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
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