What you don’t know can hurt you(r wallet!)

[Fredd Baber]

Fuel gauges not working...oil temp not working... cost to remove and replace sending units for all 3 is north of $2000. Then I read the maintenance manual which recommended checking the $2 Auto Zone fuse!! Dodged a bullet!

 

[flyingbrit]

Maybe you got lucky, but fuses don't usually blow for no reason. You may have a chafed wire which is intermittently shorting to ground and blowing the fuse. Time will tell.

 

[Huckster79]

Good job! Yea I’ve learned same thing- had intermittent radio issues. I learned to troubleshoot till out of options! I almost replaced a radio… ‘47 Cessna 140… fuse wasn’t blown, but something compelled me to flip flop fuses… it worked! Turns out the little glass tube fuses of the 40s, tho to the naked eye look the same, they are not the same as the new ones ya can get… the new ones are a little less diameter- they can work but might not always… ordered proper fuses from NOS and radio issue solved…

so check to make sure it’s the right physical size fuse…and not just amp rating

 

[Fredd Baber]

Maybe you got lucky, but fuses don't usually blow for no reason. You may have a chafed wire which is intermittently shorting to ground and blowing the fuse. Time will tell.

You’re absolutely right. Now I’m going to watch those gauges close and and see if the dump out again.

 

[Fredd Baber]

Good job! Yea I’ve learned same thing- had intermittent radio issues. I learned to troubleshoot till out of options! I almost replaced a radio… ‘47 Cessna 140… fuse wasn’t blown, but something compelled me to flip flop fuses… it worked! Turns out the little glass tube fuses of the 40s, tho to the naked eye look the same, they are not the same as the new ones ya can get… the new ones are a little less diameter- they can work but might not always… ordered proper fuses from NOS and radio issue solved…

so check to make sure it’s the right physical size fuse…and not just amp rating

Good idea! Thanks for the tip!

 

[Bell206]

Turns out the little glass tube fuses of the 40s, tho to the naked eye look the same, they are not the same as the new ones ya can get…

FYI: aircraft fuses are 9/32" in diameter and auto fuses are 1/4". The aircraft fuse designations have changed over the years from 4AG to AGS and now to ABS (ceramic) for new production fuses. Key is the 9/32" dia which are still available but mostly from aviation suppliers. The auto fuses you installed were probably an AGC which are readily available at most auto stores.

Fuel gauges not working...oil temp not working... cost to remove and replace sending units for all 3 is north of $2000. Then I read the maintenance manual which recommended checking the $2 Auto Zone fuse!!

Reported. Last I checked its against PoA ROC to spend that $2 before you spend the previous $2000.

 

[Dana]

FYI: aircraft fuses are 9/32" in diameter and auto fuses are 1/4". The aircraft fuse designations have changed over the years from 4AG to AGS and now to ABS (ceramic) for new production fuses. Key is the 9/32" dia which are still available but mostly from aviation suppliers. The auto fuses you installed were probably an AGC which are readily available at most auto stores.


Reported. Last I checked its against PoA ROC to spend that $2 before you spend the previous $2000.

Is it OK if he files a NASA report?

-Dana,
who uses automotive fuses in his experimental

 

[Bell206]

Is it OK if he files a NASA report?

who uses automotive fuses in his experimental

Ha. They're all "automotive fuses" even back to the 4AGs. I recall reading somewhere the AG = auto glass. Regardless, the fuse itself is no problem as they're all legal standard parts. The problem is a lot of older fuse holders are designed for the wider AGS fuse which can cause connection issues with the smaller fuse as noted above.

 

[Fredd Baber]

FYI: aircraft fuses are 9/32" in diameter and auto fuses are 1/4". The aircraft fuse designations have changed over the years from 4AG to AGS and now to ABS (ceramic) for new production fuses. Key is the 9/32" dia which are still available but mostly from aviation suppliers. The auto fuses you installed were probably an AGC which are readily available at most auto stores.


Reported. Last I checked its against PoA ROC to spend that $2 before you spend the previous $2000.

Can I claim plausible deniability?!?

 

[Huckster79]

Can I claim plausible deniability?!?

sure can!

mine had those installed when I bought it… and they worked fine till radio became intermittent- that’s when I discovered the difference. And frankly it was a “last ditch” effort of swapping the fuses. I didn’t notice the size difference till after the swap and it worked… so who knows how many years or decades the wrong one had worked…