Piper Arrow IV Turbo Maintenance Manual page 432

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.
REMOVAL AND REPLACEMENT OF FACE MOUNTED INSTRUMENTS.
Since all instruments are mounted in a similar manner, a description of a typical removal and installation is
provided as a guide for the removal and installation of the instruments. Special care should be taken when any
operation pertaining to the instruments is performed.
1. Remove the face panel by removing the screws from around the perimeter of the panel.
2. With the face panel removed, the mounting screws for the individual instruments will be exposed.
Remove the connections to the instrument prior for removing the mounting screws of the instrument to be
removed.
3. Installation of the instruments will be completed by reversing the removal instructions. After the
installation is completed and before replacing the instrument face panel, check all components for security and
clearance of the control column.
PIPER AIRCRAFT
PA-28RT-201 / 201T
MAINTENANCE MANUAL
—NOTE—
Tag instrument connections for ease of installation.
2G9
34-00-02
Page 34-01
December 1, 1978