TEO-540-A1A Engine Maintenance Manual
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Page 120 February 2021
YO-233-B2A Engine Maintenance Manual
Piston Inspection Checklist for YO-233-B2A Engine Models (Cont.)
NOTICE: Lycoming manufactures pistons with a taper that extends from the top to the bottom of the
skirt with the smaller diameter at the top.
Figure 22
Section Through Piston Showing Points for Measuring Diameter
Findings/Corrective Action
Measure the inside diameter of the
piston pin hole (Figure 22).
Measure the piston diameter at the top
ring land of the piston between the
top and second compression ring
grooves (at a right angle to the piston
pin hole) (Figure 22).
Measure the diameter approximately
1/8 in. above the bottom of the piston
skirt. (at a right angle to the piston pin
hole) (Figure 22).
Subtract the diameter approximately 1/8 in. above the bottom of the piston skirt from the Average
Cylinder Diameter (from the Cylinder Assembly Inspection Checklist) and compare to the acceptable
clearance in the latest revision of the Service Table of Limits - SSP-1776.
Piston skirt and cylinder clearance.
Measure the piston ring clearance.
**Compare the actual measurement against the limits in the latest revision of the Service Table of
Limits - SSP-1776. Replace the piston if any of the measurements are out of tolerance.
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