Story ID: 341
DTI's Spring-Fast Eliminates Adhesives from Wire-protection Grommets
By: Sean Broderick
Caption: Ease of installation, durability proving to be draw for OEMs and MROs.
Word Count: 585
Protecting wires from chafing is a must on every aircraft, from the assembly line to the maintenance hangar, but it's far from an aviation-only challenge. Massachusetts-based Device Technologies, Inc. (DTI, Booth C11844) has taken a concept it originally developed for the information-technology world and brought it to aerospace, and it's taking hold. DTI's snap-on, self-securing grommet edging, Spring-Fast, is being used by both original equipment manufacturers (OEMs) and maintenance providers to protect wire bundles from metal aerostructure edges. A cushioned interface provides protection on the side facing the wire bundles, while a patented polymer coating provides durability that exceeds that of traditional plastic grommets, according to DTI. 

The product, which meets FAA flammability requirements, comes in 12 variants. It is delivered in reels and can be used to provide protection around corners with an outside radius of as little as one-quarter of an inch, or an inside radius of one-eighth of an inch. This versatility means that Spring-Fast is being used on everything from lightning holes to avionics, cabin entertainment and management system and airborne connectivity installations. While the product's durability and flexibility is welcomed, the benefit that is attracting the most attention is its ease of installation, DTI says. Installing a traditional nylon grommet requires up to nine steps, including the use of potentially toxic solvents to cleaan the metal edges and adhesives to bond the nylon grommet material. Protecting a curved surface means cutting the nylon to fit, cleaning the metal, applying the adhesive and holding it in place until it has bonded to the structure. In all cases, adhesives must be dry before wire routing can continue—a process that could take 30 minutes or more, which can bring work to a halt.

Installing Spring-Fast can be done by hand or using special tools available from DTI. Basically, the installer simply pushes the Spring-Fast grommet edging "castles"—the raised portion that grips the metal structure—onto the edge of the structure and bends the metallic inner core of the grommet around any circular or curved shapes. The result is tightly fitted grommet edging installed quickly and without any additional bonding or wait time required. The product's ease of installation also makes it an ideal choice for upgrading in-service aircraft according to the company. Spring-Fast can be easily installed with minimal disruption of wiring bundles—a key factor in ensuring that additional risk isn't introduced during the maintenance process. Another advantage of Spring-Fast products is that they don't become brittle with age and exposure to heat or fuel, hydraulic fluid and other damaging substances, as is the case with nylon grommets. For applications in hot areas, Spring-Fast HIgh Heat grommets can provide protection without the risk of loss of integrity of the grommet edging.

The risks of chafed wires have been known in the defense sector and were magnified by the investigation into the 1996 accident of TWA 800, a Boeing 747-100 that investigators determined suffered an in-flight fuel tank explosion, most likely triggered by a short-circuit in damaged wiring. 

In one case, a helicopter manufacturer was looking for ways to shorten the installation time of wire protection in lightning holes. DTI brought Spring-Fast to the factory floor and a company employee, guided by the OEM's assemblers, installed it to demonstrate Spring-Fast's simplicity.

Announced Spring-Fast applications include the Sukhoi SSJ-100 and Eurofighter Typhoon. The product is also specified as original equipment on several business-aircraft platforms, and is used by a growing number of aftermarket providers.