Lost sight of the mission a bit...
Thanks for the comments, I appreciate it.
I should have mentioned Vertical Power keeps spare parts to support existing VP-50 units in stock in my earlier post. I forgot about that, sorry.
Of course Marc is absolutely right about having several other items that would keep me on the ground that I don't have backups for.
It's a delicate balance between too many backup systems (and the weight / complexity / cost associated with them) and not enough.
My day job is flying heavy transport helicopters to offshore oil / gas platforms off the Canadian East Coast in the worst kind of weather. The aircraft I fly has 2 of everything and 3 of the really important things! I am accustomed to a certain level of system redundancy.
In addition every AME I know and solicit for advice on my electrical system only have experience working on complex transport machines. They have no idea what a day VFR sport plane mission is all about. Some can?t get over the fact I?ll only have one engine out front! There is almost zero general aviation here in Halifax to draw on let alone sport aviation.
Anyway, the only VP-50 backup circuits I planned initially were to the boost pump, and flaps sourced from the battery in the unlikely event the VP-CU became U/S.
But when I started working with the VP-50 load planning worksheet I realized I was too close to my alternators limit and was running out of available VP-50 power pins. Mostly because I have heated seats (front /back) and two auxiliary power outlets to run heated (motorcycle style) vests, electric flaps, boost pump, and landing light. Cumulatively these items draw a lot of current.
My plan then evolved to incorporate an auxiliary bus (Fuse block) energized by both the alternator and battery to take care of the seat heaters, and boost pump (B/U) etc. At this point I realized the physical location of the aux buss (on the side wall under a switch console by my right knee) would make it convenient to add other items that would have had wires running in close proximity to it if routed to the VP-50 CU.
So for convenience I decided to just power those items from the aux buss as well. This lightened the load on the VP-50 and freed up some pins for future use.
My plan is still fluid and I?m fortunate to have VAF forum members and especially Marc Ausman offer comments, observations and suggestions for the purpose of improving the system.
Given Marcs recent illumination of the fact there are many single items that can ground my RV-8 I need to rethink my strategy a bit. I have to keep in mind the mission is Day/Night VFR. Not heavy weather IFR.
Thanks again, keep the comments coming!
P.S. I agree the compass has little use, but I don?t have anything else in mind for that panel position at the moment and my Dynon D-100 has a G-Meter.
P.S.S. Here is a link to my updated schematic as of yesterday. (Now I have to change it!)
http://www3.ns.sympatico.ca/jeffrey.mitchell/RV8%20Forum%20Pics/General%20Schematic%20V1.02.vsd