Repair considerations

As more composite materials find a place on aircraft, boats, bridges and hundreds of other applications where part replacement is difficult and expensive, OEM engineers are considering the repairability of structural and secondary composite components during the initial design phase.

According to a recent report by Aerostrategy Management Consulting (Ann Arbor, Mich. and Amersham, Buckinghamshire, U.K.) spending by air transport maintenance and repair organizations (MROs) on air transport maintenance materials was $16 billion (USD) and likely to increase to $20 billion by 2011. Today, composite repair materials account for a fraction of that: $15 million to $25 million annually. With the recent roll out of Boeing's 787, MROs soon will have to repair planes that are 50 percent composites by weight. One answer may be automated repairs. Publicly unveiled in 2005, the Inspection and Repair Preparation Cell (IRPC) concept is the result of an initiative begun in 1999 to improve aircraft repair practices and reduce repair time through automation. The ongoing work of a consortium of companies championed by American GFM (AGFM, Chesapeake, Va., a member of the GFM machine tool organization headquartered in Steyr, Austria), the IRPC is designed to integrate into a single, automated work cell a variety of tasks regularly performed manually by MROs. An IRPC "cell,"as currently conceived, will include a 3-D digitizing station, nondestructive testing (NDT) capability, radio frequency identification (RFID) tagging, automated machining equipment (to remove damage and cut out repair plies and core plugs) and advanced in-cell collision avoidance technologies. (For more on the IRPC concept, visit www.compositesworld.com/hpc/issues/2007/March/111325.)

Other composite components that require repair include heavy truck front ends and other automotive and marine products. Whether damage is minor or extensive, training and specific repair materials are available. A number of materials suppliers provide kits containing low- or room-temperature curing adhesives and potting compounds formulated especially for onsite repair, along with low-quantity dry fiber or prepreg and vacuum-bagging materials. At least a dozen private training companies nationally offer from one- to ten-day courses in composite repair.

Composites are increasingly being used to repair structures with other materials, such as bridge beams, bridge decks, parking garages and pipelines, including underground systems. A number of specialty contractors, like Structural Preservation Systems (Hanover, Md.) and Fyfe Co. (San Diego, Calif.) use composite fabrics and precured strips to add load capacity and strength to floors and beams. Composites also can be used to repair product pipelines, such as natural gas and petroleum pipes at oil refineries and offshore platforms.