Discussion \n\n\n\tWe issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain Bombardier, Inc. Model DHC-8-400 series airplanes. The NPRM published in the Federal Register on January 23, 2015 (80 FR 3504). \n\tThe Transport Canada Civil Aviation (TCCA), which is the aviation authority for Canada, has issued Canadian Airworthiness Directive CF- 2013-38, dated November 28, 2013 (referred to after this as the Mandatory Continuing Airworthiness Information, or ''the MCAI''), to correct an unsafe condition for certain Bombardier, Inc. Model DHC-8- 400, -401, and -402 series airplanes. The MCAI states: \n\n\n\tThere has been one in-service report of an un-commanded and un- annunciated nose wheel steering during aeroplane push-back from the gate. The investigation revealed that a design deficiency exists within the steering control unit (SCU) where an open circuit may not be adequately detected and annunciated to the flight crew. A sustained open circuit could result in an un-commanded and un- annunciated nose wheel steering input. \n\tUn-commanded nose wheel steering during takeoff or landing may lead to a runway excursion. \n\tThis (Canadian) AD mandates the installation of new cable assemblies, with a pull-down resistor, to ensure that the nose wheel steering system reverts to fail-safe free castor mode in the event of an open circuit in the steering system. \n\n\n\tYou may examine the MCAI in the AD docket on the Internet at http://www.regulations.gov/#!documentDetail;D=FAA-2014-1050-0002. \n\nComments \n\n\n\tWe gave the public the opportunity to participate in developing this AD. The following presents the comment received on the NPRM (80 FR 3504, January 23, 2015) and the FAA's response to each comment. \n\nRequest To Remove Certain Service Information Procedures \n\n\n\tHorizon Air requested that we amend paragraph (g) of the proposed AD (80 FR 3504, January 23, 2015) to exclude Part A, ''Job Set-up,'' and Part C ''Close Out,'' sections of the Accomplishment Instructions in Bombardier Service \n\n((Page 51460)) \n\nBulletin 84-32-122, Revision A, dated August 28, 2013 Horizon Air stated that Part A, ''Job Set-up,'' and Part C, ''Close Out,'' do not directly correct the unsafe condition. Horizon Air explained that requiring operators to perform the actions in these sections in a specific manner restricts the operator's ability to perform other maintenance in conjunction with performing the corrective action. \n\tWe agree with the commenter's request to exclude the ''Job Set-up'' and ''Close Out'' sections of the Accomplishment Instructions of Bombardier Service Bulletin 84-32-122, Revision A, dated August 28, 2013. We have revised paragraph (g) of this AD to require accomplishment of only paragraph B., ''Procedure,'' of the Accomplishment Instructions of Bombardier Service Bulletin 84-32-122, Revision A, dated October 4, 2013. \n\nConclusion \n\n\n\tWe reviewed the relevant data, considered the comment received, and determined that air safety and the public interest require adopting this AD with the change described previously and minor editorial changes. We have determined that these minor changes: \n\tAre consistent with the intent that was proposed in the NPRM (80 FR 3504, January 23, 2015) for correcting the unsafe condition; and \n\tDo not add any additional burden upon the public than was already proposed in the NPRM (80 FR 3504, January 23, 2015). \n\tWe also determined that these changes will not increase the economic burden on any operator or increase the scope of this AD. \n\nRelated Service Information Under 1 CFR Part 51 \n\n\n\tBombardier, Inc. has issued Service Bulletin 84-32-122, Revision A, dated October 4, 2013. This service information describes procedures for incorporating Bombardier Modification Summary (Modsum) 4-126585 to install new cable assemblies with a pull-down resistor to the pilot hand control and rudder pedal potentiometer of the nose wheel steering control unit. This service information is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section of this AD. \n\nCosts of Compliance \n\n\n\tWe estimate that this AD affects 81 airplanes of U.S. registry. \n\tWe also estimate that it will take about 6 work-hours per product to comply with the basic requirements of this AD. The average labor rate is $85 per work-hour. Required parts will cost about $2,541 per product. Based on these figures, we estimate the cost of this AD on U.S. operators to be $247,131, or $3,051 per product. \n\nAuthority for This Rulemaking \n\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\tWe are issuingthis 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\n\tWe 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\tFor the reasons discussed above, I certify that this AD: \n\t1. Is not a ''significant regulatory action''under Executive Order 12866; \n\t2. Is not a ''significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); \n\t3. Will not affect intrastate aviation in Alaska; and \n\t4. 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\nExamining the AD Docket \n\n\n\tYou may examine the AD docket on the Internet at http://www.regulations.gov/#!documentDetail;D=FAA-2014-1050; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (telephone 800-647-5527) is in the ADDRESSES section. \n\nList of Subjects in 14 CFR Part 39 \n\n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.