PA28 Low Voltage Light

On 22 Sep 2005 13:02:19 -0700, "Dave"
wrote:

Hi people,

Our PA28 has developed a problem. The Low Voltage indicator keeps
coming on. The engineer has replaced the Voltage Regulator which didn't
solve the problem at all. Then he changed the Overvolt relay. I flew it
for 50 minutes with no problems and then the next time I took it up
(some days later) the light came on within 10 minutes of takeoff, then
7 more times in the 1 hour flight.

It comes on at seemingly random times and can be reset by recycling the
alternator switch. Sometimes it stays off for 10 minutes, sometimes
half an hour (which makes tracking down the problem even harder!)

Get a voltmeter on the aircraft bus, have someone go flying with you
and have that person monitor and notate the voltages over time.

There are a lot of failure modes and failure points in a Cherokee
electrical system. Getting a handle on the bus voltages throughout
the course of a flight is a great start to finding the problem.

Grab the data, post it here, and we'll be able to generate solid
answers vs. a shotgun replacement mentality.

: Grab the data, post it here, and we'll be able to generate solid
: answers vs. a shotgun replacement mentality.

... which is unfortunately the typical "repair" procedure for electrical
gremlins. Gets expensive quickly and is almost always completely unnecessary.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
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