A radome is a covering designed to protect a radar antenna ftom the environment. The latter is usually located in the nose or a forward compartment of an aircraft. The radome is part of the airplane and should have certain physical as well as electrical properties. It must be strong enough to withstand the air loads it may encounter, and contoured to minimize drag.

Electrically, a radome should permit the radar's transmitted signals and echoes to pass through with minimum distortion and absorption. This requires that the thickness of the radome wall be maintained precisely as required for the effective performance of the equipment. Even a slight variation in physical thickness, as might be brought about by an application of paint, or a patch, could interfere with the desired clean, non-distorted, reflection-free antenna view through the radome.

All maintenance work on the radome must be performed by or under the supervision of an FAA qualified and appropriately experienced mechanic.

Radomes may be damaged by static discharge, which produces small pin-holes, almost invisible to the naked eye. Any hole, regardless of size, can cause major damage, since it would allow moisture to enter the radome wall and bring about delamination and fracturing.

If enough moisture collects the radar pattern will be distorted, and the transmitted signals and returns seriously attenuated.

Ram air entering though a small hole can also delaminate and break the inner surface of a radome and separate the skin ftom the core of the covering, which will weaken it structurally. Other types of damage include dents and scratches caused by impact with birds or debris, as well as by improper handling of the radome.

Since the accuracy and effectiveness of airborne radar can be adversely affected by the condition of the radome, this portion of the airframe deserves a careful and close examination. In addition to spotting recent damage on the radome exterior, mechanics and pilots should look for improper previous maintenance which may include:

• Patches of different thickness or material.
• Non void-ftee or oversize patches .
• Repairs overlapping.
• Holes stopped with resin, screws, metal, wood or plastic plugs.
• Cuts or cracks simply coated with resin.
• Metallic base coating.
• Moisture or other contaminants trapped in wall.
• Poor bonding of skin to core of coyering.

   

  From FAA AC43-16 April, 1989