Piper Comanche PA-24 Service Manual page 806

PIPER COMANCHE SERVICE MANUAL
11-18. Removal and Replacement of Face Mounted Instruments.
NOTE
These airplanes were originally equipped with A.C. Sparkplug or Stewart
Warner engine gauges and sending unit systems which are no longer
available. For replacement engine gauges and sending units, see the current
Comanche Pans Catalog
(pIN
752 464) or Piper Service Spares Lener No. 406.
II -19. General. Since all instruments are mounted in
Ii
similar manner, a description of a typic-al 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.
a. Remove the instrument access panel by removing the retaining screws and lifting off the panel.
b. Remove the face panel by removing the screws from around the perimeter of the panel.
c. With the face panel removed, the mounting screws for the individual instruments will be
exposed. Remove the connections to the instrument prior to removing the mounting screws of the instrument
to be removed .
NOTE
Rag instrument connections for ease of installation.
d. Installation of the instruments will be in the reverse given for removal. After the installation is
completed and before replacing the instrument access panel, check all components for security and clearance
of the control column.
11-20. Removal and Replacement of Cluster Mounted Instruments.
NOTE
These airplanes were originally equipped with A.C. Sparkplug or Stewart
Warner engine gauges and sending unit systems which are no longer
available. For replacement engine gauges and sending units, see the current
Comanche Parts Catalog
(PIN
752464) or Piper Service Spares Leiter No. 406.
1\-21. General. A cluster, located on the instrument panel, contains. individual instruments. Removal of
these instruments can be accomplished by the following procedure.
a. Remove the instrument access panel by removing the retaining screws and lifting off the panel.
b. Remove the face panel by removing the screws from around the perimeter of the panel.
c. With the face panel removed, the clear plastic cover on the cluster assembly will be exposed.
Remove this cover by removing the two center mounting screws.
d. Remove the connection(s) to the individual instrument(s) to be removed and remove the
instrument(s) from the cluster assembly.
e. Replace instrument(s) in the reverse order of removal. Check all mountings and connections for
security.
II -22. Directional Gyro.
11-23. General. The directional gyro is a flight instrument incorporating an air-driven gyro stabilized in the
venical plane. The gyro is rotated at high speed by lowering the pressure in the air tight case and
simultaneously allowing atmospheric air pressure to enter the instrument against the gyro buckets. Due to
gyroscopic inenia, the spin axis continues to point in the same direction even though the aircraft yaws to the
right or left. This relative motion between the gyro and the instrument case is shown on the instrument dial
which is similar to a compass card. The dial, when set to agree with the airplane magnetic compass, provides
a positive indication free from swing and turning error.
e
Revised: 8115198 INSTRUMENTS
3GS