Teledyne Continental Motors, Inc.
TM
Maintenance
Inspections
IOF-550 Permold Series Engine Maintenance Manual
7-25
1 April 2007
7-3.8.3. Cylinder Borescope Inspection
Background
Regular engine operation provides an oil coating for the cylinder and minimizes rust
formation. New cylinders are particularly sensitive to rust formation if the engine is
infrequently used or not properly preserved during storage.
NOTE: Ground operation of the engine is an unacceptable
substitute for in-flight engine operation. Ground operation does not
provide adequate cylinder cooling and introduces water and acids
into the Lubrication System.
Purpose
The cylinder borescope inspection provides a visual method of examining the internal
cylinder components without the necessity of engine disassembly. The borescope
inspection is performed in conjunction with the “Differential Pressure Test” to assess the
condition of the valve, piston top, combustion chamber deposits, and the cylinder barrel
hone pattern, Abnormal wear patterns, which can contribute to low differential pressure
readings or increased oil consumption may also be identified.
The cylinder wall hone pattern consists of engineered surface "scratches" which aid in
ring seating by allowing the ring and wall surface to wear uniformly and provides a
reservoir of oil for lubrication during ring travel. The cylinder walls and rings are
designed to wear over the life of the engine, particularly in the high pressure and
temperature combustion area. The visible hone pattern in the upper portion of the bore
may disappear during normal operation; this normal wear pattern is not cause for cylinder
removal.
Required Equipment
•
Mechanics tools
•
Borescope
Frequency
•
During 100-hour or annual inspections
•
If oil consumption is excessive
•
After an engine overspeed incident
•
Whenever an engine operational anomaly is suspected
WARNING
Take preventive measures to avoid burns when performing a
Cylinder Borescope Inspection on a hot engine.
Turn the Ignition Switch OFF and disconnect engine power.
Do not stand or allow anyone to stand within the arc of the
propeller.
Procedure
Turn the ignition switch OFF.
1.
Remove the engine cowling as necessary to gain access to the top spark plugs.
2.
Remove the upper spark plug from each cylinder.
