Discussion \n\n\tOn July 24, 2006, we issued a proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to all RAC Beech Models 45 (YT-34), A45 (T-34A, B45), and D45 (T-34B) airplanes. That proposal was published in the Federal Register as a notice of proposed rulemaking (NPRM) on July 31, 2006 (71 FR 43075). The NPRM proposed to supersede AD 62-24-01 with a new AD that would retain the actions required in AD 62-24-01 and only change the inspection procedure from the dye penetrant method to the surface eddy current method. \n\nComments \n\n\tWe provided the public the opportunity to participate in developing this AD. The following presents the comments received on the proposal and FAA's response to each comment: \n\nComment Issue No. 1: Change the Compliance Time for the Initial Inspection \n\n\tLarry Bierma, Joe Enzminger, John Aldous, Michael Vadeboncoeur, John Rippinger, William E. Mayher, Dan Thomas, and Victor Barrett state that the inspection compliance in the proposed AD is a duplication of the inspection for those who have done the eddy current inspection recently as part of compliance with an alternative method of compliance (AMOC) to AD 2004-25-51. \n\n\tThe commenters state that requiring another eddy current inspection within 6 months after the effective date of this AD would be unnecessary and economically burdensome for those who have already done it. The commenters request credit for the last inspection done in compliance with an AMOC to AD 2004-25-51 as compliance for the initial inspection required in the proposed AD. \n\n\tWe have rewritten the compliance time to give full credit for previously accomplished eddy current inspections done in the area affected by this AD. \n\nComment Issue No. 2: AD Is Not Necessary \n\n\tMichael Vadeboncoeur, John Aldous, Mike Talbot, Eric Evans, Earle Parks, Floyd Stilwell, Dan Thomas, Stephen Baksa, William Beitler, and Terrance Brennan state that, since the time AD 62-24-01 was issued, there have not been any accidents as a result of cracks in the horizontal stabilizer. The commenters request the proposed AD be withdrawn. \n\n\tThe commenters also request that stabilizer spars modified by Parks Industries supplemental type certificate (STC) either be exempt from the inspections or the inspection interval be increased to 1,000 hours TIS. \n\n\tWe do not agree with the commenters. In 2005, 148 of the affected airplanes were eddy current inspected. Cracks in the stabilizer spars and/or spar webs were found on 6 of these airplanes, which required the spars to be replaced. If no eddy current inspections had been done, those cracks may have grown and reached critical crack lengths, which could have compromised the integrity of the spar structure. \n\n\tIn order to increase the inspection interval or eliminate the spar inspections, we need supporting engineering analysis data regarding fatigue life, crack growth rate, etc. We have not received such data for the spars modified by the Parks Industries STC. \n\n\tIf we receive engineering analysis data that supports increasing the inspection intervals or eliminating the inspections, we may take additional rulemaking action at that time. \n\n\tWe are not changing the final rule AD action based on these comments. \n\nComment Issue No. 3: Retain the Dye Penetrant Inspection From AD 62-24- 01 \n\n\tFloyd Stilwell, Earle Parks, and Terrance Brennan state that the surface eddy current inspection is expensive and inconvenient. Qualified technicians to do the surface eddy current inspections have to be brought to the repair station from other parts of the country, which contributes to the expense of doing the eddy current inspection. The commenters request retaining the dye penetrant inspection. \n\n\tWe do not agree with the commenters. AD 2001-13-18 R1 currently requires owners/operators of all Beech Models 45 (YT-34), A45 (T-34A, B-45), and D45 (T-34B) airplanes to do repetitive 80-hour TIS eddy current inspections of the wing spar assemblies and other components following Raytheon Aircraft Mandatory Service Bulletin No. SB 57-3329, Part II, Page 3/65, Issued: February, 2000. If the wing spar and stabilizer spar inspections are properly planned, these two inspections could be done at the same time. This planning would eliminate any extra expenses. \n\n\tWe have reason to believe that damage tolerance analysis of the stabilizer spar is being conducted by some owners. This may result in additional rulemaking action that could eliminate the inspection or increase the inspection interval. Until that time, AMOCs for this AD may be approved, if requested using the procedures found in 14 CFR 39.19. \n\n\tWe are not changing the final rule AD action based on these comments. \n\nComment Issue No. 4: Surface Eddy Current Inspection Method Unwarranted \n\n\tDan Thomas, William Beitler, Floyd Stilwell, William Mayher, and Mike Talbot state that the eddy currentinspection method is no better than the dye penetrant method for detecting cracks. The level of safety will not be enhanced by changing the inspection methods. Further, the eddy current method could produce false positives and the frequent inspections could also incur damage to the stabilizer spar. The commenters request the method of inspection be at the owner's/ operator's option. \n\n\tWe do not agree with the commenters. The eddy current inspection method is a more sensitive inspection process. The dye penetrant inspection method at times could completely miss detecting the cracks. \n\n\tAll inspection methods have some inherent drawbacks. Eddy current inspection methods detect small surface cracks better than dye penetrant methods, and eddy current inspection methods are also capable of detecting subsurface cracks. Detection of cracks early is a definite advantage. Eddy current inspection methods could occasionally produce false positives; however, this could be avoided if cracks are confirmed by repeatable flaw indications. \n\n\tIf the inspections required by this AD are carefully done by qualified technicians, any damage to the spars could be prevented. \n\n\tThe 500-hour TIS repetitive inspection interval is a long interval between inspections for this type of airplane, which normally will take place once in 5 years or longer in most cases; therefore, we do not consider this inspection requirement as frequent. \n\n\tWe are not changing the final rule AD action based on this comment. \n\nConclusion \n\n\tWe have carefully reviewed the available data and determined that air safety and the public interest require adopting the AD as proposed except for minor editorial corrections. We have determined that these minor corrections: \n\n\tAre consistent with the intent that was proposed in the NPRM for correcting the unsafe condition; and \n\n\tDo not add any additional burden upon the public than was already proposed in the NPRM. \n\nCosts of Compliance \n\n\tWe estimate that this AD affects 475 airplanes in the U.S. registry. \n\n\tWe estimate the following costs to accomplish each inspection: \n\n\nLabor Cost\nParts Cost\nTotal Cost Per Airplane\nTotal Cost on U.S. Operators\n8 work-hours X $80 per hour = $640\nNot applicable\n$640\n$304,000\n\n\n\tWe estimate the following costs to do any necessary horizontal stabilizer replacements that will be required based on the results of the inspection. We have no way of determining the number of airplanes that may need this replacement: \n\n\nLabor Cost\nParts Cost\nTotal Cost Per Airplane\n4 work-hours X $80 per hour = $320\n$3,500\n $3,820\n\nCost Difference Between This AD and AD 62-24-01 \n\n\tThe only difference between this AD and AD 62-24-01 is the change of inspection method. There may be some minimal additional cost involved in doing the eddy current inspection because of possible equipment rentals necessary. No additional actions are being required. We have determined that this AD action does not increase the cost impact over that already required by AD 62-24-01. \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 AD. \n\nRegulatory Findings \n\n\tWe have determined that this AD will not have federalismimplications 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 this AD: \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 summary of the costs to comply with this AD (and other information as included in the Regulatory Evaluation) and placed it in the AD Docket. You may get a copy of this summary by sending a request to us at the address listed under ADDRESSES. Include "Docket No. FAA-2006-25105;Directorate Identifier 2006-CE-33-AD'' in your request. \n\nList of Subjects in 14 CFR Part 39 \n\n\tAir transportation, Aircraft, Aviation safety, Safety. \n\nAdoption of the Amendment \n\nAccordingly, under 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\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 FAA amends Sec. 39.13 by removing Airworthiness Directive (AD) 62-24-01, Amendment 39-508, and adding the following new AD: