How do Six Pack Flight Instruments Work

Six Pack Flight Instruments

Mmmm… beer.

But actually today we’re going to be covering the inner workings of what we commonly refer to as “the six pack” (six pack of instruments that is).  Feel free to grab your favorite cold brew and peruse the following videos to get an idea of how each of your precious instruments works.

Altimeter

• The back of the instrument contains an “out-line” for tubing connecting to the static port to provide the instrument with ambient air pressure.
• The assembly is directly connected to the hands of the altimeted, and moves when the barometric pressure knob is adjusted.
• Aneroid Wafers are filled with gas which expands and contracts with pressure, therefore moving the wafers closer or further apart and adjusting the indicated altitude.

Turn Coordinator

• The turn indicator shows “rate of turn” by using an electrically driven gyro that resists the turning motion.
• A small electric motor drives a brass weight giving the instrument “rigidity in space”. This is the same concept as a bicycle or motorcycle wheel. As the speed of the wheel increases, the wheel becomes more stable… hence the reason it is easier to balance on a bicycle at 5 MPH as compared to 1 MPH.
• Watch for the red flag during flight. This indicates the instrument is inoperative. It is possible for electrical power to the instrument to be disrupted and the instrument to still function, as the gyro spins down slowly providing more and more inaccurate information.

Attitude Indicator / Artificial Horizon

• The Attitude Indicator, or “Artificial Horizon” usually operates through the engine-driven vacuum pump. Small inlets allow air to enter the instrument and a tube to the aircraft’s engine-driven vacuum pump sucks air out.
• As with the turn coordinator, a gyro with a brass weight is used to give the instrument “rigidity in space”, allowing it to show both pitch and bank information.
• Once again… be weary as the instrument may still appear to be indicating even if inadequate suction is available to power the instrument. Know if your attitude coordinator has warning flags, and become familiar with the indications of a failing attitude indicator.

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