Pitot Air System And Static Air System Description And Operation; Rate Of Climb Indicator - Piper PA-44-180 SEMINOLE Maintenance Manual

GENERAL.
The instrument air system consists of pitot air and static air sources. The system supplies both pitot and static
air pressure for the airspeed indicator, altimeter and vertical speed indicator. These instruments are face mounted.
DESCRIPTION AND OPERATION.
The pitot air system consists of a pitot mast located on the underside of the left wing, with its related
plumbing. Impact air pressure entering the pitot is transmitted from the pitot inlet through hose and tubing routed
through the wing to the airspeed indicator on the instrument panel. A partially or completely blocked pitot head
will give erratic or zero reading on the instruments.
Static air system consists of a static port located on the bottom of the pitot mast. The static port is directly
connected to the airspeed indicator, altimeter and rate of climb indicator on the instrument panel by means of
hose and tubing routed through the wing along with the pitot line. An alternate static air source is located below
the instrument panel in front of the pilot. The alternate static source is part of the standard system and has a
shutoff valve which closes the port when it is not needed. A placard giving instructions for use is located on the
instrument panel. Pitot and static lines can be drained through separate drain valves located on the left lower side
of the fuselage interior.
FLIGHT.

RATE OF CLIMB INDICATOR.

The rate of climb indicator measures the rate of change in static pressure when the airplane is climbing or
descending. By means of a pointer and dial, this instrument will indicate the rate of ascent or descent of the
airplane in feet per minute. Due to the lag of the instrument, the aircraft will be climbing or descending before the
instrument gives the correct rate. The instrument will continue to read after the aircraft has assumed level flight.
In rough air this should not be considered a malfunction.
PIPER AIRCRAFT
PA - 4 4 - 1 8 0 / 1 8 0 T
AIRPLANE MAINTENANCE MANUAL
2I19
3 4 - 11 - 0 0
Page 34-01
Revised: May 15, 1989