it maybe necessary to insert the defueling hose in the
Normally, defueling operations are done outside
the hangar and under controlled conditions. These
conditions are specified in the general information and
servicing volume of the applicable MIM. When it is
absolutely necessary to defuel an aircraft in the hangar,
the doors should be open to provide ventilation
through the hangar. All shop doors leading into the
hangar should be closed. No work should be done on
or around the aircraft during the defueling operation.
All sources of ignition should be prohibited in the area.
Additional information on fueling and defueling
aircraft can be found in the appropriate aircraft MIMs
and the Aircraft Refueling NATOPS Manual,
Q8. Why is wind direction an important
consideration in fueling operations.
Q9. Refueling crews consist of a minimum of how
Before beginning refueling operations, what is
the first thing the refueling crew should do?
Q11. What is the advantage of pressure fueling over
Q12. What manuals provide detailed fueling
information for a specific aircraft?
Aircraft engine oils are identified by either their
military specification number (such as MIL-L-23699)
or a four-digit number (such as 2085). The four-digit
numbering system identifies the intended use and the
viscosity of the oil. The first digit designates the
intended use of the oil. The last three digits indicate
the viscosity. For example, in the oil number 2085, the
2xxx series is for aircraft engine lubrication, and the
085 identifies the oil as having a viscosity rating of 85.
Viscosity is defined as the internal fluid resistance to
flow caused by molecular attraction.
NOTE: Both the Navy and the Air Force use the
Saybolt scale for determining viscosity. Saybolt
viscosity numbers should not be confused with Society
of Automotive Engineers (SAE) numbers that you see
on automotive oil containers.
The synthetic oils used in most turbojet engines
are referred to by their military specification number,
such as MIL-L-23699.
Some aircraft engines use a combination of dry
and wet sump-type lubrication systems. Others are
lubricated entirely with a dry sump type. Wet sump
engines store the lubricating oil in the engine proper
(an automobile engine is an example of a wet sump
engine), while dry sump engines use an external tank
mounted on or near the engine. Oil in jet engines serves
the two-fold purpose of lubricating and cooling.
Servicing of the engine oil system is usually a
simple task. It involves checking the tank for the
proper oil level and bringing the oil level up to the
required amount. On aircraft that have a dry sump
system, servicing may consist of pumping
uncontaminated oil directly into the supply tank.
However, on some aircraft the tank is located in an
inaccessible compartment, and a pressure tank is
required to fill the oil tank. For specific servicing
instructions of the engine oil system, refer to the
Aircraft hydraulic fluids are identified by their
military specification number. Hydraulic fluid,
MIL-H-83282, is now being used in the hydraulic
systems of all naval aircraft. This fluid is also used in
the shock struts, shimmy dampers, and brake systems.
MIL-H-83282 hydraulic fluid is colored red. It is
available in 1-quart, 1-gallon, 5-gallon, and 55-gallon
containers, and 16-ounce spray cans. The spray can is
normally used to spray the exposed portions of oleos
(the shiny part) of actuating cylinders and struts, as
required during most daily inspections of aircraft.
NOTE: Hydraulic fluid MIL-H-46170 is a
preservative type of hydraulic fluid used in the
preservation of hydraulic systems and components.
While it is red in color and considered compatible with
MIL-H-83282 hydraulic fluid, it should NOT be used
to service aircraft hydraulic systems.
Naval aircraft hydraulic systems are serviced by
checking the fluid level (on a sight gauge usually
located on the side of the reservoir) and filling the
system to the prescribed level. Before fluid is added to
this type of reservoir, the reservoir instruction plate
should always be checked for the proper filling
instructions. The instruction plate is attached to either
the reservoir or to the aircraft structure near the filler
opening of the reservoir. The instruction plate contains
the following information:
Total capacity of the system