12.38.4(c) . the functions of the fluid in the compass bowl. 

– Supports some of the weight
– decreases the friction on the pivot
– dampens / decreases the oscillations of the magnet and float during flight

12.38.4(b) . define lubber line; 

Direct reading compass is filoled with a liquid in which a float supporting a bar magnet is pivoted
Attached to the pivot assembly is a sompass magnet / card unit
– graduated in degrees
This can be read by the pilot against a reference marker which is known as the lubber line
– lubber line attached to the bowl of the compass
–

12.38.4(a) . describe the construction of a present-day direct-reading compass; 

12.38.4. Briefly:

12.38.2. Given a sample deviation card, show how to apply corrections.

The amount of deviation on different compoass headings differs from aircrft to aircraft and can be determined through a procedure called a compass swing carried out on the particular aircraft
The results of the compass swing and any compensation taken for deviation are shown on a deviation card displayed in the cockpit
Corrections to the compass heading amy be applied to obtain an accurate magnetic heading

12.36. Pressure Instruments

12.36.16(b) . blockage of the static source. 

Indications
– if anything bllocks the static vent, air will be trapped in the static line and all 3 pressure instruments will be affected
– ASI shows lower speed than actual during a climb and higher than actual during a descent
– altimeter will indicate a constant altitude despite aircraft climbing/ descending
– VSI – will read zero even though may be climbing / descending

Actions

12.36.16(a) . blockage of the pitot tube; 

Indications
– only the ASI will be affected
– in level flight change in airspeed will not be registered by ASI
– in a climb ASI will be too high
– descent below icing – ASI too low
– if not ice blocking – ASI will have continued to be zero on take off

Actions
– clear any ice by switching on the pitot heater
– if no heater try a descent to a warmer altitude
– use pitot heat normally if going through cloud or heavy precipitation
– if something else causing the blockage ASI will be zero on take -off – so this can be aborted – or declare an emergency

12.36.16. 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;

blockage of the pitot tube in a climb..

blockage of the pitot tube in a Desent..

(b) . blockage of the static source.

blockage of the static tube in a climb..

blockage of the Static tube in a Desent..

12.36.14. Indicate the normal checks for serviceability of the pitot-static system, both preflightand during operation. 

Pre-flight
– pitot cover removed
– pitot head and static vents checked for damage and blockage
– inspect instruments for damage or malfunction
– ASI and VSI – should read zero
– set altimeter to aerodrome elevation
– take-off run check speed builds on the ASI
– entering climb check the altimeter and VSI showing correctly

During flight
– only adjustment would be to the altimeter subscale after getting amended QNH
–