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OK location for fuse blocks?

A

alpinelakespilot2000

Well Known Member
Is this an OK position for my fuse blocks?


I know a lot of people mount them on vertical surfaces, but is there any issue with mounting them on the back of the panel where, theoretically, the fuses could fall out of the blocks since the panel slopes slightly forward. I can't imagine that the fuses actually would have any tendency to fall out, because they insert very tightly, but I couldn't find anyting in 43.13b or elsewhere re: best practices on this.

The reason I'd like to have them attached to the panel is because I'm fabricating a pull out/tilt-down panel. The more I can keep wires attached to the panel, the easier this is.

Thanks for your thoughts.
 
The problem I see, is a lot of wasted space on the front of the panel, since just about everything installed has depth. And even an empty spot may be used later by you, or another owner.

My panel has no instruments or gauges there, but it's also a deep glove box in that location.

L.Adamson -- RV6A
 
Turn the fuse blocks around and face them into the cockpit where you can change a blown fuse while in flight. Also mounting the fuse block there wastes a tremendous amount of panel space, if they are hidden on the forward side.
 
alpinelakespilot2000 said:
Is this an OK position for my fuse blocks?


I know a lot of people mount them on vertical surfaces, but is there any issue with mounting them on the back of the panel where, theoretically, the fuses could fall out of the blocks since the panel slopes slightly forward. I can't imagine that the fuses actually would have any tendency to fall out, because they insert very tightly, but I couldn't find anyting in 43.13b or elsewhere re: best practices on this.

The reason I'd like to have them attached to the panel is because I'm fabricating a pull out/tilt-down panel. The more I can keep wires attached to the panel, the easier this is.

Thanks for your thoughts.
Click to expand...

Steve, I think your setup will work fine. I can't imagine a fuse falling out of the block considering how hard it is to remove one of the little buggers.

If you are not planning on using that area of the panel for anything else I can see how localizing your wiring on the modular panel would be really tidy.

As far as replacing fuses in flight.....well.....we've already put that issue to bed (I'm assuming you are a Nuckolls student). ;)
 
Thanks for the thoughts. I think I've anticipated most of them:
L.Adamson said:
The problem I see, is a lot of wasted space on the front of the panel, since just about everything installed has depth. And even an empty spot may be used later by you, or another owner.

My panel has no instruments or gauges there, but it's also a deep glove box in that location.

L.Adamson -- RV6A
Click to expand...
Good point. That said, I have everything I need in the panel already for a good VFR cross country mission and even have, if you look just below the fuse blocks, the map box in the panel already. As far as needing an empty spot later, I still have one empty location for a 3-1/8" cutout on the left side of the panel. I also could pretty easily relocate the fuse blocks to sit horizontally on top of the map box (without having to do any major re-wiring) and that would free up all of that panel space on the right side. I have only avoided mounting the fuse blocks on the map box to begin with because the panel pulls out a little easier if I unscrew the map box from the panel first.

Worst case scenario, having cut my own panel already, I realized how fast and quick it would be to cut a new one if necessary. That might not help a future owner who might be intimidated by cutting out a panel him/herself, but (knock on wood) I have no plans to sell.
Norman CYYJ said:
Turn the fuse blocks around and face them into the cockpit where you can change a blown fuse while in flight. Also mounting the fuse block there wastes a tremendous amount of panel space, if they are hidden on the forward side.
Click to expand...
I did take your idea seriously, Norman, and really appreciated the pictures you sent me of your installation. So far I've avoided that only because, aesthetically, I preferred the look of the uncut panel and don't want to see the fuses or even a cover over a panel cutout.
Sam Buchanan said:
Steve, I think your setup will work fine. I can't imagine a fuse falling out of the block considering how hard it is to remove one of the little buggers.

If you are not planning on using that area of the panel for anything else I can see how localizing your wiring on the modular panel would be really tidy.

As far as replacing fuses in flight.....well.....we've already put that issue to bed (I'm assuming you are a Nuckolls student). ;)
Click to expand...
Yes, for a VFR aircraft, my opinion (only) is that there should be no need to replace fuses in flight and that doing so might be ill-advised. And yes, localizing the wire is really important for the pull-out/tilt feature of my panel.

Other ideas? I'll try to post a picture of the front of my panel to put my question into better context. Thanks again to all for helping me think through this issue.
 
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Fuse Block

I hinged mine from the sub panel, mounted on a pice of .032 and used a 1\4 turn eared fastner(like Vans supplies for the oil door) in the instrument panel bottom flange to hold it in place.
I can swing it down in fight if required and no concern that the fuses might fall out which I doubt they woud anyway, but it leaves all that panel space avaiable for future addition if you decide to add somrthing, also easier if you decide to add anothe circuit later.
Gerry
 
Gerald Clabots said:
I hinged mine from the sub panel, mounted on a pice of .032 and used a 1\4 turn eared fastner(like Vans supplies for the oil door) in the instrument panel bottom flange to hold it in place.
I can swing it down in fight if required and no concern that the fuses might fall out which I doubt they woud anyway, but it leaves all that panel space avaiable for future addition if you decide to add somrthing, also easier if you decide to add anothe circuit later.
Gerry
Click to expand...
As I described above, my panel will pull out and tilt. Using a swing down fuse panel would complicate that and the pull out/tilt feature of the panel should make future circuit additions pretty easy.
 
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alpinelakespilot2000 said:
I also could pretty easily relocate the fuse blocks to sit horizontally on top of the map box (without having to do any major re-wiring) and that would free up all of that panel space on the right side.
Click to expand...

Unless your tilt and pull panel is a two second job, which it doesn't look like from the pics, I wouldn't put the fuse block on top of the map box either. While it's easy to access when the top skin is not on, it's near impossible to get to from underneath.

My blocks are on the subpanel behind the main, and still a bit hard to get to the fuses, with all the wiring in the way. I used a combination of fuses (on the subpanel) and some pullable circuit breakers in the area of your blank panel.

My panel is also in three removeable sections. The center is easy to remove, but the sides require disconnects of several gauges. Just makes it easy for future panel design changes.

L.Adamson
 
L.Adamson said:
Unless your tilt and pull panel is a two second job, which it doesn't look like from the pics, I wouldn't put the fuse block on top of the map box either. While it's easy to access when the top skin is not on, it's near impossible to get to from underneath.
Click to expand...
Correct, I have to remove about 20-25 screws for my panel to pull out and tilt down and give me complete access to the fuses (or the rest of the panel, for that matter). I'm not planning to have to chase down popped fuses very often (if ever), though, so I'm OK with that inconvenience. Thus, the back of panel or top of map box should be fine as far as future access. If the wiring works out as planned, I shouldn't have to break any connections when the whole thing tilts. We shall see though. Thanks for the thoughts.
 
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Sam Buchanan said:
As far as replacing fuses in flight.....well.....we've already put that issue to bed (I'm assuming you are a Nuckolls student). ;)
Click to expand...

I'm probably wrong, but I was under the impression there was an FAA requirement that the fuses/breakers must be accessable in flight. I can't recall where I read that. Is it rue or false?
 
When building your panel take a lot of time and don't rush. What you think you can live with now for easy service you will forever kick yourself if you don't. Chasing anything that needs to be fixed in the future if it is difficult will be come a major curse. Things may look easy now but what about when things are closed up? If you can't get at it now and you keep your plane for a few years age tends to make you less flexible, think things out carefully and don't be in a hurry to do it the easy way. You don't ever want to be cussing the builder.
 
FredMagare said:
I'm probably wrong, but I was under the impression there was an FAA requirement that the fuses/breakers must be accessable in flight. I can't recall where I read that. Is it rue or false?
Click to expand...
False. There is a requirement for type-certificated aircraft (FAR 23.1357(d)), but even it would allow fuse blocks that were not accessible to the pilot in flight.

FAR 2301357(d) reads:
FAR23.1357(d) said:
If the ability to reset a circuit breaker or replace a fuse is essential to safety in flight, that circuit breaker or fuse must be so located and identified that it can be readily reset or replaced in flight.
Click to expand...


Essential to safety in flight has historically been interpreted to refer to an item that must be functional in order to make it to an airport (e.g. power supply for electronic ignition on an aircraft with only one ignition system). If you have any such items, you also need to consider the failure case where that item simply fails (i.e. the fuse didn't blow). This would almost certainly drive you to installing a backup system (e.g. a second ignition system), in which case the primary system is no longer essential to safety.
 
Adding wiring changes tiltability

Keep in mind that as you add wires the hinged fuse panels don't move nearly as well (even with service loops).
 
Steve:

2 things came to mind immediately:

First, that's a lot of prime panel space you may want to put to use in the future. You have enough room to add another EFIS or dedicated engine monitor. You may be satisfied with your configuration today but after flying it for a year or 2 you may desire to make changes or additions. The point is that your fuse block location will take your "prime real estate" off the market.

You might think that you will be able to rewire your blocks to a new location should you desire to add panel features in the future however, you will not have the room to work that you have today. Your fuse blocks will need to be moved and ALL of your wiring redone to the new locale.

Second, you will need some rather lengthy service loops to clear the panel. Weight is not a problem but chafing is. Make sure the loops are well protected.

If the Dynon is front mounted like my GRT, consider placing your blocks behind it. My fuses are quickly accessible by removing my GRT which is held in with 4 screws.

My goals were to build for maintainability and facilitate future growth therefor my comments reflect the same.

Jekyll
 
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Good food for thought. Thanks for all the input.

Clearly, if I gave up on the notion of being able to pull the panel out, life would in many ways become less complex, but that is one of the challenges I wanted to take on. I think the three piece (Affordable Panels-type) modular panel is probably the best design for future accessibility for the slider models. Earlier in the desing process I considered,then ruled out, this option, but it was only for aesthetic and $$ reasons--both of which were entirely personal preference only.

Once having decided for the pull out panel, my main dilemma has come in balancing the notion of saving space for future additions and upgrades with the (seemingly) contradictory notion of keeping as much of the wiring attached to the panel as possible. If I can't do the latter, then the ability to pull the panel out enough to work on it becomes much more difficult. Somehow attaching the fuse blocks to the main panel structure will greatly decrease the number and size (and potential for chafing) of any service loops that are needed. Should I choose to add anything in the future, I've still got room for a 3-1/8" cutout to the lower right of the D180, and I have room for two or three 2-1/4" instruments (or the equivalent) above the intercom, as well as a lot of space below the D180. One of the most interesting threads I've read through in a long time has been watching Paul Dye completely rebuild a new panel in just under a month, so there's always that option as well.

One other angle on the future upgrade issue (and overall panel design) is personal preference driven. Part of my panel design process has been driven by my overall philosphy about what kind of plane I wanted to build and what kind of $$ resources I've been willing to commit to it as opposed to other life spending priorities. Putting another big glass screen (or high $$ value item) on the right side of the panel is almost out of the question. Never say never, of course, but at this point in life, I've spent about as much on a completely discretionary (and yes, selfish) hobby as I can even come close to justify personally. I don't say this to suggest that this should be anyone else's philosophy, only to help provide some context for the panel decisions I've made.

Seriously, thanks again for the input. Wrestling with other suggestions is good for my thought process. This forum is great for that.
 
Steve,

Think about future maintenance. Should a fuse pop for no other reason than it was bad, getting to it might be a challenge. Or, let us say that you want to install some fancy new gizmo that will be invented next year and it will only fit in that space, you will have a problem.

Why not set it up so it will pivot down from under the panel and present the fuses to you rather than having to lay on your back if you want to add another circuit?

You could pivot it on the aft end with a piano hinge and use a sky-bolt type fastener or two to hold it up out of the way.

Just my $.02 worth.

Get that -9 flying! The world needs more -9's!
 
Concerning the original question

These posts don't seem to address your question, which concerns a "concern" with mounting the block so the fuses are vertical with a slight downward position such that a potential exists for them to fall due to vibration. I'll point out that many cars, mine included, mount the block for these same fuses UPSIDE DOWN for ease of access in removing the fuses. They are typically under the dash by the driver's door. Plenty of vibration and bumps in the car and they are NEVER loose. I'd have no fear mounting them upside down in the airplane, and certainly not with the orientation you have:D.
 
Fuse Block location

p1296386qv6.jpg
I mounted mine under the map box. The right side of the panel can be removed (Ala Affordable Panels) exposing the fuses and giving you access to the back of the panel
p2196028fi0.jpg
 
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Thanks again for the help everyone. I've decided to take a little bit of everyone's suggestion. The final location will be quite similar to Jeff's.

I'm going to mount the fuses horizontally on top of the map box (and behind the panel). This allows me almost all of the upper right side panel space in the future if I ever find some nifty gadget to put there. I will have access to those fuses through a new hole in the panel above the map box door over which I will have an overlay, held in place by four screws, the same size and shape as the map box door. If I need to in the future, I can mount instruments there or on a new overlay. I also still have the ability to pull out and tilt the whole panel. The end result is that I have a combination of a traditional panel, a tilting panel, and an "Affordable Panels" design. This should make it very functional and flexible.

I've mocked up a few samples and think the panel is still going to look really clean when done and painted, which was one of my primary goals in panel design, second to functionality.

Thanks again.
 
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