Lubrication System Maintenance; Oil Pressure Adjustment; Oil System Inspection; Oil Line Inspection - Lycoming IO-390-D Series Maintenance Manual

IO-390-D Series Engine Maintenance Manual
IO-390-D Series Engine Maintenance Manual

1. Oil Pressure Adjustment

NOTICE: On the majority of these engines, there is an adjustment screw (Figure 1) on the oil
pressure relief valve housing. Rotation of this screw either increases or decreases the
oil pressure to keep it within the specified operational limits in Appendix A of the
IO-390-D Series Engine Installation and Operation Manual.
(1) The engine must be installed in the aircraft or on a
test stand to complete this procedure.
(2) Start and operate the engine per instructions in the
IO-390-D Series Engine Installation and
Operation Manual.
(3) Run-up the engine to 2000 rpm.
(4) Record the oil pressure reading.
(5) If the oil pressure is out of tolerance, turn off the
engine and adjust the oil pressure as follows:
• To increase oil pressure, turn the pressure
adjustment screw on the oil pressure relief valve
clockwise (Figure 1).
• To decrease oil pressure, turn the adjustment
screw on the oil pressure relief valve
counterclockwise.
(6) Start the engine and repeat the previous steps until
the oil pressure is within specified limits.

2. Oil System Inspection

A. Look for leaks around the oil sump and crankcase flanges.
B. If there are indications of leaking around the oil seals and gaskets, identify the source of the
leak and take corrective action as necessary.
C. Replace leaky oil seals and gaskets.

3. Oil Line Inspection

CAUTION MAKE SURE THERE ARE NO SHARP BENDS OR KINKS IN THE OIL
LINE ROUTING TO PREVENT INTERRUPTIONS TO OIL FLOW. MAKE
SURE OIL LINES ARE NOT TOUCHING HEAT SOURCES THAT COULD
DAMAGE THE OIL LINE AND CAUSE OIL LOSS.
A. Examine oil lines for cracks, kinks, brittleness, wear, damage or loose connections. Replace
any worn, cracked, kinked, damaged, or brittle oil line with a new oil line. Do not try to
repair the oil line.
B. Tighten any loose connection at an oil line per the torque values in the Standard Torque
Tables in the latest revision of the Service Table of Limits - SSP-1776.
© 2020 Avco Corporation. All Rights Reserved
March 2020

72-50 - LUBRICATION SYSTEM MAINTENANCE

Figure 1
Adjustment Screw on the Oil
Pressure Relief Valve
72-50
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