[通用经验] 雷达罩的透波率

REPAIR GENERAL - NOSE RADOME

1.   Applicability

A.  This repair section is applicable and approved for the repair of radomes as delivered or approved by Boeing for use on this model airplane. Repairs that are made from this repair section are not approved for radomes that have been modified, rebuilt or re-ringed using processes and materials that have not been approved by Boeing for use on this model airplane.

B.  This subject gives the general repair data for damage:

(1)  To the nose radome that is made of honeycomb core structure or foam core structure.

(2)  That is more than the allowable damage limits given by Allowable Damage 1. Refer to Allowable

Damage 1 for the type and dimension of damage that is permitted.

2.   General

A.  When you do a radome repair, do the general steps that follow: (1)  Do an inspection to find the limits of the damage.

(2)  Make a decision on a repair option for:

(a)   The maximum length and depth of the damage that is removed (b)   The number of damage locations or other repairs on the radome (c)   The type of layup materials you use.

(3)  Repair the damage with one of the applicable repair options.

(4)  On the inside of the radome, keep a record of damage and the extent of the repairs that are made.

B.  For 3-ply honeycomb core radomes, a test for the electrical transmission efficiency is not necessary for most of the repairs given in this subject.

NOTE :  Predictive wind shear requires a Class C radome as given in Document No. RTCA/DO-

213 (Minimum Operational Performance Standards (MOPS) for Nose-Mounted

Radomes). If you do not test the radome for electrical transmission efficiency, the radome will not meet the requirements for predictive wind shear.

(1)  If predictive wind shear is a requirement, an electrical transmission efficiency test is necessary after you complete Repair 1.

(a)   If predictive wind shear is not a requirement then a test is not necessary, the radome is a

Class D radome.

(2)  A test is not necessary when you do Repairs 2 thru 13.

(a)   After this repair is complete, the nose radome is classified as a Class D radome.

C.  For 4-ply honeycomb core radomes and foam core radomes, a test for the electrical transmission efficiency is not necessary for all of the repairs given in this subject.

NOTE :  After you do a repair, these radomes are classified as Class C radomes. You can do a test to find if the radome has better electrical transmission efficiency.

D.  The radome that is repaired and has primer, decorative paint, rain erosion protection applied and the lightning diverter strips installed must have the transmission efficiency requirements that follow:

NOTE :  Thicknesses of paint which are more than 0.010 inch can decrease the necessary radome electrical transmission efficiency. A radome wall that has been repaired should be put back to its initial thickness. If this is not done, radome transmission efficiency will be decreased. For repaired radomes on airplanes that have Predictive Wind Shear (PWS), and that are finished with CAAPCO erosion and p-static protection (Caapcoat B-274 as specified in BAC5880 and Caapcoat AS-P108), do a transmission efficiency test. The efficiency test must show the radome to be Class C or better.

(1)  The average transmission efficiency for a continuous scan of the antenna in the radome window area must not be less than:

(a)   84 percent for Class C radomes

(b)   80 percent for Class D radomes.

NOTE :  The radome window area is between ± 80 degrees azimuth and ± 20 degrees elevation.

(2)  The minimum transmission efficiency at a point in the radome window must not be less than: (a)   78 percent for Class C radomes

(b)   75 percent for Class D radomes.

E.  If you need to know the class of a repaired radome, measure the electrical transmission efficiency as given in Paragraph 2.4.7.1. of Document No. RTCA/DO-213 (Minimum Operational Performance Standards (MOPS) for Nose-Mounted Radomes). You can get a copy of this document from: RTCA, Incorporated 1140 Connecticut Avenue, Northwest, Suite 1020 Washington, D.C. 20036-4001 U.S.A. Telephone: 202-833-9339 Facsimile (FAX): 202-833-9434

F.  Refer to AMM 53-52-03/201 to replace the lightning diverter strip.

G.  Refer to AMM 53-52-31/401 to replace the glide slope director element.

H.  Make sure that you do the repairs in a clean location. Make sure that the air in the area has no oil, mist, exhaust fumes, gases, soot, rain, dust, or other unwanted materials.

I.  Prevent repair surface contamination. Do not touch the cleaned parts, the repair fabric, or the adhesives with your bare hands. Wear clean lint-free gloves when you work with these parts.

J.  When you repair a large area, make sure you use the applicable tool fixtures to prevent distortion of the radome.

K.  Refer to Table 201/REPAIR GENERAL for the materials used in these repairs.

L.  Refer to Table 202/REPAIR GENERAL for the resin, adhesive, and potting compound data.

Table 201:

NOSE RADOME REPAIR MATERIALS
REPAIR MATERIALS	BOEING SPECIFICATION
Potting compound	BMS 5-28, Type 15, 16, 17, 18, 19, or 20
Repair fabric for repairs with wet layup materials	BMS 9-3, Type H-2 or H-3,
Laminating resin for the BMS 9-3 repair fabric	BMS 8-301, Class 1 or Class 2
Repair fabric for repairs with preimpregnated layup materials	BMS 8-79, Style 1581 or Style 7781
Film adhesive	BMS 5-129, Type 2, Grade 5 As an alternative, use BMS 5-129 Type 4, Grade 5