Thanks for the input. I think I'll take a look
at the mounting space a little closer and see if
it can accomodate some isolation hardware.

Ronnie

"nrp" wrote in message
oups.com...
If you hold a 4509 light against your ear and hit it with your finger
tip, you can hear the high frequency lightly damped resonance of the
filiament supports. Thinking this resonance was somehow being excited
by the engine vibration and fatiguing the bulb filament, some years ago
I tried two fixes to get around the short life problem of cowl mounted
landing lights. Unfortunately I did both at the same time so I don't
know which one worked.

1) I sprayed silicon on the baffling seals whereever they touch the
cowl to minimize stick-slip engine vibration inputs to the cowl. I
also put some teflon faced tape on the cowl surface whereever the
baffles touched.

2) I removed the 8-32 mounting screws and added some 8-32 male ended
shockmounts and nuts to the landing light frame. This spaced it back
about 1/2 inch from its original position, but it still fit for my
cowling. I found the mounts in a surplus store although they look very
much like the $$ mounts that are used in the gyro instrument panel.
The purpose of the mounts was to add further vibration isolation from
the cowl and engine. Obviously this is not an approved fix, but I
suspect it is more effective than 1) above.

I'm still using the 4509 lites (2), but have not put in a new one for
at least 6 or more years.