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Doppler Shield Repar


robert ceasar
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Hi, I'm bobby from the philippine air force, i would like to ask you or any of your friend who knows structural of the c-130. one our c-130 has a crack from end to end of its doppler antenna shield or cover located at the belly of the aircraft. now, our maintenance officer just have it repair through a pieces of fiber cloth. is it advisable? will it lead to a structural failure if not replace immediately? please help me on this...

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Is this doppler the APN-218 system? Repairs to he radome skin are very limited. This if from the shop manual.

6-10.1 Radome Repair. Major radome damage requires antenna boresight correction constants be verified

once repair has been accomplished. Antenna boresighting is a depot repair function. Scratches, etc. to the

radome not exceeding 0.004 inches in depth and 3 inches in length need not be repaired. Intermediate level

maintenance is limited to repair of minor abrasions and scratches in accordance with paragraph 6-10.2 and

removal of oil and similar contaminants in accordance with paragraph 6-5. l.b. Minor radome abrasions and I

scratches are defined as follows:

a. Damaging agent has not deformed the radome surface.

b. Damaged area is free of all fragments of any type metal.

c. Abrasions or scratches do not exceeds a depth of 0.010 inches and an area of 0.06 square inches for the

APN-230 or do not exceed the dimensions shown in figure 6-1.

NOTE

Limit repair to only the damaged area of the radome and only a one time

repair of that specific area.

6-10.2 Repair of Minor Pits. Abrasions and Scratches. Make minor radome surface repairs as follows:

a. Clean radome in accordance with paragraph 6-5.

b. Wipe area to be repaired with a clean lint-free cloth dampened with Axerel 2200 or equivalent. I

c. While area is still wet, rub briskly with a dry, clean lint-free cloth, turning cloth frequently.

d. Wipe with a clean, lint-free cloth liberally dampened with P-D-680, Type III or equivalent. I

e. Rub dry with a dry, clean, lint-free cloth, turning cloth frequently.

f. Lightly abrade area with a fiberglass brush or 320 to 400 grit sandpaper and dust abraded area with

a clean, dry bristle brush.

g. Fill nicks, scratches or abrasions as required using polyester resin with 1/2 to 1% MEK peroxide as

the curing agent.

h. Using 320 to 400 grit sandpaper, sand the cured polyester resin to restore the original contour.

Repeat step d to remove sanding residues, and allow the surface to air dry for at least 30 minutes

before applying primer.

i. Apply primer coat (SCDPE0028-1); limiting thickness to existing primer coat and cure at room

temperature for one and one-half hours minimum. I j. Apply finish or urethane coating (MIL-C-83286) Color No. 26081 or 36081 (APN-218) or Color

Number 16081, 16118 or 36081 (APN-230), limiting thickness to existing outer coat and cure at room

temperature a minimum of 24 hours

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  • 3 weeks later...

good day clark,

thank u for the comprehensive information about the repair of radome. however, if it's okay with u, i am actually referring to the doppler antenna shield cover which is a carbon fiber found in the belly of the c-130. and my query is that does it form part in the structural of the aircraft and if so, if not replace immediately, does it affect the structures surroundings the said panel? again thank u for your reply. these are helpful information.

cheers,

bobby

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Bobby,

You could probably fix that with a patch, The actual name of the part is a pressure box, p/n 408323-01. A replacement would have to come from a retired aircraft in AMARG. They are a real bitch to get out, as i helped on one. The problem comes when you remove that tub, a complete DVS alignment would have to be redone.

I cannot get to drawings anymore to check the specs of the box, but I believe it is some type of resin construction. Maybe Mike Bishoff, if he's on one of these days, can tell you. If the crack is small, I would suggest stopdrilling it, then a small patch placed on top, but, I'm not an engineer.

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  • 3 years later...

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