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bakerocb

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

Posted: Tue Apr 15, 2008 4:42 am Post subject: Questions on avionics

4/15/2008



Hello Bruce, You wrote:



"1.  What does it mean to "cage" an attitude indicator?"



Some attitude indicators have a mechanical means to lock the gyro gimbals so 

that the gyro gimbals are held rigidly to the instrument case. This can 

serve two functions:



A) It can save wear and tear on the gyro if you are going to do some 

aerobatic manuevering and don't want the gyro to be moving around 

extensively as it tries to always show the proper aircraft attitude.



B) If the gyro has tumbled and one wants to erect it again to a proper 

attitude one can put the airplane in a level attitude, cage and then uncage 

the gyro, and it will then start indicating properly a level attitude from 

that new starting point.



"3.  Is purchasing a separate encoder necessary?.....I see some avionics 

vendors packaging

in a separate encoder but don't really understand why."



They are doing this because the altitude encoder in almost all of the EFIS 

being sold to the amateur built community are not TSO'd and therefore do not 

comply with FAR Sec 91.217 copied here:



"91.217: Data correspondence between automatically reported pressure 

altitude data and the pilot's altitude reference.



No person may operate any automatic pressure altitude reporting equipment

associated with a radar beacon transponder-



(a) When deactivation of that equipment is directed by ATC;



(b) Unless, as installed, that equipment was tested and calibrated to

transmit altitude data corresponding within 125 feet (on a 95 percent

probability basis) of the indicated or calibrated datum of the altimeter

normally used to maintain flight altitude, with that altimeter referenced to

29.92 inches of mercury for altitudes from sea level to the maximum

operating altitude of the aircraft; or



(c) Unless the altimeters and digitizers in that equipment meet the

standards of TSO-C10b and TSO-C88, respectively."



So you can see that an altitude encoder in use must meet either be TSO'd or 

comply with subparagraph (b) above.



Some people think that the encoder, altimeter, and transponder checks 

required every two years by FAR Sections 91.411 and 91.413 meet the 

requirements of subparagraph (b) above, but that is not the present position 

of FAA HQ. They prescribe a more elaborate, almost impossible to accomplish 

test.



So one solution to the problem created by having an EFIS with a non TSO'd 

altitude encoder installed in your airplane is to install and use a separate 

TSO'd altitude encoder.



If you want to read more on this subject go to the Matronic aeroelectric 

list archive and search for 91.217.



'OC' Says: "The best investment we can make is the effort to gather and 

understand knowledge."



PS: Some EFIS manufacturers will claim that their altitude encoder "meets 

TSO standards". Note that a claim of "meeting TSO standards" and being 

actually TSO'd are not the same thing. Ironically some of these non TSO'd 

altitude encoders are actually superior in performance and technology than 

the standards required by the TSO. The EFIS manufacturers have chosen not to 

obtain actual TSO approval for their altitude encoders because of the 

expense and bureaucratic burden involved.



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



 	  Quote: 	
		   Time: 05:57:43 PM PST US

 Subject: Questions on avionics

 From: "Rv9APlane" <rv9aplane(at)gmail.com>

 Hi all,

 I have a couple of basic questions I don't understand well:



 1.  What does it mean to "cage" an attitude indicator?  I've never flown a 

 plane

 that has had this option but I see it on some I'm considering for my 

 homebuilt.



 2.  I want a light IFR panel and have read some things about Mode S 

 transponders.

 Is there any advantage to having one over a Mode C other than the TIS 

 capability?



 3.  Is purchasing a separate encoder necessary?  I was planning on putting 

 a Blue

 Mountain EFIS One in my plane (please no negative comments as I'm already 

 committed),

 a Garmin 430W with a GI-106A CDI, and a Garmin 327 transponder (pending

 the answer to number 2 above) in my plane.  I see some avionics vendors 

 packaging

 in a separate encoder but don't really understand why.



 Thanks for your help



 --------

 Bruce Peters

 RV9A, Fuselage

 Bakersfield, CA

BobsV35B(at)aol.com
Guest

Posted: Tue Apr 15, 2008 8:35 am Post subject: Questions on avionics

Good Morning OC,

  

 Nice answer to the question asked, but may a I add a bit?

  

 If you intend to do aerobatics and intend to cage the gyros to avoid wear,  it is best to shut of the air first so that the gyro is not spinning while it is  locked up. While being caged will keep it from banging the stops, the bearings  will be exposed to abnormal wear by the gyro being restrained.  If the air  is turned of after the gyro is already spun up, a good gyro will take about  thirty minutes to get stopped. Best to shut off the air before the engine is  started.

  

 There is no real good solution, only methods of mitigation.

  

 Happy  Skies,



Old Bob

AKA

Bob Siegfried

Ancient Aviator

628 West  86th Street

Downers Grove, IL 60516

630 985-8502 

Stearman  N3977A

Brookeridge Air Park LL22

  

  In a message dated 4/15/2008 7:47:34 A.M. Central Daylight Time,  bakerocb(at)cox.net writes:

  	  Quote: 	
		  Hello    Bruce, You wrote:



"1.  What does it mean to "cage" an attitude    indicator?"



Some attitude indicators have a mechanical means to lock    the gyro gimbals so 

that the gyro gimbals are held rigidly to the    instrument case. This can 

serve two functions:



A) It can save wear    and tear on the gyro if you are going to do some 

aerobatic maneuvering and    don't want the gyro to be moving around 

extensively as it tries to always    show the proper aircraft attitude.



B) If the gyro has tumbled and one    wants to erect it again to a proper 

attitude one can put the airplane in a    level attitude, cage and then uncage 

the gyro, and it will then start    indicating properly a level attitude from 

that new starting    point.



	






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  [quote][b]

frank.hinde(at)hp.com
Guest

Posted: Tue Apr 15, 2008 9:20 am Post subject: Questions on avionics

Really the best way to do  aerobatics is to fit a glass EFIS...I regularly (like every flight) wring out my  RV and the Dynon scratches its head sometimes but returns to normal like  clockwork. Same for the TT autopilot.

  

 I noticed that Kathy  Hirtz does her airshow routines in her Wolf Pitts and has a Dynon D180  installed..And there is not a more radical aerobatic machine out  there.

  

 Its about time the  mechanical gyros went the way of the Dodo...As long as your airplane is  experimental of course.

  

 Frank



   From: owner-aeroelectric-list-server(at)matronics.com  [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of  BobsV35B(at)aol.com

Sent: Tuesday, April 15, 2008 9:29  AM

To: aeroelectric-list(at)matronics.com

Subject: Re:  Questions on avionics

 

 Good Morning OC,

  

 Nice answer to the question asked, but may a I add a bit?

  

 If you intend to do aerobatics and intend to cage the gyros to avoid wear,  it is best to shut of the air first so that the gyro is not spinning while it is  locked up. While being caged will keep it from banging the stops, the bearings  will be exposed to abnormal wear by the gyro being restrained.  If the air  is turned of after the gyro is already spun up, a good gyro will take about  thirty minutes to get stopped. Best to shut off the air before the engine is  started.

  

 There is no real good solution, only methods of mitigation.

  

 Happy  Skies,



Old Bob

AKA

Bob Siegfried

Ancient Aviator

628 West  86th Street

Downers Grove, IL 60516

630 985-8502 

Stearman  N3977A

Brookeridge Air Park LL22

  

  In a message dated 4/15/2008 7:47:34 A.M. Central Daylight Time,  bakerocb(at)cox.net writes:

  	  Quote: 	
		  Hello Bruce, You    wrote:



"1.  What does it mean to "cage" an attitude    indicator?"



Some attitude indicators have a mechanical means to lock    the gyro gimbals so 

that the gyro gimbals are held rigidly to the    instrument case. This can 

serve two functions:



A) It can save wear    and tear on the gyro if you are going to do some 

aerobatic maneuvering and    don't want the gyro to be moving around 

extensively as it tries to always    show the proper aircraft attitude.



B) If the gyro has tumbled and one    wants to erect it again to a proper 

attitude one can put the airplane in a    level attitude, cage and then uncage 

the gyro, and it will then start    indicating properly a level attitude from 

that new starting    point.



	






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[quote]



ist">http://www.matronics.com/Navigator?AeroElectric-List

ics.com

.matronics.com/contribution



[b]

BobsV35B(at)aol.com
Guest

Posted: Tue Apr 15, 2008 9:58 am Post subject: Questions on avionics

Good Afternoon Frank,

  

 Absolutely and totally agree! 

  

 The problem is that the FAA puts so many hurdles in the way that by the  time the stuff gets approved, the cost is way above what normal folks can  afford.

  

 Right now, only home builders have any chance of going with modern  equipment. 

  

 I do realize that most FAA folks are just as enthusiastic aviators as are  the rest of us, but they are hamstrung with rules that are forced on them by the  Bureaucracy and that Bureaucracy is driven by the  Congress critters who do  nothing for us at all. 

  

 All they care about is having someone to blame when anything goes  wrong.

  

 I recently had the pleasure of flying some twenty-four hours in a  Legend Cub that was equipped with the Dynon 180. I certainly did not learn how  to use all of it's many capabilities, but what I saw, was great.

  

 I have been following Jim Younkin's very rapid development of flight  instruments and autopilots. I love his attitude toward the FAA, but it doesn't  help we who fly primarily certified aircraft. 

  

 Unless someone who is willing to argue with the FAA manages to steal some  of his ideas and get the FAA approval for us to use that much better stuff, we  are stuck with 1920s technology.

  

 Had the FAA been in charge in 1920 we would not yet have mechanical  gyros, let alone anything better!

  

 Happy  Skies,



Old Bob

AKA

Bob Siegfried

Ancient Aviator

628 West  86th Street

Downers Grove, IL 60516

630 985-8502 

Stearman  N3977A

Brookeridge Air Park LL22

  

  In a message dated 4/15/2008 12:22:40 P.M. Central Daylight Time,  frank.hinde(at)hp.com writes:

  	  Quote: 	
		     Really the best way to    do aerobatics is to fit a glass EFIS...I regularly (like every flight) wring    out my RV and the Dynon scratches its head sometimes but returns to normal    like clockwork. Same for the TT autopilot.

    

   I noticed that Kathy    Hirtz does her airshow routines in her Wolf Pitts and has a Dynon D180    installed..And there is not a more radical aerobatic machine out    there.

    

   Its about time the    mechanical gyros went the way of the Dodo...As long as your airplane is    experimental of course.

    

   Frank

	






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  [quote][b]

Bill Denton

Joined: 10 Jan 2006
Posts: 97
Location: Chicago, IL USA

Posted: Tue Apr 15, 2008 10:26 am Post subject: Questions on avionics

Bob…  

   

Aspen Avionics http://www.aspenavionics.com/ recently received the TSO and the AML STC for their glass PFD.  

   

$6,000 + install for a VFR unit; $10,000 + install for an IFR unit. Not really cheap, but not as pricey as Garmin or Avidyne. So you guys flying TC aircraft can get some of the toys without totally busting the bank.  

   

And no more spinning gyros!  

     

Thanks!  

   

Bill Denton  

bdenton(at)bdenton.com  

  

       

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of BobsV35B(at)aol.com

 Sent: Tuesday, April 15, 2008 12:56 PM

 To: aeroelectric-list(at)matronics.com

 Subject: Re: Questions on avionics  

  

  

     

Good Afternoon Frank,  

    

   

    

Absolutely and totally agree!   

    

   

    

The problem is that the FAA puts so many hurdles in the way that by the time the stuff gets approved, the cost is way above what normal folks can afford.  

    

   

    

Right now, only home builders have any chance of going with modern equipment.   

    

   

    

I do realize that most FAA folks are just as enthusiastic aviators as are the rest of us, but they are hamstrung with rules that are forced on them by the Bureaucracy and that Bureaucracy is driven by the  Congress critters who do nothing for us at all.   

    

   

    

All they care about is having someone to blame when anything goes wrong.  

    

   

    

I recently had the pleasure of flying some twenty-four hours in a Legend Cub that was equipped with the Dynon 180. I certainly did not learn how to use all of it's many capabilities, but what I saw, was great.  

    

   

    

I have been following Jim Younkin's very rapid development of flight instruments and autopilots. I love his attitude toward the FAA, but it doesn't help we who fly primarily certified aircraft.   

    

   

    

Unless someone who is willing to argue with the FAA manages to steal some of his ideas and get the FAA approval for us to use that much better stuff, we are stuck with 1920s technology.  

    

   

    

Had the FAA been in charge in 1920 we would not yet have mechanical gyros, let alone anything better!  

    

   

    

Happy Skies,

 

 Old Bob

 AKA

 Bob Siegfried

 Ancient Aviator

 628 West 86th Street

 Downers Grove, IL 60516

 630 985-8502 

 Stearman N3977A

 Brookeridge Air Park LL22    

   

      

In a message dated 4/15/2008 12:22:40 P.M. Central Daylight Time, frank.hinde(at)hp.com writes:  

   	  Quote: 	
		    

Really the best way to do aerobatics is to fit a glass EFIS...I regularly (like every flight) wring out my RV and the Dynon scratches its head sometimes but returns to normal like clockwork. Same for the TT autopilot.  

   

I noticed that Kathy Hirtz does her airshow routines in her Wolf Pitts and has a Dynon D180 installed..And there is not a more radical aerobatic machine out there.  

   

Its about time the mechanical gyros went the way of the Dodo...As long as your airplane is experimental of course.  

   

Frank  	
  

  

  



 

         

  

It's Tax Time! Get tips, forms and advice on AOL Money & Finance.  

   	  Quote: 	
		    http://www.matronics.com/Navigator?AeroElectric-List 	
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2 	  Quote: 	
		   	
3 	  Quote: 	
		   	
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       [quote][b]

BobsV35B(at)aol.com
Guest

Posted: Tue Apr 15, 2008 10:43 am Post subject: Questions on avionics

Good Afternoon Bill,

  

 It's getting there! 

  

 I do know that they are now saying the entire year's production is already  spoken for.

  

 Last person I spoke to said they figure the installation they ordered would  be at least twenty grand installed. Better than a Garmin, but still a lot of  money. If it was an automotive device, produced in China, and used on a Toyota  it would be fifty bucks!

  

 Happy  Skies,



Old Bob

AKA

Bob Siegfried

Ancient Aviator

628 West  86th Street

Downers Grove, IL 60516

630 985-8502 

Stearman  N3977A

Brookeridge Air Park LL22

  

  In a message dated 4/15/2008 1:29:02 P.M. Central Daylight Time,  bdenton(at)bdenton.com writes:

  	  Quote: 	
		     

Bobâ€¦   

    

Aspen    Avionics http://www.aspenavionics.com/ recently received the TSO and the AML    STC for their glass PFD.   

    

$6,000    + install for a VFR unit; $10,000 + install for an IFR unit. Not really cheap,    but not as pricey as Garmin or Avidyne. So you guys flying TC aircraft can get    some of the toys without totally busting the bank.   

    

And    no more spinning gyros!   

       

Thanks!   

    

Bill    Denton   

bdenton(at)bdenton.com

   

 	






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  [quote][b]

frank.hinde(at)hp.com
Guest

Posted: Tue Apr 15, 2008 11:01 am Post subject: Questions on avionics

Yes I feel for the  certified guys...The last IFR proficiency ride i took my instrument student  friend and he kept babbling something about "what about the precession"....I  said "We're not in a precession, we're flying by ourselves!"

  

 Nice to hear from you  again Bob....And you were right, learning IFR in a fast airplane is not hard at  all...learning in one that happens to be aerobatic its a bit of a handful  though..

  

 Frank  RV7a



   From: owner-aeroelectric-list-server(at)matronics.com  [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of  BobsV35B(at)aol.com

Sent: Tuesday, April 15, 2008 10:56  AM

To: aeroelectric-list(at)matronics.com

Subject: Re:  Questions on avionics

 

 Good Afternoon Frank,

  

 Absolutely and totally agree! 

  

 The problem is that the FAA puts so many hurdles in the way that by the  time the stuff gets approved, the cost is way above what normal folks can  afford.

  

 Right now, only home builders have any chance of going with modern  equipment. 

  

 I do realize that most FAA folks are just as enthusiastic aviators as are  the rest of us, but they are hamstrung with rules that are forced on them by the  Bureaucracy and that Bureaucracy is driven by the  Congress critters who do  nothing for us at all. 

  

 All they care about is having someone to blame when anything goes  wrong.

  

 I recently had the pleasure of flying some twenty-four hours in a  Legend Cub that was equipped with the Dynon 180. I certainly did not learn how  to use all of it's many capabilities, but what I saw, was great.

  

 I have been following Jim Younkin's very rapid development of flight  instruments and autopilots. I love his attitude toward the FAA, but it doesn't  help we who fly primarily certified aircraft. 

  

 Unless someone who is willing to argue with the FAA manages to steal some  of his ideas and get the FAA approval for us to use that much better stuff, we  are stuck with 1920s technology.

  

 Had the FAA been in charge in 1920 we would not yet have mechanical  gyros, let alone anything better!

  

 Happy  Skies,



Old Bob

AKA

Bob Siegfried

Ancient Aviator

628 West  86th Street

Downers Grove, IL 60516

630 985-8502 

Stearman  N3977A

Brookeridge Air Park LL22

  

  In a message dated 4/15/2008 12:22:40 P.M. Central Daylight Time,  frank.hinde(at)hp.com writes:

  	  Quote: 	
		     Really the best way to    do aerobatics is to fit a glass EFIS...I regularly (like every flight) wring    out my RV and the Dynon scratches its head sometimes but returns to normal    like clockwork. Same for the TT autopilot.

    

   I noticed that Kathy    Hirtz does her airshow routines in her Wolf Pitts and has a Dynon D180    installed..And there is not a more radical aerobatic machine out    there.

    

   Its about time the    mechanical gyros went the way of the Dodo...As long as your airplane is    experimental of course.

    

   Frank

	






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[quote]



ist">http://www.matronics.com/Navigator?AeroElectric-List

ics.com

.matronics.com/contribution



[b]

rampil

Joined: 04 May 2007
Posts: 870

Posted: Wed Apr 16, 2008 3:25 am Post subject: Re: Questions on avionics

Re: TSO and altimetry sources



There is no requirement for TSO in owner built aircraft. As I said 

previously, there is only a performance requirement.



Part 23 is a separate issue.

_________________
Ira N224XS

bakerocb

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

Posted: Thu Apr 17, 2008 5:55 pm Post subject: Questions on avionics

4/17/2008



Hello Ira,



1) You wrote: "There is no requirement for TSO in owner built aircraft."**



2) FAR SEC 91.217 Says:



"Data correspondence between automatically reported pressure

altitude data and the pilot's altitude reference.



No person may operate any automatic pressure altitude reporting equipment

associated with a radar beacon transponder-



(a) When deactivation of that equipment is directed by ATC;



(b) Unless, as installed, that equipment was tested and calibrated to

transmit altitude data corresponding within 125 feet (on a 95 percent

probability basis) of the indicated or calibrated datum of the altimeter

normally used to maintain flight altitude, with that altimeter referenced to

29.92 inches of mercury for altitudes from sea level to the maximum

operating altitude of the aircraft; or



(c) Unless the altimeters and digitizers in that equipment meet the

standards of TSO-C10b and TSO-C88, respectively."



3) Please explain, with specific valid reference, why the phrase "No person 

may ..." seen above would not apply to a person flying an amateur built 

experimental aircraft.



4) You are correct that there are alternatives to using TSO'd equipment, 

when such equipment is specifically required by a regulation, provided that 

you can prove to the FAA's satisfaction that your alternative equipment is 

acceptable to the FAA. Here is how you go about doing that:



FAR Sec. 21.609   "Approval for deviation.



(a) Each manufacturer who requests approval to deviate from any performance 

standard of a TSO shall show that the standards from which a deviation is 

requested are compensated for by factors or design features providing an 

equivalent level of safety.

(b) The request for approval to deviate, together with all pertinent data, 

must be submitted to the Manager of the Aircraft Certification Office for 

the geographic area in which the manufacturer is located. If the article is 

manufactured in another country, the request for approval to deviate, 

together with all pertinent data, must be submitted through the civil 

aviation authority in that country to the FAA."



Obtaining an approval for deviation is not a trivial task and none of the 

manufacturers of non TSO'd altitude encoders contained in their EFIS units 

have done so to my knowledge.



'OC' Says: "The best investment we can make is the effort to gather and 

understand knowledge."



**PS: This statement is also not correct when it comes to the ELT installed, 

if one is required by FAR Sec 91.207, in an amateur built experimental 

aircraft.



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



Time: 04:30:41 AM PST US

Subject: Re: Questions on avionics

From: "rampil" <ira.rampil(at)gmail.com>

      Re: TSO and altimetry sources



      There is no requirement for TSO in owner built aircraft. As I said

      previously, there is only a performance requirement.



      Part 23 is a separate issue.



      --------

      Ira N224XS

echristley(at)nc.rr.com
Guest

Posted: Thu Apr 17, 2008 6:48 pm Post subject: Questions on avionics

bakerocb(at)cox.net wrote:

 	  Quote: 	
		   



 4/17/2008



 Hello Ira,



 1) You wrote: "There is no requirement for TSO in owner built 

 aircraft."**



 2) FAR SEC 91.217 Says:



 "Data correspondence between automatically reported pressure

 altitude data and the pilot's altitude reference.



 No person may operate any automatic pressure altitude reporting equipment

 associated with a radar beacon transponder-



 (a) When deactivation of that equipment is directed by ATC;



 (b) Unless, as installed, that equipment was tested and calibrated to

 transmit altitude data corresponding within 125 feet (on a 95 percent

 probability basis) of the indicated or calibrated datum of the altimeter

 normally used to maintain flight altitude, with that altimeter 

 referenced to

 29.92 inches of mercury for altitudes from sea level to the maximum

 operating altitude of the aircraft; or



 (c) Unless the altimeters and digitizers in that equipment meet the

 standards of TSO-C10b and TSO-C88, respectively."



 3) Please explain, with specific valid reference, why the phrase "No 

 person may ..." seen above would not apply to a person flying an 

 amateur built experimental aircraft.


	


I don't understand why you think what he said is wrong.



No person may operate any automatic pressure altitude reporting 

equipment ...Unless.... that equipment was tested and calibrated...; 

or...that equipment meet the standards of TSO-C10b and TSO-C88



There's an OR statement there.  One, the other, or both can be true, and 

the statement is still true  (I'm a Software Engineer by training, so I 

took a special class just for that sort of reasoning 8*)



-- 



http://www.ronpaultimeline.com

mlas(at)cox.net
Guest

Posted: Thu Apr 17, 2008 7:28 pm Post subject: Questions on avionics

I would argue that you are not looking for a deviation to the TSO you

are looking to comply with the standard of the TSO without a formal

proof.



Mike



--

mlas(at)cox.net
Guest

Posted: Thu Apr 17, 2008 7:34 pm Post subject: Questions on avionics

Read the regulation.  It says that the 'encoder' must meet the TSO

standards.  It doesn't say that it must be TSO'd.  That is a subtle

legal difference.



Mike



--

khorton01(at)rogers.com
Guest

Posted: Fri Apr 18, 2008 2:30 am Post subject: Questions on avionics

On 17 Apr 2008, at 23:29, Mike wrote:



 	  Quote: 	
		   



 Read the regulation.  It says that the 'encoder' must meet the TSO

 standards.  It doesn't say that it must be TSO'd.  That is a subtle

 legal difference.


	




But, if you read the TSO standards you would likely conclude that it  

would be a very expensive and difficult job to do the testing to  

determine whether the item met those standards.  If the item must  

meet all the TSO standards, it would almost certainly be more  

practical simply to purchase a TSO'd item.



In the specific case of altimeters and altimeter encoders, the regs  

provide an alternative - as others have noted you can comply with (b)  

OR (c).



--

Kevin Horton

RV-8 (FInal Assembly)

Ottawa, Canada

http://www.kilohotel.com/rv8

rampil

Joined: 04 May 2007
Posts: 870

Posted: Fri Apr 18, 2008 2:41 am Post subject: Re: Questions on avionics

And of course, I was referring to encoding altimeters when I said there

was no requirement for TSO. Transponders must be TSO

_________________
Ira N224XS

nuckolls.bob(at)cox.net
Guest

Posted: Fri Apr 18, 2008 5:32 am Post subject: Questions on avionics

At 06:26 AM 4/18/2008 -0400, you wrote:

 	  Quote: 	

On 17 Apr 2008, at 23:29, Mike wrote:

>

>

>Read the regulation.  It says that the 'encoder' must meet the TSO

>standards.  It doesn't say that it must be TSO'd.  That is a subtle

>legal difference.

>

But, if you read the TSO standards you would likely conclude that it

would be a very expensive and difficult job to do the testing to

determine whether the item met those standards.  If the item must

meet all the TSO standards, it would almost certainly be more

practical simply to purchase a TSO'd item.

   You got that right. The actual testing is the cheap part.

   I used to qualify products intended for use on TC aircraft

   based on oversight of a single FAA representative for the

   engineering testing in my lab. Nowadays, you first have to

   get permission to test, then write up a test plan that speaks

   to what color the walls of the lab will be painted, then schedule

   a bevy of official dispensers of holy-water and witnesses

   for testing (most of whom don't have a clue about how your

   product works) and the accomplish this all in a laboratory that

   is "certified" down to whether or not the paint cited in

   the test plan has lead in it. Finally you have to write a test

   report. Documents that support various phases of the test

   effort must be submitted to the local ACO who is not just

   allowed but EXPECTED to take 91 days to pray over it before

   granting a blessing. If they do any red-lining, then they'll

   take another 91 days to reconsider the changes. In the

   mean time, the project team is still banging the project

   work-order.

   The value-added activity for proving that a product

   meets its cited design goals is dwarfed by the no-value-added

   activities foisted upon us those-who-know-more-about-airplanes-

   than-we-do. If anyone really believes that last week's

   air transportation debacle had anything to do with real

   passenger safety is sadly deluded. It has everything to

   do with lawmakers and regulators activities that

   expand kingdoms over which they reign thereby justifying

   their fat retirement packages.

   The saddest part is that my contemporaries in the TC

   aircraft world are so distracted by requirements to dance

   to somebody else's orchestra that they're not building their

   ability to be good engineers. That's what I'm getting paid

   those big bucks for now . . . but I'm always watching for

   some bright young bucks to whom I might pass the torch.

   I think I've found a couple of new hires at HB that

   show great promise. I've already conspired with their

   boss to shield them as much as possible from the forces

   that would dilute their curiosity, creative juices and

   enthusiasm for their jobs.

   In the mean time, you who are members of the 'unwashed'

   must suffer the effects of all this pomp-and-circumstance

   and be content with the dream that "their hearts are in

   the right place . . . they're only concerned about your

   safety." But if you had a non-TSO'd encoder that lacked

   your confidence as to suitability to task, we could probably

   assuage those concerns in one day of playing around in

   the lab. To get real TSO blessings on the product would

   require a 6-12 month, 400+ man-hour effort.

   Bob . . .

bakerocb

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

Posted: Sat Apr 19, 2008 4:15 am Post subject: Questions on avionics

4/19/2008



Hello Ira, You wrote: "........I was referring to encoding altimeters when I 

said there

was no requirement for TSO."



If that encoding altimeter is the altitude encoder that is feeding the 

transponder required by FAR Sec 91.215 then it must comply with either 

91.217 (b) or (c). That is what this thread has been about.



See my response to Mike, copied below, for more information.



'OC'



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



4/18/2008



Hello Mike, Thanks for your three emails. You wrote:



1) "....you are looking to comply with the standard of the TSO without a

formal

proof."



A) I invite you to look at "Subpart O -- TSO Authorizations" of FAR Part 21.

You can access it here:



http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=9dad7a792e03c09e14fc110ded0921cb&rgn=div6&view=text&node=14:1.0.1.3.9.15&idno=14



B) Then I invite you to look at TSO-C10b. You can access it here:



http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgTSO.nsf/0/072c91c58fdc6ce686256da4005f4d1b/$FILE/C10b.pdf



C) Then I invite you to look at TSO-C88b. You can access it here:



http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgTSO.nsf/0/625ebf9767dac15e8625727c006e10df/$FILE/TSO-C88b.pdf



D) Now I invite you (and here is the gotcha) to procure and look at all the

technical references contained in those TSO's. The TSO's themselves are just

sort of shell documents, pointers if you will. All the real technical guts

and standards that must be complied with are found in the references.



E) Now I ask you to picture the average homebuilder satisfying someone that

he is complying with the standards of the relevant TSO's without formal

proof.



2) "It says that the 'encoder' must meet the TSO standards.  It doesn't say

that it must be TSO'd.  That is a subtle legal difference."



I accept your "subtle legal difference". After you have gone through steps A

through D above I ask you to picture the average homebuilder satisfying

someone that his non TSO'd altitude encoder is meeting the standards of the

relevant TSO's .



3) "So answer me this:  If you the builder /manufacturer determines that

your testing puts the encoder in compliances with the TSO standards......."



Again I ask you to picture the average amateur builder determining that his

testing puts the encoder in compliance with the TSO standards -- not some of

the standards, not just the performance standards, but the all of the TSO

standards. The reason that the EFIS manufacturers have not done this very

thing is because of the significant cost and bureacratic burden involved.



4) "...and you test the unit IAW 43.13 and it passes ......"



A) (I am not sure why you referenced 43.13. It does not appear to be

relevant here. Perhaps you meant FAR Sec 91.413. I will assume so.)



First off I, the amateur builder, am not permitted to perform the tests

required by 91.413 -- see sub paragraph (c) of 91.413.



B) "......what would be the ramifications?"



Second, assuming the tests required by 91.413 were properly performed by a

willing qualified person / entity, the automatic pressure altitude reporting

equipment containing the non TSO'd altitude encoder passed the tests, and

the test results were properly documented there probably would be no adverse

ramifications. But consider this:



B-1) Suppose a willing qualified person / entity is not readily available to

perform the 91.413 required tests because the non TSO'd altitude encoder is

not in compliance with 91.217? What are the ramifications then? Probably no

big deal, go find someone or some place that will perform the tests.



B-2) Suppose that there is a mid air collision between an amateur built

experimental aircraft and an airline aircraft with major loss of life. And

further suppose that the equipment in the amateur built experimental

aircraft had absolutely nothing to do with causing the accident, but the

media learns that the amateur built experimenal aircraft was not in

compliance with some Federal Aviation Regulation (91.217) . What are the

ramifications then?



5) "I don't see a violation of the rule as written."



I am not sure which rule you are referring to. If you are referring to

91.217 there are two choices:



A) Comply with subparagraph (c); ie have equipment that is TSO'd, or



B) Comply with the tests described in subparagraph (b). I think that the

tests required by 91.411 and 91.413 should be considered to meet the

requirements of 91.217 (b). Unfortunately, to date the FAA HQ does not agree

with me and they seem to have  a little more authority than I do.



6) "Also their is no enforcement mechanism in place to even determine

whether your in compliance or not."



True enough. I think the FAA is too busy measuring the spacing between

lacings on wire bundles in the wheel wells of airliners to make very many

ramp checks on the avionics installed in amateur built experimental

aircraft, but see the ramifications comments above and make an informed

decision.



7) "You as the aircraft certifying authority as the builder......"



The Special Airworthiness Certificate in the Experimental Category for the

purpose of Operating Amateur Built Aircraft is signed and issued by an FAA

Representative who has been delegated that authority by the FAA

Administrator. The FAA Administrator is the certifying authority, not the

amateur builder.



 "You ........ as the builder determine suitability as it pertains to the

regulations and no one else"



Try telling that to the FAA employee or DAR who comes to inspect your

amateur built experimental aircraft for its initial airworthiness

inspection. He will set you straight very quickly on who will make the

decisions regarding the suitability of your aircraft as it pertains to

regulations.



9) "Short of them scouring the wreckage for TSO tags they would have to make

an assumption."



I hope that it would never come to that, but the tenacity, search for

details, and the ill will of lawyers and journalists when they smell blood

and money should not be ignored. All I am seeking to do is to have people

make informed decisions -- I provide the information, they make the

decisions.



'OC' Says: "The best investment we can make is the effort to gather and

understand knowledge."



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



Time: 08:28:34 PM PST US

From: "Mike" <mlas(at)cox.net>

Subject: RE: AeroElectric-List: Questions on avionics



I would argue that you are not looking for a deviation to the TSO you

are looking to comply with the standard of the TSO without a formal

proof.



Mike



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

Time: 08:34:11 PM PST US

From: "Mike" <mlas(at)cox.net>

Subject: RE: AeroElectric-List: Questions on avionics

Read the regulation.  It says that the 'encoder' must meet the TSO

standards.  It doesn't say that it must be TSO'd.  That is a subtle

legal difference.



Mike



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



---

rampil

Joined: 04 May 2007
Posts: 870

Posted: Sat Apr 19, 2008 5:57 am Post subject: Re: Questions on avionics

Again, back to 91.217 (b):



(b) Unless, as installed, that equipment was tested and calibrated to 

transmit altitude data corresponding within 125 feet (on a 95 percent 

probability basis) of the indicated or calibrated datum of the altimeter 

normally used to maintain flight altitude, with that altimeter referenced to 

29.92 inches of mercury for altitudes from sea level to the maximum 

operating altitude of the aircraft; or 



This is just the performance test.  It says nothing about TSO.

Part 21 and 23 do not apply to owner built aircraft with special

airworthiness certificates

_________________
Ira N224XS

klehman(at)albedo.net
Guest

Posted: Sat Apr 19, 2008 6:03 am Post subject: Questions on avionics

This is not totally theoretical. I am aware of a recent airliner that 

took (mandatory) evasive action (and altitude bust) based on erroneous 

transponder reporting from a unreported low altitude VFR airplane with 

an unknown N number. Such TCAS inspired altitude busts are rare (but not 

rare enough) and are usually chalked up to temporary glitches, but you 

can see the risk involved. A TCAS RA warning takes precedence over ATC 

assigned altitude. It is rare to positively identify the exact cause of 

these events but apparently some transponders operate for awhile with 

issues before they are discovered. I'd prefer an uncertified encoding 

altimeter to a Tso'd blind encoder UNLESS there is any kind of legal 

challenge. For the time being I use a Tso'd blind encoder but since I do 

not often fly in controlled airspace with ATC altitude feedback, I 

occasionally check my transmitted altitude with a PCAS MRX traffic 

warning device. I suspect that such issues are one small part of the 

drive towards encoding permanent aircraft idents into the newer 

transponders.

Ken



 	  Quote: 	
		   B-2) Suppose that there is a mid air collision between an amateur built

 experimental aircraft and an airline aircraft with major loss of life. And

 further suppose that the equipment in the amateur built experimental

 aircraft had absolutely nothing to do with causing the accident, but the

 media learns that the amateur built experimenal aircraft was not in

 compliance with some Federal Aviation Regulation (91.217) . What are the

 ramifications then?

bakerocb

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

Posted: Sun Apr 20, 2008 4:55 am Post subject: Questions on avionics

4/20/2008



Hello Ira, You wrote:



1) "This is just the performance test."



I assume that you mean the testing required every two years by FAR Sec's 

91.411 and 91.413 as appropriate.



I apologize for not having made the situation clearer to you. I also wanted 

the testing required by 91.411 /  91.413 to sufficiently meet the 

requirements of 91.217 (b) so that one could operate with an EFIS that 

contained the only atitude encoder in the airplane and that altitude encoder 

would be non TSO'd. So I wrote to FAA HQ asking that question. Here is an 

exact quote of their response:



"Your letter posed the following questions:



1.    If an amateur built experimental aircraft has an installed TSO'd ATC

transponder as required by Title 14 Code of Federal Regulations (14 CFR)

section 91.215, but a non-TSO'd altitude encoder and the installation has

passed the test and inspection requirements of 14 CFR sections 91.411 and

91.413 within the preceding 24 calendar months, does the installation meet

the requirements of 14 CFR section 91.217(b), and therefore make that

installation acceptable for IFR operations?



2.    If the answer to question one is No, can you please tell me

why?



The answer to question one is "No."  The testing required to show the

transmitted altitude data corresponds within 125 feet (on a 95 percent

probability basis) is more rigorous than the requirements referenced in 14

CFR sections 91.411, 91.413, and 14 CFR, part 43 appendices E and F.  The

tests required by 14 CFR part 43 appendix E(c) measure the automatic

pressure altitude at a sufficient number of test points to ensure the

altitude reporting equipment performs its intended function.

Title 14 CFR section 91.217 paragraphs (b) and (c), state that pressure

altitude reporting equipment must be tested and calibrated to transmit

altitude data correspondence within stated specifications; or, the

altimeters and digitizers must meet the standards in TSO-C10B and TSO-C88,

respectively.



Should the owner/operator elect to exhibit compliance with tests and

calibration provided in 14 CFR section 91.217(b), a test method would need

to be developed that ensures the transmitted data corresponds within 125

feet of the indicated altitudes from sea level to the maximum operating 

altitude of the aircraft

on a 95 percent probability basis.  This testing also needs to ensure the

performance characteristics of the equipment are not impacted when

subjected to environmental conditions (voltage fluctuations temperature,

vibration, etc.) which may be encountered in airborne operations.

Completed tests and calibration results should be maintained in the

aircraft records.



Thank you for your interest in aviation safety."



So you can see that FAA HQ does not agree with our wishes. Further you can 

see that an amateur builder attempting to comply with the FAA HQ version of 

the testing requirements of 91.217 (b) in order to avoid having a TSO'd 

altitude encoder installed in his airplane would have a very difficult / 

impossible time doing so.



2) "It says nothing about TSO."



That is correct. The TSO part is found in 91.217 (c). So the person 

mentioned in the beginning of 91.217 is given two choices -- he can comply 

with either 91.217 (b) or (c).



3) "Part 21 and 23 do not apply to owner built aircraft with special 

airworthiness certificates."



Basically true, but not specifically relevant to this discussion unless the 

builder would try to use a non TSO'd altitude encoder by requesting approval 

to deviate from TSO C-88b and its references in accordance with the 

procedures of FAR Sec 21.609 -- not a trivial task.



Please let me know if I have not adequately described the situation.



'OC' Says: "The best investment we can make is the effort to gather and 

understand knowledge."



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



Time: 07:01:52 AM PST US

Subject: AeroElectric-List: Re: Questions on avionics

From: "rampil" <ira.rampil(at)gmail.com>

Again, back to 91.217 (b):



(b) Unless, as installed, that equipment was tested and calibrated to

transmit altitude data corresponding within 125 feet (on a 95 percent

probability basis) of the indicated or calibrated datum of the altimeter

normally used to maintain flight altitude, with that altimeter referenced to

29.92 inches of mercury for altitudes from sea level to the maximum

operating altitude of the aircraft; or



This is just the performance test.  It says nothing about TSO.

Part 21 and 23 do not apply to owner built aircraft with special

airworthiness certificates



--------

Ira N224XS

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