Service difficulty report · Regulator · Diamon DA42

Difficulty date
February 5, 2013
Submitted
February 6, 2013
Operation
General aviation
Aircraft
N903ER
Make and model
Diamon DA42
Aircraft serial
42280
Aircraft time
2,626 hours
Part
Regulator
Part number
VR2000282
Part serial
J090513
Condition
Loose
Location
Electrical Sys
Part time
2,626 hours
Stage of operation
CR
How discovered
O
Nature of condition
J
Precautionary procedure
A

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

DOUBLE ALTERNATOR FAILURE. RT ALTERNATOR SPIKED TO 37.5 VOLTS THEN RED X'D. ABOUT 10 SECONDS LATER THE LT ALTERNATOR DID THE SAME THING. DURING THE TROUBLESHOOTING, IT WAS DISCOVERED THAT THE TWO CIRCUIT BOARDS INSIDE OF THE ACU/VOLTAGE REGULATOR WERE NO LONGER ATTACHED TO THE CHASSIS AND THE MOUNTING HARDWARE AND STANDOFFS WERE LOOSE AND SPORADICALLY LAYING ON THE COMPONENTS OF THE THE TWO BOARDS CAUSING SHORTING AND RANDOM SPIKING OF THE ALTERNATOR OUTPUTS. THE FUSE DESCRIBED BELOW, WHEN OPEN, DOES NOT ALLOW FOR THE ACU TO SENSE THE VOLTAGE, THUS CAUSING EXTREME ALTERNATOR OUTPUT. TROUBLESHOT SYSTEM REPLACED LEFT ALTERNATOR CONTROL UNIT P/N VR2000-28-2, INSTALLED P/N-VR 2000-28-2. REPLACED 3A RIGHT SIDE OF SHUNT FUSE P/N-263003. PERFORMED SYSTEM OPERATIONAL CHECK. VERIFIED CHARGING SYSTEM OPERATIONS WITH LOAD AND NO LOAD, VERIFIED ALTERNATOR PARALLEL SYSTEM IAW DA 42 L360 REV 5 SECT 24-30 AND 92.

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