Hi Paul,
You loose nothing by having a reset possibility -
something you do not have with a fuse. Those of use who have successfully
reset a CB and regained a system just have a hard time understanding why anyone
would want to forego the possibility of being able to regain a critical
system. True, it may not work every time or even most times, but its
worked enough times for me and others (such as yourself) to make it a viable
choice. Like I say I use fuses - just not on flight critical
systems.
However, for those who decide to use fuses, I think
your discovery of apparently a apparently mismatched fuse should be
something they add to their check list when installing/replacing
fuses. I suppose if you use a different metal as the fuse link (I
don't have any ideal which alloy is used) then you might could use a
thinner link - but I would think the alloy would be pretty standard.
But, Like you said could have been made in China on a Monday or Friday or
someone hired a color-vision impaired person to put the caps
on{:>). Good detective work!
Ed
----- Original Message -----
Sent: Thursday, May 05, 2005 12:29
AM
Subject: [FlyRotary] Re: To Fuse or not
to Fuse
Hi, Ed....thanks for the links. After
successfully resetting fuses in military aircraft, I feel more comfort in
knowing that I at least have the option to reset or not to reset. In one
case, it was the landing gear motor on a King Air that got pretty hot during
touch-and-go's during a checkride. Once the motor cooled, the circuit breaker
was successfully reset, and we were able to lower the gear. I am replacing my
fuel pump fuses with CB's.
Anyway, the purpose of
this email is to comment on the fuse that blew on my fuel pump circuit. We
looked at it with a maginfying glass, and there was no dark or black area
around the break, as there often appears after a fuse blows. What we did
notice, however is that the gage of the wire inside the fuse looked
suspiciously small. We compared it to 5 or 6 other 20 amp fuses we had, and
the wire was definately smaller in gage. It looked to be the same size as a 7
1/2 amp fuse we compared it to. It did, however have the standard yellow
plastic cap and marking of 20 on it. It definately was a lighter gage
wire used for the fuse portion than the other 20 amp fuses we had. Possibly a
manufacturing defect, or maybe it was a 7 1/2 amp fuse and it received a
yellow cap marked 20 amps somewhere along the assembly line or ??? Don't
know the answer to this one, but there is no doubt at all that the wire was
similar in size to a 7 1/2 amp fuse. Maybe something to look at when
installing them. Might have been made on a Monday or a Friday.
FWIW. Paul Conner
----- Original Message -----
Sent: Monday, May 02, 2005 8:16
AM
Subject: [FlyRotary] To Fuse or not to
Fuse
Since this is the umpteenth time that the fuse
vs CB topic has come up (not just on the rotary lists but aircraft list in
general), and certainly won't e the last, I decided to do something
different than just spout my views on the topic. I surfed the net and
see if I could find anything on it.
Here are some of the URLs I found of
interest.
This guy actually did some tests and found
among other things that a fuse rated capacity can slowly degrade with
repeated high current flows even if below its burst point. But, read
it and draw your own conclusions.
This one has an interesting summary, but since
they are presented by the makers of CB can be considered Biased
Another maker of CB propaganda, however they do
point out that you can not test a fuse since it is destroyed if it proves it
works at the specified rating where as you can a CB
Here is Bob K's and his well reasoned
argument FOR fuses
It appears that there is as much debate outside
the aviation community (or more) about fuses Vs CB. It appears to me
the CB is winning there simply because of convince rather than any technical
advantage - That is once the problem causing the short is fixed, you
simply reset the CB rather than trying to find a fuse of the right rating
and shape to replace the blown one and possibly sticking in the wrong
fuse. And you know Americans - convince before all else {:>) -
At least that's the way it appears to me.
Ed
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