@ericlarsen
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One other thing that I have recently figured out regarding my brake issues. There was a bad O-ring within one of the master cylinders. It was causing intermittent issue where pedal would go straight to the floor with no braking action. It was rarely encountered, but it made troubleshooting complicated because there were actually two separate issues in my brakes. The parking brake hanging up, and bad O-ring that caused brake not to work at all. One thing we learned when taking master cylinder apart is that the actual part does not match the drawing in manual. It is not that complicated, but we had to take the master cylinder completely out of the plane to dis-assemble and inspect it on bench.
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My alternator controller (voltage regulator) is Plane Power. After a lot of anguish, this problem has now actually been solved. My Tiger developed a bad case of noise in headsets. I took it to avionics repair experts and they diagnosed that my headset jacks were corroded, and intermittently shorting out. The problem showed up only when engine was running and was intermittent, due to mechanical vibration. The worst offender was jack on center console for handheld microphone. After an expensive repair and troubleshooting session, my intercom is now clean, no noise. I also see that my ammeter needle stays rock steady almost all of the time, and I see the normal, expected readings on voltage display of 13.9-14.1 volts. What I think was going on is that when the bus was being shorted out by the defective headset jacks, the voltage regulator thought that system voltage was low, so it was toggling the alternator field on and off. Wow, what a painful long exercise this was. Thanks for the help, glad to get this figured out and I hope nobody else has to go through this expensive and painful long duration exercise.
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I spent a lot of time trying to figure out similar issue in my 1976 AA5B Tiger. You may be seeing voltage regulator turning on and off the alternator field and that is normal. The speed of the clicks is somewhat in time with the engine RPM. Watch your ammeter needle if you have one, see if the click sound happens at the same time as ammeter deflects. It is normal for this type of voltage regulator to engage and disengage. Turn your headphones down and volume up on radios to avoid distraction from the sound. You can further prove this to yourself by changing the electrical load and seeing if behavior changes. Turn on lots of load by turning on pitot heater, interior lights, etc. You might see bigger but less frequent swings on ammeter. At low load levels, pings can be very frequent.
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My local mechanic advised me to figure out a plug for the cigarette lighter socket to prevent it from shorting out if it got moisture in it, or a coin dropped in, etc. My plane leaks a little if cover is off. Mechanic gave me a plug, but it did not really fit correctly and got stuck. I fished it out and got busy with my CAD system and a 3D printer. After a few iterations I made a perfect plug. If anyone wants more details on how to do this or would be willing to buy one of the plugs from me let me know.
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After some more study, it looks like the voltage regulator I have is probably working the way it was designed. It turns the alternator field off and on, and this causes the voltage to go up and down, and this causes current to go up and down as shown in the ammeter.
So, my next question is: are there any STC’s that allow for a better voltage regulation scheme? Like, something based on a modern concept like the transistor? Maybe something that smoothly modulates voltage and holds it to a steady value instead of pulsing up and down, hammering the mechanical part of the alternator and giving wildly varying spikes of voltage and current?
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I finally did a simple thing: removed chains connecting the cable to brake pedals. Parking brake is now plackarded “inop” and everything has been working fine. I wish I had done this much sooner rather than spending so much time thinking about it and trying to figure out other solutions.
Thanks for the people that helped me sort this out by phone and email. I appreciate it!
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Here is what I now understand after a conversation with a guru (Thanks, Roscoe!):
A design change was made in the 1978 model year to replace the chain system with a valve located on the firewall. This is not perfect or ideal either due to the need to replace o-rings. The new design can be retrofitted into earlier year planes without an STC, but form 337 is required since it is a change to hydraulic system. Approval from FAA should be a routine matter since design was approved already.
Based on talking to other experts:
The general consensus is to avoid use of parking brake unless absolutely needed. The only time I can think of where it would be important is if you were flying solo and needed to hold the plane in place for a few moments until you could apply chocks.
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