AW Feature

Why do aircraft need effective Radome protection? In this feature the writer has dwelled upon one of the key elements of aircraft equipment that need to be protected in a very economical and effective solution.

By Abhik Pal

Radomes are usually large dome-shaped structures, often made up of composite, which protect the radars against rain, sand erosion and particle impact with minimal impact to attenuation of electromagnetic signals being received by the radar.

However, being a composite material, they are prone to various types of damages including erosion caused by Foreign Object Debris (FOD) such as rain and sand while flying at speeds of 200-500 mph under demanding weather conditions. Once damaged, radomes need to be removed, assessed, and repaired / replaced. Radomes are high value assets (one A320 Radome costs approx. $80,000 to replace with subsequent downtime involved with repair/ replacing the radome).

It is observed that sometimes airlines use a white coating on the damaged portion of the radome as a quick fix. However it is not a fool proof solution as the level of erosion protection offered by paints/coatings is not adequate and specialized equipment is typically required to refinish radomes per the C.M.M., (Component Maintenance Manual) making the coating repair process expensive and time consuming.

Therefore, it is desired to have economical and effective solutions available to protect those high value assets that are subject to damage. Polyurethane tapes with adhesive backing provides several advantages over coatings e.g. uniform thickness / weight, no specialized tools are needed for installation, easily repairable with patch tape and repair paste, easily removed if needed, long service life etc. Refer Fig 1 for a representative comparison between coatings and a polyurethane tape (3M™ Polyurethane Protective Tape 8673) during a rain erosion test.

Radome Boot:
A Radome “boot” is sheet of protective tape thermoformed into the same, curved shape of the radome and is preferred over flat tape which can be difficult to install over curved surfaces.

Typical Benefits of Polyurethane Radome Boots:
• Radome boots are typically made of an abrasion-resistant polyurethane and are resistant to ultraviolet light. The product is constructed with a durable, solvent-resistant, pressure-sensitive acrylic adhesive, and protected with an easy-release liner.
• Radome boots provide excellent erosion protection for aircraft, from radomes to navigation light lenses and help keep these vulnerable components looking good between heavy maintenance intervals.
• They are usually available in a variety of shapes and colors for many industrial and common aircraft applications (including radomes, wing tips, landing gear pods, etc.)
• Typically, they are transparent, paintable and can be applied over painted surfaces and forms a protective barrier between vulnerable surfaces and damaging elements.
• Radome boots do not significantly interfere with radar transmissivity. For aircraft radomes, their optimized thickness is virtually invisible to radar.
• They are extremely simple and easy to install. Once installed, they establish an excellent erosion barrier.
• Radome boots prevent paint and surface erosion, even on the most vulnerable leading surfaces of the aircraft such as radomes, wing tips, wing root fairings, horizontal stabilizer tips, tail fairings, spinners, landing gear components and more. Protective boots provide many years of paint erosion protection, making them a cost-effective aircraft paint and surface protection solution.

(The writer is Technical Lead – Aerospace at Automotive and Aerospace Solutions Division of 3M India Ltd.)