Aviationtoday.com: Bonding Experience

The rising use of composites in aircraft manufacturing also is giving rise to unexpected maintenance predicaments. Not all mechanics are adequately trained to repair these leading edge materials, which makes training of paramount importance.

This issue is relevant to avionics, because composites are increasingly used to enclose and protect super-sensitive electronics, especially in UAVs. I broached these issues in my latest podcast interview, "Why Hot Bonders are Crucial for Aircraft Composite Repair," with Craig Alexander, general manager of WichiTech Industries. You can download the podcast for free at www.aviationtoday.com/podcasts. WichiTech Industries, based in Baltimore, designs and manufactures hot bond composite repair systems.

Below are the highlights of the interview.

Persinos: Give us a quick description of what WichiTech Industries is all about.

Alexander: WichiTech Industries manufactures composite repair equipment more commonly referred to as "hot bonders." A "hot bonder" is a portable heating device used to create an exothermic reaction in epoxy resin adhesive systems. The bonder accomplishes this by supplying power to a silicon heating blanket or heat gun, and monitoring this heat by the use of thermocouples. This technology is used mainly in the aviation industry to make repairs to advanced composite structures.

Persinos: To what extent are composites becoming more common in the aviation industry and how does that trend affect MRO work?

Alexander: First, I would like to outline the difference between a composite and an advanced composite. A composite is defined as the combination of two or more substances that produce material and structural properties superior to those substances if they were used alone. An example of this would be fiberglass.

Advanced composites are defined as those materials (fibers, resin systems, cores) which when combined, have strengths and other properties far in excess of using ordinary fiberglass. The advantages of using advanced composites in aircraft construction are significant weight savings, very high resistance to fatigue and the capability to produce very complex shapes in a single piece.

Persinos: Are mechanics up to speed on the latest techniques when it comes to composite repair? Are they getting the training they need?

Alexander: We deal with mechanics and technicians who have far ranging differences in their abilities and knowledge of advanced composite repairs. They have received their training in different ways. Some of these technicians have been through training courses specializing in advanced composite materials. Others have acquired their knowledge by on-the-job training.

One thing to keep in mind is that training is only as good as the person teaching it. Training only should be performed by an individual with extensive knowledge of advanced composites and who keeps up with new advances in the industry. I highly recommend all technicians attend a training course specializing in the repair of advanced composites.

Persinos: Why is it increasingly important for composite repair to be portable, lightweight and easy to use?

Alexander: The old adage "time is money" applies here. Downtime on aircraft for repairs costs an airline a significant amount of money. Portable, lightweight, easy-to-use equipment will enable a faster repair time that will result in less downtime.

Persinos: The military has issued new rules that put more of the MRO burden on end users. It also has put more emphasis on battle damage repair that must be conducted in the field. What are the consequences of these mandates for the mechanics and technicians who conduct the repairs?

Alexander: When repairs are made in the field, it requires that the equipment being used is more versatile then equipment being used solely in a repair shop. The aspect of lightweight, portable and easy-to-use equipment applies heavily in reference to repairs done in the field.

Environmental conditions play a large role in how the repairs are made. The equipment being used needs to be adaptable to these conditions and be able to operate in less then perfect conditions and handle the abuse associated with these conditions. Power supply, source of vacuum, ease of use and the ability to operate in an explosive atmosphere all contribute to how useful the bonder is under field conditions.