Compass correction cards

Tom-D

Tom-D

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Tom-D
Where does the requirement to have one come from. It isn't in 91.205.
 
Thanks guys, it is
Sec. 23.1547 Magnetic direction indicator.
(a) A placard meeting the requirements of this section must be installed on or near the magnetic direction indicator.
(b) The placard must show the calibration of the instrument in level flight with the engines operating.
(c) The placard must state whether the calibration was made with radio receivers on or off.
(d) Each calibration reading must be in terms of magnetic headings in not more than 30° increments.
[(e) If a magnetic nonstabilized direction indicator can have a deviation of more than 10 degrees caused by the operation of electrical equipment, the placard must state which electrical loads, or combination of loads, would cause a deviation of more than 10 degrees when turned on.]
So, Amateur built does not require one?
 
Home Builts require no instruments at all.
 
You are correct tom, as an EAB does not have to meet part 23. But you will still get FAA guys and der's that will fight you on that one.
 
not thinking to well this am what is EAB ? also re car3 cert aircraft do all part 23 rules go by by?
 
tinerj said:
Home Builts require no instruments at all.
Click to expand...

An EAB still has to follow 14 CFR 91. So…

Without an airspeed indicator, how would they be able to comply with the speed limitations of 14 CFR 91.117?

Without an altimeter, how would they be able to comply with the minimum safe altitudes as prescribed in 14 CFR 91.119 or the altimeter setting requirements of 91.121?

Without an airspeed indicator how would you be able to comply with 14 CFR 91.319 and its requirements to demonstrate that the aircraft is controllable throughout its normal range of speeds to get through Phase 1? How would you be able to sign off the log entry with Vso, Vx and Vy as required in your operating limitations?

Heck, without some basic form of navigation instrument, i.e. magnetic compass, how would you be certain you are staying within your approved Phase 1 test area?

Just curious. I am by no means an expert.
 
CAR 3 airplanes go by CAR 3 rules. That is the MAJORITY of light certified normal category aircraft in use today. Part 23 does NOT apply to these aircraft.
 
From CAR 3:
§ 3.758 Magnetic direction indicator. A placard shall be installed on or in close proximity to the magnetic direction indicator which contains the calibration of the instrument in a level flight attitude with engine(s) operating and radio receiver(s) on or off (which shall be stated). The calibration readings shall be those to known magnetic headings in not greater than 30-degree increments.
 
MauleSkinner said:
Where do you find that? 91.205 still applies.
Click to expand...

91.205 is titled "Powered civil aircraft with standard category U.S. airworthiness certificates: Instrument and equipment requirements." EABs have Special (Experimental) Airworthiness Certificates, not Standard.
 
It's kind of odd in swinging the compass, you make all of the 30 degree directions (30, 60, 90 . . .) off some, if necessary, so none of them are off more than 10 degrees.

I do fly a homebuilt so a compass is not required, but I do have a compass, so I figure a compass card is a good idea, if not required.
 
"Once aligned on the heading, the
person in the cockpit runs the engine(s) to ap-
proximately 1,700 rpm to duplicate the air-
craft’s magnetic field and then the person reads
the compass"

What if your engine won't idle that slowly?
 
"What if your engine won't idle that slowly?"

I see where you're going with that.
 
Capt. Geoffrey Thorpe said:
"Once aligned on the heading, the
person in the cockpit runs the engine(s) to ap-
proximately 1,700 rpm to duplicate the air-
craft’s magnetic field and then the person reads
the compass"

What if your engine won't idle that slowly?
Click to expand...
Yea, for you prop rpm of 1700 would probably be the right number, right?
 
do folks even use the CCC when viewing the bobbling compass and setting the DG?...and the DG is only settable to +/- 2-3 degrees....

So, what difference does it really make.
 
About every jet I have ever worked on in the last 7 years went around the compass rose at the end of the job, with an avionics line tech adjusting the whiskey compass. They also issued the new correction cards and keep records of it actually being accomplished. IIRC the maintenance tracking programs track them too.

I'd bet that a good 70% of GA aircraft would be found non-compliant if audited. These are supposed to verified after any significant work which could introduce error. That could be as simple as installing a slide-in replacement radio or replacing the compass.
 
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