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PPL » Aircraft Tech Knowledge (A) » Pressure Instruments



Identify the three basic instruments which rely on air pressure for their operation.


Describe static pressure and dynamic pressure, and the main factors which affect them .


Explain the operation of a pitot-static system, including:

(a) static vent(s);

(b) pitot tube;

(c) combined pitot-static head;

(d) drain holes, heating, and pitot cover;

(e) alternate pressure source.


With respect to the airspeed indicator, describe the:

(a) basic principle of operation and serviceability checks;

(b) colour coding, and the meaning of VSO, VS1, VFE, VNO and VNE;

(c) IAS/TAS/groundspeed relationship;

(d) errors affecting the ASI, and how position error correction is applied.


With respect to the altimeter, describe the:

(a) basic principle of operation and serviceability checks;

(b) subscale settings and the meaning of QNH and QFE;

(c) errors affecting the altimeter, including subscale setting error.


With respect to the vertical speed indicator, describe the:

(a) basic principle of operation;

(b) errors affecting the VSI.


Indicate the normal checks for serviceability of the pitot-static system, both pre-flight and during operation.


Identify the cockpit indications of the following pitot-static system malfunctions, and state the actions available to the pilot to deal with the problem:

(a) blockage of the pitot tube;

(b) blockage of the static source.

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