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Reasonable qualification for flight hardware?

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nuckollsr(at)cox.net
Guest

Posted: Wed Nov 08, 2006 6:47 am Post subject: Reasonable qualification for flight hardware?

At 07:23 AM 11/8/2006 -0700, you wrote:



 	  Quote: 	
		  I am testing out a new LED comet-like flasher and 48-diode lamp to be used 

as a beacon under a clear rudder tip fairing.  Both are inexpensive 

Chinese imports designed for automotive application.  Brightness and flash 

rate/pattern are very good, but I was wondering what is a "reasonable" 

test period to run the thing on the ground before installing one in the 

OBAM plane?  100 hours, 2000 hours?


	


   Why not use the OBAM aircraft as the test bed. It's

   your airplane and nothing is preventing you from using

   whatever lighting schemes you choose.

 	  Quote: 	
		  

Clearly it should also depend on whether there is any failure, whether the 

failure is the lamp or the flasher, and whether it is a single diode burn 

out or total failure.  Also, after the testing, which will not be 

comprehensive like a commercial venture (no statistics here), would it be 

preferable to install the already-tested hardware or a completely new set?


	


   Is it your desire/intent that this product meet

   FAA requirements for lighting under FAR91? That's

   a wholly different ball game. Here the questions are

   not so much one of service life but of gross intensity

   along the various axis external to the aircraft. A really

   tedious test to do and requires some equipment with

   reasonable expectations for accuracy.



   Bob . . .



      ---------------------------------------------------------

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

      ---------------------------------------------------------

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N6030X(at)DaveMorris.com
Guest

Posted: Wed Nov 08, 2006 9:15 am Post subject: Reasonable qualification for flight hardware?

You probably need to find out whether the FARs on light intensity 

apply to experimental aircraft or not.  Google around a bit, because 

some pretty smart people have already done a lot of testing of LEDs 

for use in aircraft external lighting.



It is common in the electronics manufacturing world to do "burn-in" 

testing for at least 2 or 3 days, during which time the device is 

cycled on for a few hours, off for a few hours, preferably including 

and possibly exceeding the temperature ranges in which the device is 

likely to be operating.  Most electronic component failures are 

infant-mortality type, meaning that if they survive a few days of 

intensive testing, they will probably last a long time.



Dave Morris



At 08:23 AM 11/8/2006, you wrote:

 	  Quote: 	
		  I am testing out a new LED comet-like flasher and 48-diode lamp to 

be used as a beacon under a clear rudder tip fairing.  Both are 

inexpensive Chinese imports designed for automotive 

application.  Brightness and flash rate/pattern are very good, but I 

was wondering what is a "reasonable" test period to run the thing on 

the ground before installing one in the OBAM plane?  100 hours, 2000 hours?



Clearly it should also depend on whether there is any failure, 

whether the failure is the lamp or the flasher, and whether it is a 

single diode burn out or total failure.  Also, after the testing, 

which will not be comprehensive like a commercial venture (no 

statistics here), would it be preferable to install the 

already-tested hardware or a completely new set?



Any guidance here?



Andy Elliott

N601GE (601XL/TD, Corvair, building)

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bakerocb

Joined: 15 Jan 2006
Posts: 727
Location: FAIRFAX VA

Posted: Thu Nov 09, 2006 8:45 am Post subject: Reasonable qualification for flight hardware?

11/09/2006



Responding to a previous posting by Dave N6030X <N6030X(at)DaveMorris.com



Hello Dave Morris, You wrote: "You probably need to find out whether the 

FARs on light intensity

apply to experimental aircraft or not."



This is a question that has no clear cut answer. Let's examine the 

regulatory issue in the context of exterior lighting:



1) The Operating Limitations for each ABEA (Amateur Built Experimental 

Aircraft)** include the following sentence: "After completion of Phase I 

flight testing, unless appropriately equipped for night and/or instrument 

flight in accordance with 91.205, this aircraft is to be operated under VFR, 

day only."



2) To the FAA this sentence means that if the ABEA is operated day VFR that 

none of the instrument and equipment requirement provisions of FAR 91.205 

would apply.



3) This means that during day VFR operations not even FAR 91.205 (b) (11) 

regarding the requirement for an anticollision light system would apply.



4) But as soon as the aircraft is operated at night or in instrument flight, 

either day or night, the provisions of FAR 91.205 (b) (11), (c) (2) and (c) 

(3) regarding exterior lighting would apply.



5) Each of the subparagraphs listed in 4 above contain the word "approved".



6) But since there are no published certification standards for ABEA there 

is no criteria available to measure approval against and one could conclude 

that any exterior lighting on an ABEA would be acceptable.



7) But logic raises the issue of interface with other aircraft.## The 

purpose of exterior lighting is to permit other observers in the air and on 

the ground to see the ABEA and react accordingly. If the ABEA is 

inadequately lighted then a hazard to others could exist .



 This line of reasoning would permit the initial airworthiness inspector 

to examine the exterior lighting of the ABEA with regard to its adequacy. 

The inspector could conclude, if exterior lighting is present, that the 

builder intended to operate the aircraft at night or in instrument 

conditions and that therefore some specified level of performance should be 

attained by that lighting.



9) A reasonable level of lighting performance to be expected could be 

equivalent to that required of type certificated aircraft.



10) It is unlikely that the inspector would have either the equipment or the 

inclination to actually measure the exterior lighting performance during his 

initial airworthiness inspection.



11) One course of action for the inspector to ensure that the ABEA lighting 

installed would meet some accepted performance standard would be for him to 

require the ABEA to have installed exterior lighting approved for 

installation in type certificated aircraft.



12) The issue may become confused if the builder installs some new 

technology lighting (like LED's) that to any unbiased observer is obviously 

superior to conventional lighting, but does not carry any kind of FAA 

approval marking. To what extent is the initial airworthiness inspector 

willing to sign off such lighting?



So I think that the answer to your question: "Do the FARs on light intensity 

apply to ABEA or not?" depends upon the actions of the individual initial 

airworthiness inspector. It may also be possible that an FAA inspector 

during a ramp inspection could raise this issue.



OC -- The best investment we will ever make is in gathering knowledge.



**PS: Some people prefer the more benign sounding, but less precise term, 

OBAM (Owner Built And Maintained) aircraft.



##PS: There are other items of ABEA equipment where interface with other 

aircraft or the ATC system require specified levels of performance. Some 

that come to mind are communication radios, altitude encoders, transponders, 

navigation equipment, and ELT's. In most cases the easiest way to ensure 

that specified levels of performance will be met is to install approved 

equipment such as that marked to meet a TSO (Technical Standard Order)



Time: 09:15:45 AM PST US

From: Dave N6030X <N6030X(at)DaveMorris.com>

Subject: Re: Reasonable qualification for flight 

hardware?



You probably need to find out whether the FARs on light intensity

apply to experimental aircraft or not.  Google around a bit, because

some pretty smart people have already done a lot of testing of LEDs

for use in aircraft external lighting.



It is common in the electronics manufacturing world to do "burn-in"

testing for at least 2 or 3 days, during which time the device is

cycled on for a few hours, off for a few hours, preferably including

and possibly exceeding the temperature ranges in which the device is

likely to be operating.  Most electronic component failures are

infant-mortality type, meaning that if they survive a few days of

intensive testing, they will probably last a long time.



Dave Morris

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frank.hinde(at)hp.com
Guest

Posted: Thu Nov 09, 2006 9:21 am Post subject: Reasonable qualification for flight hardware?

Sent: Thursday, November 09, 2006 9:15 AM

To: 'aeroelectric-list(at)matronics.com'

Subject: RE: Reasonable qualification for flight

hardware?



When I was researching this I noted that the Creative Air system is

designed to meet the required FAA light intensity for certified

AC...Thats why you have to angle the LED's in a specified manner as they

are highly directional.



Mind you the best test was when my hangar neighbour was drooling over my

RV and looking at the lights and noting how cool the technology was...I

switched on the position lights for him to see not realising he was

staring straight at the lights....Temporarilly blinded the poor

guy...One could assume the FAA ramp inspector would suffer the same fate

if he doubted their effectiveness...



Frank



So I think that the answer to your question: "Do the FARs on light

intensity apply to ABEA or not?" depends upon the actions of the

individual initial airworthiness inspector. It may also be possible that

an FAA inspector during a ramp inspection could raise this issue.

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