Piper COMANCHE PA-24-180 Service Manual page 430

7B-54. OU 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 should be examined for internal damage.
a. To remove the pressure screen, remove oil temperature electrical lead 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 same
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. Sr 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:
1. 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 turn. 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 Revised: 8/15/98
PA-24-400
PIPER COMANCHE SERVICE MANUAL
2F24