SECTION 4 LYCOMING OPERATOR’S MANUAL
PERIODIC INSPECTIONS IO-320 SERIES
b. Magnetos – Check breaker points for pitting and minimum gap. Check for excessive oil in the breaker
compartment, if found, wipe dry with a clean lint free cloth. The felt located at the breaker points
should be lubricated in accordance with the magne ions. Check magneto to
engine timing. Timing procedure is described in Section 5, 1, b of this manual.
c. Engine Accessories – Engine mounted accessories such as pumps, temperature and pressure sensing
units should be checked for secure mounting, tight connections.
d. Cylinders – Check cylinders visually for cracked or broken fins.
e. Engine Mounts – Check engine mounting bolts and bushings for security and excessive wear. Replace
any bushings that are excessively worn.
f. Fuel Injector Nozzles and Fuel Lines – Check fuel injector nozzles for looseness. Tighten to 60 inch
pounds torque. Check fuel lines for fuel stains which are indicative of fuel leaks. Repair or
replacement must be accomplished before the aircraft resumes operation.
5. 400-HOUR INSPECTION – In addition to the items listed for daily pre-flight, 50-hour and 100-hour
inspections, the following maintenance check should be made after every 400 hours of operation.
Valve Inspection – Remove rocker box covers and check for freedom of valve rockers when valves are
closed. Look for evidence of abnormal wear or broken parts in the area of the valve tips, valve keeper,
springs and spring seats. If any indications are found, the cylinder and all of its components should be
removed (including the piston and connecting rod assembly) and inspected for further damage. Replace any
parts that do no conform with limits shown in the latest revision of Special Service Publication No. SSP-
1776.
6 NON-SCHEDULED INSPECTIONS. Occasionally, service bulletins or service instructions are issued by
Lycoming Engines that require inspection procedures that are not listed in this manual. Such publications,
usually are limited to specified engine models and become obsolete after corrective modification has been
accomplished. All such publications are available from Lycoming distributors, or from the factory by
subscription. Consult the latest revision of Service Letter No. L114 for subscription information.
Maintenance facilities should have an up-to-date file of these publications available at all times.
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