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Went out to the aircraft this morning to check out
the alternator problem I encountered returning from Sun & Fun. The
symptoms were lower than normal alternator voltage (13.8 vice nominal 14.8) and
field coil circuit breaker popping three times.
It appears that the cause was insufficient tension
on the belts. I drive the alternator with two belts which also wrap around
the water pump. I reached in an grabbed the pulley hub of the water pump
and could easily turn it against the belt tension. My alternator is
undedriven by approx 40%, so any further reduction is speed (due to slipping
belts) apparently is just too little pulley speed.
My voltage guardian pops the circuit breaker
whenever it encounters either an overvoltage or undervoltage condition. I
have the undervoltage limit set at 13.8 volts which was at the border line of
what the alternator was producing. So apparently the voltage dropped
below that on occasion and that apparently resulted in the popped
CK.
Tightened up the belts and voltage was back to 14.6
and battery up to 12.8 volts, so all appears to be well. Glad it was that
easy.
Ed
Ed Anderson
RV-6A N494BW Rotary
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Matthews, NC
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