ccarter
Well Known Member
Okay fellow propeller heads try this one out..
I flew the "WindDancer" to Destin, FL this weekend to do 3 things for 2 days.
1) Sit in a beach chair and listen to the waves all day
2) Sit in a beach chair and listen to the waves all day and read a book
3) See items 1 and 2.
We departed DTS last evening for home after getting Clr Dev. from Eglin, climbed to 1k and turned east down the beach. After being cleared to turn north on course for MQY I started my climb to 5500'. After a few minutes my Dynon 180 gave me a low voltage warning on airframe power.
My procedure for this event is to first check voltage on the Dynon which indicated 11.4 volts. Too low. Next to switch the E-buss "On" which I did and the voltage came back up as it should but only because the Dynon would indicate a voltage having a more direct path to the battery through the diode. I did not "hear" anything unusual at all during run up or take off. The thought actually crossed my mind I may have lost the belt. More about that in a second. Next I checked the Garmin for airports close by. There were several within easy reach while on battery. My Dynon and Garmin 496 both have internal batteries plus the firewall battery through the E-buss is available for essentials.
I've had similar experience as many builders with the stock "Nipodenso" alternators and have actually replaced 2 in 300 hours since first flight. That is WITH a cooling blast tube. The duty cycle on those little guys was just too low.
About 15 hours ago I meticulously installed a brand new Plane Power alternator. I was a happy camper.
Naturally I'm thinking, "Okay, now what? Yet another Alt. failure!". I ran through the elec. system in my head (let one of the certified guys try that one!) and realized I needed to check the Alt Field CB. One glance told the story. The breaker had tripped. However, the question was why? The Plane Power Alt. has built in overload protection and doesn?t need the external ?crowbar? I have in the system. When I installed the Plane Power I didn?t bother with disconnecting the crowbar. Still shouldn?t be a problem. I considered landing anyway but after a minute of uneventful listening and watching I decided that the CB was there just for this purpose and fear of slamming the regulator while the engine was running was a risk I could take with the heavier Plane Power Alt. I wanted to reset it and see if it tripped once more and how fast if at all. When I pushed it in the power came back up immediately to 13.4 volts. Perfect! To be honest for a second I thought it actually might just trip again. If it did I was going radio ATC and land.
I have the basic "Bob" Z-11 electrical system including the crow-bar. I spent a fair amount of time making sure I understood the system before deciding to install it and became convinced it was what I wanted.
We flew along for a few minutes with no problems. I kept waiting, voltage was steady at 13.4 as it should be. So we continued on course for home and completed the 2 hour flight with no further problems.
I?ve had the Alt. CB trip twice on me in the entire 300 hours, each time it was during the previous 2 Alt. failures and I was on the ground as fate would have it. This is the first time it?s happened in flight and this time with the new plane power Alt.
Analysis:
The only two conditions I can surmise for this event are:
1) The crowbar did not like what it saw for a brief moment and did it?s job taking the Alt. field off line? voltage spike on a DC system? That doesn?t sound right. Maybe RFI from some antennae in the area? That sounds wild too. The aircraft has been meticulously grounded back to the grounding buss on the firewall.
2) Perhaps vibration joggled the CB enough (over time?) that it tripped of its own accord. These CB?s do fail. We found a brand new one on Mike Stansbury?s RV-7 that was bad.
Any other ideas?
I flew the "WindDancer" to Destin, FL this weekend to do 3 things for 2 days.
1) Sit in a beach chair and listen to the waves all day
2) Sit in a beach chair and listen to the waves all day and read a book
3) See items 1 and 2.
We departed DTS last evening for home after getting Clr Dev. from Eglin, climbed to 1k and turned east down the beach. After being cleared to turn north on course for MQY I started my climb to 5500'. After a few minutes my Dynon 180 gave me a low voltage warning on airframe power.
My procedure for this event is to first check voltage on the Dynon which indicated 11.4 volts. Too low. Next to switch the E-buss "On" which I did and the voltage came back up as it should but only because the Dynon would indicate a voltage having a more direct path to the battery through the diode. I did not "hear" anything unusual at all during run up or take off. The thought actually crossed my mind I may have lost the belt. More about that in a second. Next I checked the Garmin for airports close by. There were several within easy reach while on battery. My Dynon and Garmin 496 both have internal batteries plus the firewall battery through the E-buss is available for essentials.
I've had similar experience as many builders with the stock "Nipodenso" alternators and have actually replaced 2 in 300 hours since first flight. That is WITH a cooling blast tube. The duty cycle on those little guys was just too low.
About 15 hours ago I meticulously installed a brand new Plane Power alternator. I was a happy camper.
Naturally I'm thinking, "Okay, now what? Yet another Alt. failure!". I ran through the elec. system in my head (let one of the certified guys try that one!) and realized I needed to check the Alt Field CB. One glance told the story. The breaker had tripped. However, the question was why? The Plane Power Alt. has built in overload protection and doesn?t need the external ?crowbar? I have in the system. When I installed the Plane Power I didn?t bother with disconnecting the crowbar. Still shouldn?t be a problem. I considered landing anyway but after a minute of uneventful listening and watching I decided that the CB was there just for this purpose and fear of slamming the regulator while the engine was running was a risk I could take with the heavier Plane Power Alt. I wanted to reset it and see if it tripped once more and how fast if at all. When I pushed it in the power came back up immediately to 13.4 volts. Perfect! To be honest for a second I thought it actually might just trip again. If it did I was going radio ATC and land. I have the basic "Bob" Z-11 electrical system including the crow-bar. I spent a fair amount of time making sure I understood the system before deciding to install it and became convinced it was what I wanted.
We flew along for a few minutes with no problems. I kept waiting, voltage was steady at 13.4 as it should be. So we continued on course for home and completed the 2 hour flight with no further problems.
I?ve had the Alt. CB trip twice on me in the entire 300 hours, each time it was during the previous 2 Alt. failures and I was on the ground as fate would have it. This is the first time it?s happened in flight and this time with the new plane power Alt.
Analysis:
The only two conditions I can surmise for this event are:
1) The crowbar did not like what it saw for a brief moment and did it?s job taking the Alt. field off line? voltage spike on a DC system? That doesn?t sound right. Maybe RFI from some antennae in the area? That sounds wild too. The aircraft has been meticulously grounded back to the grounding buss on the firewall.
2) Perhaps vibration joggled the CB enough (over time?) that it tripped of its own accord. These CB?s do fail. We found a brand new one on Mike Stansbury?s RV-7 that was bad.
Any other ideas?
