H.T. Hammes, A. Britz, A. Himmes

Having seen eight years of service, NASA's SOFIA - a heavily modified Boeing 747 SP - had to undergo scheduled maintenance and overhaul activities to meet continued airworthiness requirements. The last D-Check was performed while the airplane was extensively modified to become a flying observatory. The Heavy Maintenance Visit (HMV - NASA terminology) was performed during the second half of 2014 in the overhaul facilities of Lufthansa Technik in Hamburg. This company was chosen for its extensive and proven experience with providing maintenance and overhaul services for Boeing 747 SP airplanes. The set of task cards was geared towards the "standard aircraft" only. Modifications to the fuselage and in the cabin/aft compartment were mostly excluded from the work package. Most non-standard modifications to the airplane were removed and eventually reinstalled by NASA personnel. In a parallel effort also the telescope proper was maintained while staying attached to the A/C. This work was performed by DSI-personnel (DSI - Deutsches SOFIA Institut) with support from Lufthansa Technik. During the layover more than 3000 findings were reported. These findings included everything from small out-of-tolerance dents in the fuselage to cracks in two engines, which resulted in an exchange of those engines. For Lufthansa Technik the main challenges resulted from the ageing aircraft aspect of the SOFIA-airplane. The plane was originally built in 1977 and is now nearly 40 years old. NASA is the third owner and the documentation was not always as complete as desired. Finding spare parts for this type of airplane is another problem-area as they are increasingly hard to find. In a lot of instances existing parts had to be overhauled or refurbished and broken parts newly manufactured in Lufthansa Technik workshops. The major technical highlights were: - replacing a cracked frame in the cockpit - replacing a big fitting in the wing (wing gear support end fitting) which was installed in the wrong orientation and shifted - rectifying older repair-efforts on the engine pylons Although NASA is the owner and operator of SOFIA, the maintenance contract with Lufthansa Technik was concluded by DLR Raumfahrtmanagement. The technical content of the contract was defined by NASA, the legal and administrative part was managed by DLR.

Deutscher Luft- und Raumfahrtkongress 2015, Rostock

Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn, 2015

Conference Paper

englisch

21,0 x 29,7 cm, 9 Seiten

urn:nbn:de:101:1-201510192331

aging aircraft, maintenance

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19.10.2015