Cessna Dome Lamp

[Clip4]

I have flown late 70s and 80s Cessna 182s over a lot over the last30 yesrs. I never could figure out why the bulb in the dome lights would burn out so quickly until last week. I swapped out a GE 1818 bulb for an LED equivalent. With the slider switch in the off position, there was a faint amount of light coming from the LED bulb. The switch was allowing reduced current. Probably across corrosion within the switch. You could never see this with the incandescent bulb.

 

[dmspilot]

If we are talking about these, they are god awful switches. I'd recommend replacing them every 10 years. They can be found for a few bucks each if you don't care about them having a Cessna part number stamped on them.

 

[Dan Thomas]

If we are talking about these, they are god awful switches. I'd recommend replacing them every 10 years. They can be found for a few bucks each if you don't care about them having a Cessna part number stamped on them.

View attachment 151278

Those dome lamps used a slide switch, like this:



The rocker switches as you showed have been known to go for 40 years and more. I seldom replaced one unless it was a landing/taxi light switch. Like all switches, their contacts oxidize with age and there's also a small arc every time it opens, and the contacts start presenting a resistance to the flow; generating heat. Even then, most of the failed (like melted) landing light switches got hot because of an oxidized crimp terminal connection that got hot, not because the switch was defective. Changing to LED landing lights lowers the load dramatically on those switches.

Cessna recommends changing those landing light switches about every four years. Go here for info about that, and for a price of $8.95:

https://www.aero-lites.com/product-page/cessna-rocker-switch-replaces-s2160-1-s1824-1-s2061-1-new

I remember when they were only a couple of bucks, about 20 years ago.

 

[Clip4]

If we are talking about these, they are god awful switches. I'd recommend replacing them every 10 years. They can be found for a few bucks each if you don't care about them having a Cessna part number stamped on them.

View attachment 151278

Not that good.

 

[3393RP]

Cessna recommends changing those landing light switches about every four years.

It would be interesting to peruse the maintenance logs of the average 1970s vintage Cessna 182. I'm guessing one wouldn't find evidence the landing light switch has ever been proactively replaced, but only after failure.

 

[dmspilot]

The rocker switches as you showed have been known to go for 40 years and more. I seldom replaced one unless it was a landing/taxi light switch. Like all switches, their contacts oxidize with age and there's also a small arc every time it opens, and the contacts start presenting a resistance to the flow; generating heat. Even then, most of the failed (like melted) landing light switches got hot because of an oxidized crimp terminal connection that got hot, not because the switch was defective. Changing to LED landing lights lowers the load dramatically on those switches.

Just because they can go 40 years, doesn't mean they should. They are not good switches. The average Cessna has worn out rocker switches that feel soft and don't snap anymore like they are meant to (and do when they're new).

 

[Gary Ward]

Years ago I replaced my dome light with LED the night I got my plane back from the avionics shop with a new panel.
The next day when started it during the day lite I had non stop static in my new radio, both of them. I flew it across town to the avionics shop and they found I left the dome light on from the night before and that one bulb was causing the noise. Embarrassing.
10 years later I still have the same LED bulb installed, now if I hear static I know I forgot to turn the dome light off. I only use the dome light on the ground with the plane off.
All my other lights are LED, the dome light is the only one making noise, I don't use the dome while I am flying.

 

[Dan Thomas]

Just because they can go 40 years, doesn't mean they should. They are not good switches. The average Cessna has worn out rocker switches that feel soft and don't snap anymore like they are meant to (and do when they're new).

Just because they're worn out after 40 years doesn't mean that they aren't good switches. How many POAers are driving 40-year-old cars in which everything still works and has never been replaced? Yes, I know that cars get driven more than airplanes get flown, but much of the failure is due to age, not hours. Plastics degrade, metals oxidize. Nothing lasts forever, not even really good switches. Cessna could have spent a lot more money on switches and many other items, but then the airplane would have cost more and would not have been competitive with other OEMs that used cheaper stuff.

Cessna, in the early '60s, used a push-pull master switch that is not made anymore. Its contacts were lubricated with a white grease made for stuff like that. After 60 years the grease dried and hardened and became an insulator between the contacts. No replacements available other than used switches just as old. I had to open those switches and clean and relube them, or else spend a lot of expensive shop hours modifying the panel to install a modern master switch.