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We all know that a magnetic compass is required for day / night with VFR / IFR operations.
How do we know if the magnetic compass is not working correctly? More precisely, what amount of deviation on a known heading is allowed before the compass is not airworthy? A tricky question, I guess. Part 23 (certification of normal, ... category aircraft) should have the answer. |
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It took me awhile to figure out where I can lookup of Part 23 of the FAR's as its not in the FAR/AIM that I have at the house. I found it on the internet on the government website. Never knew it existed. 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. 1
This is an awesome question/answer, I've never seen this regulation either. A great follow up question is, if the magnetic compass is not airworthy, can you still legally fly VFR? The answer is NO. If the deviation exceeds 10 degrees the airplane is not airworthy. Ref FAR 91.7. Airworthy is not defined in the FARs, so this is just my opinion. For an aircraft to be airworthy, it must conform to it TCDS (type certificate data sheet), equipment list and any approved alterations with the exception of 91.213. Since the magnetic compass is required by 91.205 it cannot be included as inoperable in 91.213 |
