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Date: Sat, 26 Nov 2005 17:23:36 -0500
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From: Brent Regan <brent@regandesigns.com>
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Subject: Chelton and the Crossbow NAV425EX AHRS problem
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When Chelton introduced their certified EFIS they licensed Direct-To to 
market the experimental "Sport" version. In an effort to reduce price, 
Direct-To made a deal with X-Bow to design a low cost, exclusive version 
of their certified AHRS. In exchange Direct-To would provide flight 
testing resources and an established market.  The NAV425EX was the child 
of this union. X-Bow then introduced the 420 and proceeded to sell it to 
Chelton's (and Direct-To) competitors (e.g. OP). This was no great 
surprise as X-Bow had previously received significant (and critical) 
engineering assistance from Chelton during the work to certify the 
AHRS500 series, a product they then turned around and made available to 
the general market. Not to single out X-Bow because another vendor, Free 
Flight (WAAS GPS), also received critical assistance from Chelton to 
certify their product, a product also now widely used by Chelton 
competitors.

Fortunately for the customer, Chelton chooses to compete in the 
marketplace by offering a superior product, rather than trying to 
suppress and / or monopolize technological advances. A rising tide 
raises all boats.

For the past eight years Chelton (formerly Sierra) Flight Systems has 
been the leader in EFIS technology with a very long list of firsts. The 
experimental product's software is derived directly for the Level A 
certified code that runs in the certified product. In fact, due to the 
delays introduced by the ongoing certification process, the experimental 
produce's code gets feature updates before the certified product. 
Chelton has a long history of supporting their customers and have 
regularly made hardware and software updates available.

Chelton's design team is second to none. All are IFR rated pilots. The 
software's architect and chief designer has multiple engineering 
degrees, a law degree and is a former F-18 instructor! The hardware 
designers also designed EFBs for Boeing.....and Honeywell, and Rockwell 
Collins, and Canadian Marconi (CMC), and Northstar Technologies as well 
as many other products for aerospace, medical and oceanographic markets. 
It was this team that succeeded in achieving certification where 
Honeywell, after spending over $90M, failed.

Chelton already has most of the features the competitors "plan to 
introduce", "are working on" or "will be available in the next release". 
This has precipitated the introduction of some curious competitor's 
"features".  The OP approach plate display is an example. If you have a 
flight path marker, highway in the sky (HITS), VNAV and all the 
approaches in your database overlaid on terrain and obstacles, as 
Chelton does, you don't need or want to display a paper approach plate.  
Same reason you don't need an HSI display. If you know your position in 
three dimensional space then lateral position and heading (HSI) is 
already known and doesn't need to be displayed on a separate, confusing 
indicator. What is next, a sextant page?

Don't take my word for it, research it yourself and you will see that 
the Chelton systems offer the best value. Bell Helicopter came to that 
conclusion and awarded Chelton their OEM contract, reported to be worth 
in excess of $100M over the next decade. It seems Chelton will be around 
to support your future needs and they already have the largest customer 
base.

It is this large customer base that lead to the discovery of the X-Bow 
425 design problem. It is a problem that does not occur in all units or 
in any particular installation so you needed a lot of flight hours in 
many planes to even know there is a problem.  It is reasonable to expect 
that the problem is also present in the 420 (used by OP and others) but 
has not yet surfaced because there are not enough of them flying.

I know that Direct-To and Chelton are dedicated to solving this issue 
and are supporting X-Bow in their efforts. Intermittent problems like 
these are difficult to fix because they must be first isolated then 
reproduced, fixed, tested and a solution deployed. I am confident that a 
solution will be made available soon as this problem does not occur in 
the AHRS500 certified product.

These are my personal opinions and statements. I do have a business 
relationship with both Chelton and Direct-To so you should start with 
the assumption that everything I say is wrong and work your way up from 
there. I am also an arrogant, opinionated, bloviating know-it-all so 
there is no need burning bandwidth saying something that is already 
public knowledge.

Wishing all Lancair pilots and builders a Merry Christmas and a warm hanger.

Regards
Brent Regan

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<font face="Arial">When Chelton introduced their certified EFIS they
licensed Direct-To to market the experimental "Sport" version. In an
effort to reduce price, Direct-To made a deal with X-Bow to design a
low cost, exclusive version of their certified AHRS. In exchange
Direct-To would provide flight testing resources and an established
market.&nbsp; The NAV425EX was the child of this union. X-Bow then
introduced the 420 and proceeded to sell it to Chelton's (and
Direct-To) competitors (e.g. OP). This was no great surprise as X-Bow
had previously received significant (and critical) engineering
assistance from Chelton during the work to certify the AHRS500 series,
a product they then turned around and made available</font><font
 face="Arial"> to the general market</font><font face="Arial">. Not to
single out X-Bow because another vendor, Free Flight (WAAS GPS), also
received critical assistance from Chelton to certify their product, a
product also now widely used by Chelton competitors.<br>
<br>
Fortunately for the customer, Chelton chooses to compete in the
marketplace by offering a superior product, rather than trying to
suppress and / or monopolize technological advances. A rising tide
raises all boats. <br>
<br>
For the past eight years Chelton (formerly Sierra) Flight Systems has
been the leader in EFIS technology with a very long list of firsts. The
experimental product's software is derived directly for the Level A
certified code that runs in the certified product. In fact, due to the
delays introduced by the ongoing certification process, the
experimental produce's code gets feature updates before the certified
product. Chelton has a long history of supporting their customers and
have regularly made hardware and software updates available.<br>
<br>
Chelton's design team is second to none. All are IFR rated pilots. The
software's architect and chief designer has multiple engineering
degrees, a law degree and is a former F-18 instructor! The hardware
designers also designed EFBs for Boeing.....and Honeywell, and Rockwell
Collins, and Canadian Marconi (CMC), and Northstar Technologies as well
as many other products for aerospace, medical and oceanographic
markets. It was this team that succeeded in achieving certification
where Honeywell, after spending over $90M, failed.<br>
<br>
Chelton already has most of the features the competitors "plan to
introduce", "are working on" or "will be available in the next
release". This has precipitated the introduction of some curious
competitor's "features".&nbsp; The OP approach plate display is an example.
If you have a flight path marker, highway in the sky (HITS), VNAV and
all the approaches in your database overlaid on terrain and obstacles,
as Chelton does, you don't need or want to display a paper approach
plate.&nbsp; Same reason you don't need an HSI display. If you know your
position in three dimensional space then lateral position and heading
(HSI) is already known and doesn't need to be displayed on a separate,
confusing indicator. What is next, a sextant page?<br>
<br>
Don't take my word for it, research it yourself and you will see that
the Chelton systems offer the best value. Bell Helicopter came to that
conclusion and awarded Chelton their OEM contract, reported to be worth
in excess of $100M over the next decade. It seems Chelton will be
around to support your future needs and they already have the largest
customer base.<br>
<br>
It is this large customer base that lead to the discovery of the X-Bow
425 design problem. It is a problem that does not occur in all units or
in any particular installation so you needed a lot of flight hours in
many planes to even know there is a problem.&nbsp; It is reasonable to
expect that the problem is also present in the 420 (used by OP and
others) but has not <b>yet</b> surfaced because there are not enough
of them flying.<br>
<br>
I know that Direct-To and Chelton are dedicated to solving this issue
and are supporting X-Bow in their efforts. Intermittent problems like
these are difficult to fix because they must be first isolated then
reproduced, fixed, tested and a solution deployed. I am confident that
a solution will be made available soon as this problem does not occur
in the AHRS500 certified product.<br>
<br>
These are my personal opinions and statements. I do have a business
relationship with both Chelton and Direct-To so you should start with
the assumption that everything I say is wrong and work your way up from
there. I am also an arrogant, opinionated, bloviating know-it-all so
there is no need burning bandwidth saying something that is already
public knowledge.<br>
<br>
Wishing all Lancair pilots and builders a Merry Christmas and a warm
hanger.<br>
<br>
Regards<br>
Brent Regan<br>
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