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-----Original Message-----
From: DALIJOHN [mailto:[EMAIL PROTECTED]
Sent: Saturday, January 08, 2005 7:41 AM
To: Ed Burkhead; [EMAIL PROTECTED]
Subject: RE: [COUPERS-TECH] altimeter, transponder testing


Frank and Ed,

 FAR 91.411 and 91.413 are the requirement for Altimeter and Transponder
testing. The tests have to be performed by a approve repair station with
calibrated equipment. Part 43, Appendix E and F describe the test. You can
read these at the FAA's web site
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgWebcomponents.
ns
f/

Disclaimer: Do not attempt this at home as you can damage or destroy your
instruments.

To test a pitot/static system, a hose is connected to the pitot tube and a
second one is connected the static source port. Inside the tester is a
small
vacuum pump that simulates the pressure changes as an aircraft climbs to
altitude, and a small amount of pressure is applied to the pitot tube to
simulate airspeed. The aircraft instruments are compared to the calibrated
machine and the accurate is then determined. If the altimeter is checked
in
a lab it is placed in a vacuum chamber and air is suctioned out. I would
think that it would be best to check to system in the aircraft first, if
the
system was out of tolerance remove the altimeter and take it to a repair
station for a check. Know that an altimeter reading can be affected by the
pitot and static line in the aircraft.

 To test the transponders, a transponder receiver is placed outside the
aircraft and it monitors the signal that the encoding altimeter transmits
during the pitot/static test. By comparing the input on the pitot and
static
ports and the transponder signal output the accuracy is determined.

 As far as cost, it's not cheap. The good news is aircraft operating under
VFR conditions are not required to comply, as this is only a IFR
requirement. However, I would strongly encourage some type of testing to
get
an accurate reading of the scale of error in your altimeter, especially if
you do any flying after sunset.

Enjoy your new coupe,

David Johnson~NC94088
Avionics Modification Engineer
Wichita Citation Service Center

-----Original Message-----
From: Ed Burkhead [mailto:[EMAIL PROTECTED]
Sent: Friday, January 07, 2005 12:51 PM
To: Frank Durgin; Coupe-Tech
Subject: [COUPERS-TECH] altimeter, transponder testing


----[Please read http://ercoupers.com/disclaimer.htm before following any
advice in this forum.]----



Frank,

To send messages to the list, use:
[email protected]  for anything about Ercoupe flying, Ercoupe
maintenance or general aviation tech subjects.

[email protected] for things we'd talk about at flyins.

For altimeter checking, I never did anything more than dial in the
altimeter setting and compare it to field altitude.  A couple of times I
flew by tall antennas as a cross check.  If there's more required, I
really don't know what.

As for transponders, I never had one in my Coupe.  I don't know if it
can be tested in the plane or not.  I'd call an avionics shop and ask.
Let's see what answers you get from the list.  I'll forward this to the
list.

Ed Burkhead
http://edburkhead.com/
ed -at- edburkheadQQQ.com   (change -at- and remove the QQQ)

I know you believe you understand what you think I said, but I am not
sure if  you realize that what you heard is not what I meant.


-----Original Message-----
From: Frank Durgin [mailto:[EMAIL PROTECTED]
Sent: Friday, January 07, 2005 10:31 AM
To: Ed Burkhead
Subject: ?

Hi Ed:

      I would have put this out to the entire group, but I don't have
the
e-mail address.

 Got my self an ercoup a couple of months ago. I'm fast learing that
ownership is not like renting.  Things like trasnpoder testing and
alitmeter
testing are new to me.

Could you tell me something about those two questions - where does one
get
them done, how much time and money involved


Thank you

Frank Durgin




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