Piper COMANCHE PA-24-180 Service Manual page 660

the acqi knob. If gyro i not rotated and the cang knob is employed,
the gyro is not repoitioned in the cue, only the crd is omrned this
resul in checking the gyro only in one postion no matter how many
headings the card may be set to.
CAUTION
Permit no oil, grease. pipe compound, or any foreign material to
enter ports, prior to installation of fittings. Make sure that all air lines
are clean and free of foreign particles and/or residue before
connecting lines to gyro
I 1-10l Gyro Handling And Shipping. The following information applies
o
all three inch directional gyros
and attiude horizonm inrumnenut iuled
by the factory or a Piper field ervice facility.
Gyro inscrumens being returned to the factory ae to be placed in approved container with all port
properly seiaed immediately aftr removal from the aircraft inlumien panel. The intlrument must also be
accompanied by factory copies of the wrrnny and credit daim forms. Thee forms uad the pecial
containes should be available at any Piper Dealer and/or Distributor. Should any gyro inserment be
received by the factory in n unapproved container or if the ports are not sealed, the warrnty will be
immediately voided and the insmmu ent returned to the sender. The inmmn ent must be returned
immediately after removal from the aircraft (not to exceed 15 days following discovery of defect).
11-11. Vacuum Sytem. The vacuum sysem employed to operate the gyro instunens is comprised of an
engine driven vacuum pump, oil-air separator, vacuum regulator valve, and the necessary cubing to complete
the system. On the late model Comanche a dry vacuum pump has beea employed. When this type pump is
installed the need for the oil-sir separator and the hardware necesary for is installaion is eliminated. A kit
(754 356) is available for installaion of the dry vacuum pump on any of the early model Comanches.
One vacuum regulator valve is incorporated in the system to conrol vacuum prexure to the gyro
instrumens. Access to this valve for maintenance and adjusment is gained through the engine cowling. On
the early model Comanche, the regulator valve was mounted on the furewall, while the Later models have the
valve installed on the engine mount assembly.
11.12. Vacuum Regulor Valve Removal And lnsullaton. To remove the regulator valve
i
the engine
comparmenr, disconnect the three lines, remove the mounting screws and remove the valve. Install
regulator in reverre order given for removal. After installation check complere vacuum system for leaks and
proper operation.
11-13. Adjustment Of Vacuum Regulator Valve. To adjust the regulator valve, perform the
following
steps:
a Loosen the locking nut or remove the protective cap from the valve, depending on which type is
installed.
REVISED: 4/10/81 INSTRUMENTS
3 F21
PIPER COMANCHE SERVICE MANUAL