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2 Answers

Flight instruments

Asked by: 6546 views Aircraft Systems

What are the limitations of the basic instruments displayed in the cockpit? During what type of aircraft manoeuvre will the instruments be pushed to its limits such that it displays incorrect reading or worse, stop functioning altogether?

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2 Answers

  1. Charlie Hilbrant on May 11, 2011

    Excellent question. I’ll give one example. In the case where we exceed the maximum limits of the attitude indicator, the gyro inside it will “tumble”. The limits of this instrument refer to the max rotation that the gimbals will allow before the horizon kind of falls away. Older vacuum-driven model attitude indicators that I’m familiar with have bank limits of about 100-110 degrees and pitch limits of about 70 degrees. The older type vacuum-driven attitude indicators have bank limits of approximately 100° to 110°, and pitch limits of 60° to 70°. Beyond these limits, the gyroscopic rotor precesses and causes potentially damaging wear and tear on those gimbals. The rotors WILL precess back to the normal horizon plane, but at a very slow rate. A newer model attitude indicator may have larger pitch and bank limitations.

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  2. Wes Beard on May 12, 2011

    All of the flight instruments have some inherent error in them:
    Static System (Airspeed Indicator, Altimeter and VSI):  The faster an airplane goes the more error is introduced into the static system.  This is due to compressibility issues.  Some aircraft like the CL-604 have a maximum mach speed in RVSM airspace due to this error
    Heading Indicator:  Precesses at a given rate and after some time, it will no longer read the correct heading the pilot is flying.  The regulations require this precession to be no more than 5° in 15 minutes.
    Inclinometer (Ball):  When entering a spin, the inclinometer can be displaced incorrectly and the unknowing pilot who steps on the ball will further develop the spin instead of recovering.  The proper technique is to look outside the aircraft.  If that is not possible, look at the tun and slip indicator.

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