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  #11  
Old 08-11-2019, 12:40 PM
oren_rokach oren_rokach is offline
 
Join Date: Dec 2018
Location: Tel-Aviv Israel
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Quote:
Originally Posted by svyolo View Post
The only thing that I can think of would be the electric fuel pump in an EFI application. Higher current would indicate impending fuel filter clogging or just a motor about to go Tango Uniform.
For me, if a NAV/strobe light suddenly draws 2A (30W!) more than i should, its definitely a severe alert. I wouldn't pull the CAPS but would land as soon as possible to figure out what happened.

What is the Flap motors is drawing 1A when not even operated?

....etc

Oren.
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  #12  
Old 08-11-2019, 01:04 PM
Carl Froehlich's Avatar
Carl Froehlich Carl Froehlich is online now
 
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Location: Dogwood Airpark (VA42)
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Quote:
Originally Posted by oren_rokach View Post
Hi Carl,
The only occasion in which your voltage drops is when too much current is being drawn from your power source, more than it is capable.
For example, let use the strobe lights example, if it draws 8A at some point instead of 6A that it should, your 60A alternator will still show you 14.2 but you can end up with a fire in your wing, since you didn't realize that you have extra ~28W of power consumption that goes somewhere. Can be twisted hot wires. can be PCB which got burnt...etc.
Your brake fuse will also not break, since you have a 10A limit.

Same with the Glass cockpit elements, pumps, internal lights, flaps motor...etc

We need both to determine if system is healthy

-Oren
Sorry - does not work that way. How many cars do you know that had this happen? For that matter, using your example if you had a wire short in the wing, and your in line breaker did not work, the wires would indeed melt - and that would (in most cases) be the end of the event - but all this would happen before you knew you had something drawing excess current. The odds of a failure drawing “just a little more current” is in the grass. Adding the cost and complexity (and risk) of all the stuff to monitor current of every component ends up (in my opinion) making your plane less reliable.

Carl
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  #13  
Old 08-11-2019, 06:06 PM
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jdeas jdeas is offline
 
Join Date: Mar 2006
Location: SoCal
Posts: 617
Default Failure modes

The primary function is always to protect the wire (harness). Most efuse devices have the ability give you current value for free. Having that value allows you to better quantify and quickly understand the issue while in flight. The use may be limited (from a pure flight safety standpoint) but still something I would like to have as I plan my reaction. I.E. land now, land at remote field, wait for a good town and hotel or simply continue on.


I look at this like ADSB weather. Did I need it (not really if I wanted to be ultra conservative) but it has saved me several nights in hotels by knowing more while I was in flight!
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RV-7 N314SY (KWHP)
IO-360-B1B

CANbus based trim/flaps and electrical
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  #14  
Old 08-12-2019, 10:43 PM
svyolo svyolo is offline
 
Join Date: Oct 2017
Location: bellingham, wa
Posts: 134
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Quote:
Originally Posted by oren_rokach View Post
For me, if a NAV/strobe light suddenly draws 2A (30W!) more than i should, its definitely a severe alert. I wouldn't pull the CAPS but would land as soon as possible to figure out what happened.

What is the Flap motors is drawing 1A when not even operated?

....etc

Oren.
For the light, I will trust my life to the fuze. Same as every aircraft, on Earth. For the flap motor, if it isn't moving, same answer. If it is moving, big airplanes might have a warning for it.

If my fuel pump is about to die itself, or from overheating due to a clogged filter, it would be nice to know. Lots of big airplanes do have filter bypass lights or warnings for this reason.
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