wireweinie
FOUNDER
Palmer, AK
Just need to put out a reminder to check out your ground path from the engine to the airframe. Do it at least each annual. Please.
Two days ago I had to do some wiring repairs due to poor engine grounding on a very nice C-180. I was originally called because the alternator was not charging and the field breaker would pop as soon as the master was turned on. I was busy, so I attempted to troubleshoot the system over the phone. When that did not work, I went to the aircraft. The aircraft was tied to a good solid dock and had the top cowl removed (greatly appreciated!). The very first thing I saw was the regulator ground wire had NO insulation left on it due to overheating.
Some of you will remember MCS Mike and I telling about 'bad things' happening due to poor engine grounds. Here was another example. There was no ground strap connecting the crankcase to the airframe. I didn't remove the lower cowl to check but it appears that the aluminum ground straps that wrap over the Lord mounts on the engine had finally broken (this charging system has been working fine for a couple of seasons). This means that when cranking the engine or when the alternator begins to charge, the path to ground for the starter or alternator will be things like primer lines, control cables, etc. Since I run the regulator ground wire (20 gauge) to the back of the alternator for Plane-Power systems, this little wire was the first victim. Current to the starter motor trying to go through this little wire had made it hot enough to melt the insulation off and let it melt into the field wire it had been bundled with. The dead short between these wires was the reason that the field breaker would pop when the master was turned on.
The repair was actually fairly simple. I printed new regulator ground and field wires and installed them. Then I installed a braided ground strap from a stud on the accessory case to one of the 1/4" bolts that hold the regulator to the firewall. I also installed a new start relay due to an unrelated issued that was found during troubleshooting (loose battery connection had messed up the threads on the terminal) and then the owner started the engine. Low voltage light went out and the ammeter showed a positive charge. After shutdown, no burn't ground wires or primer lines were noted.
This issue has actually started fires in the past. I've also been told about control cables 'welded' immovable from this. So, please check this item out on your aircraft and avoid the extra down time for repairs.
Web
Two days ago I had to do some wiring repairs due to poor engine grounding on a very nice C-180. I was originally called because the alternator was not charging and the field breaker would pop as soon as the master was turned on. I was busy, so I attempted to troubleshoot the system over the phone. When that did not work, I went to the aircraft. The aircraft was tied to a good solid dock and had the top cowl removed (greatly appreciated!). The very first thing I saw was the regulator ground wire had NO insulation left on it due to overheating.
Some of you will remember MCS Mike and I telling about 'bad things' happening due to poor engine grounds. Here was another example. There was no ground strap connecting the crankcase to the airframe. I didn't remove the lower cowl to check but it appears that the aluminum ground straps that wrap over the Lord mounts on the engine had finally broken (this charging system has been working fine for a couple of seasons). This means that when cranking the engine or when the alternator begins to charge, the path to ground for the starter or alternator will be things like primer lines, control cables, etc. Since I run the regulator ground wire (20 gauge) to the back of the alternator for Plane-Power systems, this little wire was the first victim. Current to the starter motor trying to go through this little wire had made it hot enough to melt the insulation off and let it melt into the field wire it had been bundled with. The dead short between these wires was the reason that the field breaker would pop when the master was turned on.
The repair was actually fairly simple. I printed new regulator ground and field wires and installed them. Then I installed a braided ground strap from a stud on the accessory case to one of the 1/4" bolts that hold the regulator to the firewall. I also installed a new start relay due to an unrelated issued that was found during troubleshooting (loose battery connection had messed up the threads on the terminal) and then the owner started the engine. Low voltage light went out and the ammeter showed a positive charge. After shutdown, no burn't ground wires or primer lines were noted.
This issue has actually started fires in the past. I've also been told about control cables 'welded' immovable from this. So, please check this item out on your aircraft and avoid the extra down time for repairs.
Web
