TO 00-25-172 - Robins Air Force Base

TO 00-25-172
similar to an electrical condenser (capacitor) plate. The potential
required for a discharge from these floating objects to
the tank is less than that required to cause a discharge from
the liquid surface to the tank. Therefore, the hazard is greatly
increased by the presence of such objects. The Air Force
now incorporates a conductivity additive to decrease the relaxation
time of electrostatic charges in order to preclude
these problems. Also, the use of a higher flash point fuel
such as JP-8 or JP-5 in lieu of JP-4, when permitted by the
applicable aircraft technical orders, reduces the vapor ignition
hazard. Research has suggested that if fuel flow is kept
below the following maximum rates, hazardous levels of
static electricity charges will not occur:
2.9 GROUNDING AND BONDING POLICY.
Grounding is not required for parked aircraft or aircraft fuel
servicing operations unless required by specific MDS technical
orders. In any case, aircraft stored/parked at the
AMARG desert storage (TO 1-1-686) do not need to be
grounded. Aircraft will be bonded to fuel servicing equipment
at all times during fuel servicing operations. Hydrant
fuel servicing vehicles and hose carts will also be bonded to
the hydrant system in addition to bonding to the aircraft.
(This hydrant-servicing vehicle or hose cart bonding requirement
applies only when the aircraft is not grounded.)
NOTE
These limits do not apply for JP fuels having antistatic
additives with at least 50 Conductivity
Units (CU).
Nozzle/Hose/
Gallons/Minutes
Pipe Diameter
0.75 inches 32
1.50 inches 125
2.00 inches 225
2.50 inches 352
3.00 inches 470
4.00 inches 627
5.00 inches 783
6.00 inches 940
2.7 LIGHTNING.
Even if an aircraft were statically grounded, a severe hazard
to servicing personnel could exist if lightning strikes the aircraft
or within several hundred feet of the aircraft. Servicing
personnel should be evacuated from the area when there is
danger of a direct or close proximity lightning strike. Personnel
inside an aircraft will be in no danger as long as all
aircraft doors, hatches, and canopies are closed. Potentials in
the range of several million volts exist between clouds and
earth. High points such as vertical stabilizers and antenna
masts are most susceptible to strikes. These strikes are of
short duration (approximately 1/100 second duration per
strike) and even though high energy levels exist, the ramp
grounding system will generally conduct the energy safely to
earth. An electrical storm can be dangerous even if several
miles from the servicing area.
2.8 OTHER SOURCES OF STATIC ELECTRICITY.
Operating aircraft engines, rotor blades, and propeller blades,
can generate high static electricity voltages. These static
sources are especially hazardous because the static voltages
may be generated continuously as long as the engines/blades
continue to operate.
When applicable, aircraft/equipment must be
grounded and/or bonded prior to connecting the
single point nozzle to the aircraft; however, the
hydrant coupler will be connected to the hydrant
outlet prior to bonding the hydrant servicing vehicle
to the aircraft.
Grounding/Bonding clamps/plugs shall not be allowed
to drag across the ramp. Clamps/plugs shall
be carried to reels on equipment.
NOTE
• If the bonding wire becomes disconnected, reconnect
it immediately. The sequence makes no
difference.
• Bonding is not required for all-metal pantograph,
as long as there is a continuous metal
structure from the fuel servicing equipment to
the aircraft.
a. Grounding of aircraft or supporting servicing equipment
during either fuel servicing, Liquid Nitrogen
(LIN) servicing, or Gaseous Nitrogen (N 2 ) servicing is
not required. Recent electrostatic studies have demonstrated
that grounding aircraft or supporting servicing
equipment for these situations is unnecessary. Unless
required by specific MDS technical orders, grounding
is not required for aircraft except for the following
four operations (only one grounding wire is necessary):
(1) Undergoing munitions loading/unloading operations.
(i.e, loading bombs, missiles, etc., to combat
aircraft store and release locations.) Aircraft
grounding is not required for driving/carrying on
munitions or hazardous cargo onto cargo aircraft.
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