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Inaccurate turn coordinator

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Well-known member
Dec 23, 2004
I can't find this answer so I am turning to the good people of FlightInfo.

While flying the other day I noticed the standard coordinator was not accurately showing a standard rate turn. It was actually about 1 1/2 minutes for the two minute turn.

I am getting back into general aviation after a 20 year absence and can't recall if this type of calibration is required for instrument flight.

Does anyone have this answer?

91.205(d)(3) is the requirement for a gyroscopic rate of turn indicator. I tried to find an accuracy specification for that instrument but failed. You're supposed to calibrate the turn coordinator or T+B before you use it to perform timed turns anyways, so perhaps they're known to vary! (see chapter 5 of the instrument flying handbook http://www.faa.gov/library/manuals/aviation/) The only ground check I'm aware of for the T+B/TC is to verify it deflects in the correct direction when you're taxiing.

If you have a trustworthy AI, you'll get your standard (3deg/sec) rate turn at 1.5 * (airspeed/10) degrees of bank.


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