Who can inactivate a turn coordinator?
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What to do when a non-required instrument fails and while waiting for repair/replacement.  Example: turn coordinator in a plane where it's not required by 91.205 for VFR, is not listed in the type certification data sheet, and can be inactivated by pulling a fuse on the panel.  This scenario is on the ground, not in flight. The goal is for the aircraft to be airworthy for VFR flight. 

Person A says, take it to an A&P to pull the fuse, placard it, and make a log entry.
Person B says, pull the fuse and placard it yourself.

Near as I can tell, 91.213 doesn't restrict who is allowed to inactivate by removing a fuse, unless it's "maintenance".  Is it? 1.1 defines maintenance as "inspection, overhaul, repair, preservation, and the replacement of parts, but excludes preventive maintenance."

If it's not maintenance, my read says anyone can do it as long as a pilot or A&P gives their okay:
91.213(d) says that for the inactivation & placarding to be okay, "A determination is made by a pilot, who is certificated and appropriately rated under part 61 of this chapter, or by a person, who is certificated and appropriately rated to perform maintenance on the aircraft, that the inoperative instrument or equipment does not constitute a hazard to the aircraft."

So, assuming that the determination is made by a certificated and rated person, can anyone pull the fuse and placard it, or does it need to be a certificated pilot, or an A&P? Is a logbook entry required?

Thanks!
4 Replies
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Ethan Benatan:
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If it's not maintenance, my read says anyone can do it as long as a pilot or A&P gives their okay:
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So, assuming that the determination is made by a certificated and rated person, can anyone pull the fuse and placard it, or does it need to be a certificated pilot, or an A&P? Is a logbook entry required?

Thanks!

Your read is correct.  Replacing fuses isn't listed as preventive maintenance, so it's not that.  So, if you pull the fuse, does that constitute "replacement of parts"? Pilots have been replacing fuses for 100 years or so (long before the FAA invented preventive maintenance) without the FAA caring about them not having an A&P ticket or making logbook entries, so I think you're in the clear in that.  And since pulling a circuit breaker Is not even preventive maintenance, no log entry would be required if that was how you deactivated the instrument.  

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Your example using a turn coordinator may not be the best choice as that instrument typically does not have a manual circuit breaker that you can pull. In that case you would have to physically remove the circuit breaker which then can be considered maintenance which a PIC is technically not authorized. 
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No question that physically removing the c/b is "maintenance" requiring an A&P and a logbook entry.  Of course, c/b's are usually connected with a soldered joint while the wire terminal is screwed to the instrument, making it much easier to disconnect/reconnect at that end -- still "maintenance" requiring an A&P and a logbook entry.  And FWIW, my experience is that TC's are usually run through either a fuse or a pullable breaker, making that the easiest deactivation mode -- and one which I think a pilot can do without either a log entry or an A&P.  I do suggest that if you pull a breaker, in addition to placarding, you use a tie-wrap to "collar" the c/b so it can't be inadvertently reset.  And if you remove the instrument itself, there will be a W&B correction needed, too, as well as an A&P-signed maintenance record entry..

But to the question actually asked (pulling the fuse out), I'll stand by my original answer -- just do it and placard it.  Only thing you have to watch out for is checking whether anything else is on that circuit, and then making sure you a) can fly without it, and b) placard it..
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Thank you both. It's a hypothetical question that my CFI asked me to research. As suggested by Prometheus, in the plane I'm flying (a 150) there's no non-maintenance way to inactivate the TC. But if there were a fuse I could pull to inactivate only the TC, I conclude that I could legally do so, and placard it--even as a student pilot--as long as a certificated pilot or mechanic determines that it does not create a hazard.

In the real world, the instrument was recently replaced :-)

Ethan