A question for DARs on lighting

[Don]

When I bought my tail kit I also bought Whelen lights from Van's. I have no doubt these meet or exceed the FARs. I've been considering switching to LED lights (position lights and strobes) produced by Thor, LLC (www.thorllc.net). I first encountered Frank and his wife at the Virginia EAA Fly-In and I encountered them again at Oshkosh last month. The reason I'm considering changing are the Thor lights weigh less than a pound, they eliminate the "controller" for the strobes that's heavy and produces extraneous RF noise (instead the Thor units have a small circuit boad that's installed near the lights), and they offer the promise of better reliability.

When I asked Whelen about their plans for an LED lighting system they got downright defensive and declared that the technology for 12v LEDs wasn't capable of meeting the FARs. They claimed no one could use 12v LEDs and comply with the FARs. They said the LED maker they were familiar with (no names were used) had a disclaimer on their website about not promising to meet the FARs. Finally, then they played the emotional card about how this is all about safety and why would I consider anything that isn't thoroughly proven.

As I evaluate Whelen's statements, I see no disclaimer on Thor's website. In fact I also see Thor specifically states, "our light systems [are] built to meet and exceed all FAA regulations", which I read as a warranty of sorts, provided you install the lights correctly. When they tried to win me over based on an emotional argument, they've lost most of my respect. I want to see data in an argument - when I want my heart strings plucked I'll watch a sappy movie.

So, my question is this, when you guys inspect an airplane I'm sure you evaluate the lighting system for compliance with the FARs. I'd expect you'd base issuance of the airworthiness certificate and the day/night limitations in part on what you find. If I go with the Thor, LLC lights will I be setting myself up for trouble when I apply for an airworthiness certificate? Or, will Thor's statement plus your inspection be enough to satisfy this part of the inspection?

Don

[gmcjetpilot]

I had the same question so I went with a Aeroflash "traditional" system. Here is the short two part answer I found:

Part one - You are experimental. Your lights can be experimental. Done

Part two - Experimental LED nav/strobes probably don't meet the FAR's, see part 1.

The measurement of light intensity, color, coverage is a fairly complex archaic convoluted science. I am pretty sure experimental light makers don't do more than stand back and go, looks good. From what I know about the requirements, just by inspection I can see many (all) don't meet the requirements. The one you mention looks questionable in my opinion.

The other side of the coin is the coverage, color and / or intensity is too much. Too bright and too much coverage with a NAV light is NOT GOOD. You want a standard so all planes look the same from similar direction and distance and angle.

I looked into making my own NAV lights and talked to a guy who tried to make LED nav lights that met the FAR's. He was very scientific and used the FAR's as a guide and optical and electrical characteristics of LED's. He took an engineering approach. I was left with the opinion that making LED's per the FAR is difficult (12/24v). If anything the measurement and calibration is hard with out optical lab.

The 12v and 24v thing? No doubt it is what LED's are available and the technology at this time. Frankly most LEDs run down in the 2-3 volt range, so I am not sure about that.

I have talked to Whelen and they gave me the same info, some was wrong as applied to experimentals, especially strobes (see part 1 above). You could if you wanted get a step up 12 to 24 volt converter. However spending $200 on a 12/24v converter and very expensive 24v Whelen NAV lights will cost too much and be heavier. I get the feel Whelen is just jealous that we have the freedom we do. No doubt they went through grief getting their 24v LED Nav lights certified. BF Goodrich also has LED lights.

Right now the only inexpensive NAV light that works on 12V that looks like it should work is a taillight (white) NAV light. You can get white LED's that are super bright AND have a wide range. The catch 22 of LED's is as intensity goes up the coverage or angle narrows. Also, finding red and green LED's in the correct wave length, intensity and angle is not easy (impossible at this time). Therefore you get these 20 or 30 LED monsters. The good news LED technology keeps improving. Someday they'll have single LED's that will fill the bill, but right now it's marginal in my opinion, at least in the 12v according to Whelen.

If you want to use your experimental NAV lights go ahead (see part 1). You are experimental and so are your lights.

If you are into meeting FAR 23 and other FAR's that apply to certified planes (as I am when possible), than get "real" NAV lights.

Bottom line, Whelen is probably right, but so what, we don't have to buy there stuff. I have Aeroflash strobes/navs. Whelen told me that they where not good or acceptable. I checked with the FAA, more than once and they are fine even if the Joules are down a little (see part 1 above). The answer was "you are experimental, right?", "your plane is not certified, right?".

If you want to have a high level of confidence your lights meet the regs (if that is what you want), than the only way to assure this is buy a certified system, like Whelen or test what you install. The latter test may be hard to do for an individual. That's probably where Whelen is coming from, we have done the test so buy our stuff. The few amps and pound of savings LED's would save me, was not enough for me to use them, at this time.

As far as DAR's, that is up to them, but I have been told they don't get into the lights. According to the FAA inspectors I have talked to it would not be an issue. Remember YOU the builder certify the plane for NIGHT FLIGHT with a log book endorsement, not the FAA or DAR.

[Mel]

The DAR will inspect your lighting system and advise you accordingly. This is just a courtesy. Your operating limitations will state:
"After completion of phase I flight testing, unless appropriately equipped for night and/or instrument flight in accordance with part 91.205, this aircraft is to be operated under day only VFR."
This puts the monkey on your back. If your lighting system meets 91.205, then you are good to go. In the real world, if your system looks like it meets 91.205, no one is going to question it. One of the few things people overlook is the light coverage. If your wingtip strobes cannot be seen from the rear, then you must have a tail strobe as well.

[Davepar]

Originally Posted by gmcjetpilot

The measurement of light intensity, color, coverage is a fairly complex archaic convoluted science. I am pretty sure experimental light makers don't do more than stand back and go, looks good.

From the CreativAir web site: "If assembled properly, the LED Position Lights meet or exceed the FAA illumination requirements in all directions. Step-by-step instructions on how to confirm FAA illumination compliance are included in the kit."

[az_gila]

Originally Posted by Davepar

From the CreativAir web site: "If assembled properly, the LED Position Lights meet or exceed the FAA illumination requirements in all directions. Step-by-step instructions on how to confirm FAA illumination compliance are included in the kit."

The key is to ask them specifically "have you tested the instalation to see if it meets the FAR requirements?"

From some earlier e-mail traffic on the subject, the answer seemed to be "I copied what Whelen did and used the same LEDs"

Not quite what you want if you want regulatory compliance.
Did Whelen select high power LEDs from the standard part number? - more $$ for selected parts.
Did they copy the exact light reflectivity of the surrounding materials? - makes a big difference to the light distribution.

Note the the FAR requirements have very specific output requirements in the "overlap" area where two nav lights can be seen.

I agree with George - the tests need to be done on a similar installation to the one you are constructing....

Given my knowledge from a long time ago past job (Chief Engineer for a light measuring equipment company) - these are not trivial measurements - but could be performed with the correct, calibrated equipment in a dark room.

gil in Tucson

[gmcjetpilot]

Originally Posted by Davepar

From the CreativAir web site: "If assembled properly, the LED Position Lights meet or exceed the FAA illumination requirements in all directions. Step-by-step instructions on how to confirm FAA illumination compliance are included in the kit."

That is fine, I would like to read it. The info is available from the FAA and found in several references, FAR's and Advisory Circular (AC). It's not that I don't care, but it does not matter it is experimental. If it is close it is good enough.

The part about exceeding the REGS means what? Well you don't really want to exceed the coverage, angles and intensities. Will it create a safety hazard if its a little too bright? No. If coverage is too great it could be a little confusing to other planes I guess. Again no big deal.

On the fine points of really measuring light intensity, angles, wavelength and coverage, is it seems really complex. If you look at the regulations, specs and AC it is pretty complex physics, at least to me. The units are crazy.

Certainly you can SWAG it. Most guys get about as scientific as "I turned it on in my garage, and it was REALLY BRIGHT! I walked out side, and I could still see it DOWN THE STREET!" That is good enough. Good enough for me, but if you really want to know or have a "certified NAV Strobe" light system it will take a lot more than that. To be honest some of the experimental systems look suspect to me. For example:

-Strobes, with out a lens is not kosher. They have a max intensity at one plane not a all over scatter pattern of a bare strobe tube.

-NAV lights, some look like they just shotgunned as many LEDs as they could fit. Using LED's to do this is tricky. One "trick" I see is the use of reflectors, aka mirrors, since LED's are throwing a way light to the side. You also have to shield that extraneous side lobe light as well for proper coverage.

Hats off to those who try to make their own. However those who sell them need to do some home work (no names mentioned). LED's are getting better, wider patterns and more intensity, while price drops.

Again it does not matter it is experimental and you (the builder) are boss. If you want to make your own system it would be fun. If you get into the regs and rules you will learn a lot. I started to look into it thinking you could throw LED's in there and it was more effort. I kind of wanted to know I had a "standard" system so I went with aeroflash.

LED's are getting better, wider patterns and more intensity, while price drops. When they can make a system that only needs one or a few LEDs I'll buy one. Right now those Christmas trees don't appeal to me. What if one burns out. Get a solder iron.

[Paul Thomas]

I think I had read about a cozy builder whose DAR would not issue an pass the airplane until the leds were removed. The gentleman had to remove them because once you start the paperwork with one DAR, you can't switch because you can't work out your issues.

I hate to bring something like this to the discussion because I can't recall the exact facts or where I read about it. Hopefully this will job someone's mind.

[rvpilot]

"After completion of phase I flight testing, unless appropriately equipped for night and/or instrument flight in accordance with part 91.205, this aircraft is to be operated under day only VFR."

If you look at 91.205, it calls for "approved position lights", "approved red or white anticollision lights". Since the exp LED systems are not approved, just meet or exceed the requirements, then do you really meet the above requirement as entered in the flight restrictions by the DAR???

[aadamson]

This one also claims they meet the standard.

www.gs-air.com

I saw a Lancair Legacy at OSH, that had the strobes and nav lights embedded in the tip of the wings and then on the trailing edge of each wing at the tip, they had a row of white LED's... Nothing on the tail. Just goes to show you how much people with get away with...

[az_gila]

Originally Posted by aadamson

I saw a Lancair Legacy at OSH, that had the strobes and nav lights embedded in the tip of the wings and then on the trailing edge of each wing at the tip, they had a row of white LED's... Nothing on the tail. Just goes to show you how much people with get away with...

Alan... this is actually quite legal.

Quote from 23.1385
(c) Rear position light. The rear position light must be a white light mounted as far aft as practicable on the tail or on each wing tip.

And is similar to the "all-in-one" Whelen A600 units, which I have seen on large commercial jets.

But I bet they never measured the intensity in different planes, which is the "getting away with it" bit...

If you can't go to sleep, and want to know some physics, then this describes the "candles" of light intensity that the FAA uses in FAR 23. Note that the correct modern terminology is "candela", not "candles".

http://en.wikipedia.org/wiki/Luminous_intensity

gil in Tucson - reliving an old job....