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  Intermittent Alternator Out Light




Does your Beechcraft Alternator Out light flicker or come on and you confirm that your alternator is working just fine?


If it does this then you might have a cracked alternator out light printed circuit board. This circuit board is subject to all the engine vibration that occurs out there and has been found to have a tendency to crack.


PS: If you even THINK you need an alternator or starter rebuild, repair or overhaul, you've got to check out Modified Aircraft Accessories. I've been using them for my needs for over 15 years and there's none better in quality, service or price. See narrative page HERE


Here's a fix for the circuit board contributed by Beech Lister Eric T.





Above is a photo of the repaired mini-PCB Board. The resistor is on the other side of the PCB.  The copper wires at either end were my add.

Initially I took the circuit board and checked for continuity and it seemed that the traces on the circuit board cracked causing the open circuit.  I then took some thin gauge copper wire, and soldered a loop from where the resistor passed through the circuit board to the terminal mounting pads at the ends the circuit board.  The notion being to provide a more mechanically robust conductor from the resistor to the terminals at the ends of the circuit board.



Here's a pirep from F33 owner Shep J., regarding his experience with a flickering Alt Out light:

"I have CE-559 and my Alternator OUT light would sometimes flicker, and sometimes stay on for long periods despite the alternator charging normally. The cause was an old fuse that had a loose filament that would vibrate and make an intermittent connections. Try replacing the fuse first, it is easy and cheap. If that doesn't do it check the AUX terminal at the alternator for a loose connection. The fuse block is located on the firewall on the pilot side." As seen below.



A great article in the October 2008 ABS Magazine, written by John Collins on page 10998 and 10999, discusses the history of the alternator out lights and their components and how they work in the system.


Some very interesting Beechcraft parts, available at RAPID,  outlined in this article that could be of interest to you and your mechanic in repairing or retrofitting your system with alternator out lights are:


P/N 36-380000-1 (14V Alternator Out Sensor) $196


P/N 36-380000-3 (28V Alternator Out Sensor) $138 (as of 5/20/2014)


P/N 36-380000-11 (Baron Replacement Alternator Out) $119


P/N 55-3025-1 S (Replacement PCB Kit) $108


Here is the pdf for the Lamar Alternator Out Relay



Here is more info on the Lamar sensor from a Beech Lister, Mike Ter.:


The basic circuit of the Lamar alt inop sensors is:  Green wire gives ground for warning light through the sensor's black wire.  Raw voltage from the alternator stator post (aux) is supplied through the red wire.  When the voltage from the red wire meets the voltage from the green wire, the ground circuit is disabled for the green wire and therefore the warning light goes out.  The red wire from the alternator is usually protected by a fuse.  If you ground the wire that attaches to the green one and your lamp lights up, the circuit is ok.


If the lamp does not light up when the sensor is correctly wired then you sensor is bad. The Lamar PN for the 28v sensor is A-00258-2.  You can get them at Aviall.  It retails for about $120.


For more info on an Alternator Out Light Install click HERE