Piper COMANCHE PA-24-180 Service Manual page 440

PIPER COMANCHE SERVICE MANUAL
The oil pressure filter element. located on the aceasory housing. is provided us a means to filter ny
solid partcles that may have psed through the suction screen in the nump. After being filtered through
the pressure filter, the oil is fed through a drilled passage to the oil presure relief valve, located in the upper
right side of the crankcase forward of the accesory housing.
This relief valve regulates the engine oil presure by allowing excess oil to return to the sump, while the
balance of the premure oil is fed to the main oil gallery in the right half of the ankcase. Residual oil is
returned by grviy
to the sump where, after passing through the sucton screen, it is again circulated
through the engine.
The rurbochagers are lubicated by engine oil which is supplied to the turbo oil gallery by lines
connected to the engine ccesory housing. Incorporated in the oil supply line is a pressure regulator poppet
valve. The use of a resricted firing reduces engine oil pressure to 30-35 psi presr required for the
turbochargers. Oil is scavenged from the turbocharger sump and returned to the engine sump by scavenger
pump installed on the hydraulic pump drive pad of the engine accessory houing.
7C-3. Troubleshooring. Troubles peculiar to the power plant are listed in Table VIIC-II in the back of ths
section. along with their probable causes and suggested remedies. When troubleshoutmg engines, ground the
magneto primary circuit before performing any checks on the ignition system.
7C-4. Engine Cowling.
7C-5. Removal Of Engine Cowling.
a. Ascertain rhat the m ster switch and magneto switches are in the off position.
b
Release the three cowl fasteners on each side of the engine comparment.
c. Remove attching screws from the top cowl at the firewall.
d. Remove attaching srews from the nose section parting surfaces.
e.
Remove the two ataching nuts. washers and screws secunng the top cowl channels to firewall.
f. Lift the top cowl from the engine assembly.
g. Disconnect nose gear door actuating rods.
h. Disconnect cowl flap control cables.
i. Disconnect gear door frame channels from firewall and attachment sraps from tubular structure
by removing screws.
j.
Disconnect drain lines from bottom cowl.
k. Remove bottom cowl by removing screws scuring it to the firewall.
7C-6. Cleaning, Inspection And Repair Of Engine Cowling.
i.
Clean cowling with a suitable cleaning solvent and wipe dry with a clean cloth.
b. Inspect cowling for dents. cracks, loose nvets, ciongated holes and damaged or missing fasteners
c.
Repair ill defects to prevent further damage. Fiberglass repair procedures may be accomplished
according to Fiberglass Repairs. Section IV.
POWER PLANT
ISSUED: 8/18/72
2G10