Hamburg-built bulkheads for the Super Star
These days visitors to the workshop area of Airframe Related Component Services at the Lufthansa Technik base in Hamburg can enjoy a small journey in time. The core business of the department includes the overhaul of large engine cowlings and thrust reversers from the latest fiber composite materials, sections of VIP cabins built in-house and conversion kits for a Boeing 737 modification. But in parallel to this is the small batch production of up to 180 aluminum sheet bulkheads for the Deutsche Lufthansa Berlin-Stiftung´s Lockheed L-1649A, originally built in 1957.
The subject of bulkhead production for the Super Star is not new. Premium Aerotec in Nordenham has been building individual components for the L-1649A on Lufthansa Technik´s behalf since the autumn of 2010. Their first task was to close up the holes that appeared on the port side of the fuselage following the removal of the two cargo doors, then they built the door frames for the passenger version now under construction. But thorough structural examination of the aircraft brought to light that about 180 bulkheads in the lower fuselage area needed to be replaced. As a result of water accumulated in the fuselage over the years since before the start of the restoration work, they were so heavily corroded that it was more cost-effective to replace them completely than to repair the existing bulkheads.
Seven staff from four specialist departments are involved in building the new bulkheads at Airframe Related Components. While
Premium Aerotec produces the bulkheads using metal stretching processes, the pre-milled bulkheads are edged by Lufthansa Technik using individual wooden templates. This method is also approved by the FAA, and is performed following FAA-authorized engineering instructions from the Super Star engineering team in Auburn. Due to the curved, dolphin-shaped fuselage of the L-1649A, virtually every bulkhead is unique and so is every template.
Production Manager Joerg Hennicke, who is in charge of the project at Airframe Related Components, says: "The staff who are working so enthusiastically on this project are masters of their trades – especially when it is a matter of skilled work and the special expertise required for this production method. These days it is no longer widely used but is still highly cost-effective and produces high quality." All the activities are being carried out within the framework of Lufthansa Technik´s license to operate as a manufacturing organization and hence to certify the finished components via an EASA Form 1 (which simultaneously serves FAA certification purposes).
But before it comes to that, the soft aluminum sheets supplied in "zero state" have to undergo a stabilizing heat treatment after the edging and the implementation of joggles for later riveting. Once the bulkheads have been quenched in cold tanks and rolled out cold to align the molecular structures, they acquire the status of T42 "cured aluminum sheet".
Altogether it takes the experts five working days to produce one bulkhead. The additional work involved includes an NDT crack inspection after the cold rolling out, electroplating for optimal corrosion protection, the application of a coat of primer and subsequent final painting. Up to ten bulkheads are produced each week by the small Super Star team at Airframe Related Components.
The bulkheads supplied by Premium Aerotec also arrive at the Hamburg workshops unpainted in T42 condition. Here they are electroplated and painted to acquire their finish, and after passing a quality and NDT test with an EASA Form 1 "dual release" they are cleared for FAA-compliant installation in the L-1649A in Auburn.