MIL-DTL-2845E (SH)
3.14.1.1 Air emission system. Prior to the application of strippable
compound, ships' propellers incorporating an air emitter system shall have the
air inlet and air emitter openings covered with minimum 3/4-inch wide pressure
sensitive tape in accordance with MIL-T-22085, type II. The tape shall be
centered over the air emitter holes. Acrylic or transparent protective
coatings or coverings shall not be applied in lieu of tape.
3.14.1.2 Closure of hub openings. Monobloc propeller bore openings equal to
or less than 12 inches shall be sealed with tape in accordance with MIL-T-22085,
type II or a minimum 0.004 inch thick polyethylene film secured with tape as
specified herein. When the covering is vulnerable to damage (puncture, tearing, and
so forth.) the covering shall be further protected by use of weather-resistant
hardboard, wood, plywood, or metal covers. Pipe and fitting ends shall be sealed
with metal or plastic caps or plugs. Monobloc propellers with bore openings greater
than 12 inches shall be closed as specified below.
3.14.1.2.1 Forward end closure. The forward end of the propeller hub shall be
fitted with a 0.75-inch thick, marine grade plywood in accordance with APA PS-1,
disk held in place with hex head bolts. Bolt heads shall be countersunk into the
plywood disk. The outer diameter of the disk shall be equal to the outside diameter
of the hub forward face. The inner diameter of the disk shall be 0.5 inches larger
than the bore at the hub forward face. The forward end closure shall be reusable.
A single layer of barrier material in accordance with MIL-B-121, type I, grade A,
class 2 shall be placed between the wood disk and propeller.
3.14.1.2.2 Aft end closure. The aft end of the hub shall be fitted with a
thick steel plate attached to the hub aft face with hex head bolts. The plate shall
be machined with a step that will fit into the aft face counterbore. The plate
thickness shall be a minimum of 0.375 inch thick but of suitable size to resist
deflection during transportation of the propeller on a tilt-type fixture. The plate
outer diameter shall be equal to the outside diameter of the hub aft face and the
inner diameter shall be 6 inches. Cut outs shall be provided in the steel plate to
permit shouldering the eyebolts. A minimum of two eyebolts shall be installed in
the aft face, 180 degrees apart. The aft end closure shall be reusable. A single
layer of barrier material in accordance with MIL-B-121, type I, grade A, class 2
shall be placed between the metal disk and propeller.
3.14.1.2.2.1 Long term protection. For storage longer than 60 days, the
center holes in the plywood disk and steel plate shall be covered with 0.75-inch
thick marine grade plywood in accordance with APA PS-1, of sufficient diameter to
cover the hole. The plywood covers shall be bolted with hex head bolts to the
plywood disk and steel plate. The bolts shall be countersunk into the plywood disk.
The peripheral joints between the plywood disk, steel plate, plywood covers, and
hub faces shall be covered with tape in accordance with MIL-T-22085, type II. The
tape and center plywood covers may be removed at the time of shipment if the
propeller is to be shipped utilizing a propeller shipping frame (see figure 1).
After shipment, the tape and plywood covers shall be replaced.
3.14.1.2.2.2 Short term protection. For temporary protection of less than 60
days, the center hole in the plywood disk and steel plate shall be covered with tape
in accordance with MIL-T-22085, type II. The tape may be removed at the time of
shipment if the propeller is to be shipped utilizing a propeller shipping frame (see
figure 1). After shipment, the tape shall be replaced.
3.14.1.2.3 CP blade palm protection. The bottom of CP blade palms shall be
covered with barrier material in accordance with MIL-B-121, type I, grade A, class
2. A marine grade plywood disk of 3/8 thickness shall then be applied to the CP
blade palm and secured by bolting with corrosion resistant (stainless steel) hex
head bolts through the CP blade bolt holes. Marine grade plywood washers shall be
inserted into the top of the corresponding CP blade bolt holes. Barrier material in
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