Engine Preservation Guidelines - 31 To 60 Days - Lycoming IO-390-D Series Installation And Operation Manual

Engine Preservation Guidelines - 31 to 60 Days

The main emphasis in engine preservation is to decrease the risk of corrosion of engine parts which
can decrease engine service life. The engine cylinders, piston rings, valves, valve guides, camshaft,
and lifters are of primary concern with regards to corrosion prevention. Corrosion prevention uses
rust inhibitive compounds applied to vulnerable surfaces to prevent corrosion.
CAUTION DO NOT MANUALLY (HAND) OPERATE THE PROPELLER TO
LUBRICATE THE ENGINE CYLINDERS. LUBRICATION IS INEFFICIENT
WITH MANUAL OPERATION AND CAN CAUSE PREMATURE WEAR OF
ENGINE PARTS FROM SCUFFING AND SPALLING.
Engine preservation is necessary, especially for engines that are not operated at least for 1
continuous hour every 30 consecutive days. If you know that an aircraft will not be operated for a
minimum of 30 days, then you must follow this procedure.
NOTICE: Ground operation of the engine for brief periods of time is not a substitute for hour-long
continuous engine flight. Short ground operation can make corrosive conditions worse.
The engine preservation procedure includes a spray application of preservative oil to the walls of
each engine cylinder.
You will need the following to complete this procedure:
• Engine preservation oil mixture made up of 24% MIL-C-6529, 71% SAE J1966 Grade 1065
or MIL-PRF-21260 Grade 30, 5% Cortec M-529)
• Airless spray gun or garden sprayer
• Clay desiccant bags
NOTICE: Recommend starting this preservation procedure at the end of the last flight before
putting the engine into storage.
For engines installed in aircraft stored for 31 to 60 days:
1. Operate the engine until it is at the specified operating temperature in Appendix A. If
temperatures are below freezing, the oil temperature must be at least 165ºF (74ºC) before the
engine is stopped in the next step.
2. Stop the engine.
3. Refer to Chapter 12-10 in the IO-390-D Series Engine Maintenance Manual to complete
the following steps:
A. Drain the lubricating oil from the sump or system.
B. Remove, clean, and install the oil suction screen plug.
4. Fill the sprayer with the preservative oil mixture.
5. Fill the oil sump with the specified preservative oil mixture up to the quantity of oil sump
capacity in Table A-1 in Appendix A.
6. Operate the engine until it is at the specified operating temperature. If temperatures are below
freezing, the oil temperature must be at least 165ºF (74ºC) before the engine is stopped in the
next step.
7. Stop the engine.
Engine Preservation and Storage
Page 48
IO-390-D Series Engine Installation and Operation Manual
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March 2020