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Power house

Having attended the opening, Ian Harbison returned to Arnstadt for the 10th anniversary of N3 Engine Overhaul Services, the joint venture between Lufthansa Technik and Rolls-Royce

One of the most immediate differences in returning to the N3 Engine Overhaul Services (N3) facility after a decade of operation is that it no longer sits in isolation. Instead, only the 32m high exhaust stack of the test cell is visible above the newer surrounding buildings. This is important, as the selection of Arnstadt had great political significance as a high technology project, and received considerable funding assistance, in order to bring skilled jobs to an area of high unemployment in Thuringia, formerly part of East Germany.


This was evident in the attendance of the Federal Chancellor, Dr Angela Merkel, and Thuringia’s Minister President, Dieter Althaus, at the ceremony to lay the foundation stone on 2 May 2006. Althaus would also attend the official opening in April 2007, alongside Wolfgang Tiefensee, the Minister of Transport, Construction and Urban Development, and State Secretary Dr Joachim Würmeling, Ministry of Economic Affairs and Technology. At an equally high level, the partners were represented by Wolfgang Mayrhuber, CEO of Deutsche Lufthansa, August Wilhelm Henningsen, Chairman of Lufthansa Technik and a member of the N3 supervisory board, and Sir John Rose, CEO of the Rolls-Royce Group.


This time, the political representation included Dr Wolfgang Scheremet, Head of the Department of Industrial Policy at the Federal Ministry of Economics and Energy, and Wolfgang Tiefensee, now Thuringia’s Minister of Economy, Science and Digital Society.

Also returning was Henningsen, still a member of the N3 supervisory board after retiring as Chairman of Lufthansa Technik, having been replaced by Dr Johannes Bussmann, who was also present, while Rolls-Royce was represented by Eric Schulz, President Civil Aerospace. 


This heavyweight involvement is understandable as N3 has been part of a successful regeneration of the region, with unemployment falling by more than 10% over the last decade. Indeed, in the same period staff numbers at the company have grown from 270 to 600. The original local workforce did feature a pool of skilled labourers in the electrical and metalworking industries, but the company was keen to expand this number, and set up a range of training courses with local educational institutions that also brought on younger people, eventually leading to an apprenticeship programme, which began in 2008. To date, N3 has trained approximately 12 aircraft mechanics in the field of engine technology every year. So far, 54 young men and women have finished their training and found permanent positions at N3. There are currently another 40 young men and women in training at the moment. Soon, says the company, every seventh engine specialist will be a graduate from internal training programmes, which were supplemented last year by the first course for warehouse logistics specialists.


The entire site covers 12 hectares, while the Repair & Overhaul Shop measures 25,000m². Using experience from the Rolls-Royce main production facility in Derby, the shop was designed from the outset to follow LEAN principles. That original layout was so efficient that very little has changed in 10 years, says Alexander Stern, N3’s Director and General Manager. Engines flow in an anticlockwise direction around a U-shape line, stopping off for disassembly, examination, cleaning, crack detection, repair, storage and assembly. This ensures optimum material flow, short travel distances and allows maintenance progress to remain clearly
visible at all times.


On arrival, the engine is placed on a disassembly stand and thoroughly examined (including endoscopy) to identify any concealed damage. After all the non-modular components such as piping are removed, the engine is hoisted into a vertical position using a crane and disassembled into its eight modules. These are then taken to module disassembly booths where they are further dismantled into their individual parts and components. Whenever repair work is needed, the components are either taken to N3’s internal repair shop or dispatched for external revamp.


Other facilities include a semi-automatic cleaning line, NDT (dye penetrant, magnetic particle, eddy current and ultrasonic), metal and plasma spraying. The machine park includes a five-axis milling machine, two horizontal lathes, a vertical lathe, a coordinate-measuring machine, a high-speed surface grinding machine, and two balancing machines. 


Final assembly is also carried out vertically. The engine’s own weight helps to ensure that joints and seals make good contact and produce a better performing engine, although horizontal assembly will be used for minor checks.


The engine is then transferred to the test cell, one of the biggest installations of this kind in an overhaul facility. Designed by Cenco, the intake tower is 23m tall while the exhaust stack is 32m high. It has a 110m x 14m x 14m noise-attenuation shell with a test stand capable of taking engines – including the Trent 500, Trent 700, Trent 900 and Trent XWB – up to a maximum thrust of 150,000lb.


The Trent 500 powers the Airbus A340-600 and was the first powerplant to be overhauled at N3. Just over 120 aircraft were produced and about a third of the fleet is currently parked, Stern says, as airlines now prefer more fuel-efficient twin-engine aircraft. Lufthansa, Iberia and South African Airways are the main customers, but he expects numbers to dwindle over the next few years. However, a capability will be retained as Rolls-Royce has a commitment to support the engine until the last aircraft is phased out. >>

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