Southwest Airlines

June 7, 2011 Mr. Ali Bahrami Manager, Transport Airplane Directorate, Aircraft Certification Service C/O: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor Room W12-140 1200 New Jersey Avenue, S.E. Washington, DC 20590 Subject: Docket No. FAA-2011-0384; Directorate identifier 2010-NM-058-AD Dear Mr. Bahrami, Southwest Airlines would like to submit the following comments for NPRM Docket No. FAA-2011-0384 which proposes an AD to prevent failure of the seat attachment structure and possible injury to passengers during an emergency landing. Southwest Airlines has an interest in this NPRM because we recently acquired 46 of the aircraft affected by this proposed rule. Southwest Airlines interpretation of the proposed rule is that it is to prevent an unsafe condition that only exists when Recaro 3510A351-()-() series seats are installed where the aft leg attachment fitting spans the STA 521.45 seat track split. It is Southwest Airline’s intention to retrofit the above mentioned 46 aircraft and replace the Recaro seats with new B/E Aerospace seats to match the previously certified and compliant Southwest Airlines current configuration. Southwest Airlines feels the NPRM should be withdrawn since the Boeing SBs listed in the NPRM have already been accomplished and the unsafe condition no longer exists. Furthermore, the airframes listed will be retrofitted to a configuration that makes the AD irrelevant and will be accomplished before the proposed AD deadline. If the NPRM is not withdrawn, Southwest Airlines is requesting the applicability of the AD to apply only to aircraft operating with Recaro seats installed in a specific configuration. If the aircraft does not have Recaro seats and is not installed with the foot at STA 521.45 then the unsafe condition does not exist and the AD should not apply. Sincerely, Amy Oonk Director – Engineering Amy.Oonk@WNCO.com (214) 792-2733 Cc: Ross MacArthur - Manager – Systems