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bakerocb
Joined: 15 Jan 2006
Posts: 727
Location: FAIRFAX VA
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 Posted: Mon Apr 21, 2008 3:13 am Post subject: Encoding Altimeter |
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4/20/2008
Hello Anonymous, You wrote:
1) "You seem to be saying that the only practical way to meet the
requirements is to use a TSO'd source for the altitude information the
transponder is transmitting."
That is close. Here is how I would phrase it: "At present the only practical
way to be in compliance with FAR Section 91.217, Data Correspondence Between
Automatically Reported Pressure Altitude Data and the Pilot's Altitude
Reference, is to use a TSO'd equipment source for the altitude information
the transponder is transmitting."
2) "That, of course, would eliminate valuable functionality of many
non-TSO'd electronic EFISs including the serial output to the transponder."
Specifically, the serial altitude data output to the transponder from a non
TSO'd altitude encoder within an EFIS would not, at present, be in
compliance
with either 91.217 (b) or (c).
3) "Clearly, that isn't happening in the real world. These are selling
well."
Correct.
4) "Are you against that?"
Not at all. Here are my positions:
A) People should make informed decisions.
B) If I can provide accurate information to people that will permit them to
make informed decisions I should do so.
C) The decisions that those people make, after I have given them the best
information that I have available, is theirs to make, not mine. The risks
that they chose to take, or not take, are theirs, not mine.
D) Most of the EFIS available to the amateur built community represent a
significant improvement in performance, reliability, and safety over
previously available flight instrument technology.
E) Most of the EFIS available to the homebuilt community contain a non-TSO'd
altitude encoder that is superior in performance, reliability, granularity,
and accuracy over altitude encoding equipment that was manufactured to
versions of TSO-C88 prior to TSO-C88b.
F) Amateur built experimental aircraft have flown thousands of hours using
EFIS with non-TSO'd altitude encoders feeding their transponders with no
apparent problems.
G) Hundreds of amateur built experimental airplanes are under construction
using EFIS containing non-TSO'd altitude encoders.
H) The FAA should recognize and accept the real world conditions described
in D, E, F, and G above.
I) The best way for the FAA to accept the real world conditions described in
D, E, F, and G above is to interpret the tests required by FAR Secs 91.411
and 91.413 (as appropriate) as fulfilling the requirements of FAR Sec 91.217
(b).
J) My initial attempts to accomplish H and I above with FAA HQ were met with
resistance and I ceased activity in this regard.**
K) If the FAA, and the people / entities who perform the tests required by
91.411 / 91.413, decided that every non-TSO'd altitude encoder in an EFIS
was not airworthy because it did not meet the requirements of either 91.217
(b) or (c) this decision would be a serious blow to the amateur built
community.**
L) I do not proactively broadcast the information in K above, but if someone
asks a specific question on this issue or posts a position that I know to be
in error I revert to my positions A and B above.
M) I am open to improvements or changes in my positions.
'OC' Says: "The best investment we can make is the effort to gather and
understand knowledge."
**PS: The FAA decision makers who perpetrated the recent fiasco involving
hundreds of airline flights being canceled and thousands of people being
stranded over the issue of the exact spacing of electrical wire cable ties
in the landing gear wheel wells of airline aircraft are capable of such
thinking and actions.
------------------------------------------------------------
---
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bakerocb
Joined: 15 Jan 2006
Posts: 727
Location: FAIRFAX VA
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| Posted: Tue Apr 22, 2008 5:26 am Post subject: Encoding Altimeter |
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4/22/2008
Hello Bill, Thanks for your input. You wrote:
1) "OR...you could buy a Dynon ........."
Since the Dynon units do not contain a TSO'd altitude encoder operating the
Dynon unit alone to feed a transponder in flight would presently leave one
in violation of FAR Sec 91.217 (as interpreted by FAA HQ). There are two
ways to approach this condition:
A) Purchase and install a separate TSO'd altitude encoder and use that
encoder to feed the aircraft's transponder.
B) Decide that violation of 91.217 is an acceptable risk and feed the
transponder from the non TSO'd altitude encoder contained in the Dynon unit.
2) ".....and save even more during the IFR recertification check."
My local avionics shop charges a flat fee for the FAR Sections 91.411 and
91.413 required testing. This fee has been the same no matter whether I do
the labor of removing and reinstalling the altimeter and TSO'd altitude
encoder, for bench testing and any adjustments needed prior to the airplane
side testing, or they do that labor. (By the way, four years ago that flat
fee was $150, now it is $300.)
3) "........the avionics shops actually prefer the Dynon due to their
accuracy and simplicity."
I hope that the avionics shops continue this practice without any regard for
what FAR Sec 91.217 says.
4) ".......the avionics shops actually prefer the Dynon due to their
accuracy and simplicity."
I wonder about the complexity of removing and reinstalling an EFIS from the
airplane compared to the complexity of removing and reinstalling an
altimeter and separate TSO'd altitude encoder should any bench testing and
adjusting be needed.
A) Maybe EFIS removal and reinstallation is no big deal, but I envision a
bunch of connections, particularly if it is the type of EFIS that also
includes displaying engine performance parameters.
B) Maybe the EFIS's have no means of local avionics shop adjustment.
C) Maybe the EFIS's would never need adjustment.
D) What has been the experience of EFIS operators that have actually been
through FAR 91.411 and 91.413 checks, as appropriate, after flying for at
least two years?
Would any EFIS owners and operators care to comment on these points?.
'OC' Says: "The best investment we can make is the effort to gather and
understand knowledge."
---------------------------------------------------
Time: 09:05:34 PM PST US
From: "William Gill" <wgill10(at)comcast.net>
Subject: RE: Encoding Altimeter
OR...you could buy a Dynon and save even more during the IFR
recertification check. In fact, the avionics shops actually prefer the
Dynon due to their accuracy and simplicity.
Bill
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echristley(at)nc.rr.com
Guest
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| Posted: Tue Apr 22, 2008 7:36 am Post subject: Encoding Altimeter |
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bakerocb(at)cox.net wrote:
| Quote: |
A) Maybe EFIS removal and reinstallation is no big deal, but I
envision a bunch of connections, particularly if it is the type of
EFIS that also includes displaying engine performance parameters.
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I don't know about others, but the Dynon unit is one DB-25 connector and
the pitot, static, and AoA connections.
http://www.dynonavionics.com/downloads/EFIS%20D100.pdf
It slides into a rack with one screw to lock it into place.
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wgill10(at)comcast.net
Guest
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| Posted: Tue Apr 22, 2008 5:39 pm Post subject: Encoding Altimeter |
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Yep...there are a lot of inconsistencies among FSDO folks. There is an
FAA inspector that monitors this site and he stated that the Dynon did
not need to be TSO'd, but simply meet the altitude testing at the
avionics shop to be legal (I'm surprised he has not yet chimed in --
check the archives). That's good enough for me. Also, a local KC FSDO
inspector called the individual on this site and he too now agrees that
the tested Dynon is legal. I'm not trying to argue, but there are
thousands flying with the Dynon encoder and the FAA folks I have queried
stated that the Dynon IS legal. I am also aware that some areas of the
country have met with resistance from avionics shops as well as their
local FAA folks. What gives?
Best regards,
Bill
--
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BobsV35B(at)aol.com
Guest
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| Posted: Tue Apr 22, 2008 6:19 pm Post subject: Encoding Altimeter |
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Good Evening Bill,
Nothing new here except another data point!
Our granddaughter just finished her Texas Star home built kit and had the altimeter, transponder and altitude for the 430W certified by a local shop from the area near Sulphur Springs, Texas. He had no compulsion about using the Dynon and her airplane is now OK for IFR flight as per the requirements as listed on the appropriate paperwork.
Happy Skies,
Old Bob
AKA
Bob Siegfried
Ancient Aviator
628 West 86th Street
Downers Grove, IL 60516
Do Not Archive
630 985-8502
Stearman N3977A
Brookeridge Air Park LL22
In a message dated 4/22/2008 8:40:49 P.M. Central Daylight Time, wgill10(at)comcast.net writes:
| Quote: | Yep...there are a lot of inconsistencies among FSDO folks. There is an
FAA inspector that monitors this site and he stated that the Dynon did
not need to be TSO'd, but simply meet the altitude testing at the
avionics shop to be legal (I'm surprised he has not yet chimed in --
check the archives). That's good enough for me. Also, a local KC FSDO
inspector called the individual on this site and he too now agrees that
the tested Dynon is legal. I'm not trying to argue, but there are
thousands flying with the Dynon encoder and the FAA folks I have queried
stated that the Dynon IS legal. I am also aware that some areas of the
country have met with resistance from avionics shops as well as their
local FAA folks. What gives?
|
Need a new ride? Check out the largest site for U.S. used car listings at AOL Autos.
[quote][b]
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