Changing overhead map light bulbs

[aviator22]

Hi all, I'm trying to change the lightbulbs in the torpedo-shaped, overhead map lights, but having trouble figuring out how to release the bayonet-socket bulbs.

Please see the photos below.

Is the silver metal cuff with the vertical slots supposed to twist off? Or is the bulb supposed to rotate slightly at this point to release the bayonet? I can't get the metal cuff or the bulb to twist, and I'm afraid I'll break the bulb if I keep trying to force it. I've tried it on two of my overhead lights, and can't get either bulb to budge.

Thanks for any tips.

 

[Hank]

Generally, the brass base of the bulb twists a little bit. Often there's a spring behind it, pushing two tabs into forward slots so that it doesn't vibrate out. Push gently on the bulb and twist both ways, see if it loosens up. I've not had to replace these lights in my Mooney yet, but that was common practice "back in the day" for small bulbs.  

[N201MKTurbo]

It wouldn’t hurt to spray some lube in the base. They get a bit corroded after a few decades. 
 

Push It in and out until it loosens up. If you twist it too hard while it is stuck, you will twist the bulb out of its base.

[aviator22]

Aha, it never occurred to me to push it in. I'll try that and see if there's a spring behind it. Thanks for the tips.

[carusoam]

Welcome aboard 22!

If you have purchased the bulbs already…

The new bulb will give a hint of how it needs to be put in…

If it has two ears… they will go in slots… a rotation of the bulb will get the ears into the lock…

A spring is needed to keep the bulb in the lock…

Pushing gently will compress the spring… while rotating to move the ears in or out…

Be gentle, glass bulbs can break in your fingers…

Do a search for LED lights for that application… you might find some interesting reading… 

Pp thoughts only, not a mechanic…

Best regards,

-a-

[Bob E]

Here's what the bottom looks like.  What works for me is:  using a soft thin cloth, push down firmly and twist counterclockwise to remove.

Regarding an LED replacement:  The two overhead lights are the only incandescents remaining in my M20C, for two reasons:  (1) these are behind the rheostat dimmer, which LEDs don't like (I experimented), and (2) I haven't been able to find LED replacements for this particular bulb anyway.  The LEDs that fit the base aren't short enough to allow the torpedos to fit back on the clips.

However, FYI, it is possible to add dimmable 12v red LEDs in parallel to the existing lights.  That leaves the original lights intact.  It's a great solution, especially since I found some tiny LEDs mounted on a swivel base, which I simply added to the torpedos. Now there's light wherever I need it:  flap and trim indicator, notepad, whatever, and the LEDs dim right along with the original lights.

I lashed the LEDs to the to each torpedo with wire ties, with a thin layer of insulation in between since the torpedo gets hot.  It turned out that four LEDs were more than I needed (6 lights total), so I removed them from one torpedo.  Result = four independently adjustable lights.  I've used them for a couple of years now.

 

[aviator22]

Pushed the bulbs in and that worked. Thanks so much, everybody.

I tried some LED bulbs from both Aero-Lite and SuperBrightLEDs, but once you put the housings back on, they are noticeably dimmer than the incandescents. That's probably because most of their light comes out of the top of the bulb and not the sides. That was disappointing. 

[carusoam]

Great follow-up 22!

Best regards,

-a-