The International Cessna^® 170 Association

gahorn wrote:OK, Well, I believe I'm at the point where I can say without reservation that the RED and GREEN LED's, installed in the wingtip positions are GREAT! The color is correct, and the brilliance is as good at night as the original incandescent lamps. I am IMPRESSED!

I attempted to take pics but my camera doesn't do justice to the matter. Up-close, within 5' to 15' ....the LEDs appear to have small areas about 45-degrees right or left somewhat dimmer than incandescents. However, moving farther away, say farther than 25-30 feet, the diffusion of the light-angles dissappear and the LEDs appear every bit the same as incandescent, and just as bright. I'd venture that unless you knew about it, no one would notice. If I back off 50' and look at both airplanes, one incandescent and one LED, they appear exactly the same except in certain angles the LEDs have a sharper brilliance (probably the result of when an individual LED is pointed directly at you.) Even farther way, more than 150' the two systems cannot be distinguished, one from the other. I hope to get the DER in Austin to agree without an expensive program of something other than light-meters and color-check. Whether the SAT-FSDO "rear-seat-squad" will go along with it may be another matter.

George,
We missed you and Gar at the Convention.

Have you made any progress with the SAT-FSDO regarding substituting LED bulbs?
Johneb

Apparently you must think dealing with the FSDO-SAT is a simple one or two month matter.

If you want LEDs.... I suggest you read between the lines.

Remember, order the RED and GREEN LEDs for wingtip lights, and the white is fine for the tail. Don't look directly at them for more than a few minutes without sunglasses or a welding helmet.

George,
I did read between the lines. One issue I have noted is trying to achieve a consistant ground on the bulb base after filing off one of the bases locking pins. I have applied a single layer wrap of Aluminum tape to the base and this seems to help. Perhaps is these bulbs do win approval the bulb manufature will make some that have the pins in the proper location.

I have had no problem obtaining a consistent ground at the bulb base. I use Dow-Corning DC-4 Silicone Grease on all bulbs (regardless of type) when I install them. I do not think it wise to use aluminum foil on these bulbs due to corrosion and electrical-short possibilities with foil. If you encounter a "ground" problem I suggest you consider whether your existing fixture has a fault. (The removal of one pin on an 1156 type base bulb should not affect this installation.)

George, I can hardly believe what I am apparently reading here. I have alays believed you to be purer than the driven snow and maybe even purer than Ivory Soap. I simply cannot believe that you would actually even consider installing a "less than FAA approved" light bulb in your airplane. Is the TIC170A falling apart?
What kind of an example is this setting for the average member that does not have the vast experience of the leaders and the utter gall of bootleggers like me?
I'm sort of chagrinned that I didn't think of it first.

When the FSDO-SAT, Ol'Gar, all agree, and Rush and Newt come out of the closet and Nancy and O'Reilly admit to their affair...I'll bring my airplane out of the hangar and fly it with LEDs. Until then, you can rest assured that I don't have a clue what you're talking about.

that will be an exciting day. I assume the Vikings will win the Super Bowl as well

HA wrote:....I assume the Vikings will win the Super Bowl as well

Hey! I resemble that!!!!

George,
I just picked a tidbit of information, regarding LED lights, that is anecdotal at best, I heard that LED tail lights in cars are worth 20 feet in improved recognition reaction time.
Johneb

I showed Ol'Gar and Deana a demonstration of the LEDs and it's pretty amazing how bright they are. The green nav light fully illuminated a mesquite tree 30 feet away in the darkness and the tail nav LED completely illuminated the interior of the 50 X 50 open hangar 40 feet behind. It's amazing, and no more electrical draw than a watch-battery.

It's a shame George that you couldn't fly up to Duluth and demonstrate the illumination of the LEDs. Of course we probably could have had a demonstration at Duluth had we thought about it. Right johneeb.

Maybe The problem with trying to demonstrate LEDs in northern Minnesota is that it does not get dark until well after sane airmen are in bed (asleep ).

George, are you suggesting that if one were to find a way to use the LEDs for the wingtips, it would be wise to use colored LEDs and clear lenses so that the lenses don't reduce the light output or change the color?

Peace!

I'll beat George to the answer. As George found out about the same time that I informed him. Harley owners long ago it seems found out it is much better to use the same color LED behind what ever color lens you are illuminating. So you would want a red LED behind a red lens and a green one behind a green lens. If you were to use LEDs on an airplane.

If you use a clear lens you will get a red or green light but perhaps not the color we would like. At least without purpose built LEDs. And that is what we are talking about. Upgrading regular Grimes type fixtures with now readily available LED bulbs.

Has to do with light spectrum and filtering I'm sure.

Bruce has it correct. Think of it this way: If an incandescent Whelen or Grimes lamp (which puts out an IMPURE "white"....really a "warm-white" beam) is placed behind an aviation green or aviation red lens.... then the resultant glow is the product of that lens "filtering out" all the visible spectrum EXCEPT aviation red or green. So a large amount of the visible light spectrum which the incandescent lamp produces is.... BLOCKED by the colored lens. And that is a reduction of the output capability of that incandescent lamp.

But if a RED or GREEN lamp is substituted, then MORE of the desired spectrum is produced to begin-with....and LESS unwanted spectrum is blocked and therefore lost. The result is that for similar initial-outputs.... the colored lamps will eventually pass more of their light thru the aviation lens.

This was demonstrated when I first installed a "white" LED behind the colored lenses .and the visible result was not red or green... but was amber and blue. It turns out that very little of the light produced by that "white" LED was in the aviation red/green spectrums ...and therefore very little light passed thru the lens....and further what little light passed was not the desired spectrum (color) because so little of that spectrum was actually available to be filtered.

Additonally, I discovered the 5mm "super LED's" from the website were indeed much brighter in whatever color desired. Although those are slightly larger devices, and when fitted to the fixture they actually make contact with the colored lens.... I think that's a better lamp to use, and the physical contact between the LED and the lens is unimportant because vibration is not an issue with LEDs as it is with filament-type lamps which have glass globes.

Another point: The Whelen or Grimes wingtip navigation lamps can puzzle one who has never worked on them. The fixtures are not like automotive fixtures in that they are "bottomless". If one attempts to install/remove a lamp one might find it frustratingly difficult due to the "tightness" of the "fit" of the lamp within the socket. This is due to the threaded "ferrule" which holds the actual spring-loaded contact in the bottom of the fixture.

The Answer? Remove the entire fixture from the wing (this involves two simple phillips screws which mount it to the wingtip) and "unscrew" the ferrule a few turns. Or all the way, if you like. The lamp will now be easily removed.

Install the new lamp, then re-attach or screw the ferrule back onto the base of the fixture until "snug". (Don't force it too tight. The ferrule will accomodate lamps of various minor imperfections in this fashion.) Now reinstall the assembly back onto the wingtip. Reinstall te lens and lens cover/retainer, and enjoy!

You will likely only have to do this ONCE in your lifetime, as LEDs will outlast incandescent lamps by decades. (Use a dab of silicone grease or Dow Corning DC-4 smeared onto the base of the lamps. This will prevent corrosion over the long-term, and is a good idea for ALL types of lamps.)

As a concluding comment, I found the best LED for the WINGTIPS to be their 36 Super Bright S25 LED Light, Product Code: 49785 , Price: $13.99 ... RED and GREEN.
http://www.ledlight.com/s25-36-super-br ... light.aspx
For the TAIL, I found S25 39 LED Light , Product Code: 48451, Price: $14.99 in WHITE to be best.
http://www.ledlight.com/s25-39-led-light.aspx

In all cases, it is the 1156-base which worked for me, and I used a bench-grinder (but a file would also be fine) to grind off ONE of the pins on the base of the red and green lamps. This allowed it to fit the staggered-pin socket of the wingtip lamp sockets. The tail light does not need alteration. Nor does any interior lighting require alteration, as LEDs are made with the common bases already in use. (All the original aircraft interior lighting is common automotive lighting.)

Summary & Disclaimer: This is not an "approved" replacement lamp by authorities, despite the fact that Cessna has abandoned FAA-PMA lamps for taillight fixtures and now lists a common automotive lamp for the tail nav light, and despite the fact the LEDs will meet/exceed light output while drawing incredibly lesser amounts of current and produce nowhere near the heat of incandescent lamps. Whelen now produces approved LED navigation lamps for aircraft should this experiment convince you as well as it did myself, to convert to LEDs. <EDIT> However Advisory Circular 23-27 provides the basis of approval for using automotive lamps in aircraft built before Jan '71. I have been using these in my airplane now for 2 yrs and am very satisfied with them. One should make a log entry to the effect that LED "standard part" lamps have been installed as direct replacements. IMO