Today's Message Index:
----------------------
1. 09:25 AM - Re: Should a tripped circuit breaker be reset in flight? (Bill Watson)
Message 1
INDEX | Back to Main INDEX |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Should a tripped circuit breaker be reset in |
flight?
> My own preference for not re-setting breakers has
> more to do with builder competence in crafting
> and pilot competence in carry out a Plan-B. These
> are exercises in pre-incident planning that go
> to making breaker resets or fuse replacements
> irrelevant.
>
> This isn't about fires, it's about avoiding that
> deer-in-the-headlights look that overcomes too
> many of our span-can driving brothers. Incidents
> described in detail over decades of what I've called the
> "Dark n Stormy Night" stories popular with the
> journals . . . Sport Aviation not withstanding
FWIW, I tried to follow this thinking in my plane. I ended up with 4
breakers and 2 fuse panels in my Z-14).
Breakers 1&2 = for (2) LRC3 Voltage Regulators per installation
instructions.
Breaker 3 = flap motor (my thinking was that flap deployment at
highspeeds could/might pop the breaker and I'd like to be able to
reset. Casual testing indicated that the motor just 'stalls' or 'slips'
but never pops the breaker)
Breaker 4 = Autopilot because the TruTrak unit doesn't have an on/off
switch. Intent is to use it as an emergency on/off switch.
In retrospect after 3 years and 500 hours , Breaker 3 was a mistake and
is not needed, a fuse for wire protection would do. Breaker 4 still
makes sense to me though such an emergency has never been encountered.
However I wish I had either installed 3 additional breakers or at least
on/off switches for my (3) GRT EFIS screens. These devices lack on/off
switches and are always-on when main power is on. That is how I
normally operate. But they are major consumers of electrons and any
load shedding exercise would benefit from being able to shut down 1 or 2
of them. With 2 batteries and 2 alternators, all scenarios that involve
loss of a single battery or alternator allow me to complete the flight
without a problem with all (3) on. But starting a cold engine, on a
cold day, with the critical battery drawn down (the one without the (3)
EFISs) can be impossible unless the (3) EFISs are taken off line. It's
happened and it's required pulling their fuses.
If I maintain and manage my batteries properly, this should never be a
problem; but I didn't and it was. On the other hand it's just an
on-the-ground non-emergency situation.
In the end, only the (2) breakers for the LRC voltage controllers are
needed. I would like all my avionics to have an on/off capability. For
those devices that don't (AP and the 3 EFISs), it seems that breakers
can serve as infrequently used on/off switches.
Bill "happily flying with a fully equipped kitchen and sink" Watson
Addendum: One other thing that breakers can do for you is to
visually indicate what circuit popped. LED equipped blade fuses can
do the same and do it quite well. My fuse panels are installed in
the passenger seat foot well and have transparent panels. While not
easily reached by the pilot in flight, they are easily visible.
Combined with a panel diagram (or transparent panel labeling) it is
easy to see what fuse is popped.
The only fuse that ever popped in flight was for the strobe unit.
The fix was to replace the unit with one that didn't require a power
run from the rear mounted battery, forward to the on/off switch, and
back to the rear mounted strobe unit. Now there is an unreachable
inline fuse between the battery and the strobe unit. The on/off
switch controls the unit via some sort of relay.
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|