Greg Farris wrote:
In article ,
says...


"Michael" wrote:
Light bulbs have a very long MTBF, especially DC bulbs.

Depends how you run them. If you're trying to get the most illumination
for a given electrical power, you run them at full rated voltage and get a
relatively short lifetime. On the other hand, if you run them at less than
rated voltage, you get much lower conversion efficiency, but also much
longer lifetime. I'm guessing that most panel lighting bulbs are run this
way.


Unless it's a rental - and you find that all the panel lights are full-on
during the day for nobody knows how long. The plane hasn't flown at night for
over a month, but has logged 80h in daylight during that time. There are no
spare bulbs in the plane, and obviously the FBO won't replace them unless
they are actually burnt out.

Yeah, but even with the knob turned to full brightness, they're
probably not running at the voltage the bulbs are rated for.