Lycoming SI 1037P - Approved Pistons, Rings and Cylinders for Use on Lycoming Aircraft Engines

MODELS AFFECTED: All Lycoming opposed series aircraft engines .

TIME OF COMPLIANCE: When installing new rings, pistons, valves and cylinders.

This Service Instruction identifies part numbers for pistons, rings, cylinders and valve combinations currently available for use in Lycoming engines in Table 1.

CAUTION

CHROME-PLATED PISTON RINGS (IDENTIFIED BY THE LOWERCASE LETTER “c”

AFTER THE PART NUMBER) ARE USED IN PLAIN OR NITRIDED STEEL CYLINDER BARRELS, BUT NEVER IN CHROME-PLATED BARRELS. SERIOUS ENGINE DAMAGE WILL OCCUR IF CHROME-PLATED PISTON RINGS ARE INSTALLED IN CHROME PLATED CYLINDER BARRELS.

NOTE

Chrome plated cylinder assemblies and kits containing chrome plated cylinders are no longer available from Lycoming Engines. However, compatible piston and ring combinations used with chrome-plated cylinders are still available and identified herein.

NOTE

For replacement piston rings, there could be different piston ring combinations for cylinders

with different materials use for the barrel.

Engine models that have serial number suffix “A” or “E” are built with crankcase configurations for wide cylinder base mounting flanges, and consequently must be assembled with wide deck cylinders.

Table 1 uses alphabetical symbols to identify various components as follows:

C* - Chrome plated steel cylinder barrel

FW - Full-Wedge compression ring

HW - Half-Wedge compression ring

N - Nitride hardened steel cylinder barrel

P - Plain steel cylinder barrel

S - Suffix to piston P/N to indicate service application

a - 3/16 inch “wide” oil regulating ring

b - 5/32 inch “narrow” oil regulating ring

c - Chrome plated piston ring

d - Cold forged piston

e - Requires long reach spark plugs

f - 1/2 inch diameter Inconel sodium cooled exhaust valve

g - 1/2 inch diameter sodium cooled exhaust valve

h - 7/16 inch diameter sodium cooled exhaust valve

j - 1/2 inch diameter chrome plated sodium cooled stem exhaust valve

k - Solid stem exhaust valve

m - 1/2 inch diameter Nimonic sodium cooled exhaust valve (TIO/TIGO-541)

p - Plain steel ring

r - Angle valve cylinder head (cylinders not marked “r” have parallel valves)

* - If choked chrome cylinder assemblies are used in any of the engine applications in Table 1, the compression ring gap must be increased to 0.045/0.055 inch (1.143 to 1.397 mm) which is the same for nitrided cylinder assemblies. Refer to the latest revision of SSP-1776, Table of Limits.