Circuit Breakers without a Switch

[rwanttaja]

When posting to another forum, a question came to mind. About 18 months ago, I completely redid the electrical system of my Fly Baby, moving all the components from a box on the floor to the panel itself.

One thing I didn't restore was the nav lights and strobe. Operating a Sport Pilot, these aren't really needed (my Fly Baby is old). I basically ran out of panel space to mount either the combination switch-circuit breakers I had before (neat, but huge) or to add two switches and Klixon pull-type circuit breakers.

However, thinking about it, I might have room just for the circuit breakers themselves. Now, I rarely use the lights...would it be acceptable to NOT install switches, and just leave the breakers out all the time? Seems reasonable to me, but....

Ron Wanttaja

[Jim Heffelfinger]

Ron you may consider resettable fuses and a switch. Here is the wiki info. http://en.wikipedia.org/wiki/Resettable_fuse and Mouser connect...http://www.mouser.com/Circuit-Protection/Fuses/Resettable-Fuses/_/N-badyq/?gclid=CJ2w2dyHhrsCFRGBfgodETAApA

I have these in my boat panel and allowed me to add switches to the panel - no fuse holder, and the common contact resistance around the fuse in a marine environment.

[WLIU]

One other approach that you might consider is to have the switches on the front face of the instrument panel and mount fuses or CB's under the bottom of the instrument panel, facing down, with labels on the bottom edge of the front face of the instrument panel identifying their circuit and function. Older Cessnas have the panel and overhead light dimmer reostats mounted this way. Whenever I get into an older Cessna after flying newer ones for a while I have to remind myself where to reach to adjust the night lighting.

Best of luck,

Wes
N78PS

[martymayes]

Now, I rarely use the lights...would it be acceptable to NOT install switches, and just leave the breakers out all the time? Seems reasonable to me, but....

It is reasonable. Once upon a time, CB's were routinely used as switches but the FAA put the kibosh on that practice a number of yrs ago with policy changes.

[rwanttaja]

Ron you may consider resettable fuses and a switch. Here is the wiki info. http://en.wikipedia.org/wiki/Resettable_fuse and Mouser connect...http://www.mouser.com/Circuit-Protection/Fuses/Resettable-Fuses/_/N-badyq/?gclid=CJ2w2dyHhrsCFRGBfgodETAApA

I have these in my boat panel and allowed me to add switches to the panel - no fuse holder, and the common contact resistance around the fuse in a marine environment.
Shoot, those are interesting...never even knew of them. I like that they "latch," they don't just cool and close the circuit again.

However, I have to kick the gravel and mention that I didn't include one important bit of data: I already have the Klixon circuit breakers, and would just as soon use those. Marty indicates the FAA is not really fond of the idea of controlling the power to an item solely by the CB. I'm not too fired up about it myself... the lights are almost never going to be used, and would irritate me to have them sit there in the pulled state all the time.

Yes, I'm sensitive. :-)

When i did the electrical rebuild, I used automotive blade-type fuses for the radio and transponder. Here's the little fuse holder I picked up at Napa Aerospace:

3516
I put a strip of velcro on the back, with a matching line of velcro on the far side of the bulkhead where the instrument panel resides. If I have to get at them, they're an easy reach. You can see the fuzziness of the velcro on the back.

I used this type of fuse holder due to repeated BAD experiences with the classic in-line fuse holders for the cylindrical Buss fuses. They get brittle with age and eventually break, leaving live wires loose behind the panel and the unit de-powered.

Here's a write-up describing the electrical work I did last year:

http://www.bowersflybaby.com/tech/new_elect.html


Ron Wanttaja

[CraigCantwell]

Ron: If you want to have just the breaker, make some collars like this: http://www.skylox.com/images/01-1A-505-1_(Rev-2010)%20WP028.pdf Figure 8. We use thiese to lock out breakers all the time at work. While none of our breakers are accessable by the flight crew, should the circuit need to be activated, it only take a second to pop the collar off and push the breaker in. Just collar yours off and lablel correctly with a sub label "Emergnecy use Only" Easy fix and easy to prevent inadverntant activation.

[Bob Dingley]

Your plan sounds reasonable. The FAA did come out with a SAIB (SAIB CE-10-11, Dec 23, 2009) regarding RE-SETTING A TRIPPED C.B. IN FLIGHT. Not your situation. The concern was if that gizmo tripped the breaker, it was bad. Reset and you may burn up the airplane. Get on the ground and investigate. I recall lots of discusion at the time. That said, I checked out in an aircraft at one operator years ago and the guy told me "when we shut down, we dont use the switch on the radio, instead we pull the breaker." It seems that while they had a radio shop, they had to send out the KX170s for switch replacement. "Circuit breakers are cheaper than switches." Or so he said.


Many complex aircraft have many more C.B.s than switches. The factory check lists even have you do system checks by "pull CB for #2 and run #1 through full range, reset and pull CB for #1, check system #2 full range." No switch installed. Check list has "FAA approved" on it.


I like Wes's idea too.


Bob

[rwanttaja]

Ron: If you want to have just the breaker, make some collars like this: http://www.skylox.com/images/01-1A-505-1_(Rev-2010)%20WP028.pdf Figure 8. We use thiese to lock out breakers all the time at work. While none of our breakers are accessable by the flight crew, should the circuit need to be activated, it only take a second to pop the collar off and push the breaker in. Just collar yours off and lablel correctly with a sub label "Emergnecy use Only" Easy fix and easy to prevent inadverntant activation.
Craig, that's perfect. Thanks!

Ron Wanttaja

[Bob Dingley]

Another thing that you may like is a color coded collar that can be installed on Klixon CBs. ACS also carries these cheap & several colors.
http://www.dallasavionics.com/cgi-bin/products.cgi?master=install&category=circuitbreakers&man=collars&url=10164.html


Red ones are installed on the "Chip detector" and "Fuzz Buster" CBs on turbine A/C. No switch installed. The C.L. has the pull/reset routine.


Bob

[Bob Dingley]

Sorry. Link to wrong collar. These are the ones.


http://www.dallasavionics.com/cgi-bin/products.cgi?master=install&category=circuitbreakers&man=locks&url=locks.html


If you install this on a CB labeled "GUNS or ROCKETS", you will be permited to park up front facing the FBO. Otherwise you get exiled to the back 40.


Bob

[Mike M]

... Now, I rarely use the lights...would it be acceptable to NOT install switches, and just leave the breakers out all the time?...Ron Wanttaja

You had me going with the red herrings about being "old" and operating "sport pilot". Yes, the anticollision (a/c) requirement changes with aircraft type certificate issue date and manufacture date, but I couldn't find where the pilot certificate of the PIC affects the required equipment. Macht nichts. It does not have a standard category U.S. airworthiness certificate, so a/c lights aren't required for day VMC under CFR 14 91.205.

So. You don't have the system installed because the wiring is not completed. No problem. Not required, and you knew that.

You're flying E-AB, and I haven't found a CFR requirement for E-AB to comply with standard category requirements like switches AND cb's. So you install the c/b's and only set them when you need the lights. Fine. But. You're going to wear the a/c cb out turning it on and off all the time. "But I don't use the a/c lights!"

CFR14 91.209(b). If an a/c system is installed, it must be used. No mention of aircraft age or category of airworthiness certificate. If installed, must be used. Exception - if PIC determines safer to leave it off. Also, AIM 4-3-23.

So. No switches, just c/b's. Leave the nav light breaker out, the a/c cb in all the time if that's what you want to do. a/c will come on with the master, go off with the master. You're only operating day, so it won't blind anybody. Pull the breaker if you need to have the master on during maintenance for some reason. You'll also be more likely to notice if you left the master on after shutdown.

I may have missed a reg, so this comes with no guarantee.

[Sam Buchanan]

When i did the electrical rebuild, I used automotive blade-type fuses for the radio and transponder. Here's the little fuse holder I picked up at Napa Aerospace:

3516
I put a strip of velcro on the back, with a matching line of velcro on the far side of the bulkhead where the instrument panel resides. If I have to get at them, they're an easy reach. You can see the fuzziness of the velcro on the back.

I used this type of fuse holder due to repeated BAD experiences with the classic in-line fuse holders for the cylindrical Buss fuses. They get brittle with age and eventually break, leaving live wires loose behind the panel and the unit de-powered.

Ron, while you were at NAPA Aerospace you should have picked up one of these:

http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Fuse-Block-14-Position-Long-Base-Fuse-Block/_/R-BK_7823205_0407673634

The fuse block uses the convenient and reliable automotive blade fuses and can be mounted behind the panel where you can run your entire aircraft bus through the block. Much neater than the single fuse holders you purchased. :) The Fast-on terminals are super easy to use and won't fail even under high vibration. Here is a similar block on my RV-6:

3534

With this architecture you can use simple switches on the panel to control lights and devices.

[Mike]

verticalpower.com

[Jim Heffelfinger]

While vertical power's solution is an amazing device the $1500 price tag for a very simple VFR panel/plane seems a bit overkill just to turn on and off a few accessories. I ask, how many cycles will a CB be exposed to if used as a switch in this example over a period of say 10 years? Perhaps a 1000 ? Change out the CB every X years.