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UNSCHEDULED MAINTENANCE
Unscheduled maintenance events include but are not
limited to:
PROPELLER STRIKES
A propeller strike is any incident, whether or not the
engine is operating, that requires repair to the
propeller or any incident while the engine is operating
in which the propeller makes contact with any object
that results in a loss of engine RPM. Propeller strikes
against the ground or any object, can cause engine and
component damage even though the propeller may
continue to rotate. This damage can result in engine
failure.
When the propeller is damaged by a small foreign
object during operation, such as a small stone,
inspection and repair must be accomplished in
accordance
with
the
published instructions.
damage requires propeller removal for repairs the
incident is considered a propeller strike.
Following any propeller strike a complete engine
disassembly and inspection is mandatory and must be
accomplished prior to further operation. Inspect all
engine
accessories
manufacturer's instructions.
HYDRAULIC LOCK
General Information
Hydraulic lock is defined as a condition in which a
volume of liquid, equal to or greater than the
clearance volume of the combustion chamber is
present in the cylinder during starting. Incompressible
liquid restricts piston travel during the compression
stroke. Damage occurs after the preceding cylinder or
cylinders in the firing order have fired providing the
required force to drive the piston of the fluid filled
cylinder through the compression stroke.
Hydraulic locks in horizontally opposed aircraft
engines are due to excess fuel accumulation in the
propeller
manufacturer's
Any time foreign object
in
accordance
with
induction system and/or cylinder assembly or failure
to properly drain preservation oil.
Damage from a hydraulic lock can be extensive.
Engine components such as connecting rods, cylinder
assemblies, pistons, piston pins, crankcase and
crankshaft can be damaged due to overstress.
In the event the operator starts an over-primed/flooded
engine, hydraulic lock may result.
hydraulic lock are difficult to detect since the engine
will not normally exhibit any unusual operation once
the fuel-air mixture stabilizes. Therefore, the operator
must be cognizant of the fact that a hydraulic lock can
occur
during
over-primed/flooded engine.
In the event of a hydraulic lock perform the following
inspection:
1. Remove all cylinders and connecting rods in
accordance with the current TCM Overhaul
Manual.
accordance with the current TCM Overhaul
Manual.
2. If all connecting rods meet the criteria specified
the
by TCM, reassemble the engine in accordance
with the current TCM Overhaul Manual.
3. If any connecting rod does not meet TCM
specifications, remove and disassemble the engine
to allow inspection of the crankcase and
crankshaft in accordance with the current TCM
Overhaul Manual. Replace any part that does not
meet
TCM
non-conforming connecting rod and its associated
piston, piston pin and cylinder assembly.
CAUTION...
Any parts that require replacement must be destroyed
to prevent future installation.
4. Clean, inspect, repair, reassemble and test the
engine in accordance with the current TCM
Overhaul Manual.
Unscheduled Maintenance
an
attempt
to
Inspect
the
connecting
specifications.
Indications of
start
an
rods
in
Replace
each
1-11
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