On September 27, 2002, the FAA issued AD 2002-20-07, amendment 39-12903 (67 FR 62341, October 7, 2002), applicable to all Boeing Model 737 series airplanes, to require installation of a new rudder control system and changes to the adjacent systems to accommodate that new rudder control system. That action was prompted by FAA determinations that the existing system design architecture is unsafe due to inherent failure modes, including single- jam modes and certain latent failures or jams, which, when combined with a second failure or jam, could cause an uncommanded rudder hardover event and consequent loss of control of the airplane. Additionally, the current rudder operational procedure is not effective throughout the entire flight envelope. The actions required by that AD are intended to prevent the identified unsafe condition. \n\nActions Since Issuance of Previous Rule \n\n\tAD 2002-20-07 would have superseded seven existing ADs. However, since the issuanceof that AD, the FAA finds that only three of those ADs should have been superseded. By superseding the other four ADs, we inadvertently eliminated the requirements of those four ADs as of the effective date of AD 2002-20-07, instead of upon accomplishment of the actions required by that AD. We find that retaining the requirements of those four ADs is necessary to maintain the current level of safety until the requirements of this new AD are accomplished. This finding does not impose any additional burden on any operator because the requirements of those four ADs already exist. \n\n\tThe requirements of the following four ADs remain in effect until installation of the new rudder control system and corresponding changes to the adjacent systems: \n\nAD 97-09-15 R1, amendment 39-10912 (63 FR 64857, November 24, 1998), applies to all Boeing Model 737-100, -200, -300, -400, and - 500 series airplanes. That AD requires a one-time inspection of the engage solenoid valve of the yaw damper on the rudder power control unit (PCU) to determine the part number (P/N) of the valve, and replacement of certain valves with specified P/Ns if necessary. Retaining this requirement will ensure that the appropriate engage solenoid valve is installed on the rudder PCU of all affected airplanes until accomplishment of this new AD. \n\nAD 97-14-04, amendment 39-10061 (62 FR 35068, June 30, 1997), applies to all Boeing Model 737-100, -200, -300, -400, and -500 series airplanes. That AD requires tests of the main rudder PCU to detect excessive internal leakage of hydraulic fluid, stalling, or reversal, and to verify proper operation of the PCU; and replacement of the PCU with a unit having a different part number if necessary. That AD also requires replacement of the PCU and the vernier control rod bolts with newly designed units, leak tests of the PCU, and replacement of the PCU with a serviceable or newly designed unit if necessary. Retaining these requirements will ensure that the appropriate vernier control rod bolts and main rudder PCU are installed and properly maintained until accomplishment of this new AD. \n\nAD 99-11-05, amendment 39-11175 (64 FR 27905, May 24, 1999). A correction of that AD was published in the Federal Register on December 13, 1999 (64 FR 69392). That AD applies to all Boeing Model 737 series airplanes, and requires repetitive displacement tests of the secondary slide in the dual concentric servo valve of the PCU for the rudder, and replacement of the valve assembly with a modified valve assembly if necessary. Retaining these requirements will ensure that the repetitive displacement tests will continue to be performed until accomplishment of this new AD. \n\n\tThe AD number and Federal Register citation for AD 99-11-05 appeared incorrectly in AD 2002-20-07. This information is specified correctly in the preceding paragraph. \n\nAD 2000-22-02, amendment 39-11948 (65 FR 64134, October 26, 2000). A correction of that AD was published in the Federal Register on November 16, 2000 (65 FR 69239), as AD 2000-22-02 R1, which applies to all Boeing Model 737 series airplanes. Those ADs require revising an FAA-approved Airplane Flight Manual (AFM) procedure to simplify the instructions for correcting a jammed or restricted flight control condition. Retaining this AFM change will ensure that the flightcrew continues to be advised of the procedures necessary to address a condition involving a jammed or restricted rudder until accomplishment of this new AD. \n\n\nExplanation of Requirements of Rule \n\n\tSince an unsafe condition has been identified that is likely to exist or develop on other airplanes of this same type design, this new AD revises AD 2002-20-07, which would have superseded seven existing ADs. This new AD continues to require installation of a new rudder control system and changes to the adjacent systems to accommodate that new rudder control system. This new AD also removes any reference to superseding four of those seven existing ADs. \n\n\tParagraph (b) of this AD specifies that installation of a new rudder control system and changes to the adjacent systems to accommodate that new rudder control system terminates the requirements of ADs 97-09-15 R1, 97-14-04, 99-11-05, and 2000-22-02 R1. \n\nDetermination of Rule's Effective Date \n\n\tSince a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days. \n\nComments Invited \n\n\tAlthough this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number andbe submitted in triplicate to the address specified under the caption ADDRESSES. All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed. \n\n\tSubmit comments using the following format: \n\nOrganize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues. \n\nFor each issue, state what specific change to the AD is being requested. \n\nInclude justification (e.g., reasons or data) for each request. \n\n\tComments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All commentssubmitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket. \n\n\tCommenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made:"Comments to Docket Number 2001-NM-251-AD." The postcard will be date stamped and returned to the commenter. \n\nRegulatory Impact \n\n\tThe regulations adopted herein 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. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132. \n\n\tThe FAA has determined that thisregulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a"significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption ADDRESSES. \n\nList of Subjects in 14 CFR Part 39 \n\n\tAir transportation, Aircraft, Aviation safety, Safety. \n\nAdoption of the Amendment \n\n\tAccordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows: \n\nPART 39--AIRWORTHINESS DIRECTIVES \n\n\t1. The authority citation for part 39 continues to read as follows: \n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\n§ 39.13 (Amended) \n\n\t2. Section 39.13 is amended by removing amendment 39-9199 (60 FR 18981, April 14, 1995); amendment 39-9954 (62 FR 9679, March 4, 1997); and amendment 39-10283 (63 FR 1903, January 13, 1998); and by adding a new airworthiness directive (AD), amendment 39-12940, to read as follows: