Fusing Film Pieces Together.

TM 55-1520-238-S

to each other and larger pieces as required. Landing gear struts should be covered with sufficient

material to allow for strut extension if the helicopter is hoisted (film on landing gear struts will not be

shrunk).

(2) The larger sections to be wrapped include the vertical stabilizer, the stabilator, and the fuselage.

(a) The vertical stabilizer can be wrapped with a piece of film measuring 12' x 14'.

(b) The horizontal stabilizer requires a section of film 12' x 14'.

(d) The remainder of the fuselage can be sectionalized by using the width of the bulk film and cutting

it to a length equivalent to the helicopter circumference for the section (plus overlap). For

example, with 14 foot wide film:

1. section from the vertical stabilizer forward to the engines requires a piece 14' x 151/2'.

2. next section, over the top of the engines, requires a piece of film 14' x 31'.

3. section from the front of the engines forward requires a piece of film 14' x 261/2'.

4. final section, covering the nose, requires a piece of film measuring 14' x 14'.

(3) Large void areas in the film covering are to be avoided. This can be done by using polyester strapping.

For example voids beneath the engine areas can be minimized by wrapping each engine nacelle,

lengthwise, and tying strapping snug. Also to prevent voids, slits may be cut in large pieces of covering

to allow previously covered small protrusions to stick through. These protrusions such as steps,

handholds, and antennae will be fused as in paragraph G5d below.

d. Fusing Film Pieces Together.

(1) After the helicopter has been completely covered, all seams and pieces must be fused together

before the film is shrunk. Where two pieces come together to form a horizontal seam, the top piece

should overlap the bottom to prevent the possibility of water entrapment.

WARNING

Prior to operation the heat cannon, insure that all requirements of paragraph

have been complied with.

CAUTION

To prevent water leakage at seams insure seams are completely bonded.

(2) To fuse two pieces together to form a seam, pull the pieces together to form a snug fit around the area

being covered. A minimum overlap of 6 inches is required for fusing. Hold pieces in place with heat

shrink tape. Heat the area to be fused by first shooting the flame between the top and bottom layers

to be fused and then holding the heat cannon 8 to 12 inches from the seam and moving the head along

the seam. As the film becomes soft, pat the seam gently with a safety gloved hand (the film is HOT).

(3) Repeat this process until all seams are fused.

(4) After film is cooled, test seams for proper bonding by trying to pull seam apart with fingernails. If seam

comes loose, reseal it.

e. Shrinking Film.

NOTE

To allow strut extension during loading, do not not shrink film on landing gear.

(1) After all the seams have been fused and the helicopter has been completely enclosed in film, the

shrinking process should be accomplished. To shrink the film, hold the heat gun 8 to 12 inches from

the surface and move the gun evenly along the surface. Apply just enough heat to soften the film. After

the heat is removed, the film will shrink to a glove tight fit.

(2) If a hole is inadvertently burned through, it may be easily repaired by fusing a piece of film to the

damaged area and / or repairing with heat shrink tape.

f. Inspection. When the shrinking process is completed and allowed to set for approximately 30 minutes,

inspect the helicopter covering to determine if any areas require further shrinking. Insure that all seams

are completely fused and that no holes are present. Repairs may be made as required by applying the

procedure in paragraph G5e above. Insure good seals around landing gear struts and other procedures.