Lufthansa German Airlines

Ladies and gentlemen, please find enclosed a comment for NPRM Docket No. FAA-2009-0607, Directorate Identifier 2009-NM-024-AD: The proposed AD requires modifying the frame-to-tension-tie joints at body stations 1120 through 1220 (including related investigative actions and corrective actions if necessary), which would provide a terminating action for the repetitive inspections mandated per AD 2007-23-18. The proposed AD would also require new repetitive inspections after the modification, corrective actions if necessary, and additional modification requirements at a specified time after the first modification. Lufthansa is anticipating a severe operational and monetary burden for their fleet. Lufthansa is intensely seeking for alternative solutions and intervals to produce relief in view of the huge design deficiency driven modification work lately being dropped onto the 747. Lufthansa is asking for (a) 'Zero Timing' (modification using new parts with the existing part number instead of the modification with new parts/partnumbers) as alternative solution to the modification given in SB 747-53A2559 (b) a detailed explanation about the decision making leading to the compliance threshold of 17.000FC (damage tolerance analysis, calculations, findings). This threshold seems inconsistent considering the requirement of the stage 2 inspection threshold at 16.000FC as per SB 747-53A2507 (AD 2007-23-18) (c) an extended threshold of 20.000FC for the modification if technically justifiable (considering alternative minimum maintenance requirements, if necessary, at A- or better C-Check interval and with low depth) Best regards Jacob Hirsch Project Manager Aircraft Engineering B747 Deutsche Lufthansa AG Technical Operations, FRA OB/M-E E-Mail: jacob.hirsch@dlh.de