If not more than two additional
granular particles are found during screen and sump
inspection after runup, engine may be released for
service in accordance with the applicable maintenance
When aluminum flakes are found,
proceed as follows:
Aluminum flakes may not necessarily
require engine removal In winter
operations, when warped piston ring
lands are frequent, considerable
quantities of aluminum from pistons
may be discharged Into engine oil
system. It will be necessary to
exercise judgment before continuing
with the following procedure, for
Instance, if oil sump or screen is
found choked with a mass of
regardless of size, it will probably be
necessary to remove engine even
though faulty piston can be located.
Make a careful Inspection of
cylinders by examination of cylinder bores and a
compression check In an effort to locate faulty piston.
When not more than two faulty
pistons are found, change faulty piston and cylinder
assemblies before continuing with procedure. When
more than two faulty pistons are found, remove engine
If two or less faulty pistons are found, continue with
Drain oil system, flush oil tank,
and clean oil screen.
Test engine In accordance with
the applicable maintenance manual.
If more than five additional
aluminum flakes are found during screen and sump
inspection after runup, remove engine. If less than this
quantity is found, engine may be released for service in
accordance with the applicable maintenance manual.
(4) Silver particles. Silver particles in granular
form indicate a master rod bearing failure in advanced
stages. When these particles are found in any quantity,
remove engine. Silver is used in plating numerous
other parts, and silver flakes, not exceeding 10 in
number, do not necessarily indicate a part failure. Since
silver is quite soft, some small flakes will occasionally
be released by normal working of these parts. A very
small quantity of silver from master rod bearings will
make a large number of tiny flakes as it passes through
roller bearings or gears within engine. Large quantities
of silver flakes indicate an excessive loss of bearing or
plating surface and engine must be removed as a
Copper or bronze particles. Copper or
bronze particles, in granular form and in quantities
greater than a few particles, indicate disintegration of a
bushing or valve guide and engine must be removed.
Copper or bronze flakes, in quantities not exceeding 10
flakes, do not necessarily indicate part failure. Bronze
flakes may be formed in small quantities through normal
seating of bushings or valve guides. Larger quantities
of copper or bronze flakes, however, may Indicate
excessive loss of bushing metal and engine must be
removed as a precautionary measure.
Additional Metal Particles Test. This test is
made to subject engine to sufficient operations to cause
any additional metal in oil system to collect on oil screen
and in main sump and also to reveal any Incipient
trouble. This additional metal will determine whether
engine needs to be removed or allowed to continue In
service Test using the following procedures.
Drain and flush external oil system
Run engine to bring it to operating
temperatures and make a minimum of three power
checks (Allow engine to cool between checks). Take
care not to exceed allowable limits for ground operation.
Again remove oil screens and examine
for metal accumulation. Examine main sump plug and
screen for metal accumulation. If engine is released for
service, it must be watched closely for next 25 hours for
any indications of malfunctions or internal failure.
Excessive Spark Plug Copper or Silver Runout.
If copper runout is noted, replace cylinder from which
spark plug was removed as this Indicates the cylinder
temperature has exceeded 1981 °F (1083
runout may be caused on a fine wire electrode-type
spark plug if plug is subjected to pre-ignition and/or
detonation. Excessive temperature may cause the
silver spindle of the center electrode to flow toward the
firing end of the electrode. Copper or silver runout
Engines having runout on more than 25 percent of the
cylinders should be removed.