Compass correction card: Airworthiness Limits?

[MarkH]

I understand that a compass correction card is required, but is there any limit on how large the correction can be?

background:

I’m doing a checkout in a new plane, my CFI gives me a heading for maneuvers, I orient myself based on the compass and then he tells me that I’m 30 degrees off heading (Admittedly, this is my fault for not reading the card). When I look at the MFD, he’s right, then I check the card and see that the card declares a 30 degree correction. After that experience, I will always check the correction card now, but I am also wondering if that is OK. That seems like a massive error to just be recorded and accepted but I can’t find anything that suggests it is an issue (under the regs), is there any regulation that limits the acceptable error?

 

[Greg Bockelman]

Yeah, that needs to be adjusted out. Or otherwise fixed.

 

[Dan Thomas]

The historical FARs gave it this way:

Sec. 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).

That was the requirement for aircraft to receive certification, and maintenance is intended to keep the airplane at that standard. Now, that FAR, along with a whole raft of others, has been moved into Advisory Circulars, so I'm not sure what the regulatory requirement is now.

 

[MarkH]

Yeah, that needs to be adjusted out. Or otherwise fixed.

If it were my plane, I would do something about regardless of regs, but its a rental so I don't have much say (but it is otherwise well maintained).

 

[Bell206]

but is there any limit on how large the correction can be?

The rule of thumb is 10 deg but as noted above 1547(e) allows more if caused by electrical equipment requiring it to be noted on the card. But yes, outside of some specialized installations its usually best to get it back within 10 deg when possible.

so I'm not sure what the regulatory requirement is now.

The new rules only affect new aircraft type certifications. 1547(e) still valid.

 

[AggieMike88]

I had this compass card question posed to me today by a student:

If the correct card is missing, does that affect airworthiness until it is replaced?

(at least I think it was an airworthiness question. Student has purchased an airplane and the card is not present)

 

[Bell206]

If the correct card is missing, does that affect airworthiness until it is replaced?

Technically, yes, as it is a certification requirement for CAR 3/Part 23.

 

[mandm]

I had this compass card question posed to me today by a student:

If the correct card is missing, does that affect airworthiness until it is replaced?

(at least I think it was an airworthiness question. Student has purchased an airplane and the card is not present)

compass correction card is required to be airworthy.