Sheaves and Winches
Generally all sheaves should be free running,
have no indication of turning of the lips, or
indication of jamming by terminals. No slippage of
the sheave on races should be evident, and any fault
of this nature should be corrected. Winches should
be checked for running and positioning. Both
sheaves and winches should be kept clean of debris
or foreign matter, and be regularly lubricated.
BELOW DECKSTHE ARRESTING ENGINE
The greatest safety factor in the operation of the
arresting engine is constant attention to inspection,
maintenance, and overhaul. Preventive maintenance
is particularly necessary.
inspection after each arrestment, and depending on
the unit involved, inspection and maintenance at
regular intervals nullify many of the conditions that
might arise to endanger operating and flight
personnel. Always keep hands and body clear when
engine is operating or in a condition to become
Weight Selector Settings
The safe arrestment of incoming aircraft can be
directly attributed to proper setting of the aircraft
Aircraft weight selector settings
should always be made according to current aircraft
recovery bulletins. Maximum efficiency is obtained
from the arresting engine through proper weight
settings. There is one distinct error in arrestment
that can be directly attributed to improper weight
settings or error in the gross weight estimate. This
error results in TWO-BLOCKING the engine.
TWO-BLOCKING is a condition in which the
weight selector is set too light for the incoming
aircraft. This condition causes the ram to ride
forward into the cylinder until the crosshead bangs
into the mouth of the cylinder. A wooden block
assembly, called a ram block, is positioned at the
crosshead end of the ram to act as a shock absorber
by preventing metal-to-metal contact between the
crosshead and the mouth of the cylinder.
BOUNCEBACK is the movement of an arrested
aircraft backward and is caused by the stretch
inherent in the purchase cables. Bounceback is
desirable because the hook is disengaged, allowing
rapid deck clearance for future landings. Pilots are
instructed to allow for bounceback before braking.
Control Valve Failure
Prime failure, with resultant disastrous
consequences, could be failure of the drive system
that would result in improper opening or closing of
the CRO valve.
Cam alignment is equally
important, as improper alignment would result in
fluid flow through the CRO valve at a ratio
different from that indicated on the aircraft weight
selector indicator. Thus, while the operator would
have an indication of a proper setting, actual flow
control would be different.
Drive System Hazards
Much of the cable system is contained behind
U-channels to protect personnel during operation.
This cable, with connections, is subject to wear and
fatigue and should be checked against failure.
Failure of the drive system could cause serious
injury to operating and aircraft personnel.
The accumulator is built to take a 400-psi initial
charge and such additional pressure as is developed
This capacity provides for an
overloading factor. However, it is most important
that the accumulator blow-down valve on the
charging panel be kept open. Should leakage occur
from high-pressure piping as the result of
this, with the additional
compression loading during arrestment, could cause
an extremely dangerous accumulator pressure. One
operating indication of excessive accumulator
pressure is retraction that exceeds normal speed.
Initial accumulator pressure must be held at 400 psi.
A safety diaphragm is installed on the air side of the
accumulator to eliminate the possibility of an
Fluid Level Indicator Safety
When the engine is in BATTERY position, the
fluid level indicator must read BATTERY. Should
any other reading be indicated, the engine must not
be operated until a battery indication is effected.
Malfunctions and Safety
Personnel must always be certain that their
method of operation is not responsible for a
malfunction. Possible malfunctions, causes, effects,
and remedial action are listed in NAVAIR