Significance of Metal Particles. Generally, when
metal particles are found and kind of metal present is
determined, serviceability of engine will depend upon
quantity and form of metal. Granular metal particles, in
any amount greater than a trace, require a very careful
inspection of engine, as presence of these particles is
usually an indication of an impending failure. Each kind
of metal, however, must be judged individually.
Paragraphs (1) through (5) are intended as a guide in
judging serviceability of engine after kind of metal has
Steel particles. When steel particles are
found in splinter or In granular form, the engine must be
removed Thin steel flakes, when found In quantities not
greater than 20 flakes, may not require engine removal.
A small quantity of steel flakes will not cause engine
bearing failure. When thin steel flakes accompanied by
aluminum flakes are found, these flakes are probably
the result of a warped piston ring land or hole burned in
a piston. Replacement of a defective piston and
cylinder assembly will correct the difficulty. When
not accompanied by aluminum flakes, it Is possible that
steel flakes are from foreign matter introduced into
engine through oil tank.
Test engine in accordance with the
applicable maintenance manual If more than five
additional flakes are found on oil screen and sump
inspection after runup, remove engine. If five or less
flakes found, the engine may be released for service in
accordance with the applicable maintenance manual.
When not more than 20 thin steel
flakes are found and they are accompanied by thin
aluminum flakes, proceed as follows
Carefully inspect cylinders by
visual examination of cylinder bore and by compression
check In an effort to locate faulty piston. A bright streak
along cylinder barrel or any evidence of scuffing would
be an indication of a warped piston ring land. Warped
lands are predominant In winter operations and occur
most frequently on lower cylinders.
When not more than two faulty
cylinders are found, replace faulty piston and cylinder
assemblies before continuing with procedure. When
more than two faulty cylinders are found by inspection,
After faulty cylinders have been
changed or when no faulty cylinders are found, test
engine In accordance with the applicable maintenance
If more than 2 additional steel
flakes or 15 aluminum flakes are found during screen
and sump inspection after engine runup, remove engine.
If less than these quantities are found, engine may be
released for service in accordance with the applicable
Ring fuzz may be on oil sump plug of
any normal engine. These very fine
hairlike particles are the result of
normal seating of piston rings and
cylinders and are not cause for any
concern regarding serviceability of
Tin particles. Tin in any quantity may be
disregarded. Since tin is used only in plating engine
parts and in thickness not greater than 0.0005 inch,
granular tin will not be found.
Aluminum particles. When aluminum
particles are found, perform the following procedures:
When granular aluminum particles
are found, proceed as follows:
The presence of aluminum particles
indication of piston failure
examination of cylinder bores and a compression check
in an effort to locate a faulty piston.
When not more than two faulty
pistons are found, faulty pistons and cylinder assemblies
will be changed before continuing with procedure.
When more than two faulty pistons are found by
inspection, remove engine. After faulty pistons and
cylinder assemblies have been changed, or when no
faulty pistons are found, continue with procedure.
Drain oil system, flush oil tank,
and clean oil screens.
Test engine in accordance with
the applicable maintenance manual.