Guys,
I had a problem tripping field breakers on my ES with the IO-550N. After troubleshooting the regulator and checking all the connections, and spoke to a gentleman at B&C (I've forgotten his name). He related that the problem is often the design of the engine mounted alternator. It is a modified automotive design that doesn't do well in the AC vibration environment, and the field wiring often shorts due to the vibration causing the insulating varnish on the wire to wear through and the field to short to the armature. He recommended have the alternator overhauled by an aircraft electrical shop in the Chicago area (I don't remember the name-great help huh) that he recommended their work. Not exactly Craig's problem as this only apples to the Main alternator.
As a possible work around he recommended reversing the field connections at the alternator. If the short is at one end of the windings it will still have a majority of the field resistance still in the circuit. I did this and by some miracle the problem went away. Not very elegant but it saved the cost of an overhaul and weeks of downtime.
Paul Bricker
Had similar issues with just the backup alternator system. I put a
recording voltmeter on the circuit to try to diagnose. Found
voltage spikes that tripped the regulator. Changed alternators,
batteries, a lot of wiring and B&C regulators before I found the
very slightly loose ground connection on the firewall. Hasn't been a
problem since. Would recommend a thorough check of all ground
connections on engine, alternators, batteries and into airframe
before replacing other "parts." I am convinced that your problem is
with a ground as that's probably the only common connection between
the two charging systems.
Barry Knotts
L-IV P, N4XE
On 3/5/2012 8:21 AM, Craig Gainza wrote:
Dear Listers,
Recently, I completed my annual and test flew the airplane.
Upon lifting the gear both primary and secondary alternator
field breakers popped. Pushed them back in and all charging
returned to normal on the primary and secondary alternators.
Landed, checked connections, put in a different battery, ran
through B and C voltage regulator troubleshooting guide (came
out normal) and did a ground run up. When lifting the flaps,
hydraulic pump kicked on both field breakers popped again.
Right now I am assuming it is the voltage regulator (both pri
and sec are B and C), alternator , or a connector.
Anyone have similar issues and can recommend the next course of
action?
Thank you,
Craig Gainza
IV-P TSIOF 550
782 hours and holding
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