AD 2007-03-07

The FAA is superseding an existing airworthiness directive (AD) that applies to all Boeing Model 737 airplanes. The existing AD currently requires installation of a new rudder control system and changes to the adjacent systems to accommodate that new rudder control system. For certain airplanes, this new AD adds, among other actions, repetitive tests of the force fight monitor of the main rudder power control unit (PCU), repetitive tests of the standby hydraulic actuation system, and corrective action; as applicable. For those airplanes, this new AD also adds, among other actions, replacement of both input control rods of the main rudder PCU and the input control rod of the standby rudder PCU with new input control rods, as applicable, which ends the repetitive tests. For certain other airplanes, this new AD adds installation of an enhanced rudder control system in accordance with new service information. This AD results from a report of a fractured rod end of an input controlrod of the main rudder PCU and a subsequent report of a fractured rod end of the input control rod of the standby rudder PCU. We are issuing this AD to prevent failure of one of the two input control rods of the main rudder PCU, which, under certain conditions, could result in reduced controllability of the airplane; and to prevent failure of any combination of two input control rods of the main rudder PCU and/or standby rudder PCU, which could cause an uncommanded rudder hardover event and result in loss of control of the airplane.

Final rule; request for comments.

2007-03-07 Boeing: Amendment 39-14918. Docket No. FAA-2006-26323; Directorate Identifier 2006-NM-150-AD. \n\nEffective Date \n\n\t(a) This AD becomes effective February 16, 2007. \n\nAffected ADs \n\n\t(b) This AD affects the ADs specified in paragraphs (b)(1), (b)(2), and (b)(3) of this AD. \n\n\t(1) This AD supersedes AD 2002-20-07 R1. \n\n\t(2) For airplanes on which the actions required by paragraph (f) of this AD have been done before the effective date of this AD: Doing the actions in paragraph (f) of this AD ends the requirements of the ADs listed in Table 1 of this AD. \n\n\t(3) For airplanes on which the actions required by paragraph (f) of this AD have not been done before the effective date of this AD: Doing the actions in paragraph (h) of this AD ends the requirements of the ADs listed in Table 1 of this AD. \n\n\tTable 1.--Other ADs \n\n\nAD -\nAmendment -\n97-09-15 R1\n39-10912\n97-14-04\n39-10061\n99-11-05\n39-11175\n2000-22-02 R1\n39-11948\n\n\nApplicability \n\n\t(c) ThisAD applies to all Boeing Model 737-100, -200, -200C, - 300, -400, -500, -600, -700, -700C, -800 and -900 series airplanes, certificated in any category. \n\nUnsafe Condition \n\n\t(d) This AD results from a report of a fractured rod end of an input control rod of the main rudder power control unit (PCU) and a subsequent report of a fractured rod end of the input control rod of the standby rudder PCU. We are issuing this AD to prevent failure of one of the two input control rods of the main rudder PCU, which, under certain conditions, could result in reduced controllability of the airplane; and to prevent failure of any combination of two input control rods of the main rudder PCU and/or standby rudder PCU, which could cause an uncommanded rudder hardover event and result in loss of control of the airplane. \n\nCompliance \n\n\t(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done. \n\nRequirements of AD 2002-20-07 R1 \n\nInstallation \n\n\t(f) Except as provided by paragraphs (h) and (i) of this AD: Within 6 years after November 12, 2002 (the effective date of AD 2002-20-07), do the actions required by paragraphs (f)(1) and (f)(2) of this AD, in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA. \n\n\t(1) Install a new rudder control system that includes new components such as an aft torque tube, hydraulic actuators, and associated input control rods, and additional wiring throughout the airplane to support failure annunciation of the rudder control system in the flight deck. The system also must incorporate two separate inputs, each with an override mechanism, to two separate servo valves on the main rudder PCU; and an input to the standby PCU that also will include an override mechanism. \n\n\t(2) Make applicable changes to the adjacent systems to accommodate the new rudder control system. \n\nNew Requirements of This AD \n\nFor Certain Airplanes: Tests, Suspension of Certain Master Minimum Equipment List Item, Replacements, Inspection, and Corrective Actions \n\n\t(g) For airplanes on which the actions required by paragraph (f) of this AD have been done before the effective date of this AD: Do the actions in paragraphs (g)(1) through (g)(4) of this AD, as applicable. \n\n\t(1) At the applicable times listed in paragraph 1.E., "Compliance,'' of the applicable service bulletin specified in Table 2 of this AD; except, where the service bulletin specifies a compliance time from the date on the service bulletin, this AD requires compliance within the specified compliance time after the effective date of this AD: Do the tests specified in Table 2 of this AD, until all applicable actions required by paragraph (g)(4) of this AD have been done in accordance with the applicable service bulletin specified in Table 4 of this AD. Do all applicable corrective actions specified in Table 2 of this AD before further flight. \n\n\tTable 2.--Repetitive Tests for Certain Airplanes\n\n\n\nFor Model -\nDo -\nIn accordance with the Accomplishment Instructions of -\n(i) 737-100, -200, and -200C series airplanes identified as Group 1, Configuration 1, in the service bulletin\nThe "Rudder Main Power Control Unit Force Fight Test," the "Standby Rudder Actuator Shutoff Valve Test," and any applicable corrective action\nBoeing Alert Service Bulletin 737-27A1281, dated June 14, 2006.\n(ii) 737-300, -400, and -500 series airplanes identified as Group 2, Configuration 1, in the service bulletin\nThe "Rudder Main Power Control Unit Force Fight Test," the "Standby Rudder Actuator Shutoff Valve Test," and any applicable corrective action\nBoeing Alert Service Bulletin 737-27A1281, dated June 14, 2006.\n(iii) 737-600, -700, -700C, -800, and -900 series airplanes identified as Group 1, Configuration 1, in the service bulletin\nThe "Rudder Main Power Control Unit Force Fight Monitor Test," the "Operational Test of the Standby Hydraulic Actuation System," and any applicable corrective action \nBoeing Alert Service Bulletin 737-27A1280, dated May 25, 2006.\n(iv) 737-600, -700, -700C, -800, and -900 series airplanes identified as Group 2 in the service bulletin\nThe "Rudder Main Power Control Unit Force Fight Monitor Test," and any applicable corrective action\nBoeing Alert Service Bulletin 737-27A1280, dated May 25, 2006.\n\t\n\n\t(2) At the applicable times listed in Table 3 of this AD, do the "Operational Test of the Standby Hydraulic Actuation System,'' and any applicable corrective action, until all applicable actions required by paragraph (g)(4) of this AD have been done in accordance with the applicable service bulletin specified in Table 4 of this AD. The actions must be done in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-27A1280, dated May 25, 2006. Do all applicable corrective actions before further flight. \n\n\tTable 3.--Repetitive Operational Tests forCertain Airplanes\n\n\nFor Model -\nOn which the input control rod of the standby rudder PCU -\nDo the "Operational Test of the Standby Hydraulic Actuation System" -\nAnd repeat the test at intervals not to exceed -\n(i) 737-600, -700, -700C, -800, and -900 series airplanes identified as Group 2 in the service bulletin \nHas not been replaced as required by paragraph (g)(4)(v) of this AD\nWithin 110 flight hours or 7 days after the effective date of this AD, whichever occurs later\n110 flight hours or 7 days, whichever occurs later\n(ii) 737-600, -700, -700C, -800, and -900 series airplanes identified as Group 2 in the service bulletin \nHas been replaced as required by paragraph (g)(4)(v) of this AD\nWithin 60 days after the effective date of this AD\n500 flight hours\n\n\t(3) As of the effective date of this AD, do not use the Master Minimum Equipment List Item 27-21, "STBY RUD ON light,'' until all applicable actions required by paragraph (g)(4) of this AD are done. \n\n\t(4) At the applicable time specified in Table 4 of this AD, do the replacement(s) and inspection, as applicable, specified in that table. Do all applicable corrective actions specified in Table 4 of this AD before further flight. Doing all applicable actions ends the requirements of paragraphs (g)(1) through (g)(3) of this AD. \n\n\tTable 4.--Replacement of Input Control Rods, Inspection, and Corrective Action, as Applicable \n\n\nFor Model -\nDo the following action(s) -\nIn accordance with -\nAnd do the replacement(s) and inspection, as applicable -\n(i) 737-100, -200, and -200C series airplanes identified as Groups 1 through 9, Configuration 3, in the service bulletin\nReplace both input control rods of the main rudder PCU with new input control rods\nPart 2 of the Accomplishment Instructions of Boeing Service Bulletin 737-27-1252, Revision 3, dated May 12, 2006\nWithin 24 months after the effective date of this AD\n(ii) 737-300, -400, and -500 series airplanes identified as Groups 1 through 19,Configuration 3, in the service bulletin\nReplace both input control rods of the main rudder PCU with new input control rods\nPart 2 of the Accomplishment Instructions of Boeing Service Bulletin 737-27-1255, Revision 3, dated May 10, 2006\nWithin 24 months after the effective date of this AD\n(iii) 737-600, -700, -700C, -800, and -900 series airplanes identified as Groups 1 through 20, Configuration 3, in the service bulletin\nReplace both input control rods of the main rudder PCU with new input control rods, inspect the input control rod of the standby rudder PCU to determine if part number (P/N) 251A3495-1 is installed, and do any corrective action\nPart 2 of the Accomplishment Instructions of Boeing Service Bulletin 737-27-1253, Revision 3, dated May 12, 2006\nWithin 24 months after the effective date of this AD\n(iv) 737-600, -700, -700C, -800, and -900 series airplanes identified as Group 1 in the service bulletin\nReplace both input control rods of the main rudder PCU with new input control rods\nThe Accomplishment Instructions of Boeing Alert Service Bulletin 737-27A1279, dated June 20, 2006\nWithin 24 months after the effective date of this AD\n(v) 737-600, -700, -700C, -800, and -900 series airplanes identified as Group 1 in the service bulletin\nReplace the input control rod of the standby rudder PCU with a new input control rod\nThe Accomplishment Instructions of Boeing Alert Service Bulletin 737-27A1279, dated June 20, 2006\nWithin 90 days after the effective date of this AD\n\nFor Certain Other Airplanes: Install New Rudder Control System Per Service Information \n\n\t(h) For airplanes on which the actions required by paragraph (f) of this AD have not been done before the effective date of this AD: As of the effective date of this AD, use the applicable service bulletin specified in Table 5 of this AD to do the actions required by paragraph (f) of this AD at the time specified in that paragraph. \n\n\tTable 5.--Service Bulletins for Installation of New Rudder Control \n\n\nFor Model -\nIdentified as -\nDo the actions required by paragraph (f) of this AD in accordance with -\n(1) 737-100, -200, and -200C series airplanes\nGroups 1 through 9, Configurations 1 and 2, in the service bulletin\nPart 1 of the Accomplishment Instructions of Boeing Service Bulletin 737-27-1252, Revision 3, dated May 12, 2006.\n(2) 737-300, -400, and -500 series airplanes\nGroups 1 through 19, Configurations 1 and 2, in the service bulletin\nPart 1 of the Accomplishment Instructions of Boeing Service Bulletin 737-27-1255, Revision 3, dated May 10, 2006.\n(3) 737-600, -700, -700C, -800, and -900 series airplanes\nGroups 1 through 20, Configurations 1 and 2, in the service bulletin\nPart 1 of the Accomplishment Instructions of Boeing Service Bulletin 737-27-1253, Revision 3, dated May 12, 2006.\n\n\n\t(i) Before or concurrently with the requirements of paragraph (h) of this AD, do the actions specified in Table 6 of this AD. \n\n\tTable 6.--Before/Concurrent Requirements\n\n\nBefore or concurrently with the actions specified in - \nDo these actions - \nIn accordance with the Accomplishment Instructions of - \n(1) Paragraph (h)(1) of this AD\n(i) Remove the rudder position sensor of the automatic flight control system\nBoeing Service Bulletin 737-22-1042, Revision 1, dated April 5, 1985.\n\n(ii) Replace the rudder feel and centering assembly with a new all-mechanical unit\nBoeing 737 Service Bulletin 27-1026, dated January 15, 1971.\n\n(iii) Install the rudder pressure reducer and yaw damper coupler\nBoeing Service Bulletin 737-27A1206, Revision 3, dated December 14, 2000.\n\n(iv) Install provisional wires for rudder system enhancement\nBoeing Service Bulletin 737-27-1246, Revision 1, including Appendix A, dated February 21, 2002.\n\n(v) Replace the P5-3 panel with a new panel\nBoeing Service Bulletin 737-27-1263, Revision 1, dated September 25, 2003.\n\n(vi) Replace the input lever for the auxiliary rudder power control package with a new inputlever\nSmiths Aerospace Actuation Systems Service Bulletin 1150-27-05A, dated August 28, 2003.\n(2) Paragraph (h)(2) of this AD\n(i) Install provisional wires for rudder system enhancement\nBoeing Service Bulletin 737-27-1246, Revision 1, including Appendix A, dated February 21, 2002.\n\n(ii) Replace the P5-3 panel with a new panel\nBoeing Service Bulletin 737-27-1264, Revision 1, dated April 3, 2003.\n\n(iii) Install a new yaw damper coupler\nBoeing Service Bulletin 737-27A1206, Revision 3, dated December 14, 2000.\n\n(iv) Inspect the trailing edge beam on the vertical fin and rework if necessary\nBoeing Service Bulletin 737-55-1052, Revision 1, dated August 5, 2004.\n\n(v) Replace the input lever for the auxiliary rudder power control package with a new input lever\nSmiths Aerospace Actuation Systems Service Bulletin 1150-27-05A, dated August 28, 2003.\n(3) Paragraph (h)(3) of this AD\n(i) Install provisional wires for rudder system enhancement\nBoeing Service Bulletin 737-27-1247, Revision 1, dated July 25, 2002.\n\n(ii) Replace the P5-3 panel with a new panel\nBoeing Service Bulletin 737-27-1262, dated December 19, 2002.\n\n(iii) Relocate the wire bundle routing in the vertical stabilizer\nBoeing Alert Service Bulletin 737-27A1239, dated January 11, 2001.\n \n\nParts Installation \n\n\t(j) As of the effective date of this AD, no person may install an input control rod, P/N 251A3495-1, on any airplane. \n\nAlternative Methods of Compliance (AMOCs) \n\n\t(k)(1) The Manager, Seattle ACO, FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19. \n\n\t(2) Before using any AMOC approved in accordance with Sec. 39.19 on any airplane to which the AMOC applies, notify the appropriate principal inspector in the FAA Flight Standards Certificate Holding District Office. \n\n\t(3) Except as provided by paragraph (j) of this AD: AMOCs approved previously in accordance with AD 2002-20-07 R1 are approved as AMOCs forthe corresponding provisions of paragraphs (f) and (h) of this AD. \n\nMaterial Incorporated by Reference \n\n\t(l) You must use the applicable service bulletin specified in Table 7 of this AD to perform the actions that are required by this AD, unless the AD specifies otherwise. Boeing Service Bulletin 737- 22-1042, Revision 1, dated April 5, 1985, contains the following effective pages: \n\n\nPage Nos. \nRevision level shown on page\nDate shown on page\n1-7, 9\n8\n1\nOriginal \nApril 5, 1985\nJuly 1, 1983\n\n\nThe Director of the Federal Register approved the incorporation by reference of these documents in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207, for a copy of this service information. You may review copies at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the National Archives and Records Administration (NARA). For information on the availabilityof this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal-register/cfr/ibr-locations.html . \n\n\tTable 7.--Material Incorporated by Reference\n\n\n\nService Bulletin\nRevision Level\nDate\nBoeing Alert Service Bulletin 737-27A1239\nOriginal\nJanuary 11, 2001\nBoeing Alert Service Bulletin 737-27A1279\nOriginal\nJune 20, 2006\nBoeing Alert Service Bulletin 737-27A1280\nOriginal\nMay 25, 2006\nBoeing Alert Service Bulletin 737-27A1281\nOriginal\nJune 14, 2006\nBoeing Service Bulletin 737-22-1042\n1\nApril 5, 1985\nBoeing Service Bulletin 737-27A1206\n3\nDecember 14, 2000\nBoeing Service Bulletin 737-27-1246, including Appendix A\n1\nFebruary 21, 2002\nBoeing Service Bulletin 737-27-1247\n1\nJuly 25, 2002\nBoeing Service Bulletin 737-27-1252\n3\nMay 12, 2006\nBoeing Service Bulletin 737-27-1253\n3\nMay 12, 2006\nBoeing Service Bulletin 737-27-1255\n3\nMay 10, 2006\nBoeing Service Bulletin 737-27-1262\nOriginal\nDecember 19, 2002\nBoeing Service Bulletin 737-27-1263\n1\nSeptember 25, 2003\nBoeing Service Bulletin 737-27-1264\n1\nApril 3, 2003\nBoeing Service Bulletin 737-55-1052\n1\nAugust 5, 2004\nBoeing 737 Service Bulletin 27-1026\nOriginal\nJanuary 15, 1971\nSmiths Aerospace Actuation Systems Service Bulletin 1150-27-05A\nOriginal\nAugust 28, 2003

Discussion \n\n\tThe FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that supersedes AD 2002-20-07 R1, amendment 39-12940 (67 FR 67518, November 6, 2002). The existing AD applies to all Boeing Model 737 airplanes. That NPRM was published in the Federal Register on November 15, 2006 (71 FR 66474). That NPRM proposed to continue to require installation of a new rudder control system and changes to the adjacent systems to accommodate that new rudder control system. For certain airplanes, that NPRM proposed to add, among other actions, repetitive tests of the force fight monitor of the main rudder power control unit (PCU), repetitive tests of the standby hydraulic actuation system, and corrective action; as applicable. For those airplanes, that NPRM also proposed to add, among other actions, replacement of both input control rods of the main rudder PCU and the input control rod of the standby rudder PCU with new inputcontrol rods, as applicable, which would end the repetitive tests. For certain other airplanes, that NPRM proposed to add installation of an enhanced rudder control system in accordance with new service information. \n\nActions Since NPRM Was Issued \n\n\tSince we issued the NPRM, we have received a report of a fractured rod end on the input control rod of the standby rudder PCU on a Model 737-700 series airplane. This condition was discovered during accomplishment of an operational test of the standby hydraulic actuation system in accordance with Boeing Alert Service Bulletin 737- 27A1280, dated May 25, 2006 (one of the actions specified in the NPRM). Investigation revealed that, although the input control rod had an existing crack of significant size, it ultimately fractured due to fatigue damage. Fatigue damage is caused by repetitive forces being applied (i.e., cyclic loading). \n\n\tThis finding of fatigue damage is not consistent with the results of our investigation that led to actions specified in the NPRM. The actions and compliance times specified in the NPRM were based on our finding that, while the input control rod may have been cracked during assembly, no significant loading was present to further degrade the integrity of the input control rod over time, causing it to fracture. \n\n\tTherefore, we have determined that, for certain Model 737-600, - 700, -700C, -800, and -900 series airplanes on which the suspect input control rod of the standby rudder PCU was installed during production, the compliance times for the following actions in the NPRM will not detect and correct failure of the input control rod of the standby rudder PCU in a timely manner: \n\n\tThe initial compliance time and repetitive intervals for the operational tests specified in paragraph (g)(1), and \n\n\tThe threshold for the replacement of the input control rod of the standby rudder PCU specified in paragraph (g)(3).\n \n\tFailure of one of the two input control rods of main rudder PCU,under certain conditions, could result in reduced controllability of the airplane; and failure of any combination of two input control rods of the main rudder PCU and/or standby rudder PCU could cause an uncommanded rudder hardover event and result in loss of control of the airplane. \n\nRelevant Service Information \n\n\tAs discussed in the "Relevant Service Information'' section of the NPRM, we have reviewed the following service information: \n\n\tRelevant Service Information \n\n\nService Bulletin\nRevision Level\nDate\nBoeing Alert Service Bulletin 737-27A1239\nOriginal\nJanuary 11, 2001\nBoeing Alert Service Bulletin 737-27A1279\nOriginal\nJune 20, 2006\nBoeing Alert Service Bulletin 737-27A1280\nOriginal\nMay 25, 2006\nBoeing Alert Service Bulletin 737-27A1281\nOriginal\nJune 14, 2006\nBoeing Service Bulletin 737-22-1042\n1\nApril 5, 1985\nBoeing Service Bulletin 737-27A1206\n3\nDecember 14, 2000\nBoeing Service Bulletin 737-27-1246, including Appendix A\n1\nFebruary 21, 2002\nBoeing Service Bulletin 737-27-1247\n1\nJuly 25, 2002\nBoeing Service Bulletin 737-27-1252\n3\nMay 12, 2006\nBoeing Service Bulletin 737-27-1253\n3\nMay 12, 2006\nBoeing Service Bulletin 737-27-1255\n3\nMay 10, 2006\nBoeing Service Bulletin 737-27-1262\nOriginal\nDecember 19, 2002\nBoeing Service Bulletin 737-27-1263\n1\nSeptember 25, 2003\nBoeing Service Bulletin 737-27-1264\n1\nApril 3, 2003\nBoeing Service Bulletin 737-55-1052\n1\nAugust 5, 2004\nBoeing 737 Service Bulletin 27-1026\nOriginal\nJanuary 15, 1971\nSmiths Aerospace Actuation Systems Service Bulletin 1150-27-05A\nOriginal\nAugust 28, 2003\n\n\n\tAccomplishing the actions specified in the service information is intended to adequately address the unsafe condition. \n\nComments \n\n\tWe provided the public the opportunity to submit comments regarding the NPRM and have considered the comments that have been received. \n\nSupport for the NPRM \n\n\tThe Air Line Pilots Association and Boeing support the NPRM. \n\nRequests To Issue Stand Alone AD \n\n\tDelta and Southwest Airlines request that we issue a stand alone AD that addresses the control rod issues only instead of superseding AD 2002-20-07 R1. Delta states that a stand alone AD will minimize the amount of revisions to engineering authorizations (EAs). Delta points out that a supersedure AD would result in their revising four EAs whereas a stand alone AD would result in revising only one EA. Southwest Airlines states that a stand alone AD would be more cost effective because a supersedure AD results in document revision, record keeping, and computer tracking issues. \n\n\tWe do not agree. As explained in the "Actions Since Existing AD Was Issued'' section of the NPRM, we have received a report of a fractured rod end on one of the two input control rods of the main rudder PCU on a Model 737-800 series airplane. The incident airplane had been modified to comply with the requirements of AD 2002-20-07 R1. We determined that accomplishment of the actions required by AD 2002- 20-07 R1 introduces a new unsafe condition (i.e., failure of the input control rods of the rudder control system, which, under certain conditions, could result in reduced controllability of the airplane and/or loss of control of the airplane), and that a substantive change to that AD was necessary. \n\n\tOur current policy specifies that, whenever a substantive change is made to an existing AD that imposes a new burden, we must supersede the AD. Substantive changes are those made to any instruction or reference that affects the substance of the AD. Substantive changes include part numbers, service bulletin and manual references, compliance times, applicability, methods of compliance, corrective action, inspection requirements, and effective dates. We consider the changes to the existing AD to be substantive. This superseding AD is assigned a new amendment number and new AD number, and the previous amendment is removed from the system. This procedure facilitates the efforts ofprincipal maintenance inspectors in tracking ADs and ensuring that affected operators have incorporated the most recent changes into their maintenance programs. \n\n\tWith regard to paperwork changes required by affected operators, Sec. 121.380(a)(2)(vi) ("Maintenance recording requirements'') of the Federal Aviation Regulations (14 CFR 121.380(a)(2)(vi)), requires that persons holding an operating certificate and operating under part 121 of the Federal Aviation Regulations must keep "The current status of applicable airworthiness directives, including the date and methods of compliance * * *.'' Whether an existing AD is superseded or a new stand alone AD is issued, the new AD is assigned a new AD number. In either case, the new AD is identified by its "new'' AD number. In light of this, affected operators updating their maintenance records to indicate the current AD status would have to record a new AD number in both cases. Further, operators are always given credit for work previously performed according to the existing AD by means of the phrase in the compliance section of the AD that states, "* * * unless the actions have already been done.'' Therefore, we have determined that a supersedure AD is appropriate. \n\nRequest To Supersede Other ADs \n\n\tIf the AD does supersede AD 2002-20-07 R1, Southwest Airlines requests that the AD also supersede the following ADs: \n\n\tAD 95-06-53, amendment 39-9199 (60 FR 18981, April 14, 1995); \n\n\tAD 97-05-10, amendment 39-9954 (62 FR 9679, March 4, 1997); and \n\n\tAD 98-02-01, amendment 39-10283 (63 FR 1903, January 13, 1998). \n\n\tSouthwest Airlines states that these additional ADs were all listed in AD 2002-20-07 R1. Southwest Airlines states that if these changes are not made, operators will be required to report the status of obsolete ADs. \n\n\tWe do not agree. AD 2002-20-07 R1 revises AD 2002-20-07, amendment 39-12903 (67 FR 62341, October 7, 2002), and supersedes ADs 95-06-53, 97-05-10, and 98-02-01. As of November 12, 2002 (the effective date of AD 2002-20-07 R1), those ADs were effectively superseded (cancelled) and thus no further action is required in regard to those ADs. \n\nRequest To Change List of Affected ADs \n\n\tSouthwest Airlines also requests that AD 97-14-04, amendment 39- 10061 (62 FR 35068, June 30, 1997), be added to the list of ADs in Table 1 of the NPRM.\n \n\tWe agree. Our intent was to retain all requirements of AD 2002-20- 07 R1. AD 97-14-04 was included in paragraph (b) of AD 2002-20-07 R1. However, we inadvertently omitted it from Table 1 in paragraph (b) of the NPRM. Doing the action required by paragraph (f) or (h) of this AD ends the requirements of AD 97-14-04 and the other ADs identified in Table 1 of this AD. We have revised Table 1 accordingly. \n\nRequest To Revise the Applicability \n\n\tSouthwest Airlines requests that the applicability of the NPRM be revised to affect Model 737-600, -700, -700C, -800 and -900 series airplanes (i.e., 737 next generation airplanes), line numbers 1 through 1947 only (no change requested for affected Model 737-100 through -500 series airplanes). Southwest Airlines states that the effectivity of Boeing Alert Service Bulletin 737-27A1279, dated June 20, 2006; and Boeing Alert Service Bulletin 737-27A1280, dated May 25, 2006; indicate that 737 next generation airplanes with line numbers 1948 or higher have an enhanced rudder control system with the improved rods already installed. Southwest Airlines also states that it is a hardship to require AD reporting on airplanes that have been modified in production. \n\n\tWe do not agree with Southwest Airlines to exclude airplanes on which an enhanced rudder control system with new input control rods has been installed in production from the applicability of this AD. Paragraph (j) of this AD states, "As of the effective date of this AD, no person may install an input control rod, P/N 251A3495-1, on any airplane.'' All Model 737 airplanes, including those in production now and inthe future, are subject to this requirement. Therefore, we have determined that the applicability of the AD is correct as proposed. \n\nRequest To Exclude Certain Airplanes From Paragraph (g) of the NPRM \n\n\tSouthwest Airlines requests that paragraph (g) be revised to exclude airplanes for which maintenance records can conclusively show that the suspect rods have not been installed. Southwest Airlines states that some airplanes have had control rods replaced or modified with the latest kits. \n\n\tWe partially agree. We agree with Southwest Airlines that no further work is required by paragraph (g) for airplanes on which the input control rods have been replaced in accordance with paragraph (g)(4) of this AD. We also find that no further work is required by paragraph (h) for airplanes on which the input control rods have been installed in accordance with paragraph (h) of this AD. We have determined that those actions adequately address the identified unsafe condition of this AD related to the input control rods. However, we do not agree to revise this AD. Operators are given credit for work previously done by the means of the phrase in the "Compliance'' section of the AD that states, "* * * unless the actions have already been done.'' Therefore, in the case of this AD, if the actions required by paragraph (g)(4) or (h) of this AD (i.e., replacement of input control rods or installation of a new rudder control system) have been done in accordance with the service information identified in Table 4 or 5 of this AD, respectively, before the effective date of this AD, this AD does not require those actions to be repeated. \n\nRequest To Delete Reference to Certain Group Configurations \n\n\tAirTran Airways supports the proposed actions described in the NPRM, but points out a discrepancy between the NPRM and a referenced service bulletin. AirTran Airways notes that paragraph (g)(1)(iii) of the NPRM is applicable to airplanes identified as Group 1, Configuration 1, and Group 2, Configurations 1 and 2, in Boeing Alert Service Bulletin 737-27A1280, dated May 25, 2006. AirTran Airways states that the service bulletin does not contain any configurations for Group 2. \n\n\tFrom this comment, we infer that AirTran Airways is requesting that we delete the reference to Configurations 1 and 2 for Group 2 specified in paragraphs (g)(1)(iv), (g)(2)(i), and (g)(2)(ii) of this AD (paragraph (g)(1)(iii) in the NPRM). We agree and have revised this AD accordingly. \n\nRequest To Delete Concurrent Requirements \n\n\tSouthwest Airlines states that it is impossible to install the enhanced rudder system without doing the concurrent requirements in paragraph (i) of the NPRM. Southwest Airlines notes that each of the service bulletins identified in Table 5 of the NPRM, except "(Boeing) (S)ervice (B)ulletin 737-55-1042,'' is listed in the initial release of the primary service bulletins identified in Table 4 of the NPRM. Southwest Airlines believes it is impossible to trim thespar as illustrated in the primary service bulletins unless the trim was previously accomplished per "(Boeing) (S)ervice (B)ulletin 737-55- 1042.'' Southwest Airlines also believes that the NPRM validates this by not requiring rework other than for the discrepant control rods. \n\n\tFrom this comment, we infer that Southwest Airlines is requesting that the concurrent requirements specified in paragraph (i) of the NPRM be deleted. Since Boeing Service Bulletin 737-55-1042 describes procedures unrelated to the subject of this AD, we also infer that Southwest Airlines meant to refer to Boeing Service Bulletin 737-55- 1052, Revision 1, dated August 5, 2004 (referred to in paragraph (i)(2)(iv) of this AD as a concurrent requirement). We do not agree with Southwest Airlines to delete the concurrent requirements of this AD. Our current policy specifies that service information must be "published'' (i.e., incorporation by reference (IBR)) if the AD mandates a method of compliance that is contained only in the referenced service information. As in the case of this AD, the concurrent requirement actions specified in Table 6 of the AD are contained only in the service information identified in that table, not in the primary service information identified in Table 5 of this AD. Therefore, we have made no change to this AD in this regard. \n\nFAA's Determination and Requirements of This AD \n\n\tThe unsafe condition described previously is likely to exist or develop on other airplanes of the same type design. For this reason, we are issuing this AD to supersede AD 2002-20-07 R1. This AD supersedes AD 2002-20-07 R1 and retains the requirements of the existing AD. This AD also requires accomplishing the actions specified in the applicable service information identified previously, except as discussed under "Differences Between the AD and Certain Service Information.'' For certain airplanes, this AD also requires suspending a certain Master Minimum Equipment List item, until all improperly heat-treated input control rods are replaced. \n\nDifferences Between the AD and Certain Service Information \n\n\tFor certain Model 737-600, -700, -700C, -800, and -900 series airplanes on which the suspect input control rod of the standby rudder PCU was installed during production, the compliance times for the following actions required by this AD are different (i.e., shorter intervals) than those specified in Boeing Alert Service Bulletin 737- 27A1279, dated June 20, 2006; and Boeing Alert Service Bulletin 737- 27A1280, dated May 25, 2006: \n\n\tFor the operational tests of the standby hydraulic actuation system: This AD specifies an initial compliance time of within 110 flight hours or 7 days after the effective date of this AD, whichever occurs later, and repetitive intervals of 110 flight hours or 7 days, whichever occurs later, whereas Boeing Alert Service Bulletin 737-27A1280 specifies an initial compliance time of within 60 days and repetitive intervals of 500 flight hours. \n\n\tFor the replacement of the input control rod of the standby rudder PCU: This AD specifies a compliance time of within 90 days after the effective date of this AD whereas Boeing Alert Service Bulletin 737-27A1279 specifies a compliance time of 24 months. \n\n\tAs discussed previously in the "Discussion'' section of this AD, the proposed compliance times for these actions may not detect and correct failure of the input control rod of the standby rudder PCU in a timely manner. While we do not yet have data on the growth rate of these cracks, we believe the revised compliance times described previously are adequate to ensure safety without imposing undue burdens on air commerce. In developing appropriate compliance times for these actions in this AD, we considered the safety implications, parts availability, and normal maintenance schedules for the timely accomplishment of the operational tests and replacements. In consideration of these items, as well as the reported failures of the input control rods in service, we have determined that the compliance times in this AD will ensure an acceptable level of safety and allow the actions to be done during scheduled maintenance intervals for most affected operators. \n\nChanges to NPRM \n\n\tAs a result of the differences between the AD and certain service information described previously, we have revised the applicable compliance times in this AD and changed certain paragraph identifiers and tables and added others. \n\n\tIn certain places in the NPRM, we referred to the incorrect year of the issuance date of Boeing Alert Service Bulletin 737-27A1280. The correct issuance date is May 25, 2006, not May 25, 2005. We have corrected this error in this AD. \n\nFAA's Determination of the Effective Date \n\n\tRegarding the reduced compliance times described previously, an unsafe condition exists that requires the immediate adoption of this AD; therefore, providing notice and opportunity for public comment before the AD is issued is impracticable, and good cause exists to make this AD effective in less than 30 days. \n\nComments Invited \n\n\tRegarding the reduced compliance times described previously, this AD is a final rule that involves requirements that affect flight safety and was not \npreceded by notice and an opportunity for public comment; however, we invite you to submit any relevant written data, views, or arguments regarding this AD. Send your comments to an address listed in the ADDRESSES section. Include "Docket No. FAA-2006-26323; Directorate Identifier 2006-NM-150-AD'' at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the AD that might suggest a need to modify it. \n\n\tWe will post all comments we receive, without change, to http://lldms.dot.gov , including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this AD. Using the search function of that Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov. \n\nExamining the Docket \n\n\tYou may examine the AD docket on the Internet at http://dms.dot.gov , or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647- 5227) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the Docket Management System receives them. \n\nAuthority for This Rulemaking \n\n\tTitle 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority. \n\n\tWe are issuing this rulemaking under the authority described in subtitle VII, part A, subpart III, section 44701, "General requirements.'' Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action. \n\nRegulatory Findings \n\n\tWe have determined that this AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. \n\n\tFor the reasons discussed above, I certify that the regulation: \n\n\t1. Is not a "significant regulatory action'' under Executive Order 12866; \n\n\t2. Is not a "significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and \n\n\t3. Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. \n\n\tWe prepared a regulatory evaluation of the estimated costs to comply with this AD and placed it in the AD docket. See the ADDRESSES section for a location to examine the regulatory evaluation. \n\nList of Subjects in 14 CFR Part 39 \n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. \n\nAdoption of the Amendment \n\nAccordingly, under the authority delegated to me by the Administrator, the FAA amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows: \n\nPART 39--AIRWORTHINESS DIRECTIVES \n\n1. The authority citation for part 39 continues to read as follows: \n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\nSec. 39.13 (Amended) \n\n2. The Federal Aviation Administration (FAA) amends Sec. 39.13 by removing amendment 39-12940 (67 FR 67518, November 6, 2002) and adding the following new airworthiness directive (AD):