PIPER
COMANCHE SERVICE MANUAL
7B-54.
00
Screens.
The
oil screens are the pressure screen, located in a dome shaped housing, above
and
between the magnetos
and
the suction screen located in the aft section
of
the sump. These screens should
be
cleaned
at
each
oil change
to
remove any accumulation
of
sludge
and
to examine for metal filings
or
chips.
If
metal
particles
arc
found in the oil screens, the engine sbould be examined for internal damage.
a. To remove the pressure screen, remove oil temperature elecuica1lead
or
the temperature bulb
and
the
cap
screws securing the housing. Note the location
of
the screws
as
the round fillister head screw,
if
installed,
must
be
returned
to
upper right
comer
of
the housing.
If
the fillister head screw is not reinstalled in the
SlUlle
hole from which it was removed, it is possible
to
crack the mounting flange
of
the vacuum pump.
b. With the housing and screen removed, clean and inspect both items, check the mating surface
of
the
housing
and
accessory
case
of
gasket particles.
c. Insert
the
screw into
the
housing
so
that the screw fits flush with the housing base. Using a
new
gasket, secure the housing
to
its mounting
pad
and
torque cap screws to 75 inch pounds.
d.
The
suction screen is removed from
the
sump by removing the hex head plug at the lower aft
part
of
the sump. Clean and inspect
the
screen and gasket, replace the gasket
if
over compressed
or
damaged. Insert
the screen fully into the sump, install gasket
and
plug.
S,
',ty
the plug.
7B-55.
Oil
Cooler.
a.
When
conducting a routine engine inspection, the oil cooler(s), lines and fittings should be checked
for the following:
I.
Oil cooler line attachments should be examined to be certain that all are tight and there is
no
indication
of
cross-threading. (See c, below,
for
oil line torque.)
2.
Oil
lines
must
have adequate clearance and be properly aligned.
3.
Oil line supports should be tight, properly positioned and
if
worn should be replaced.
4.
Oil cooler should be checked for leakage
or
distorted cells.
5. Cooling fins should be clean
and
undamaged.
b. During each
engine
overhaul, at indication
of
high oil temperatures
or
during a
500
hour inspection,
the oil
cooler
should be removed, cleaned and checked for damaged fins and cells. When replacing the cooler,
properly align and do not
over
tighten the mounting bolts so that the cooler would be damaged. While the oil
cooler
is removed, the oil lines should be disconnected and flushed. .
c.
If
it is found that oil is leaking around the line compression nuts, check that the nuts are tightened to
125 inch pound wet torque
or
the nut may be backed off, retightened finger tight, plus a 3/4 tum.
Do
not
over
torque.
d.
Should
oil
continue
to
leak, it
may
be
necessary
to
replace
the
seal rings.
Also
remove
the
compression
nuts and inspect the line ends in the area
of
the swaged ferrules for collapsed tubing.
This
condition
may
be observed by looking into the tubing ends. Should the tubing show indications that it is
collapsed and new seal rings and proper torque does not stop leakage, the oil lines should be replaced. Also
inspect the surfaces
of
the
mating fittings for damage.
POWER
PLANT
PA-l4-4OO
2F24
Revised:
8115198
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