Advanced Tube Bending Maintains Latest-Generation Aircraft
To maximize operational efficiency, British Airways maintains its fleet of aircraft in-house. The loss of revenue resulting from the grounding of a modern aircraft can be astronomical, making fast-turnaround MRO capabilities vital to economic performance.
To that end, Unison has won a major tube bending machinery order from British Airways for use in its Heathrow-based aircraft MRO facility. Unison will supply a unique turnkey solution for fabricating precision tubular parts based on two bending machines that are widely used in the aerospace industry. One machine is a semi-manual bender with CNC control; the other is a fully CNC all-electric model. Unison will also provide all associated tooling, together with a portable coordinate measuring machine and advanced program generation software.
Unison's tube bending solution will meet the long-term needs of this critical repair and maintenance workshop. British Airways has embarked on a major upgrade to its fleet of long-haul aircraft, which is set to include Boeing 787 Dreamliners and Airbus A380 superjumbos over the next 10 years. The introduction of these latest-generation aircraft poses numerous new challenges for the airline's repair and maintenance personnel.
Meeting Needs for the Long Term
One area receiving particular attention is the fabrication of replacement rigid hydraulic tubes. The central hydraulic systems of Boeing 787 and Airbus A380 aircraft operate at 5,000 psi - most commercial aircraft have 3,000 psi systems - to allow use of smaller, lighter hydraulic components. Much of the interconnecting hydraulic pipework is manufactured from specialist aerospace materials such as titanium alloy, using thick tube walls to accommodate the high working pressures; a 25 mm hydraulic tube for an aileron actuator, for example, would typically have a wall thickness of 2.5 mm.
Fabricating replacement high pressure hydraulic tubes from these materials economically - without generating expensive scrap - and to the very high quality and safety standards demanded by the aerospace industry requires precision bending and measurement equipment, backed by application-specific knowledge.
Following the decision to upgrade the tube fabrication capabilities of its repair and maintenance workshop, British Airways sought a tube bending machine company with proven expertise in the aerospace sector. Unison was an obvious contender; the company's all-electric tube bending technology is used by a number of leading aerospace manufacturers, including Boeing and Airbus, to produce parts for engines and airframes. In fact, Unison machines are already used to produce hydraulic fluid lines for both the 787 Dreamliner and A380.
Complete Turnkey Package
For the British Airways application, Unison configured a complete turnkey MRO package for tubular components, to provide quick and cost-effective repair of fluid lines on aircraft by reverse-engineering OEM parts and then recreating them in the workshop. The package covers tube sizes from a few millimeters up to 40 mm in diameter and accommodates the variety of materials used in this application, including stainless steel and titanium alloy.
For demanding bending tasks, such as rotary draw bending of thick-walled titanium alloy or large diameter tubes, the package includes a single-stack 40 mm machine from Unison's Breeze range of all-electric tube benders (see photo, right). This machine will also be equipped with Unison's unique laser-controlled springback measurement and correction. The system ensures bending precision by automatically compensating for the natural tendency of metal tubes to spring back slightly after being bent, eliminating expensive scrap by facilitating right-first-time results.
For cost-effective bending of intricate stainless steel tube parts with smaller diameters up to 30 mm, Unison is supplying British Airways with an EvBend 1000 machine. Capable of extremely accurate left- and righthand bending, this CNC controlled, manually powered machine is a popular choice with metal fabricators for precision low-volume work, such as aerospace parts manufacture. Originally developed by a specialist tube manipulation company, Silkmead Tubular, EvBend 1000 machines are now manufactured by Unison in Scarborough.
If a suitable CAD file for the tubular part is available, tube fabrication data can be extracted and downloaded direct to the appropriate bending machine. However, a more likely scenario is that, at least in the first instance, there will be no supporting design data for a tube that needs replacing. In this instance, after removing the worn or damaged part from the aircraft, maintenance personnel will obtain the tube's physical measurements and then process the information to create a suitable bending program.
The package being supplied to British Airways also includes a FARO coordinate measuring machine (CMM) that uses laser and tactile measurement techniques to acquire detailed and highly accurate 3D representations of tubes, together with VTube-LASER software from Advanced Tubular Technologies. This software automatically converts CMM data into a form suitable for use on bending machines, enabling tubular parts to be cloned in a matter of minutes.
Under the terms of the order from British Airways, in addition to supplying the complete turnkey tube fabrication solution, Unison is responsible for all aspects of bending machine integration and associated equipment connectivity.
"This turnkey solution demands tight integration of hardware and software resources to create a seamless production environment for efficient on-demand manufacture of specialist precision parts," Alan Pickering, Unison's managing director, points out. "By assigning responsibility for the performance of the entire installation to Unison, British Airways can be confident that its tube fabrication requirements are fully met from the outset."
