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 TB 740-97-4
the removal of the plastic bubble dome. Use existing plywood blanks on dome coaming where in serviceable condition;
apply wood preservative and completely coat with strippable compound.
(d) Miscellaneous sealing. Edges of doors, windows, hatch covers, and all other openings in the nature of
seams or joints between closely opposed surfaces which access to dehumidified area, including bilge plug openings, will
be sealed with strippable coating and bituminous coating.
(e) Dehumidification piping system. The points of entry of all air ducts into compartment and the connecting
joints of all air ducts will be sealed with strippable coating and bituminous coating. The sealing will be carried over and
around flanges, adapters, and other devices used to attach or introduce the tubing or ducts.
(4) Installation of dehumidification system. Normally a dynamic dehumidification system will be installed for each
group of two lighters to provide dynamic dehumidification of the cab, engine compartment, and the differential and transfer
transmission area. When dynamic dehumidification of the lighters is accomplished on an individual basis, installation of
the dynamic dehumidification system will be in accordance with this bulletin.
(a) Dehumidification machine. A package dehumidifier, single desiccant bed, absorbent type, 10,000 cubic feet
capacity, 110-volt, alternating-current, will be installed as shown on figures 38 and 39. The machine will be mounted on a
stand and protected with a cover, fabricated in accordance with figure 40.
1. The machine will be installed on the engine hatch cover (for lighters, stored as shown in figure 38) in
a manner to require a minimum of turns in the ductwork and will be secured in place to prevent movement.
2. For lighters, stored as shown in figure 39, the machine will be mounted on a stand at lighters' stern;
the stand will be secured in place, with existing bolts in position, to provide the most direct connection for opening to
ducting connection in metal blank on radiator grill. Dimensions shall be taken from hull. The machine stand will be
fabricated, generally, in accordance with figure 41 and protected with a cover, fabricated in accordance with figure 40.
(b) Machine connections. Connection of ducts to the dehumidification machine will be made of unions or slip
joint connections, which permit easy removal of the machine for servicing.
(c) Duct installation. Four-inch-diameter, No. 26 gage, galvanized tubing, with necessary ells, reducing fittings
and connections, will be installed, generally, as shown on figure 38 or 39. Flanges of galvanized metal will be joined to the
ductwork to attach it to openings in the blanks prepared for its entrance into the lighter. The flanges will be constructed
with collars or suitable tabs to resist dislodgment from the blank openings. Ductwork will be supported, as necessary, by
use of wooden or metal A-frames or other structures.
(d) Humidistat. A hair-type humidistat will be set to maintain a 40-percent relative humidity, plus or minus 5
percent, within the dehumidified areas. The humidistat will be installed, approximately three feet above the floor plate, in
the compartment of the lighter, from which moist air is ducted back to the dehumidification machine. A bracket will be
provided to retain the humidistat. The humidistat will be wired to the dehumidifier with No. 18, two-conductor, rubber
covered cable. The cable will follow the moist-air return ducting for support and shall penetrate the hull through blank, as
shown in figures 38 and 39.
(e) Humidity sensing elements. Humidity sensing elements will be installed in the blanks for lighters, stored as
shown in figure 38. For lighters, stored as shown in figure 39, the sensing elements will be installed in one of each
hydraulic, bilge pump, overboard discharge, hull fitting, as shown in figure 39. The humidity sensing element will be held
in place by a fabricated adapter plate.
c.
Preparation of Rubber Tires for Storage.
(1) Blocking lighters during storage. Lighters will not require blocking during storage. Pneumatic tires will be
inflated to 30 pounds per square inch.
(2) Protection of tires during storage. Lighters stored in open areas or shed storage in excess of 90 days will
have the tires protected as specified below:
(a) Installed pneumatic and semipneumatic tires, manufactured from natural or synthetic compounds or a
combination thereof, will be protected during storage by In closing tires and wheels within protective polyethylene bags, as
outlined in Specification MIL-T-46755 (MO).
(b) Tires identified as manufactured with OZ compounds (as illustrated in fig. 2 of MIL-T46755(MO)) do not
require additional protection until 2 years from the date of manufacture. After 2 years from the date of manufacture, tires
will be protected as specified in (a) above.
(c)
When a lighter is equipped with a
K-2 Change 2
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