Hot-Side Enclosure

I was thinking about how it might be convenient to house some of the electrical components on the hot side of the firewall inside of an environmentally sealed plastic box.  Most land vehicles use something similar, and if I remember correctly Cessna started doing something similar on their post-1997 production singles.  The items that I had in mind were the contactors, current limiters, shunts, maybe a small fuse block for the battery bus, and that sort of thing.  The box would keep out the engine compartment grime, and there are lots of different designs available in the sporting goods industry.  Has anyone done something similar, or can anyone think of why this would be a bad idea?  [quote][b]

rhdudley1(at)bellsouth.ne
Guest

Posted: Sat Aug 14, 2010 7:02 am Post subject: Firewall Hot-Side Enclosure

Hi Jared,

  

 I looked through my collection of construction photos and  found three that might be of interest. I made a cover of fiberglass to  physically protect electrically "hot" components that had large exposed areas.  My concern was more for protecting them from any possibility of conductive  contact to airframe ground more than for protection from dust or oil  vapors. The two components protected were an ammeter shunt and  an ANL 60 fuse to the output from the alternator. Both of these were at  battery positive potential when the master switch was closed.

  

 I made the cover of fiberglass. It had openings  on two sides: to the alternator, ammeter and  the master contactor. I attached it to the firewall with screws and  nutplates.

  

 There are three photos, one of the components  uncovered, and two of the fiberglass cover in place. The cover was later painted.

  

 I hope this is of some help.

  

 Best regards and good luck,

  

 Richard Dudley

 RV-6A (sold)

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email(at)jaredyates.com
Guest

Posted: Sat Aug 14, 2010 7:29 am Post subject: Firewall Hot-Side Enclosure

Richard, thanks for taking the time to search your archives.  Did you encounter any problems with your box in service?



On Sat, Aug 14, 2010 at 11:00 AM, Richard Dudley <rhdudley1(at)bellsouth.net (rhdudley1(at)bellsouth.net)> wrote:

 [quote]       Hi Jared,

  

 I looked through my collection of construction photos and  found three that might be of interest. I made a cover of fiberglass to  physically protect electrically "hot" components that had large exposed areas.  My concern was more for protecting them from any possibility of conductive  contact to airframe ground more than for protection from dust or oil  vapors. The two components protected were an ammeter shunt and  an ANL 60 fuse to the output from the alternator. Both of these were at  battery positive potential when the master switch was closed.

  

 I made the cover of fiberglass. It had openings  on two sides: to the alternator, ammeter and  the master contactor. I attached it to the firewall with screws and  nutplates.

  

 There are three photos, one of the components  uncovered, and two of the fiberglass cover in place. The cover was later painted.

  

 I hope this is of some help.

  

 Best regards and good luck,

  

 Richard Dudley

 RV-6A (sold)

 [quote]   ---

rhdudley1(at)bellsouth.ne
Guest

Posted: Sat Aug 14, 2010 8:22 am Post subject: Firewall Hot-Side Enclosure

Jared,

  

 No problems over 140 hours over tree years flying mostly in  Florida. 

  

 Rich

  

  

 ---

icubob(at)gmail.com
Guest

Posted: Sat Aug 14, 2010 9:22 am Post subject: Firewall Hot-Side Enclosure

richard,

  i noticed your conventional baffling for cooling your jab. i am a few months away from a first flight and i did the same type of cooling. how has this baffling worked for cooling? was there much ''tweaking'' after it was done to get the temps down enough?

   bob noffs

 On Sat, Aug 14, 2010 at 10:00 AM, Richard Dudley <rhdudley1(at)bellsouth.net (rhdudley1(at)bellsouth.net)> wrote:

 [quote]  Hi Jared,

  

 I looked through my collection of construction photos and found three that might be of interest. I made a cover of fiberglass to physically protect electrically "hot" components that had large exposed areas. My concern was more for protecting them from any possibility of conductive contact to airframe ground more than for protection from dust or oil vapors. The two components protected were an ammeter shunt and an ANL 60 fuse to the output from the alternator. Both of these were at battery positive potential when the master switch was closed.

   

 I made the cover of fiberglass. It had openings on two sides: to the alternator, ammeter and the master contactor. I attached it to the firewall with screws and nutplates.

  

 There are three photos, one of the components uncovered, and two of the fiberglass cover in place. The cover was later painted.

  

 I hope this is of some help.

  

 Best regards and good luck,

  

 Richard Dudley

 RV-6A (sold)

 [quote] ---

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Aug 14, 2010 9:33 am Post subject: Firewall Hot-Side Enclosure

At 04:09 PM 8/13/2010, you wrote:

 	  Quote: 	
		  I was thinking about how it might be convenient to house some of the 

electrical components on the hot side of the firewall inside of an 

environmentally sealed plastic box.  Most land vehicles use 

something similar, and if I remember correctly Cessna started doing 

something similar on their post-1997 production singles.  The items 

that I had in mind were the contactors, current limiters, shunts, 

maybe a small fuse block for the battery bus, and that sort of 

thing.  The box would keep out the engine compartment grime, and 

there are lots of different designs available in the sporting goods 

industry.  Has anyone done something similar, or can anyone think of 

why this would be a bad idea?


	


    The strongest motivation for doing such

    things in production had to do with modularizing

    certain tasks which were ultimately farmed out

    to other firms. Lamar and Kelly were both

    examples of firms offering assemblies of

    many parts that were installed as a simpler,

    single operation on the production line.



    While elegant in terms of labor to install,

    it was less than elegant in terms of weight,

    cooling, being able to optimally position

    contained components and hassles of working

    inside a more constrained space for maintenance.



    Nonetheless, it's something of a "fad" . . .

    There's a big power distribution box in

    the tail of a Premier that's easy to install,

    easy to take out and set on the bench . . .

    but in the airplane it's impossible to

    troubleshoot and out of the airplane you

    can't operate it for the purposes of

    troubleshooting.



    Production line convenience was traded for

    weight and constraints on field maintenance.



    What ever rings your bells . . .

   Bob . . .

rhdudley1(at)bellsouth.ne
Guest

Posted: Sat Aug 14, 2010 9:33 am Post subject: Firewall Hot-Side Enclosure

Hi Bob,

  

 I did nothing special, only following Van's parts and plans  for the baffling. I did seal around the edges of the rear baffle. The  temperatures ran normal without any tweaking. The engine is a O-320-D1A  purchased new from Van's and my oil cooler was firewall mounted on the right  side.

  

 Regards,

  

 Rich

 RV-6A (sold)

 [quote]   ---

bmwr606(at)yahoo.com
Guest

Posted: Sun Aug 15, 2010 6:49 am Post subject: Firewall Hot-Side Enclosure

speaking from experience,

the Lamar "box"  as found in current production Cessna's is a royal PITA for maintenance....



job...replace starter relay 2000 cessna 172 (for the second time!)

remove ground wire from battery

remove several buss bars (mounting bolts obstructed)

remove master relay (mounting bolts obstructed)

remove avionics relay (mounting bolts obstructed)

remove ground power relay (mounting bolts obstructed)

remove and replace starter relay (mounting bolts obstructed)

replace ground power relay (remember those (at)#%& obstructed mounting bolts?)

replace avionics relay (remember those (at)#%& obstructed mounting bolts?)

replace master relay (remember those (at)#%& obstructed mounting bolts?)

replace buss bars  (remember those (at)#%& obstructed  mounting bolts?)

replace ground wire to battery



TIME INVOLVED over 2 hours



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

job...replace starter relay 1971 cessna 150



remove ground wire at battery (optional IMO as there are NO hot wires near the starter relay)

remove and replace starter relay

 replace ground wire at battery (optional IMO as there are NO hot wires near the starter relay)



TIME INVOLVED 10 minutes (15 if ground wire removed)

 

Scott A Klemptner

bmwr606 on Yahoo IM



The difference between genius and stupidity is that genius has its limits- Anonymous

F

Time: 10:33:00 AM PST US

From: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)>

Subject: Re: Firewall Hot-Side Enclosure

At 04:09 PM 8/13/2010, you wrote:

 	  Quote: 	
		  I was thinking about how it might be convenient to house some of the 

electrical components on the hot side of the firewall inside of an 

environmentally sealed plastic box.  Most land vehicles use 

something similar, and if I remember correctly Cessna started doing 

something similar on their post-1997 production singles.  The items 

that I had in mind were the contactors,  current limiters, shunts, 

maybe a small fuse block for the battery bus, and that sort of 

thing.  The box would keep out the engine compartment grime, and 

there are lots of different designs available in the sporting goods 

industry.  Has anyone done something similar, or can anyone think of 

why this would be a bad idea?


	


    The strongest motivation for doing such

    things in production had to do with modularizing

    certain tasks which were ultimately farmed out

    to other firms. Lamar and Kelly were both

    examples of firms offering assemblies of

    many parts that were installed as a simpler,

    single operation on the production line.



    While elegant in terms of labor to install,

    it was less than elegant in terms of weight,

    cooling, being able to  optimally position

    contained components and hassles of working

    inside a more constrained space for maintenance.



    Nonetheless, it's something of a "fad" . . .

    There's a big power distribution box in

    the tail of a Premier that's easy to install,

    easy to take out and set on the bench . . .

    but in the airplane it's impossible to

    troubleshoot and out of the airplane you

    can't operate it for the purposes of

    troubleshooting.



    Production line convenience was traded for

    weight and constraints on field maintenance.



    What ever rings your bells . . .

   Bob . . . 

 

_

 





 



         [quote][b]

email(at)jaredyates.com
Guest

Posted: Sun Aug 15, 2010 7:19 am Post subject: Firewall Hot-Side Enclosure

Good points, thanks for the info. With your advice and Bob's, I'll save the trouble and find something else to spend time on. On a related note, would the "liquid electrical tape" stuff be suitable for insulating some of those exposed hot conductors?



On Aug 15, 2010, at 10:47, Scott Klemptner <bmwr606(at)yahoo.com (bmwr606(at)yahoo.com)> wrote:



[quote]speaking from experience,

the Lamar "box"  as found in current production Cessna's is a royal PITA for maintenance....



job...replace starter relay 2000 cessna 172 (for the second time!)

remove ground wire from battery

remove several buss bars (mounting bolts obstructed)

remove master relay (mounting bolts obstructed)

remove avionics relay (mounting bolts obstructed)

remove ground power relay (mounting bolts obstructed)

remove and replace starter relay (mounting bolts obstructed)

replace ground power relay (remember those (at)#%& obstructed mounting bolts?)

replace avionics relay (remember those (at)#%& obstructed mounting bolts?)

replace master relay (remember those (at)#%& obstructed mounting bolts?)

replace buss bars  (remember those (at)#%& obstructed  mounting bolts?)

replace ground wire to battery



TIME INVOLVED over 2 hours



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

job...replace starter relay 1971 cessna 150



remove ground wire at battery (optional IMO as there are NO hot wires near the starter relay)

remove and replace starter relay

 replace ground wire at battery (optional IMO as there are NO hot wires near the starter relay)



TIME INVOLVED 10 minutes (15 if ground wire removed)

 

Scott A Klemptner

bmwr606 on Yahoo IM



The difference between genius and stupidity is that genius has its limits- Anonymous

F

Time: 10:33:00 AM PST US

From: "Robert L. Nuckolls, III" <[url=mailto:nuckolls.bob(at)aeroelectric.com]nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)[/url]>

Subject: Re: Firewall Hot-Side Enclosure

At 04:09 PM 8/13/2010, you wrote:

 	  Quote: 	
		  I was thinking about how it might be convenient to house some of the 

electrical components on the hot side of the firewall inside of an 

environmentally sealed plastic box.  Most land vehicles use 

something similar, and if I remember correctly Cessna started doing 

something similar on their post-1997 production singles.  The items 

that I had in mind were the contactors,  current limiters, shunts, 

maybe a small fuse block for the battery bus, and that sort of 

thing.  The box would keep out the engine compartment grime, and 

there are lots of different designs available in the sporting goods 

industry.  Has anyone done something similar, or can anyone think of 

why this would be a bad idea?


	


    The strongest motivation for doing such

    things in production had to do with modularizing

    certain tasks which were ultimately farmed out

    to other firms. Lamar and Kelly were both

    examples of firms offering assemblies of

    many parts that were installed as a simpler,

    single operation on the production line.



    While elegant in terms of labor to install,

    it was less than elegant in terms of weight,

    cooling, being able to  optimally position

    contained components and hassles of working

    inside a more constrained space for maintenance.



    Nonetheless, it's something of a "fad" . . .

    There's a big power distribution box in

    the tail of a Premier that's easy to install,

    easy to take out and set on the bench . . .

    but in the airplane it's impossible to

    troubleshoot and out of the airplane you

    can't operate it for the purposes of

    troubleshooting.



    Production line convenience was traded for

    weight and constraints on field maintenance.



    What ever rings your bells . . .

   Bob . . . 

 

_

 





 



          	  Quote: 	
		  



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

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

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

ums.matronics.com">http://forums.matronics.com

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

http://www.matronics.com/contribution">http://www.matronics.com/contribution

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



	


[b]

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Aug 15, 2010 9:11 am Post subject: Firewall Hot-Side Enclosure

At 10:18 AM 8/15/2010, you wrote:

 	  Quote: 	
		  Good points, thanks for the info. With your advice and Bob's, I'll 

save the trouble and find something else to spend time on. On a 

related note, would the "liquid electrical tape" stuff be suitable 

for insulating some of those exposed hot conductors?


	


   To what purpose? There are thousands of instances

   on multi-millions of vehicles where there are "exposed

   hazards". Fans, fan belts, whirling propellers, sucking

   engine intakes, pinch points, non-insulated electrical

   connections, etc. etc.



   http://aeroelectric.com/Pictures/Breakers/Breaker_Panel_Busing_2.jpg



   The firewall of an A36 Bonanza is covered with exposed,

   high current electrical connections.



   The questions to be asked and answered are, what conditions

   are necessary to make risks for these potential hazards

   to rise to significance. For example, taxiing up to the pumps

   on a little airport with no human being in sight is a

   significantly lower risk for getting your propeller messy

   than at an airshow with little kids running around with abandon.



   Take each instance of concern. Are there others like it on

   other airplanes? Particularly airplanes with long production

   histories? Imagine the task of approaching this configuration

   with crowbar and hammer in hand with a task, "go forth my son

   and cause some part of the airplane to contact this exposed

   terminal."



   With some reasonably attentive study and application

   of common sense, I think you'll find that the risks

   are so low as to not be worthy of concern . . . for

   there are OTHER risks to flight that are worthy of

   much concern.



   Finally, "liquid tape" is probably not a material

   worthy of critical application anywhere. It's nothing

   more robust than some coating of plastic paint that

   one might brush over any surface.



   It's been my experience that the more you try to

   "cover things up" for what ever reason, the more

   likely you are to trap moisture underneath imperfect

   coatings and set up conditions for corrosion to

   progress un-observed.



   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Aug 15, 2010 9:47 am Post subject: Firewall Hot-Side Enclosure

At 09:47 AM 8/15/2010, you wrote:

 	  Quote: 	
		  speaking from experience,

the Lamar "box"  as found in current production Cessna's is a royal 

PITA for maintenance....



job...replace starter relay 2000 cessna 172 (for the second time!)

remove ground wire from battery

remove several buss bars (mounting bolts obstructed)

remove master relay (mounting bolts obstructed)

remove avionics relay (mounting bolts obstructed)

remove ground power relay (mounting bolts obstructed)

remove and replace starter relay (mounting bolts obstructed)

replace ground power relay (remember those (at)#%& obstructed mounting bolts?)

replace avionics relay (remember those (at)#%& obstructed mounting bolts?)

replace master relay (remember those (at)#%& obstructed mounting bolts?)

replace buss bars (remember those (at)#%& obstructed mounting bolts?)

replace ground wire to battery



TIME INVOLVED over 2 hours


	


   Yup, your first hand experience conforms with my

   first-hand impressions for having seen one such

   assembly for the first time. I'll suggest that

   such inventions are the product of folks who have

   never turned a wrench yet are charged with "modularizing"

   portions of the airplane for "manufacturing convenience".



   This trend gives rise to the notion that if you

   modularized 99% of the airplane's components

   and systems, those modules can be farmed out.

   Then all we have to do is bring in truck-loads

   of tinker-toys, put tab-A-into-slot-B and presto-

   changeo, you have an airplane.



   That concept bit Boeing in the hind end

   big time on the 787. But it's amazing to watch

   the same experiment being tried over and over

   again by individuals who are surprised with

   the results.



   I'm not suggesting that modularizing is always

   bad. Certainly engines, radios, instruments,

   etc have been proven by many repeatable experiments

   to lend themselves well to outside production.

   But there are limits beyond which the return

   on investment becomes exceedingly poor.



   Bob . . .

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