Avionics Circuit Breaker

[Roscoe]

Hi all

Shortly after start up, the Avionics Circuit Breaker on my 9 yo Jabiru popped for the first time ever, I lost all my electrics.

Pressed it back in, and everything returned to normal, short flight with no issues.

I did not have any extra load on at start up, and I always switch on the Avionics Master with engine running.

Apart from a faulty Circuit Breaker, any thoughts on what may have caused the breaker to pop?

Thanks

[Roscoe]

18 minutes ago, Roscoe said:

Hi all

Shortly after start up, the Avionics Circuit Breaker on my 9 yo Jabiru popped for the first time ever, I lost all my electrics.

Pressed it back in, and everything returned to normal, short flight with no issues.

I did not have any extra load on at start up, and I always switch on the Avionics Master with engine running.

Apart from a faulty Circuit Breaker, any thoughts on what may have caused the breaker to pop?

Thanks

Just to clarify, only items connected to the Avionics Bus, is MGL CHT/EGT gauge, fuel scanner, 1 Radio, Transponder.

[skippydiesel]

Gut feeling (2 scientific methods in one) - could just be random and may not happen again - see how you go (another leap of non logic) AND what rating is the circuit breaker? could be tat its been operating near its rated limit all these years and a slight increase in current draw has put it over the limit.

[Roscoe]

Thanks Skippy, its a 10amp thing.

Will get a new breaker anyway in case it happens again

[RFguy]

There is no such thing as random for this . The total load all active should not trip the breaker.

 

When you say just after startup- was this as you increased RPM so the battery voltage began to rise as the battery began to take charge ? Or before you  went over 1500 RPM ?

 

Roscoe, take a good look with glasses on and lots of light at the wiring you can see.

 

Change the circuit breaker.  See if it occurs again. 

 

[Old Koreelah]

1 hour ago, Roscoe said:

Hi all

Shortly after start up, the Avionics Circuit Breaker on my 9 yo Jabiru popped for the first time ever, I lost all my electrics.

Same thing happened to me after departing Narromine AusFly a few years ago. Because of the amount of traffic, I’d turned on my landing lights for takeoff and forgotten to turn them off. I hadn’t installed a relay in the system, so they pulled a fair amount of current, eventually tripping the CB. 

 

It shouldn’t have been an issue, but I’d never had a CB trip before and had totally forgotten how I’d wired up the plane.

Lack of logical thinking led to a couple of hours wasted on the ground in Dubbo before a young, fresh set of eyes noticed that little button sticking out a bit more than the others. Embarassing!

[Roscoe]

45 minutes ago, RFguy said:

There is no such thing as random for this . The total load all active should not trip the breaker.

 

When you say just after startup- was this as you increased RPM so the battery voltage began to rise as the battery began to take charge ? Or before you  went over 1500 RPM ?

 

Roscoe, take a good look with glasses on and lots of light at the wiring you can see.

 

Change the circuit breaker.  See if it occurs again. 

 

Thanks Glen

I started up, turned on the Avionics Master and after 5 mins of taxiiing at low RPM, stopped and noticed the blank avionics data before running up and doing pre take off checks.

Shut down and then noticed the popped breaker. Re set it, started up again, and all normal after that.

[Roscoe]

9 minutes ago, Old Koreelah said:

Same thing happened to me after departing Narromine AusFly a few years ago. Because of the amount of traffic, I’d turned on my landing lights for takeoff and forgotten to turn them off. I hadn’t installed a relay in the system, so they pulled a fair amount of current, eventually tripping the CB. 

 

It shouldn’t have been an issue, but I’d never had a CB trip before and had totally forgotten how I’d wired up the plane.

Lack of logical thinking led to a couple of hours wasted on the ground in Dubbo before a young, fresh set of eyes noticed that little button sticking out a bit more than the others. Embarassing!

I know exactly how you felt!

[Blueadventures]

I have the aviation grade c/b switches for my circuits and a main c/b as per engine wiring (Rotax in mine).  The lower the amp rate of switch the dearer they were. The amp load is stamped in the end of toggle. (Saves labling) Available from aircraft spruce and other outlets. Good piece of kit all round.

[RFguy]

mmm.

I'd like you to locate the regulator, unplug from the harness ,  physically inspect the connector in situ, and replug it in snug.  Also is your engine a Gen4 with the CB  in series with the alternator stator ?

 

anyway, buy a spare breaker . carry it . take a look at the wiring- make sure all plugs for instruments panel pushed home. Could be a bit of equipment got an overvoltage and decided to crowbar (puts a short on the bus) , maybe something not right in the regulator/alternator wiring.

 

 

 

[Roscoe]

21 minutes ago, RFguy said:

mmm.

I'd like you to locate the regulator, unplug from the harness ,  physically inspect the connector in situ, and replug it in snug.  Also is your engine a Gen4 with the CB  in series with the alternator stator ?

 

anyway, buy a spare breaker . carry it . take a look at the wiring- make sure all plugs for instruments panel pushed home. Could be a bit of equipment got an overvoltage and decided to crowbar (puts a short on the bus) , maybe something not right in the regulator/alternator wiring.

 

 

 

Gen 3. New Breaker on the way.

[onetrack]

Check all harness wiring connectors, and bolted/screwed connections for corrosion, and ensure all bolted connections are tight. Unsealed harness connectors and exposed bolted/screwed connections are notorious for corroding over time, with exposure to salt air, moist air, and dust in the air. Corrosion is an insidious factor in wiring that gradually alters voltages and amperage.

Circuit breakers do also wear out (weaken) with age and constant use with substantial power loads. Check the actual amperage running through the CB when the electrical loading is at its highest, it may be higher than originally calculated.

[facthunter]

In some situations only ONE reset is recommended. If they are used as switches they must  wear more. Split your systems  if you want troubleshooting capability.  Nev