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1983 M20J: left nav light died


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Hi folks,

I noticed that the left wingtip nav light stopped working in my 1983 J model.

I have no idea if it's the bulb or the connection or something more serious, but since bulbs are cheap and 14 CFR part 43 appendix A specifically calls out

(17) Replacing bulbs, reflectors, and lenses of position and landing lights.

as preventative maintenance, I thought I'd give replacing it a try.

How would I go about figuring out what kind of lightbulb I need to replace it with? 

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Yes, replacing nav light bulbs are most certainly something the owner pilot can carry out provided that the task doesn't involve any crazy tooling or procedures (it doesn't).

Most M20J nav lights use a half-dome type bulb (usually Type 7512-12) that you can easily purchase online (namely Aircraft Spruce). An easy method of identifying the bulb you have is to remove the bulb and look if there's any markings on it that may give you a hint of what it exactly is.

As for determining if the bulb failed vs. something else ... one easy way is to look at the bulb's insides to see if the filament is broken. If it is, bulb's dead. If not, then try checking the bulb with a multimeter and if that still checks out OK, then check for aircraft voltage at the bulb receptacle tip compared to the receptacle housing. Statistically, the actual wires in an aircraft rarely fail, so I doubt you'll need to be fishing wires out of the wing.

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Not sure if its the same as the one that came on my ovation, but be careful when you take the bulb out.  That colored lens will suddenly liberate itself from the wing tip and if it hits the floor it will cost you $40-80 depending on how good you are at ebay.  

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These aren’t cheap. Lots of folks are going to LED replacements. Just be aware that some LED bulbs seem to cause the Gear Down annunciator light to be dim all the time (if all nav bulbs are replaced with LEDs) because of interaction with the nav light circuit.

515528026_Screenshot2021-03-01at7_20_26PM.thumb.png.33d8dbcb804af33702a8bc531fafffbd.png

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I took the old bulb out and confirmed that the filament is indeed broken, which is great news for me!

The socket appears to be a GRIMES A-1825, but the bulb itself just says "G-22 SL" which doesn't get any Google hits.

Here are the pics: https://photos.app.goo.gl/MvHAWMgCH3xYdTCn6

 

The bulb definitely seems very similar to https://www.aircraftspruce.com/catalog/pnpages/11-01964.php?gclid=Cj0KCQiAvvKBBhCXARIsACTePW8DLqaCPcY7osB0H_CSIOm9N94dzaRjYDia7Zaiaj0MvCDJ766jFrgaAok0EALw_wcB, however "A-1825" is not listed under the "Grimes P/N" compatibility table on this page.

 

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Grimes is probably the original light bulb manufacturer for the Wright brothers...

If you can’t figure out the part number or get a replacement...

Talk to Dan at Lasar... he is the Mooney parts guy guru...

You might be the first person to ever wear out a nav bulb.... :)

Best regards,

-a-

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1 hour ago, carusoam said:

Grimes is probably the original light bulb manufacturer for the Wright brothers...

If you can’t figure out the part number or get a replacement...

Talk to Dan at Lasar... he is the Mooney parts guy guru...

You might be the first person to ever wear out a nav bulb.... :)

Best regards,

-a-

Nope, my green bulb recently burned out, so it does happen!  

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