Flap indicator light replacement

[krellis]

I know this is an old thread and this is a slightly different issue. Our flaps up indication does not work. I've replaced the bulb with a new one and then a known good bulb - still no up indication. The flaps operate normally to T/O and LDG and to UP.

I suspect the flaps up microswitch (S1) is bad or out of adjustment. Any other thoughts or suggestions? Diamond tech support is minimally staffed for the holidays, so I don't expect to hear back from them until after the New Year.

Krea Ellis
DA40XLS N616ML

[carym]

I went thru several replacement bulbs (for one of my main landing gear gear-down lights) until I learned that the bulbs are directional and have to be put in so the contacts on the bulb meet the contacts in the socket. I found this out when I removed a good bulb and put it back in and it didn't work. I then called my mechanic who told me about the directional issue, so I carefully removed a third working bulb to see what direction it should be inserted. This solved the problem when I replaced the other bulbs in the correct position. Give this a try before worrying about a more complicated possibility.

[krellis]

I went thru several replacement bulbs (for one of my main landing gear gear-down lights) until I learned that the bulbs are directional and have to be put in so the contacts on the bulb meet the contacts in the socket. I found this out when I removed a good bulb and put it back in and it didn't work. I then called my mechanic who told me about the directional issue, so I carefully removed a third working bulb to see what direction it should be inserted. This solved the problem when I replaced the other bulbs in the correct position. Give this a try before worrying about a more complicated possibility.

Thanks for the suggestion. Interesting that an incandescent bulb would be directional, but the AMM does talk about LED indicator bulbs for the flap positions. LED's would be directional, but I'm surprised that they would burn out so quickly.

I will let you know what happens.

Krea Ellis

[krellis]

Cary,

You were spot on. While the bulbs are not polarity sensitive (like an LED), they can be installed such that they do not make contact with the pins in the base of the socket. So, it appears there are two proper ways to install them and many more incorrect ways.

Also, the DA-40 AMM refers in several spots to the LED bulbs in the flap position indicator. I did hear from Diamond Tech Support and there are no LED's in the indicator. They stated they will look at the AMM and correct it when they return from winter holiday.

Happy New Year to all.

Krea Ellis

[Urquhart]

Make sure the dimmer switches are all the way off (the two rotational knobs at the top left on the panel), if not clicked all the way off the flap light will not be illuminated

[krellis]

Make sure the dimmer switches are all the way off (the two rotational knobs at the top left on the panel), if not clicked all the way off the flap light will not be illuminated

Thanks. The flaps up indicator bulb was indeed burned out. The T/O and LDG indications operated normally, the flaps operated normally - all pointing to a burned out bulb and not a microswitch or wiring issue. The UP indication is constantly illuminated, so it is likely that this bulb burns out more often.

LED replacements would be welcome in this application, but I suspect they would have problems with dimming given the circuitry used in the 40.

Krea Ellis

[CFIDave]

LED replacements would be welcome in this application, but I suspect they would have problems with dimming given the circuitry used in the 40.

A few months ago when I had to replace a burned out flap position indicator bulb in our DA42, I noticed a change to Diamond's parts list that specifies LED lights can now be used as substitutes for the old incandescent bulbs. I looked up the LED part number and it's a standard automotive LED bulb available from multiple Internet sources. No change to the aircraft circuitry is required.

I was thinking of pro-actively replacing the identical bulbs in our DA42 gear position indicators, to minimize the chance of not seeing "three green" when I put the gear down (and to keep me from soiling my pants if a bulb burned out. :-D ). I've not replaced the incandescent bulbs with LEDs --- yet.

[rwtucker]

Embarrassing moment in my early time with the DA40. Forgot to shut the dimmer off after a night flight. Then forgot to retract the flaps for awhile the next day with a cockpit full of chatty people. No light to remind me!

[carym]

I was thinking of pro-actively replacing the identical bulbs in our DA42 gear position indicators, to minimize the chance of not seeing "three green" when I put the gear down (and to keep me from soiling my pants if a bulb burned out. :-D ).

Do it. Don't be like me an have that soiling pants episode I had in Alaska when I didn't get 3 green and had to do a fly by. Ground people said it looked OK, but I was still worried that one of the gear was not "locked".

A few months ago when I had to replace a burned out flap position indicator bulb in our DA42, I noticed a change to Diamond's parts list that specifies LED lights can now be used as substitutes for the old incandescent bulbs. I looked up the LED part number and it's a standard automotive LED bulb available from multiple Internet sources. No change to the aircraft circuitry is required.

Where did you find that parts list? I don't see the change in the AMM.

[carym]

Dave,
I found the information on LED substitutions. And, as I would have guessed by the well knon customer support, it is NOT allowed in the DA42, only in the DA42-NG or the DA42-VI. Another example of how Diamond is fully supportive of those of us who took a chance with them and purchased a DA42