allowable compass error...

§ 23.1327 Magnetic direction indicator.
(a) Except as provided in paragraph (b) of this section-

(1) Each magnetic direction indicator must be installed so
that its accuracy is not excessively affected by the
airplane's vibration or magnetic fields; and

(2) The compensated installation may not have a deviation in
level flight, greater than ten degrees on any heading.

(b) A magnetic nonstabilized direction indicator may deviate
more than ten degrees due to the operation of electrically
powered systems such as electrically heated windshields if
either a magnetic stabilized direction indicator, which does
not have a deviation in level flight greater than ten
degrees on any heading, or a gyroscopic direction indicator,
is installed. Deviations of a magnetic nonstabilized
direction indicator of more than 10 degrees must be
placarded in accordance with §23.1547(e).

[Amdt. 23-20, 42 FR 36969, July 18, 1977]


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--
James H. Macklin
ATP,CFI,A&P

"Casey Wilson" N2310D @ gmail.com wrote in message
news:0sylg.2531$DI2.2291@trnddc05...
| Okay, Jim, I think you said an error greater than ten
degrees will ground
| the airplance. I'll accept that. Can you give me the
reference for the ten
| degree figure? Are you saying that the airplane should be
taken to the
| compass rose during the annual or is there some "quick
check?"
|
| "Jim Macklin" wrote
in message
| news:NBplg.49163$ZW3.16236@dukeread04...
| Part 23 and Part 43.
|
| Runways are to the nearest 5 degrees and will be
renumbered
| as required. During the annual inspection the compass
| should be checked to be sure it is within degrees on all
| headings and any time there has been a change in the
| airplane that would cause the deviation to change.
|
|
| Yes, an error greater than 10 degrees, even with the
| correction card, requires correction.
|
|
| --
| James H. Macklin
| ATP,CFI,A&P
|
| "RomeoMike" wrote in
message
| ...
| | Don't know, but if you are using the runway heading to
| judge whether
| | your compass reading is in error, remember that runway
| headings are not
| | always true. There are other ways to calibrate your
| compass.
| |
| | Casey Wilson wrote:
| | My FARAIM is at my daughter's house and I can't find
| anything on the 'net to
| | answer my questions. Please indulge me....
| |
| | Scenario:
| | 1) line up with runway centerline[for my
| hypothetical, the runway is
| | dead nuts to the compass]
| | 2) note compass heading
| | 3) add/subtract compass card correction
| |
| | Questions:
| | 1) How much error is allowable between known
heading
| and corrected
| | compass reading?
| | 2) Does a significant error down the airplane as
| unworthy?
| | 3) Where can I find applicable references?
| |
| |
| |
|
|
|
|

If you are tracking a radial on a VOR
couldn't you compare the radial to the compass heading and get a good idea of
the compass error?

Only with no crosswind.

Jose
--
The monkey turns the crank and thinks he's making the music.
for Email, make the obvious change in the address.

A 100 KIAS with a 50 knot 90 degree crosswind can be flown
without any compass at all, you just need a stable heading
reference, but it is so far from being close to any easy
reference, it tells you nothing about the compass accuracy.

You need an accurate compass/heading reference for ADF
tracking and it does help with getting and staying on course
with radio navigation.

The question is not how bad can it be, but how good can it
be.



--
James H. Macklin
ATP,CFI,A&P

"Casey Wilson" N2310D @ gmail.com wrote in message
news:Y3Flg.22377$YI2.20622@trnddc01...
| I've got no problem with that George, as a general
indication of
| discrepancy. On the other hand, I sure that some of the
nitpickers in our
| RAP community would want to immediately toss in the VOR
calibration and
| accuracy, crab angle caused by crosswind drift relative to
the actual course
| versus heading, yadda, yadda...
|
| What my question really is, is how much difference (for
discussion I'll
| agree that the method described is acceptable) between
that compass heading
| and the VOR radial is tolerable before the airplane should
be grounded and
| the compass readjusted, repaired, or replaced? Secondly,
what is the
| applicable reference for that?
|
|
| "GeorgeC" wrote in message
| ...
| I had a thought, what do you think? If you are tracking
a radial on a VOR
| couldn't you compare the radial to the compass heading
and get a good idea
| of
| the compass error?
|
|
| On Mon, 19 Jun 2006 14:17:23 GMT, "Casey Wilson" N2310D
@ gmail.com
| wrote:
|
| Thanks, I know about compass roses and swinging the
compass. What I'm
| looking for is an indication that the compass needs
swinging. That's why
| my
| hypothetical scenario stated that the runway alignment
is correct. That
| does
| happen, by the way, even if the odds are against it.
|
| GeorgeC
|
|

Ah, Jim, finally.... thank you, thank you...

Casey


"Jim Macklin" wrote in message
news:FqFlg.49206$ZW3.9522@dukeread04...
' 23.1327 Magnetic direction indicator.
(a) Except as provided in paragraph (b) of this section-

(1) Each magnetic direction indicator must be installed so
that its accuracy is not excessively affected by the
airplane's vibration or magnetic fields; and

(2) The compensated installation may not have a deviation in
level flight, greater than ten degrees on any heading.

(b) A magnetic nonstabilized direction indicator may deviate
more than ten degrees due to the operation of electrically
powered systems such as electrically heated windshields if
either a magnetic stabilized direction indicator, which does
not have a deviation in level flight greater than ten
degrees on any heading, or a gyroscopic direction indicator,
is installed. Deviations of a magnetic nonstabilized
direction indicator of more than 10 degrees must be
placarded in accordance with '23.1547(e).

[Amdt. 23-20, 42 FR 36969, July 18, 1977]

I misread read your post. I "read" that you wanted to check to see if your
compass was out of tolerance, but your question was what were the tolerances.
Which I see James answered.

On Mon, 19 Jun 2006 21:56:08 GMT, "Casey Wilson" N2310D @ gmail.com wrote:


What my question really is, is how much difference (for discussion I'll
agree that the method described is acceptable) between that compass heading
and the VOR radial is tolerable before the airplane should be grounded and
the compass readjusted, repaired, or replaced? Secondly, what is the
applicable reference for that?

GeorgeC