More Than Patchwork

Robert W. Moorman examines how the increased use of composites on commercial airliners has sparked a corresponding need for highly trained aircraft maintenance technicians (AMTs).

Years ago, commercial airliners contained a small amount of composite structures while the rest of the plane was made of aluminum. Today, metal has taken a back seat over the stronger, lightweight, fuel saving composite-filled aircraft.

Early Boeing 747 wide bodies contained just 1% composite structure, 3% for the 757 and 767 series twinjets, which included rudder and elevators. Today it is a much different story. 50% of the primary structure of the 787 twin-engine widebody is composites, 80% by volume. More than 50% of the Airbus A350 XWB’s airframe and most of the wing contains composites. Twenty-percent of the Airbus A380, the world’s largest airliner is made of composites. While the A380 production will cease in 2021, those still in revenue service for Emirates, Qantas, Air France and other airlines must be maintained, and that includes the repair, enhancement and replacement of composite structures.

With the record number of orders of composite-filled airliners, the need for advanced composite training for existing and newly minted AMTs is of paramount importance, state composite experts.

“I believe it to be absolutely critical,” said Wilson Boynton, president and principal instructor of Advanced Composites Training (ACT) of London, Ontario. “Most of the AMEs [Aircraft Maintenance Engineers] get very little exposure to the radically advanced composite materials, processes and repair skills in the new commercial aircraft.”

Boynton added: “The material changes and structure designs are coming so rapidly that the education of these AMTs is desperately behind where it needs to be.” ACT provides 17 different courses in composite technologies, from repair and mold making, to computer-aided design and manufacturing techniques.

Advancements

Numerous developments have occurred in recent years in terms of manufacturing processes, from hand layup [resin and composites] to automation to actual materials. The quality assurance and amount of fiber used in the structures have “increased dramatically,” said Boynton.

Working on aircraft composite structures can be challenging from a regulatory perspective. At one time, Boynton’s company was a Transport Canada (TC) approved training organization for AMTs or AMEs, as they’re known in Canada.

Unfortunately, with the rewrite of Canadian aviation regulations some time ago, came a requirement that the director of maintenance for a company was “responsible for choosing what is considered acceptable training,” said Boynton. The one exception is given to community colleges (aka career training colleges).

CAT posed the obvious question: How could ACT stay in business under the new training regulation: “Because we don’t advertise our course as specifically for AMTs,” he explained.

Repair procedures, which used to be rudimentary, have become more complex. Years ago, AMTs would apply wet resin repairs to secondary, tertiary structures. Today it is not uncommon to have bonded, bolted titanium repairs to fix large monolithic composite structures, such as the entire pressure vessel, the fuselage, CAT learned.

Working on composites has become big business.

“The composite training market is definitely growing,” said Mike Hoke, president of Reno, Nevada-based Abaris Training Resources Inc., which provides composite maintenance training in Nevada, Georgia, Brazil, the United Kingdom and in Long, Island, NY.

Enhanced composite training should be “taught at the entry level at A&P schools, said Hoke. “The requirement now is one week of very basic wet lay up fiberglass repair. Which is fine, if you’re repairing a wheel panel on a Cessna 150. But it is not adequate if you’re doing pressure vessel repairs on a 787.”

Abaris provides composite maintenance instruction for FlightSafety International (FSI) through FSI’s Maintenance Learning Center in Wichita, Kansas. The training goes beyond the trained eye “tap testing” method. The five-day courses offered include Phase 1, Phase 2 and Phase 3 Advanced Composite Structures: Fabrication and Damage Repair; Adhesive Bonding of Composites and Metals; Mold Fabrication for Production and Repairs; Non Destructive Inspection Techniques for Technicians and Inspectors; and Repair of Bonded Aluminum Structures.

Detecting Damage

Students learn how to detect composite damage through Non Destructive Inspection (NDI) and Non Destructive Testing (NDT). Among the more prominent means of identifying composite flaws are: thermal wave imaging, a specific process of thermography; shearography, a laser-based process; and ultra sound, the most prominent way of finding flaws in composites. The use of NDT technology has evolved and expanded, in part, because of the difficulty of finding damage within the layered structures of composites. As many composite experts note: It’s not what you see, it’s what you can’t see that is challenging.

“There has been a steady increase in the acceptance of thermography for aerospace NDT, as it has proved to be well-suited to composite materials and the large structures and geometries that are widely used in modern aircraft,” said Steven M. Shepard, Ph.D., president of Thermal Wave Imaging, Inc.

Shepard added: “However, to take full advantage of the available NDT tools and apply them to modern composite aircraft, training is essential to ensure that the inspector can not only operate the instrumentation properly, but also understand the underlying physical principles.”

Thermal Wave Imaging and the Snell Group, an expert on the use of infrared thermography (IR), offer training classes on Thermography for Aerospace NDT and Material Characterization. The courses cover basic (Level I) and advanced (Level II) thermography concepts, with particular focus on flaw detection and measurement, application issues, and understanding when thermography can (and can't) be applied. Hands-on lab sessions give students the opportunity to work with state-of-the art-thermography equipment.

OEMs & MROs

Larger Original Equipment Manufacturer (OEMs) led by Boeing and Airbus provide more in-depth composite training in-house for AMTs working on their respective aircraft.

Typically, AMTs come to Boeing and Airbus with many years of experience inspecting, installing and repairing metal airplanes. These aircraft have composite parts, but are applied in secondary structures like aerodynamic fairings.

“The latest generation of airplanes use composite materials in more mission-critical areas and therefore require a greater degree of scrutiny to inspect and maintain,” said Tom Wagner, senior manager, Maintenance Training, Boeing Global Services. “For this reason, we have supported more in-depth composite training with a variety of new composite repair and inspection courses.”

Wagner said Boeing offers specialist training to technicians preparing to repair, design or analyze repairs to those structures. In addition, Boeing has increased content of its training for line and base certifying staff to raise awareness of best maintenance practices when working on or around composite-filled airplanes.

Driving the need for more composite training at Boeing is the 787. Boeing Flight Services has a three-tiered program on how to identify and assess levels of composite damage to the aircraft and then recommend an appropriate means of repair. Boeing also teaches inspectors how to use damage identification and assessment tools.

The second tier instructs AMTs to make repairs in accordance with the B787 structural repair manual. The third level trains engineers to design their own composite repairs not covered in the structural repair manual.

A2 Technologies, a major supplier to Boeing and Airbus, and a division of Agilent Technologies, sells its handheld 4100 Exoscan spectroscopy to airlines and MROs for NDT testing on composites.

Airbus offers a five-day introductory repair course for AMTs. The aim of the course is to familiarize technicians with composite materials and their application on Airbus aircraft. The course includes basic standard practice for bonded and bolted repairs and performing standard repairs of sandwich structures and solid laminates. It is a pre-requisite before taking the following courses: Advanced Composite Repair for Technicians Course (XSA3); Composite Repair Technicians Course (SA7); and Radom Repair for Technicians Course (SA9). This nine-day course is offered at various Airbus Training Centers.

ACT provides 17 different courses in composite technologies, from repair and mold making, to computer-aided design and manufacturing techniques. Image credit: Advanced Composites Training (ACT).

Increasing Levels of Training

Independent and airline-aligned Maintenance, Repair and Overhaul (MRO) businesses are out of necessity increasing their level of composite inspection and repair, which is becoming a lucrative element of the maintenance business.

“ST Engineering's Aerospace sector developed basic and advanced courses with hands-on training to up skill its engineers and technicians in composite structures repair, said Ang Chye Kiat, executive vice president of Aircraft Maintenance & Modification, ST Engineering Aerospace. “Our training capabilities, coupled with our in-house design and engineering expertise allow us to adapt quickly and ramp up the necessary capabilities to meet any evolving needs related to new design or advanced materials.” On training its AMTs, ST Engineering works with major OEMs to develop skills involving the latest composite inspection and repair techniques, Kiat added.

Lufthansa Technik AG has developed a method for the partially automated repair of fiber composite materials on aircraft structural components, mainly aircraft fuselage and wing structures. Following a damage assessment, the composite surface is scanned to the nearest hundredth of a millimeter using an optical measurement technique. A computer-controlled milling machine then creates the bonded surfaces. The perfectly matched pre-cuts of individual composite layers are then superimposed on the damaged component, bonded and cured.

Lufthansa Technik developed this new repair in cooperation with industry and research partners iSAM Ag, Cassidian, GOM-Gesellschaft für optiche Messtechnik, Electro Optical Systems (EOS and Eurocopter.

Tulsa, Oklahoma-based NORDAM, an aerospace manufacturing and repair business, with nine facilities on three continents, conducts its own composite training repair program for AMTs. Technicians, who are new to working on aero structures “are required to complete basic composite training classes through a cooperation with a local technical school before taking on any work assignments,” stated the company.

NORDAM said composite repair and installation at its facilities has become as important as repair of aluminum structures. “We have seen an increase in composite repairs over the years and often receive components containing a combination of metal and composite structures,” stated the company. “Each material requires its own unique technical analysis and repair methods. So it’s important to excel in techniques for both types of structure.”

Global Standards

One of the principal goals of those in the composite world is the development of composite maintenance standards, which are almost impossible to create because OEMs have their own standard for composite maintenance. Several different ways to repair the same composite part exist. Hence, establishing a global standard is very difficult, according to several composite repair experts.

The Aerospace Division of the Society of Automotive Engineers years ago created the Commercial Aircraft Composite Repair Committee (CACRC). The Committee created numerous reference documents regarding composite work.  One document, the Aerospace Recommended Practice (ARPs) is earmarked for training mostly. The practices were developed from input from the MROs and OEMs worldwide. Those prospective AMTs expecting the rewrite of Part 147 to clarify exactly what kinds of composite maintenance training will be required to obtain their A&P certification will likely be disappointed.

“The current rewrite of Part 147 rulemaking does not specifically address composite maintenance training,” said an FAA spokesman. “Instead, we are going to address the training specifications through the new airman certification standards (ASC),” said Crystal Maguire, executive director, Aviation Technician Education Council (ATEC). Those standards have been in development for the last few years through a joint industry/government committee.

To avoid being handcuffed to an inflexible rule, ATEC and 29 signatories asked the FAA to remove training requirements for several maintenance disciplines out of the Part 147 rule, including rules for composite training.

Much of the content of Part 147 is to assist AMT Schools to develop and deliver training at the entry level. Part 147 represents only one of the three paths an applicant for an Airframe and Powerplant (A&P) certificate may take in order to earn a certificate.

Advisory Circular (AC) 65-33 provides composite information to technicians.

Composite training for inspection and repair is very specific and intended for the more advanced technicians, and is controlled through proprietary practices of the OEM or MRO. The current regulation, said the FAA, puts the responsibility for training on the responsible industry group.

“That makes sense because each MRO or airline would have different technician needs, depending on what they are repairing,” said the FAA spokesman.

Part 147 has driven training requirements for schools historically. Yet, with the new ACS as the training guide, “we can revise the standard as technology changes,” said Maguire. “It is easier to revise the standard than it is to drive the knowledge and skills requirements through a regulation.”

She summed up: “The schools will have more flexibility to address industry employer needs - such as composites training - once specific, static training requirements are removed from Part 147.”

AMT Shortage

While some ponder how best to train aircraft maintenance technicians (AMTs) to repair airplanes, including complex composites properly, trainers face the dilemma of not having enough mechanics to instruct.

The 2018 Boeing Pilot & Technician Outlook forecasts a need for 754,000 new AMTs over the next 20 years to work on commercial (622,000), business (89,000) aircraft and (43,000) civil rotorcraft. Most mechanics are needed in the Asia-Pacific region, with a projected call for 257,000.

Hard numbers on the present AMT shortage in the US and elsewhere are hard to come by. And how extensive the shortage is and what is causing it depends on whom you ask.

“Addressing and solving the workforce [AMT] shortage is one of our highest priorities,” said Sarah McCann, director of Communications, General Aviation Manufacturers Association (GAMA). “As an industry, we have a responsibility to recapitalize our workforce through education and training while continuously promoting the dynamic nature of careers available in aviation.”

AMTs say the issue they’re leaving aviation for the automobile and other industries is because of the low salaries and lack of benefits. Others believe there is a greater issue at stake.

Sarah MacLeod, executive director of the Aeronautical Repair Station Association (ARSA), believes a change in mindset by airlines and upper-tier business aircraft operations is needed as it relates to the performance of maintenance and those providing it. “We need to specialize the maintenance workforce,” she said.

MacLeod said this notion that all technicians must be certificated mechanics is a dated, expensive concept. Taking advantage of more-specialized skills by training technicians - regardless of their personal certification - on a particular task area, such as composites repair, is the way to go.

Brett Levanto, vice president of Operations, ARSA added: “In situations when broader work is performed, a certificated AMT can be invaluable because of his or her ability to quickly troubleshoot an aircraft-wide issue or understand how the entire system works together.” Levanto pointed out that a “limited number of A&P mechanics or certificated repairmen can allow an air agency certificate holder to meet the limited regulatory requirements for supervisory personnel and those signing off on work for return to service.”

To expect some prospective mechanic to go to school for two years, accumulate $50,000 of debt, and still have to be trained to a specific requirement is no longer acceptable.

“This [MRO] industry has to stop being so hidebound; it needs to look for ways that the regulations support useful, job-focused career paths for the aviation maintenance technician,” said MacLeod. “Focusing solely on certificated mechanics ignores the ability to seek the right skill sets.”

NATA president Gary Dempsey added “Among the top concerns of our members is the challenge of attracting and retaining technician talent. In response, NATA led a coalition of organizations representing a broad cross-section of the aviation industry to successfully include a workforce development grant program in the most recent FAA funding bill. Building on the coalition’s success, NATA is working to ensure the program is fully implemented and plans to assist members in securing grant funding.”

Published in CAT issue 2/2019