Lately I've had two electrical hickups. The first, is the accessory jack (aka: cigarette lighter). It has an in-line fuse (forget the amperage atm) and this fuse keeps blowing as soon as I turn on the master switch. Doesnt matter whether something is plugged into the jack or not.
The second issue, is that on about 3/4 of my flights, within about 5 minutes of takeoff, the comms CB pops. This one if memory serves is a 7amp CB. It just goes to a King (forget the model) comms (no nav) radio. Initially, I was letting the circuit "cool" for about 5 to 10 minutes, and then I'd turn the radio off, reset the CB, and turn the radio back on. And I'd be on my way. Whether it be for another 30 minutes or another 2 hours. It seems never to trip more than one a flight. The last time that happened, I tried resetting it a few seconds later, but it wouldnt stay in. With my mind thinking about reaching the fire extinguisher and staying in the circuit at the airport, every 30 seconds or so I tried resetting the CB, about 3 or 4 times, but it wouldnt stay in. Finally I got the message and left it alone for 10 minutes, then reset it and it stuck. I flew for another 45mins to an hour and it didnt pop.
So with that backstory, whats the best way to go about troubleshooting these two issues? No other electrical components, CBs, or fuse, have been affected by this. Could these two issues be linked somehow? All CBs and fuses (except the accessory jack inline fuse) are connected to a bus bar, Im not sure how the accessory jack fits in to this, I'd have to look at the electrical diagrams.
Thanks for any advice,
electrical woes
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corroded_camshaft
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Re: electrical woes
Your accessory jack is shorting out somehow and when power is applied through the main bus the path goes to ground and pop goes the fusal. The jack may be wired backwards or it may be an internal short. The accessory jack fuse should be between the buss and the jack, the ground wire for the jack goes to airframe. With nothing coneccted(wires disconnected from the jack) there should be no continuity between the two pins on the accesory jack.
As for the CB popping, it could be several different things. As simple as a worn out CB or it could be a chafed/loose wire or your radio shorting internally. A good engineer will be able to track these problems down in an hour.
Worst case, call your local smoke farmer.
As for the CB popping, it could be several different things. As simple as a worn out CB or it could be a chafed/loose wire or your radio shorting internally. A good engineer will be able to track these problems down in an hour.
Worst case, call your local smoke farmer.
Re: electrical woes
Shots in the dark:
1) replace your cigarette lighter (sorry, "Power Point"). They are extremely cheaply made. I have seen them short out internally, which causes exactly the problem you are seeing.
2) your comm CB is probably worn out. Can you try another one of the same amperage? Do NOT increase the amperage. If a new CB of the same amperage still pops, you have a short somewhere. A comm radio draws very little power when receiving, and a LOT more while transmitting. If your transmit button isn't stuck on, a comm radio should not draw more than an amp (max two). Also make sure that you don't have more than one thing connected to a single CB. This is very cheesy, but you see it a lot.
1) replace your cigarette lighter (sorry, "Power Point"). They are extremely cheaply made. I have seen them short out internally, which causes exactly the problem you are seeing.
2) your comm CB is probably worn out. Can you try another one of the same amperage? Do NOT increase the amperage. If a new CB of the same amperage still pops, you have a short somewhere. A comm radio draws very little power when receiving, and a LOT more while transmitting. If your transmit button isn't stuck on, a comm radio should not draw more than an amp (max two). Also make sure that you don't have more than one thing connected to a single CB. This is very cheesy, but you see it a lot.
Re: electrical woes
Get involved in your plane but get some oversight as well. Regardless of your ability, a second pair of eyes is the standard approach in this business. C/B's protect wiring not components, if your radio had an internal short it's unlikely that it would recover and work again. Hedley's advice is right on as early CB's in light production aircraft suffer quality issues or there's a rats nest behind the panel.
Re: electrical woes
First of all, (only) if you feel you have the knowledge and experience to replace the auxiliary power jack, replace it with the intended part number. If it's a cheaply made type, it either likely isn't made for aircraft or its not the original part number. Don't buy it at Canadian Tire. More like Aircraft Spruce. For some aircraft, Cessnas for example, there the IPC lists the part number.
http://www.aircraftspruce.com/catalog/p ... ighter.php
And you might want to browse the ADs for your airplane. Many Cessna models (for example) have active ADs for cigarette lighter installations. You don't want to go through all that work just to have it ripped out at your next inspection.
With respect to the COM circuit breaker, in my experience, that sort of snag is indicative of a wire chafing. The fact that it seem to happen shortly after takeoff, which is the phase with the highest vibration, points to that sort of snag.
You may wonder why the CB didn't pop during takeoff rather than a few minutes later. Circuit breakers are designed to trip with time delays inversely proportional to the degree of the over-current.
http://www.sensata.com/klixon/circuit-b ... #tripcurve
At 101% load it may take several minutes to trip. You won't get consistent immediate tripping until the short is much more than 100% of the load. You must also consider that circuit breakers degrade every time they are used especially when they trip in response to an over-current. Keeping them installed after several "trips" can be dangerous. They are designed to fail safe but just like any electrical switch, there is a possibility of the contacts fusing together which may eventually lead to a fire in the shorted circuit.
Most aircraft circuit breakers are only rated for a maximum of about 100 "trips". Some, like the "no pull" types found in many Cessna Singles are junk and I wouldn't trust them after a few trips.
To check for chafing wires, start with a visual inspection. Using a bright flashlight, crawl under the instrument panel and look for wire bundles that aren't properly secured. Move the control column while you're doing this. Any bundle that is being pinched or is rubbing against the airframe must be adjusted and properly secured. Check for scorching, soot or any other indication of shorting and chafing and repair/replace any damaged wiring.
If that doesn't produce results, after you replace the circuit breaker (use ONLY the same part number) then remove the COM. Turn on the master switch and then crawl under the instrument panel, grab the wiring bundles and move them around. Watch for sparks and for the circuit breaker to trip. If either occurs, you really need to get someone with experience and knowledge to look at it as well as the COM transceiver which may be the problem.
By the way, it's preferable to do the above procedure with an ohm meter that has an audible alarm. It's safer and won't do more damage.
http://www.aircraftspruce.com/catalog/p ... ighter.php
And you might want to browse the ADs for your airplane. Many Cessna models (for example) have active ADs for cigarette lighter installations. You don't want to go through all that work just to have it ripped out at your next inspection.
With respect to the COM circuit breaker, in my experience, that sort of snag is indicative of a wire chafing. The fact that it seem to happen shortly after takeoff, which is the phase with the highest vibration, points to that sort of snag.
You may wonder why the CB didn't pop during takeoff rather than a few minutes later. Circuit breakers are designed to trip with time delays inversely proportional to the degree of the over-current.
http://www.sensata.com/klixon/circuit-b ... #tripcurve
At 101% load it may take several minutes to trip. You won't get consistent immediate tripping until the short is much more than 100% of the load. You must also consider that circuit breakers degrade every time they are used especially when they trip in response to an over-current. Keeping them installed after several "trips" can be dangerous. They are designed to fail safe but just like any electrical switch, there is a possibility of the contacts fusing together which may eventually lead to a fire in the shorted circuit.
Most aircraft circuit breakers are only rated for a maximum of about 100 "trips". Some, like the "no pull" types found in many Cessna Singles are junk and I wouldn't trust them after a few trips.
To check for chafing wires, start with a visual inspection. Using a bright flashlight, crawl under the instrument panel and look for wire bundles that aren't properly secured. Move the control column while you're doing this. Any bundle that is being pinched or is rubbing against the airframe must be adjusted and properly secured. Check for scorching, soot or any other indication of shorting and chafing and repair/replace any damaged wiring.
If that doesn't produce results, after you replace the circuit breaker (use ONLY the same part number) then remove the COM. Turn on the master switch and then crawl under the instrument panel, grab the wiring bundles and move them around. Watch for sparks and for the circuit breaker to trip. If either occurs, you really need to get someone with experience and knowledge to look at it as well as the COM transceiver which may be the problem.
By the way, it's preferable to do the above procedure with an ohm meter that has an audible alarm. It's safer and won't do more damage.
