I was airborne shortly after daybreak and the darkness required a relatively high electrical load. It did not take long before I was hearing the strobe lights in my headset. Whenever I can hear the strobes causing electrical interference I know that something is amiss. I looked up at the field circuit breaker and it was popped. I pushed it back in only to have it blow again immediately. I turned all the electrical off and tried reseting the alternator field circuit a third time…. it worked.
When I got the Cub home I went to the miserable task of trouble shooting. I was suspicious of the alternator but I did not have one immediately available, and after consulting with my mechanic we both agreed that the regulator was the likely culprit. I swapped voltage regulators and took the manufacturers advise by re-wiring the way the voltage regulator senses voltage from the bus. This sounds complicated, but was rather straight-forward once I understood what I was doing. I did not get this all squared away until late at night and long after dark. The following morning I went out for a test flight to see what $300 and 6 hours of work had accomplished … nothing.
The good new is that I now have a spare voltage regulator. The bad news is that my plane was still broke. So today I tore into her for a second time. I started by checking continuity through the field wire and it showed zero resistance. The next step was to change the connectors. This alternator is a modified automotive alternator and there are two spade terminals for the field that do the exact same thing. When this style alternator was installed 10 years ago it was recommended to use only one of the two spades since they both did the same thing. Since that time the manufacturer has learned that the field circuit will pop as vibration and time loosens the spade terminal. I was really happy to hear this because I knew it would be a cheap and easy fix to simply re-crimp and attach a jumper wire between the two spades.
I picked up the plastic housing for a dual spade connector, the appropriate spade terminal, and 4 inches of 20 gauge wire. I carefully attached the new wiring to the alternator and … shazam! …. It still did not work.
So, after much thrash, I ended up back at my initial hunch … lets change the alternator.
This is the B&C Alternator which is an awesome product, light weight, and dependable. Mike and I have put thousands and thousands of hours on this system with very little maintenance required. I highly recommend this system.
Remove the prop spinner first with phillips screw driver.
Cut the safety wire, and then, using a 5/8 socket, remove the propeller…don’t drop it :o)
Remove the nose bowl.
Now you have easy access to the ring gear, alternator, starter, and oil cooler.
Remove the ring gear and alternator belt and you are there. The alternator is held in place by two bolts; the hinge point, and the adjustment bolt.
I installed the new alternator, and walla, the whole system works perfectly. It irritates me that the alternator was my first inkling, and the last thing that I replaced. As a general rule of thumb it is a very expensive practice to remove and replace (R&R) parts as a trouble shooting technique. It is generally much cheaper to professionally trouble shoot the problem and then replace only the broken part. Mike and I have worked hard to accumulate duplicates or triplicates of everything “Cub”. We have a long ways to go, but engine accessories are a must. Mechanicals are inevitable in this line of work and the less time that we spend broken, the more time we can spend in the air. Isn’t that what we all want ?