Fearless

Fearless

Well Known Member
I know i am early in the build but I been thinking of what electrics components I need to incorporate into the plane. I'm reading the AeroConnection book and what Bob has to say about fuse boxes.

Other than Mike in Texas with his 9a who else is using the automotive fuse boxes instead of circuit breakers in their build?

Thanks,
 
Using Fuses

I've building an all electric airplane and using fuseblocks per essentially the AeroElectric z-19 architecture.
 
Do a search in the forums to read the various threads...

There's been a lot of discussion about this. I don't think there's a wrong way, only a matter of personal preference. If you read the book you understand Bob's logic in going with the fuse blocks. I used the fuse blocks per Aero' Bob in my 7A and am happy with that decision. I'd do it again.
 
Fuses in mine

I went with fuses and am happy with it. The ten-fuse block drops down between your knees for service. Takes no panel space and saved a couple pounds.

Bob Kelly
 
Yep, fuses.

wiring_bundle.jpg
 
FUSE BLOCKS (3)

20 - main power
10 - endurance buss
6 - hot buss

2 - circuit breakers (alt field, stdy alt field)

Kent
 
Little of both!

I'm using both fuses and circuit breakers. Anything that moves (flap motors, elect. trims, auto pilot ect.) get a breaker, this way if it runs a way I can shut it down.
Hope this helps!

Adam Silversten
Finish RV-8
 
Used fuses. My only regret is that my fuses are kind of hard to get to. They are hinged on the bottom of the instrument sub-panel, and fold up to be securded on the FORWARD side of that panel. So to get at them, I have to unsecure and fold them down. I just wish I had found a better, more accessible place for them. Can't beat 'em for cost and simplicity.
 
Hybrid

Some use the aeroelectic idea (auto motive fuse box) with a few select Circuit breakers on high demand items like flap motor or may be boost pump. Some people want a direct indication (pop) or tripping and possible chance to reset that one circuit or item.

The whole fuse idea is make sure its something you can live without. Fix it when you land. Also the idea is if it blows, would you really want to reset it in the air? Its a "philosophy" and works pretty good for a GA plane. The main gain is its lighter and cheaper. It works in your car, right. Now for me?

I have 18-19 CB's in my panel. I like the control, but the main reason was I just happen to get a good deal on a box of new surplus Klixon TI aerospace quality mini CB's. If I was doing it today and could not get a deal on CB's (which are not cheap) I'd go fuse. If you do go CB's don't cheap out, get the Aerospace/MIL spec CB's.
 
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circuit breakers

Originally, we planned to use fuses until I spoke to two test pilots and a mechanic with 30 years of experience working on UPS airplanes. Consistently they said when something blows that last thing you wanna do is look around for fuses.

Further, the UPS mechanic regaled me with stories of all the pilots who kept their finger on the pull type breakers till they got the airplane on the ground.

Instead of $70 in fuse blocks, we're looking at $450 in pull breakers but that's only 1 percent of the project. I have two fuse blocks I may sell or more likely I'll use them in the 55 Chevy I'm building which rarely gets airborne.
 
MrNomad said:
Consistently they said when something blows that last thing you wanna do is look around for fuses.

Further, the UPS mechanic regaled me with stories of all the pilots who kept their finger on the pull type breakers till they got the airplane on the ground.
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1) If something blows in the air and the system is properly designed, there will NEVER be a reason to have to replace the fuse in the air (or push the breaker back in). If you need it to safely fly the plane, then you need a backup. Period. What happens if the avionic dies instead of the fuse blowing? Do people carry around spare GNS-480's as well? Design the system properly and you WILL be able to complete the flight without the affected item.

2) Holding down a non-trip free breaker is an amazingly BAD idea. The breaker blew for a reason. When they set the plane on fire pulling this stunt, what breaker would they have pulled to put the fire out?? Trip-free breakers (practically everything Klixon sells for aircraft) will not even allow this to happen. The only time this trick will help you, anyhow, is if the breaker mechanism is somehow broken and the only way to keep it shut is to hold it down manually. This problem goes away entirely if you use a fuse instead (no mechanism to break). If it's truly an overload, the last thing you want to do is stick a penny in the socket (i.e. hold down the breaker).

Lots of folks won't agree with any of this....it's just my opinion and how I personally will outfit my own aircraft.
 
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Forcing the breaker

10 to 15 years ago there were several fires in Piper Navajos that were traced to the pilot holding in the breaker for the gas heater.

When you are up high in the winter and the heater quits it is just a matter of minutes and the cabin temp is below is below freezing. The temptation is great to hold the breaker in because it is right there on the panel within the reach of the pilot.

On the twin Cessna I flew they retained the breaker for the heater but mounted it inside the front wheel area allowing no reset from the air.

Most things are best trouble shot from the ground.

Don
RV-7
 
Shudda rules supreme

It is always interesting to read what SHOULD never happen and what we SHOULD do when mishap occurs. In our RV, we've planned for redundant efis/ems w/4hr ups backup, & redundant radios followed by a Sportys with comm and nav. The second radio has two power sources and an emergency bypass. We have both vor and gps with ups backup. And if all else fails a Magellan gps is at arms length with a good set of batteries checked before each x cntry.

All that SHOULD guide us to the nearest destination. It SHOULD.

Our mags don't require external power so they SHOULD function when all else craps out. But after all the redundancy fails to address the crisis at hand, then what? Ask your wife to look for fuses? "Honey, we're in the clouds, looks like ice and all three systems failed. Hold the stick while I look for fuses. There SHOULD be a 5 amp in there somewhere".

No sane person forces breakers and risks electrical fire when options exist. I know, proper planning SHOULD preclude emergency and my Rogaine SHOULD be working by now.

FYI: Connectors to the fuse box or circuit breakers SHOULD be screw types or soldered (not slip on) for the best possible connection, least likely to corrode or detach & short when your pepsi goes flying. But slip on connectors SHOULD work, most of the time.

Last, my M14 SHOULDN'T have jammed in the jungle but my savvy drill instructor trained us to have a tube of lip ice in case it did.
 
MrNomad said:
It is always interesting to read what SHOULD never happen etc etc
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Since it's my choice of words and not substance that bothers you, I have removed all the "shoulds" from my post. Thanks for pointing that out :)



MrNomad said:
FYI: Connectors to the fuse box or circuit breakers SHOULD be screw types or soldered (not slip on)
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I don't know why this myth persists but FastOn connectors are no less secure than a screw. Unless you're forcefully yanking on the connector, there's no way it's ever going to come off. Also, I would bet that the electrical connection is BETTER for a FastOn connector....it's most certainly not worse than a screw type....no way.
 
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body bags, rifles that jammed, equipment that failed

jcoloccia said:
Since it's my choice of words and not substance that bothers you, I have removed all the "shoulds" from my post. Thanks for pointing that out :)

Hi John. It's great to have a place for this dialogue and I urge everyone to send Doug a few bucks and get one of the cool window decals. Some words just stick to you, such as SHOULD. While not aviation related, I cannot begin to tell you the number of Marines who lived to see another day cause they had a tube of lip ice when their rifle jammed in the swamps. Of course, the vendor claimed it SHOULDN'T happen but having access to an extraordinary solution sent guys home vertically rather than in bags.

As the situation degrades and the possibility of ruining years of work (forget your life) you look for every opportunity to save your butt. Forcing breakers is admittedly a last resort but it's better to have it.

Faston connectors: Thank you. I stand corrected. That panel was truly a work of art. I SHOULD have viewed it earlier.
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MrNomad said:
Hi John. It's great to have a place for this dialogue and I urge everyone to send Doug a few bucks and get one of the cool window decals. Some words just stick to you, such as SHOULD.
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Good point :D I haven't donated yet this year but probably will...the decal's cool.

And you're right about the should's. As an engineer/scientist, I've all but stricken the word from my vocabulary. I wish there was more data readily available so that we could easily put a real number on the true reliability of a system. Then we could all build our aircraft with precisely the right amount of redundancy for our own comfort level, which is really what we're all struggling with here.
 
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