327 / 387 lamp vs LED
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327 / 387 lamp vs LED
Has anyone replaced 327/387 lamps with the Light Emitting Diode (LED) version in the Master Caution/Warning annunciator panel? I’m interested in something like a King Air, 1900, any aircraft that has a large block of annunciators that use a pair of 327/387 lamps to show status. If you have, is it a do it once like it should be (4,000 hours for a 327 vs 100,000 hours for an LED MTBF rate) or do you end up changing them more often than you would have thought you would?
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I don't know about the application you speak of, but I have replaced 387 bulbs with LED ones in the coffee maker ON/OFF annunciator light in a B767. Seems to work well, lasts a long time. And these coffee makers are mostly in the ON mode, all the time!
Join Date: May 2000
Location: coventry, uk
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I've passed the spec sheet on the airframe manufacturer for feedback, although I'm sure they will come out with a more expensive fix!
http://www.datasheetarchive.com/pdf/...874.pdf&scan=n
Phil
We had a retrofit program for the Nav Lights from incandescent to LED, but the MTBF rates were never met, a lot better than they used to be though.
http://www.datasheetarchive.com/pdf/...874.pdf&scan=n
Phil
We had a retrofit program for the Nav Lights from incandescent to LED, but the MTBF rates were never met, a lot better than they used to be though.
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One big problem,
The annunciator dimming will not work, LED,s work at the rated supply voltage and will only dim if an electronic assembly is developed and fitted that would track the existing dimming system.
Some annunciator manufacturers, Vivisun for instance, make LED annunciator assemblies that will work and the electronics are encapsulated in the annunciator head
The annunciator dimming will not work, LED,s work at the rated supply voltage and will only dim if an electronic assembly is developed and fitted that would track the existing dimming system.
Some annunciator manufacturers, Vivisun for instance, make LED annunciator assemblies that will work and the electronics are encapsulated in the annunciator head
Thread Starter
Interesting, I did not think of the dimmer circuit. Not sure at the moment if our simulator even dims at all, will have to check that detail out. It also might ALWAYS be in dim, since the cockpit is darker than the real world.
Did find another problem, white LED's (or at least the ones I picked up) work ok in the Red Warning panel, but when installed in one of the caution (amber) places the light becomes yellow instead of amber. Must be the light temperature. I had hoped to use just a collection of white, but might have to use different colors for different spots.
Thanks.
Did find another problem, white LED's (or at least the ones I picked up) work ok in the Red Warning panel, but when installed in one of the caution (amber) places the light becomes yellow instead of amber. Must be the light temperature. I had hoped to use just a collection of white, but might have to use different colors for different spots.
Thanks.
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Yup you need to make sure if there is a coloured lens on top that the LED is either that colour, or you might be able to get away with white. The 100,000 hours does depend a lot on how you drive them, obviously if you are driving them harder than you should (more power), they aren't going to last as long. The main advantage IMO is that they are really rugged!
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KLM is installing LED lights in all the Fokker 70's interior, eventually it will save 20 % energy and a approx. weight of 8 kg.
And of course it lasts longer and the light will be distributed better in the cabin.
source: KLM Cityhopper / Wolkenridder
And of course it lasts longer and the light will be distributed better in the cabin.
source: KLM Cityhopper / Wolkenridder
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I point to consider for LED life in aircraft is the voltage.
A 12 volt system may run at 13.8/14 volts and a 24 volt will be 27.6/28.
So 12/24 volt LEDs are a nono use 14/28 volt. Some lamps can have voltage regulators built in, these can use pulse width modulation, to hold the light output constant and protect the LED with changing voltages. Switching at very high frequency can radiate RFI, affecting radios ect. I have this problem on my 23ft cabin cruiser, the 15watt LED bulbs wipe out the VHF FM radio.
I would only fit 14/28 volt none voltage regulated bulbs and if dimming is required, then have mechanical shutters on the bulb holders.
A 12 volt system may run at 13.8/14 volts and a 24 volt will be 27.6/28.
So 12/24 volt LEDs are a nono use 14/28 volt. Some lamps can have voltage regulators built in, these can use pulse width modulation, to hold the light output constant and protect the LED with changing voltages. Switching at very high frequency can radiate RFI, affecting radios ect. I have this problem on my 23ft cabin cruiser, the 15watt LED bulbs wipe out the VHF FM radio.
I would only fit 14/28 volt none voltage regulated bulbs and if dimming is required, then have mechanical shutters on the bulb holders.
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One operator here has replaced all warning lights using 327 and 387 lamp assys with a drop in LED assy. I took the panel off yesterday and they are manufactured by Korry and have a part number 434-1031-2001. Maybe a call to their marketing dept may shed some light on SB's STC's etc.
Rgds
TC
Rgds
TC
