Page 25 - AAA SEPTEMBER - OCOTBER 2017 Online Magazine

LANDING GEAR
MRO FEATURE XXXXXXXXX XXXX
TURE
MRO FEA

opposite pAge: The increased use
of composite materials in landing
gear assemblies will not only
reduce weight, but also provide
benefits in terms of improved
corrosion resistance
leFt: Despite their increasingly
widespread use, repair of
composite parts is limited, as parts
are more likely to be replaced
with traditional materials such as
aluminium or titanium

reliably examining a structure built from Especially the complicated detection of assembly has two braces and that the Boeing
composite materials for damage and faults damages and their professional repair and 787 is equipped with two such assemblies,
that was commensurate with the scale and painting procedures require very special the weight savings are anything but
variety of ways that they are used in modern equipment. One of the most important negligible. Composite materials also offer
commercial aircraft. examples are the autoclave ovens which are better corrosion resistance, which keeps
The shift to composites has created an essential for the curing of composite parts from maintenance work to a minimum and reduces
opportunity to rethink the maintenance, a certain size onwards. While smaller structures servicing costs. The highly sophisticated
repair, and overhaul (MRO) operations needed can be “cold cured” at room temperature, technology chosen by Messier-Dowty to
to keep aircraft in top form. bigger components have to be heated up in an produce these landing gear braces is 3D
Air France Industries KLM Engineering & autoclave at 250 or 350 degrees Fahrenheit weaving, a specialty of Albany International,
Maintenance (AFI KLM E&M) is pitching its in order to gain their full strength. According a company with which Safran has been in
new Helios facility at the Paris Charles-de- to the engineer, within the Lufthansa Technik partnership for over ten years, adapting this
Gaulle airport to handle all types of airframe Group, four such ovens are already in use, one in technique to aeronautical applications. The
parts, with a special emphasis on composites. Hamburg in Germany, two in Tulsa in Oklahoma fibers are consolidated using RTM (Resin
AFI KLM E&M is leveraging its proficiency on and another one in Shenzhen in China. To cure Transfer Moulding) injection. This application
the Boeing 777 and the Airbus A380 to position even bigger parts a new autoclave with 16 feet in for the landing gear braces was developed by
itself on the 787 and A350 MRO market. “The diameter and 26 feet in length was constructed the Messier-Dowty engineering department,
high-tech facility packed with innovations in Hamburg in 2009. in particular with respect to the transition
is capable of repairing more composite between the yoke joint (the eye-shaped
components on the growing fleets of Boeing Handling Composite Parts in Landing Gear section) and the cylindrical section.
787s and Airbus A350s, say Helios project The extent of composites use in aircraft The matrix is first of all flat-woven
manager Laurent Rousselle. “The treatment has continued to grow. Indeed, as the using carbon fibers then shaped prior to
of composite parts occupies a position of Boeing 787 and, more recently, the Airbus injection of the resin under pressure. As
choice, with a full complement of dedicated A350 XWB, entered service, the use of designed and managed by Messier-Dowty,
maintenance resources. More importantly, composites extended far beyond flaps, with the technical support of Boeing, the
the facility’s highly flexible configuration ailerons and other control surfaces, engine development of the material for the braces
means it can adjust in real time to demand and nacelles, fairings and the vertical tail, to the is the fruit of collaboration between several
to market requirements,” Rousselle adds. entire forward wing structure, fuselage and companies of the Safran group.
Composites continue to make inroads landing gear. Main landing gear assemblies Lufthansa Technik’s Landing Gear Services
on airframe and engine components, but of the B787s are equipped with braces has designed flow-principled workshops and
for MROs in the composite structure repair made of composite materials. “It’s the first provides vast in-house capabilities at its four
business, managing the exotic carbon-fiber time that a commercial aircraft featured landing gear overhaul facilities worldwide. To
materials and adhesives is a challenge. “With this technology,” says Patrick Dunleavy, avoid ground time for repairing or overhauling
several decades of experience in maintaining Mechanics & Composites expert at Messier- landing gear, a set going into overhaul is
commercial aircraft with major composite Dowty. The braces are the two leg struts that immediately replaced by a spare. Lufthansa
components, we are the operationally proven hold the main landing gear in place during Technik has an exchange gear pool of hundreds
partner for composites repair and overhaul,” the landing and taxiing phases. These parts of spares – a capital-intensive service that, in
says an engineer at the Lufthansa Technik. were predominantly made of steel. The use conjunction with sophisticated logistics, keeps
The steady increase in the use of of composite materials enables the mass your aircraft in the sky and brings your budget
composite materials holds many challenges of the aircraft to be reduced significantly. down to earth.
for MRO-companies like Lufthansa Technik. Bearing in mind that a main landing gear During overhaul, a landing gear proceeds
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