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brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Fri Jan 13, 2006 1:15 pm Post subject: EFIS Comparisons

Bruce Gray wrote:

 	  Quote: 	
		   

 

 No, No, No. You want dual AHRS, with an electronic comparator hopefully. No

 if it's a VFR ONLY airplane, anything goes.


	


My brain is the comparator. I have to compare the display from the 

EFIS-1 to the Dynon or 3-pack and make a decision as to which is right.



Brian Lloyd

brian-yak at lloyd dot com

_________________
Brian Lloyd
brian-yak at lloyd dot com
+1.916.367.2131 (voice) +1.270.912.0788 (fax)

I fly because it releases my mind from the tyranny of petty things . . .
- Antoine de Saint-Exupery

cjensen(at)dts9000.com
Guest

Posted: Fri Jan 13, 2006 1:56 pm Post subject: EFIS Comparisons

Alan,



This was just poking a bit of fun at the idea of two AHRS giving one

true redundancy.  In the case of the reference to the Crossbow AHRS,

right now if you have two....you have none, since the AD has taken them

out of service due to an identified deficiency which can make them

fail--hence unreliable for IFR work.  So, in this instance, having two

of the same thing doesn't double your reliability.



Note:  This was not a slam on the Crossbow.  Just recognition that they

have a problem right now that they are working to resolve. How they fix

it and how they interact with their customers which they have

inconvenienced will be more revealing of their character than any flaw

that might have been missed despite certification testing and their best

design and QA efforts.  Stuff happens.



To close out these ramblings, two of something, especially of the same

thing, does not constitute true redundancy of systems as they may share

the same fail-points.



Chuck Jensen


<aadamson(at)highrf.com>



QUOTE: As an example....if you have two Crossbow AHRS, what do you have?

END QUOTE:



Not sure what that is suppose to mean.... It means the same thing

whether

you have two Crossbow, or GRT, or BMI, or XYZ company AHRS.

aadamson(at)highrf.com
Guest

Posted: Fri Jan 13, 2006 2:46 pm Post subject: EFIS Comparisons

Yes, but Chuck, let's make sure we have the correct information... The

certified version, the Crossbow 500 which ships in the certified Chelton

(and others), does *NOT* have the problem.  There currently exists *NO* AD,

that I'm aware of.  



The experimental EFIS companies that utilize the 425 series crossbow AHRS,

do have a problem, but it only exists as a service letter from crossbow at

the moment.  Because there are none of these in certified airplanes, there

will never be an AD issued.  So, this makes the crossbow problem, no

different than the "leaning" problem that BMA, Dynon, GRT, etc have at any

moments notice.  You are advised of the problem, suggested that you use the

equipment for VFR only, but not grounded.



http://www.d2av.com/news_images/Service_Letter_NAV425_010506.pdf



Alan  



--

jschroeder(at)perigee.net
Guest

Posted: Fri Jan 13, 2006 2:54 pm Post subject: EFIS Comparisons

Brian -



We have the EFIS/ONE and the Dynon D-10A as the backup. So far, it has  

been fairly straight forward to install and check out. I just wish we  

didn't have to fool around with all those pesky voltage dividers. There  

are 18 resistors and a bunch of connections to add to the parts count.



Since we want to fly and file IFR, the major concern we have is putting  

too many functions in one box (EFIS/ONE CPU). We decided against having  

the BMA autopilot and installed a TruTrak DFC-250. This is controlled for  

navigation purposes by a separate, certified IFR enroute and terminal  

GPS/Com/Nav. The BMA GPS is simply not very powerful, especially with  

entering and storing flight plans and is not certified for IFR navigation.  

We wired the GPS to a separate CDI for legal IFR approaches. To make the  

EFIS/ONE capable of monitoring a 6 cyl Continental, we would have had to  

buy the extra card and still not have the value of features dedicated  

engine data monitors, such as lean find. So we installed a JPI EDM 700 for  

that. We also tapped off an oil pressure sender to run both the Hobbs and  

a low oil pressure light. Finally, we installed a Proprietary Systems  

Software AOA that is separate from most everything except the pitot and  

systems.



Just another approach by two other OBAM builders. We did install Bob's  

Z-14 as written.



Good to have you back on this list.



John Schroeder

Lancair ES - Painting

On Fri, 13 Jan 2006 13:11:36 -0800, Brian Lloyd <brian-yak(at)lloyd.com>  

wrote:



 	  Quote: 	
		   You sound like you are on the right track. I am debating between a Dynon

 D-10 and a 3-pack for my backup. Decisions, decisions ...


	


--

brinker(at)cox-internet.c
Guest

Posted: Fri Jan 13, 2006 3:02 pm Post subject: EFIS Comparisons

The GRT will also display the HSI from the SL30. And will tune the 

SL30 from the MFD. Not to mention ILS and Localizer  And will display your 

engine monitor to either display you choose. Not sure how you get 6k for 

engine monitoring. Last I checked a 6cyl was around $1100 with EIS and 

probes. GRT is very helpful if there is a way to make it work they will try. 

I have a KLN90B gps that Todd is trying figure out if it will work with 

they're system now. It looks favorable, I am keeping my fingures and toes 

crossed.



Randy



---

BobsV35B(at)aol.com
Guest

Posted: Fri Jan 13, 2006 3:22 pm Post subject: EFIS Comparisons

In a message dated 1/13/2006 5:06:21 P.M. Central Standard Time,  

harley(at)agelesswings.com writes:



Can't  let it go without mentioning these new guys based right down the 

field  from my hangar:



http://xerionavionix.com/



Harley Dixon

Long  EZ N28EZ

Canandaigua, NY



Good Evening Harley,

 

It sure looked good at Oshkosh. How are they doing?

 

Do Not Archive

 

Happy  Skies,



Old Bob

AKA

Bob Siegfried

Ancient Aviator

Stearman  N3977A

Brookeridge Air Park LL22

Downers Grove, IL 60516

630  985-8503

brinker(at)cox-internet.c
Guest

Posted: Fri Jan 13, 2006 3:24 pm Post subject: EFIS Comparisons

Just curious, why a separate CDI for IFR approahes if the BMA 

show's CDI on screen ?

---

harley(at)AgelessWings.co
Guest

Posted: Fri Jan 13, 2006 6:00 pm Post subject: EFIS Comparisons

>>How are they doing?<<



Well...they're new! <G>



I haven't been back there in awhile, what with winter and all, but the 

last time I was, they were discussing the installation of their unit in 

a couple of local birds for testing, and to train the two pilots so they 

could be field reps, I would guess. 



The VP stopped in to see my plane, and tried to talk me into one, as 

well, but I have already purchased another brand ...and I probably 

wouldn't be installing it in a time frame that they could use.



He did tell me that they are looking at certification for one of their 

models in April or May. Then they'll have units available for both 

certified and non-certified installations.



They have an assembly/test area and offices set up on the second floor 

of the main hangar at Canandaigua. Still pretty small...but that's how 

flying started, didn't it? <G>



Harley

 



BobsV35B(at)aol.com wrote:



 	  Quote: 	
		  



 

 

In a message dated 1/13/2006 5:06:21 P.M. Central Standard Time,  

harley(at)agelesswings.com writes:



Can't  let it go without mentioning these new guys based right down the 

field  from my hangar:



http://xerionavionix.com/



Harley Dixon

Long  EZ N28EZ

Canandaigua, NY



Good Evening Harley,

 

It sure looked good at Oshkosh. How are they doing?

 

Do Not Archive

 

Happy  Skies,



Old Bob

AKA

Bob Siegfried

Ancient Aviator

Stearman  N3977A

Brookeridge Air Park LL22

Downers Grove, IL 60516

630  985-8503

jschroeder(at)perigee.net
Guest

Posted: Fri Jan 13, 2006 6:23 pm Post subject: EFIS Comparisons

I know that the GAMI & Advanced Pilot Seminar guys are very interested in  

this engine monitor. They think it has the potential to be one of the  

best, if not the best, on the market.



John Schroeder



Do not archive

On Fri, 13 Jan 2006 21:00:00 -0500, Harley <harley(at)AgelessWings.com> wrote:



 	  Quote: 	
		   



  >>How are they doing?<<



 Well...they're new! <G>



 I haven't been back there in awhile, what with winter and all, but the

 last time I was, they were discussing the installation of their unit in

 a couple of local birds for testing, and to train the two pilots so they

 could be field reps, I would guess.



 The VP stopped in to see my plane, and tried to talk me into one, as

 well, but I have already purchased another brand ...and I probably

 wouldn't be installing it in a time frame that they could use.



 He did tell me that they are looking at certification for one of their

 models in April or May. Then they'll have units available for both

 certified and non-certified installations.



 They have an assembly/test area and offices set up on the second floor

 of the main hangar at Canandaigua. Still pretty small...but that's how

 flying started, didn't it? <G>



 Harley



 BobsV35B(at)aol.com wrote:



> 

>

> In a message dated 1/13/2006 5:06:21 P.M. Central Standard Time,

> harley(at)agelesswings.com writes:

>

> Can't  let it go without mentioning these new guys based right down the

> field  from my hangar:

>

> http://xerionavionix.com/

>

> Harley Dixon

> Long  EZ N28EZ

> Canandaigua, NY

>

> Good Evening Harley,

>

> It sure looked good at Oshkosh. How are they doing?

>

> Do Not Archive

>

> Happy  Skies,

>

> Old Bob

> AKA

> Bob Siegfried

> Ancient Aviator

> Stearman  N3977A

> Brookeridge Air Park LL22

> Downers Grove, IL 60516

> 630  985-8503

>





	


--

cjensen(at)dts9000.com
Guest

Posted: Sat Jan 14, 2006 6:35 am Post subject: EFIS Comparisons

Alan,



You are accurate all around, first, that the problem is only on the

non-certified Crossbow (which is still likely of greatest interest to

most AE posters) and second, other manufacturer and their product often

have problems also as they grow and mature.  



The POINT I was too subtlety (or inartfully) intending to make has not

changed, namely that two of the same thing (i.e. AHRS) do not give true

redundancy.  Ask the guy that hooked two AIs up to the same vacuum

system how the flying was when the vacuum pump turned to dust.  It's

just a system design consideration. For instance (with NO technical

basis to support these numbers), two AHRAS from the same manufacturing

run, of the same model with the same software from the same bus system

may improve reliability/availability 10% to 25%--certainly not 100%.



Chuck

Do Not Archive




<aadamson(at)highrf.com>



Yes, but Chuck, let's make sure we have the correct information... The

certified version, the Crossbow 500 which ships in the certified Chelton

(and others), does *NOT* have the problem.  There currently exists *NO*

AD,

that I'm aware of.  



The experimental EFIS companies that utilize the 425 series crossbow

AHRS,

do have a problem, but it only exists as a service letter from crossbow

at

the moment.  Because there are none of these in certified airplanes,

there

will never be an AD issued.  So, this makes the crossbow problem, no

different than the "leaning" problem that BMA, Dynon, GRT, etc have at

any

moments notice.  You are advised of the problem, suggested that you use

the

equipment for VFR only, but not grounded.



http://www.d2av.com/news_images/Service_Letter_NAV425_010506.pdf



Alan  




--> <cjensen(at)dts9000.com>



Alan,



This was just poking a bit of fun at the idea of two AHRS giving one

true

redundancy.  In the case of the reference to the Crossbow AHRS, right

now if

you have two....you have none, since the AD has taken them out of

service

due to an identified deficiency which can make them fail--hence

unreliable

for IFR work.  So, in this instance, having two of the same thing

doesn't

double your reliability.



Note:  This was not a slam on the Crossbow.  Just recognition that they

have

a problem right now that they are working to resolve. How they fix it

and

how they interact with their customers which they have inconvenienced

will

be more revealing of their character than any flaw that might have been

missed despite certification testing and their best design and QA

efforts.

Stuff happens.



To close out these ramblings, two of something, especially of the same

thing, does not constitute true redundancy of systems as they may share

the

same fail-points.



Chuck Jensen


<aadamson(at)highrf.com>



QUOTE: As an example....if you have two Crossbow AHRS, what do you have?

END QUOTE:



Not sure what that is suppose to mean.... It means the same thing

whether

you have two Crossbow, or GRT, or BMI, or XYZ company AHRS.

Bruce(at)glasair.org
Guest

Posted: Sat Jan 14, 2006 6:51 am Post subject: EFIS Comparisons

Well then I guess all those Part 121 airplanes flying around out there with

dual independent EFIS with an electronic comparator/alerter and a third gyro

(tie breaker) are all wrong.



Bruce

www.glasair.org

 



--

cjensen(at)dts9000.com
Guest

Posted: Sat Jan 14, 2006 7:15 am Post subject: EFIS Comparisons

Nope.  Not wrong, just expensive.  OBAM aircraft are probably somewhat

more interested in something a little more pedestrian (and affordable

than) than "dual independent EFIS with an electronic comparator/alerter

and a third gyro

(tie breaker)."  Heck, I'm still trying to figure out the nuances of the

discussion on wiring the master switch.



Our mission profile requires a craft a bit less teched-out than a Part

121 airplane, but for anyone that it trips-their-trigger, then by all

means......

 

Chuck Jensen

Do Not Archive


<Bruce(at)glasair.org>



Well then I guess all those Part 121 airplanes flying around out there

with

dual independent EFIS with an electronic comparator/alerter and a third

gyro

(tie breaker) are all wrong.



Bruce

www.glasair.org

aadamson(at)highrf.com
Guest

Posted: Sat Jan 14, 2006 7:26 am Post subject: EFIS Comparisons

Now, that is exactly the point... And I couldn't agree more!  Sorry, I just

took exception to the dig (what appeared to be) at crossbow.



Alan 



--

Bruce(at)glasair.org
Guest

Posted: Sat Jan 14, 2006 7:46 am Post subject: EFIS Comparisons

OK, I can understand that.



I hope you've been following the EFIS discussion on this list. Let me beat

my drum one more time.



These low cost EFIS displays (Pick your favorite) are hypnotic and

compelling, if cross checks start to disagree, the pilot is going to want to

keep on flying that pretty EFIS unless you hit him over the head. We don't

know all their failure modes and their software (with the exception of

Chelton) remains untested to the extent necessary to pass DO 178, their

hardware is not DO 160 certified. That means you're the beta tester. Do you

want to bet your life in that situation? Mark my words, we're going to have

some experimental airplanes equipped with low cost EFIS systems get into

some serious fatal trouble. That body count is going to raise the level of

visibility of this issue with the FAA and soon big brother will be breathing

down our necks.



Low cost, noncertified EFIS system are OK for VFR airplanes. But stay out of

IFR conditions.



Bruce

www.glasair.org

 



--

cjensen(at)dts9000.com
Guest

Posted: Sat Jan 14, 2006 8:32 am Post subject: EFIS Comparisons

<Bruce(at)glasair.org>



OK, I can understand that.



I hope you've been following the EFIS discussion on this list. Let me

beat

my drum one more time.



These low cost EFIS displays (Pick your favorite) are hypnotic and

compelling, if cross checks start to disagree, the pilot is going to

want to

keep on flying that pretty EFIS unless you hit him over the head. We

don't

know all their failure modes and their software (with the exception of

Chelton) remains untested to the extent necessary to pass DO 178, their

hardware is not DO 160 certified. That means you're the beta tester. Do

you

want to bet your life in that situation? Mark my words, we're going to

have

some experimental airplanes equipped with low cost EFIS systems get into

some serious fatal trouble. That body count is going to raise the level

of

visibility of this issue with the FAA and soon big brother will be

breathing

down our necks.



Low cost, noncertified EFIS system are OK for VFR airplanes. But stay

out of

IFR conditions.

Bruce

At the risk of further pounding on this dead horse whose meat is already

well-tenderized, the admonishment to avoid the noncertified EFIS for IFR

is a bit broad (IMHO).  I fly with a dual GRT EFIS (this does not give

me redundancy, just contemporary PFD and EIS display) driven by a single

AHRS.  For redundancy, I rely on old round AS, Alt and vertical compass

and, most importantly, a Mid-Continent AI with its own internal battery.

Secondary redundancy (but reliant on the same electrical system as the

AHRS/EFIS is a TruTrak A/P which will take me where I want to go as long

as the lights are on.  



So, I would concede your proposition with just a bit of technical

modification, "low cost, noncertified EFIS systems are okay for VFR

airplanes but stay out of IFR conditions unless you have a well thought

out, well designed redundant primary flight system."  But of course, I

would make the same admonishment for a certified EFIS!



Chuck

aadamson(at)highrf.com
Guest

Posted: Sat Jan 14, 2006 8:56 am Post subject: EFIS Comparisons

Which is exactly why there are zero certified EFIS systems that are

certified as *primary* (in small single engines anyway).  The G1000 in my

C182, is specified as secondary, the primary instruments are the AS, AI, ALT

- regular old vacuum driven 3.125" steam gauges... 



Alan 



--

Bruce(at)glasair.org
Guest

Posted: Sat Jan 14, 2006 9:16 am Post subject: EFIS Comparisons

Quite often, in discussions like these, we tend to be hardware orientated

and totally overlook the human factors engineering in the systems. With your

dual GRT EFIS you're a step ahead of most. Are you cross checking as part of

your normal scan?



Again, the part of this equation that most worries me is (except in black

screen failures) the time it takes the pilot to realize that something is

seriously wrong, determine the failed instrument, and take corrective

action. In some stages of IFR flight that amount of time will just not be

there. If the ADI rolls inverted at 8,000 feet when you're on top, no

problem. But if you're 300 AGL on the ILS?? This is the main reason for dual

systems/electronic comparator/3rd gyro, to give you a chance to survive when

time is of the essence.



You're free to fly with whatever you want as long as it fits your comfort

level. But when I see builders wanting to charge off into hard IFR with a

BMA, T&B, and ASI, I just got to say - Are you sure you want to do this?



Bruce

www.glasair.org

 



--

Bruce(at)glasair.org
Guest

Posted: Sat Jan 14, 2006 9:24 am Post subject: EFIS Comparisons

Good point. I'm going to check with Garmin, Chelton, and Avidyne and get the

certification status of their systems.



Bruce

www.glasair.org

 



--

jschroeder(at)perigee.net
Guest

Posted: Sat Jan 14, 2006 12:24 pm Post subject: EFIS Comparisons

Alan -



Try this link on the BMA board:  

http://www.bluemountainavionics.com/talk/showthread.php?t=127



It has the ref and cite for the EAA paper.



As I understand it, you can legally do an IFR ILS or VOR approach using  

external VOR/ILS inputs connected to the EFIS/ONE. However, as I read this  

thread and understand the BMA EFIS, you cannot use the GPS for anything  

other than navigation assistance. Thus, if one wants to navigate and do  

approaches IFR using GPS, the box has to meet more stringent criteria. I  

have not found the reference yet, but I believe that a WAAS approach using  

a GNS 480 has to have an OBS/CDI. We wired our 480 to an MD200-306(?). The  

EFIS/ONE cannot provide this because it cannot communicate fully with the  

480. The EFIS/ONE is a wonderful piece of equipment and we look forward to  

using it. But it is not, in my opinion, a box into which I want to put all  

the eggs.



I can't comment on the uncertified Chelton line because I have not  

followed or worked with them.



John



 	  Quote: 	
		   <aadamson(at)highrf.com>



 John, I might be wrong and just went to look on the BMA site.  I didn't  

 find

 anything specifically, nor did I find it on or searching around the EAA

 site.



 Can you post a link?  You sure you aren't confusing the issue of using  

 the

 BMA with a CNX-480 and the fact that you can't get all the nav signals  

 that

 are needed, some most are using an external head?



 The link to specifics would help if you could please?  I'm curious as  

 well

 as I'm going down the road to a chelton panel for a Legacy and want to  

 make

 sure I don't mess up.  Guys at D2AV say I don't need and external CDI...



 Alan

aadamson(at)highrf.com
Guest

Posted: Sat Jan 14, 2006 1:33 pm Post subject: EFIS Comparisons

Ah, ok, now that helps...



Ok, so here is some help.  The chelton fully interfaces with the SL-30

(notice I didn't say 480 yet) for resolver info and GS, LOC signals.

Actually it does this via a serial interface.  The problem is the 480, which

supposedly uses the same engine as the SL-30, didn't implement the serial

interface the same as the SL-30 and so you can't get all the data to drive

the BMA interface.



You don't technically need an external display, you just need a display that

can give GS and LOC information in an displayable format (could be HSI,

could be HITS, could be up/down, left/right).



Notice I've left alone the conversation about GPS approaches for the moment.



So on an ILS or LOC/VOR approach, the BMA or Chelton can be the only display

if talking to an SL-30.  If there is a 480 involved, it most likely needs an

external display due to the limitations of the 480 and it's inability to

provide the signals that the eFIS wants.  You actually can do it on the

Chelton, but it requires an expensive ARINC 429 to serial converter.



I'm not going to get into the GPS approach topic.  There are a whole set of

issues there.  However, if you have a GPS which delivers the right outputs

for either the Chelton or the BMA and it's Approach certified, you don't

technically need the external CDI.  There is no requirement that I'm aware

of that specifically requires a TSO'd (don't even think there is a TSO for a

CDI anyway) indicator or switch panel for that matter.



As you can tell, this gets all complicated, and even more so depending on

what radio the EFIS is trying to talk to... But then this isn't an Avionics

forum and I'm not an expert 



Thanks tho and I'll go read the links you provided.



Alan 



--

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