Cleaning Guidelines For A Soaked Engine; Cleaning Method For Non-Destructive Testing - Lycoming IO-390-D Series Maintenance Manual

B. To remove volcanic ash:
(1) Wear personal protective equipment (gloves, respiratory, and eye protection).
(2) Per the aircraft manufacturer's instructions, thoroughly remove the ash or particulate
from the aircraft by hand brushing or air/vacuuming. Make sure that all ash is removed
from the engine and cowling.
C. Examine the induction filters, induction system, and engine baffles for blockage or damage.
D. Refer to the section "Volcanic Ash/Particulate Contamination" in Chapter 05-50 for further
details.
E. Refer to the aircraft manufacturer's instructions for additional information

17. Cleaning Guidelines for a Soaked Engine

A. Clean the engine, especially all recessed areas where debris and silt can get trapped.
B. When cleaning parts removed from an engine that was soaked, especially ferrous (iron)
metals, do not use hot acidic cleaning agents or electrolytic cleaning methods (such as
cathodic cleaning) since they can cause hydrogen embrittlement. This embrittlement can
cause a metallic part to weaken and fail.
C. Additionally, acids can generally attack the metals and cause pitting or other corrosion
damage.
D. Be sure to remove all cleaning agents.
E. Rinse the part thoroughly.
F. Dry the part.
G. There must not be any cleaning agent residue on the metal surfaces. Any chemical that could
either corrode the metal or create hydrogen gas which can cause hydrogen embrittlement
during service.
H. Paint strippers are usually organic solvents like MEK or acetone or toluene, etc. and typically
will not cause any damage to metals. Except for chlorinated solvents (such as trichloroethane,
trichloroethylene, "perc"-degreaser, etc.), just about any other type of solvent can be used on
steel or aluminum parts. Chlorinated solvents can react with moisture and produce some
hydrochloric acid which could harm the metal.

18. Cleaning Method for Non-Destructive Testing

A. Remove all traces of:
• Paint
• Gasket materials
• Oil
• Grease
• Dirt
05-30
Page 44
• Corrosion
• Smeared metal
• Plating
• Chemical residues
IO-390-D Series Engine Maintenance Manual
IO-390-D Series Engine Maintenance Manual
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March 2020