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in a subcritical configuration providing in the dry storage cask, there would be a slow boron dilution event would not result in reasonable assurance that excessive fuel boron dilution event, a slow approach to elevated fuel temperature and subsequent cladding temperatures and subsequent fuel criticality, and indication of an accidental fuel damage. Therefore, for a slow boron damage would not occur. criticality from the required criticality dilution event, there is no benefit to the The third scenario involves those dry monitors. As such, this case would be very additional criticality analysis. The NRC storage casks that would remain filled with similar to the unintentional dilution case further determined that the probability of borated water. The possibility exists for a described above. having a rapid drain down event result in licensee to cause a boron dilution event in In the fourth scenario, the NRC assumed elevated fuel temperatures and subsequent the dry storage cask when spraying the fuel that the licensee was able to repair the fuel damage was highly unlikely. Based on stored in the SFP racks. The location of the damage to the SFP and reflood the pool. In its analysis, the NRC concludes there is no dry storage cask might be close enough to the this scenario as the licensee reflooded the safety benefit from requiring a licensee to SFP storage racks that it could inadvertently SFP the dry storage cask would either reflood conduct a site specific analysis in support of be sprayed at the same time as the SFP racks, as the SFP was filled (for those casks with storage cask loading, fuel storage, or overfilling the dry storage cask, and drain ports at the bottom); if the cask had unloading activities and that the proposed eventually diluting the boron. Under these dried out it would reflood once the water rule change is therefore acceptable. conditions, the boron concentration would level in the SFP reached the top of the cask slowly decrease and this scenario becomes and water began spilling into the cask; or if [FR Doc. E6–19372 Filed 11–15–06; 8:45 am] very similar to a slow boron dilution event the cask remained flooded following the BILLING CODE 7590–01–P as discussed previously. The criticality rapid drain down event, there would be a monitors required for dry cask loading would slow dilution of the boron in the water in the still be available and would provide cask as the SFP level continued to rise. In DEPARTMENT OF TRANSPORTATION indication of an accidental criticality. With each of these cases, as the cask was filled indication of an accidental criticality, it is with water or as the boron dilution of the Federal Aviation Administration reasonable to assume that the licensee would water in the cask occurred, the possibility take action to stop the boron dilution from increases that an accidental criticality might continuing and restore the dry storage cask occur. However, because of the relatively 14 CFR Part 39 to a subcritical configuration. slow reactivity addition that would occur [Docket No. FAA–2006–23734; Directorate Actions the licensee could take to return during each of these cases, the approach to Identifier 2005–NM–174–AD; Amendment the dry storage cask to a subcritical criticality would be reasonably slow. As 39–14827; AD 2006–23–15] configuration could include: noted previously, the licensee is required to 1. Stop spraying unborated water into the have criticality monitors in place during dry RIN 2120–AA64 dry storage cask and allow the water in the storage cask loading (or unloading) activities. cask to heat up with a subsequent reduction These criticality monitors would provide Airworthiness Directives; Boeing in the moderation provided by the water that indication that an accidental criticality had Model 757 Airplanes would eventually re-establish a subcritical occurred. Once identified, it is reasonable configuration at a higher water temperature. that the licensee would take action to re- AGENCY: Federal Aviation In this condition, the temperature of the establish a subcritical configuration. Administration (FAA), Department of water may be high enough that the water However, as discussed above for the third Transportation (DOT). would eventually boil off (be higher than 212 scenario, even if there were an accidental ACTION: Final rule. degrees F at atmospheric conditions). If this criticality, the likelihood of fuel damage is were to occur, the cask would eventually very remote. SUMMARY: The FAA is adopting a new become dry and the fuel would be in a The possibility of an accidental criticality airworthiness directive (AD) for certain subcritical configuration and cooled in the fourth scenario is even less likely Boeing Model 757 airplanes. This AD consistent with the design of the cask. As the given the following factors: water boiled off, it would continue to provide 1. Dry storage casks are typically loaded requires installing a control wheel cooling to the fuel such that the fuel would with fuel that has significant burnup that damper assembly at the first officer’s not experience significantly elevated reduces the reactivity of the assembly. As drum bracket assembly and temperatures and there would be no fuel such, it is reasonable to conclude that even quadrant beneath the flight deck floor in damage; or in an unborated condition, the fuel stored in section 41; doing a functional test and 2. Spray water into the cask from a borated the cask would remain subcritical. adjustment of the new installation; and water source to increase the boron 2. As the licensee refilled the SFP, it is doing related investigative/corrective concentration, re-establishing a subcritical reasonable to assume that it would be actions if necessary. For certain configuration and keeping the fuel cooled. injecting borated water to re-establish the airplanes, this AD also requires doing an In each case, the fuel would not be subject boron concentration level required by plant to excessive temperatures and therefore, technical specifications as soon as practical. additional adjustment test of the re- there would be no fuel damage that could Based on the above, even if there were an located control wheel position sensor, impact public health and safety. event that caused a rapid drain down of a and an operational test of the flight data Under this third scenario there is also the SFP while a dry storage cask was in the SFP, recorder and the digital flight data possibility that the licensee might the likelihood of a boron dilution event acquisition unit. This AD also requires intentionally spray water into the dry storage causing fuel damage is very remote. installing vortex generators (vortilons) cask in an attempt to keep the fuel in the cask Therefore, the NRC concludes there is no on the of the outboard cool. Given that the cask will already be safety benefit from requiring the licensee to main on certain airplanes. This AD filled with water and the importance of conduct a site specific analysis in support of results from several reports that cooling the fuel in the SFP storage racks dry storage cask loading, fuel storage, or (where there is no water following a rapid unloading activities. flightcrews experienced unintended roll drain down event), the NRC considers the oscillations during final approach, just possibility of the intentional diversion of V. Conclusion before landing. We are issuing this AD cooling water from the fuel stored in the SFP As discussed above the NRC assessed the to prevent unintended roll oscillations racks to the fuel stored in the dry storage cask safety benefit of requiring licensees to near touchdown, which could result in to be very remote. Therefore, the NRC does conduct an additional criticality analysis to loss of directional control of the not consider this as a factor that would have meet the requirements of 10 CFR 50.68 while airplane, and consequent airplane an adverse affect on its determination with loading a transportation package or dry damage and/or injury to flightcrew and regard to the acceptability of the proposed storage cask in the SFP. The NRC determined change to 10 CFR 50.68. However, even if the that the controls required by 10 CFR Part 71 passengers. licensee intentionally diverted water from or 72 for the associated package or cask DATES: This AD becomes effective cooling the fuel in the SFP racks to the fuel provide reasonable assurance that a slow December 21, 2006.

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The Director of the Federal Register development of this AD. We have schedules vary among operators, we approved the incorporation by reference considered the comments received. could not assure that the airplanes of certain publications listed in the AD would be modified during that Support for the NPRM as of December 21, 2006. maximum interval if we changed the ADDRESSES: You may examine the AD American Airlines supports the compliance time to incorporate the docket on the Internet at http:// NPRM. heavy maintenance visit. We have not dms.dot.gov or in person at the Docket Requests To Change Compliance Time changed the AD in this regard. Management Facility, U.S. Department Air Line Pilots Association (ALPA) Request To Include Part Number (P/N) of Transportation, 400 Seventh Street, supports the intent of the NPRM, but Change for Vortex Generators SW., Nassif Building, Room PL–401, feels that the 24-month compliance time Washington, DC. America West states that the NPRM should be reduced. ALPA states that, does not include a change in P/N after Contact Boeing Commercial given the serious consequences of Airplanes, P.O. Box 3707, Seattle, installation of vortex generators in unintended roll oscillations near the accordance with paragraph (f)(2) of the Washington 98124–2207, for service ground, a shorter compliance time information identified in this AD. NPRM. America West points out that should be imposed. this could result in the installation of FOR FURTHER INFORMATION CONTACT: John Air Transport Association (ATA), on pre-modification outboard main flaps on Neff, Aerospace Engineer, Flight Test behalf of US Airways and United post-modification airplanes. America Branch, ANM–160S, FAA, Seattle Airlines, requests that we lengthen the West recommends that Boeing revise Certification Office, 1601 Lind compliance time from 24 months to the Boeing Alert Service Bulletin 757– Avenue, SW., Renton, Washington later of 36 months or the next heavy 57A0058, Revision 1, to include a 98057–3356; telephone (425) 917–6521; maintenance check. ATA states that the change in P/N; and that the NPRM be fax (425) 917–6590. NPRM would impose more work and revised to prohibit installation of pre- SUPPLEMENTARY INFORMATION: elapsed hours than stated in the modification flaps on an airplane after preamble of the NPRM and would it has been brought into compliance Examining the Docket require operational tests after certain with the AD. You may examine the airworthiness modifications, and that the We disagree. Determining whether or directive (AD) docket on the Internet at accomplishment would be constrained not an airplane is in compliance with http://dms.dot.gov or in person at the by long production lead times for vortex the vortex generator installation can be Docket Management Facility office generators. Further, ATA states that the confirmed easily by visual inspection, between 9 a.m. and 5 p.m., Monday manufacturer’s service instructions on or off the . Therefore, we through Friday, except Federal holidays. recommend compliance within 36 determined that renumbering the flap The Docket Management Facility office months. US Airways comments that a assembly is an unnecessary burden to (telephone (800) 647–5227) is located on longer compliance time is appropriate the manufacturer and to the operators of the plaza level of the Nassif Building at because of the long lead time for getting the affected airplanes, as the part the street address stated in the the vortex generator installation kits (40 marking, drawings, and other ADDRESSES section. weeks, as stated in Boeing Alert Service documentation would have to be Bulletin 757–57A0058, Revision 1, Discussion revised as well. Boeing agrees that the dated January 10, 2002). renumbering is unnecessary. In We disagree. In developing the The FAA issued a notice of proposed addition, section 39.7 of the Federal compliance time for this AD action, we rulemaking (NPRM) to amend 14 CFR Aviation Regulations (14 CFR 39.7) considered not only the safety part 39 to include an AD that would prohibits operation of an aircraft that is implications of the identified unsafe apply to certain Boeing Model 757 not in compliance with an AD. condition, but also the average airplanes. That NPRM was published in Therefore, it is not necessary to include utilization rate of the affected fleet, the the Federal Register on January 31, the specified prohibition in the AD. We practical aspects of an orderly 2006 (71 FR 5021). That NPRM have not changed the AD in this regard. proposed to require installing a control modification of the fleet, the availability wheel damper assembly at the first of required parts, and the time necessary Request To Clarify Differences officer’s drum bracket assembly and for the rulemaking process. After the Paragraph aileron quadrant beneath the flight deck release of Boeing Alert Service Bulletin Boeing and UPS both request that we floor in section 41; doing a functional 757–57A0058, Revision 1 (which was clarify the third paragraph in the section test and adjustment of the new referenced in the NPRM as an of the NPRM titled ‘‘Differences installation; and doing related appropriate source of service Between the Proposed AD and the investigative/corrective actions if information for accomplishing certain Service Bulletins.’’ That paragraph necessary. For certain airplanes, that required actions), we came to an states: NPRM also proposed to require doing an agreement with Boeing that a compliance time of 24 months was ‘‘Although Boeing Alert Service Bulletin additional adjustment test of the re- 757–27A0146 and Boeing Alert Service located control wheel position sensor, appropriate. When we notified Boeing Bulletin 757–27A0147 specify that operators and an operational test of the flight data of this NPRM, Boeing increased the may contact the manufacturer if a just- recorder and the digital flight data procurement of the vortex generator installed (new) wheel damper does not acquisition unit. That NPRM also installation kits to ensure an adequate function properly, this proposed AD would proposed to require installing vortex supply to support the proposed require operators to correct that condition generators (vortilons) on the leading compliance time. Therefore, we have according to a method approved by the edge of the outboard main flap on determined that the compliance time, as FAA.’’ certain airplanes. proposed, represents the maximum Boeing also states that clarification is interval of time allowable for the needed because customers have asked if Comments affected airplanes to continue to safely Boeing is about to revise the existing We provided the public the operate before the installations are done. service bulletins referenced in the opportunity to participate in the In addition, since maintenance NPRM to incorporate possible

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alternative modifications. Other an operator needs to replace an existing number of work hours necessary to do customers have asked Boeing if the FAA control wheel position sensor the required actions based on the best will be adding another requirement to installation before the service bulletin data available. This number represents the AD that is not currently in the kit can be delivered, they would appear the time necessary to perform only the NPRM regarding the replacement of a to be out of compliance in just repairing actions actually required by the AD. We damper assembly. the airplane to the as-delivered recognize that, in doing the actions UPS asks that, if possible, we provide condition. Boeing suggests revising required by an AD, operators may incur additional information on the approved paragraph (g) to include these words, incidental costs in addition to the direct method that we are considering to ‘‘After the incorporation of the wheel costs. The cost analysis in AD correct any problems with the newly damper assembly to comply with this rulemaking actions, however, typically installed damper. UPS suggests that, if AD * * *.’’ does not include incidental costs such we are considering a requirement to We agree that operators may continue as the time required to gain access and install a new damper and/or flight tests to install the existing affected parts and close up, time necessary for planning, or to certify the installation, we include assemblies until the airplane is time necessitated by other these specifics and have a new comment modified to bring it into compliance administrative actions. Those incidental period after the specific actions have with this AD. Therefore, we find that costs, which may vary significantly been defined. the Parts Installation paragraph is not among operators, are almost impossible We agree that the paragraph Boeing necessary, and we have removed that to calculate. We have not changed the quoted needs clarification. However, paragraph and reidentified the following AD in this regard. since that section of the preamble does paragraphs accordingly. Conclusion not reappear in the final rule, we have Request To Include Cost for ‘‘Lost instead changed the following to Time’’ We have carefully reviewed the provide clarification: • United Airlines states that Boeing available data, including the comments We have changed the ‘‘Interim received, and determined that air safety Action’’ section of the AD to specify that Alert Service Bulletins 757–27A0146, dated October 14, 2004; and 757– and the public interest require adopting no additional fixes have been identified; the AD with the changes described however, as investigation into the 57A0058, Revision 1, dated January 10, 2002, state that no ‘‘lost time’’ work previously. We have determined that unsafe condition continues, additional these changes will neither increase the fixes may be deemed necessary in the hours are included in the cost estimates in the NPRM. United Airlines states economic burden on any operator nor future. increase the scope of the AD. • We have revised paragraph (f)(1) of that, if the tasks specified in the service the AD to specify that, if a just-installed bulletins are accomplished during non- Interim Action (new) wheel damper does not function routine maintenance, then lost-time properly, operators should correct the hours must be included in the cost We consider this AD interim action. condition in accordance with the estimates, and unscheduled downtime The manufacturer is currently procedures specified in paragraph (i) of must also be considered in those cost investigating an additional modification the AD, Alternative Methods of estimates. If lost time is included, that may further reduce or eliminate the Compliance (AMOCs). An AMOC for United Airlines states that the total unsafe condition identified in this AD. this condition could include removing work hours would increase to Once this modification is developed, the defective part and returning the approximately 31 total work hours and approved, and available, we may airplane to the original configuration, or 19 elapsed-time hours. In addition, consider additional rulemaking. Should securing the installation in a method United Airlines states that unscheduled any additional modification be required acceptable to us until the affected part downtime for accomplishing the as a result of further rulemaking can be replaced or repaired within the required tasks is estimated to cost activities, that modification would be in compliance time of the AD. $35,000 per day. United Airlines addition to, not a replacement for, the estimates the additional cost for modifications required by this AD. Request To Revise Parts Installation accomplishing both service bulletins Costs of Compliance Paragraph during an unscheduled maintenance Boeing requests that we change visit to be $36,000 per day. Therefore, There are about 1,036 airplanes of the paragraph (g), ‘‘Parts Installation,’’ of the United Airlines requests that the cost affected design in the worldwide fleet NPRM to allow operators that have not estimates be updated to reflect the work and about 629 U.S.-registered airplanes. yet performed the new damper accomplished for both service bulletins. The following table provides the installation to replace any part for the We disagree. The cost information estimated costs for U.S. operators to existing control wheel position below describes only the direct costs of comply with this AD. Not all of the installation during the initial 24-month the specific actions required by the AD. required actions must be done on all compliance time. Boeing explains that if The manufacturer provided us with the U.S.-registered airplanes.

ESTIMATED COSTS

Number Work Average Cost per of U.S.- Action hours labor rate Parts airplane registered Fleet cost per hour airplanes

Install control wheel damper assembly, and do 9 to 11 ... $65 $7,640 to $8,225 to 578 $4,754,050 to functional test (Model 757–200, –200PF, and $10,550. $11,265. $6,511,170. –200CB series airplanes). Install control wheel damper assembly, and do 15 ...... 65 $10,550 ...... $11,525 ...... 51 $587,775. functional test (Model 757–300 series air- planes).

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ESTIMATED COSTS—Continued

Number Work Average Cost per of U.S.- Action hours labor rate Parts airplane registered Fleet cost per hour airplanes

Install vortex generators (Model 757–200, 10 ...... 65 $3,336 ...... $3,986 ...... 527 $2,100,622. –200PF, and –200CB series airplanes).

Authority for This Rulemaking the States, on the relationship between the FAA amends 14 CFR part 39 as Title 49 of the United States Code the national government and the States, follows: or on the distribution of power and specifies the FAA’s authority to issue PART 39—AIRWORTHINESS rules on aviation safety. Subtitle I, responsibilities among the various levels of government. DIRECTIVES section 106, describes the authority of For the reasons discussed above, I the FAA Administrator. Subtitle VII, I certify that this AD: 1. The authority citation for part 39 Aviation Programs, describes in more (1) Is not a ‘‘significant regulatory continues to read as follows: detail the scope of the Agency’s action’’ under Executive Order 12866; Authority: 49 U.S.C. 106(g), 40113, 44701. authority. (2) Is not a ‘‘significant rule’’ under We are issuing this rulemaking under DOT Regulatory Policies and Procedures § 39.13 [Amended] the authority described in subtitle VII, (44 FR 11034, February 26, 1979); and I 2. The Federal Aviation part A, subpart III, section 44701, (3) Will not have a significant Administration (FAA) amends § 39.13 ‘‘General requirements.’’ Under that economic impact, positive or negative, by adding the following new section, Congress charges the FAA with on a substantial number of small entities airworthiness directive (AD): promoting safe flight of civil aircraft in under the criteria of the Regulatory air commerce by prescribing regulations Flexibility Act. 2006–23–15 Boeing: Amendment 39–14827. for practices, methods, and procedures We prepared a regulatory evaluation Docket No. FAA–2006–23734; Directorate Identifier 2005–NM–174–AD. the Administrator finds necessary for of the estimated costs to comply with safety in air commerce. This regulation this AD and placed it in the AD docket. Effective Date is within the scope of that authority See the ADDRESSES section for a location (a) This AD becomes effective December because it addresses an unsafe condition to examine the regulatory evaluation. 21, 2006. that is likely to exist or develop on Affected ADs products identified in this rulemaking List of Subjects in 14 CFR Part 39 action. Air transportation, Aircraft, Aviation (b) None. safety, Incorporation by reference, Regulatory Findings Applicability Safety. (c) This AD applies to Model 757–200, We have determined that this AD will Adoption of the Amendment –200PF, –200CB, and –300 series airplanes, not have federalism implications under certificated in any category; as identified in Executive Order 13132. This AD will I Accordingly, under the authority the applicable service bulletin or bulletins in not have a substantial direct effect on delegated to me by the Administrator, Table 1 of this AD.

TABLE 1.—BOEING SERVICE BULLETINS

Boeing Alert Service Bulletin Revision Date Model

757–27A0146 ...... Original ...... October 14, 2004 ...... 757–200, –200PF, and –200CB series airplanes. 757–27A0147 ...... Original ...... October 14, 2004 ...... 757–300 series airplanes. 757–57A0058 ...... 1 ...... January 10, 2002 ...... 757–200, –200PF, and –200CB series airplanes.

Unsafe Condition Installations Boeing Alert Service Bulletin 757–27A0146 (d) This AD results from several reports (f) Within 24 months after the effective specifies to contact Boeing if a just-installed (new) wheel damper does not function that flightcrews experienced unintended roll date of this AD, do the actions in paragraphs properly, correct that condition in oscillations during final approach, just before (f)(1) and (f)(2) of this AD, as applicable. accordance with the procedures in paragraph landing. We are issuing this AD to prevent (1) For all airplanes: Install a control wheel damper assembly at the first officer’s drum (i) of this AD. unintended roll oscillations near touchdown, bracket assembly and aileron quadrant (2) For Model 757–200, –200PF, and which could result in loss of directional beneath the flight deck floor in section 41; –200CB series airplanes: Install vortex control of the airplane, and consequent and do all applicable functional and generators (vortilons) on the leading edge of airplane damage and/or injury to flightcrew operational tests and adjustments of the new the outboard main flap in accordance with and passengers. installation, and all applicable related the Accomplishment Instructions of Boeing investigative/corrective actions before further Alert Service Bulletin 757–57A0058, Compliance flight after the installation. Do all actions in Revision 1, dated January 10, 2002. (e) You are responsible for having the accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin Actions Accomplished in Accordance With actions required by this AD performed within Previous Revision of Service Bulletin the compliance times specified, unless the 757–27A0146, dated October 14, 2004 (for actions have already been done. Model 757–200, –200PF, and –200CB series (g) Actions done before the effective date airplanes); or Boeing Alert Service Bulletin of this AD in accordance with Boeing Special 757–27A0147, dated October 14, 2004 (for Attention Service Bulletin 757–57–0058, Model 757–300 series airplanes). Where dated March 9, 2000, are acceptable for

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compliance with the actions in paragraph authority to approve AMOCs for this AD, if accordance with 5 U.S.C. 552(a) and 1 CFR (f)(2) of this AD. requested in accordance with the procedures part 51. Contact Boeing Commercial found in 14 CFR 39.19. No Reporting Required Airplanes, P.O. Box 3707, Seattle, (2) Before using any AMOC approved in Washington 98124–2207, for a copy of this (h) Although the Accomplishment accordance with § 39.19 on any airplane to service information. You may review copies Instructions of Boeing Alert Service Bulletin which the AMOC applies, notify the at the Docket Management Facility, U.S. 757–27A0146 and Boeing Alert Service appropriate principal inspector in the FAA Department of Transportation, 400 Seventh Bulletin 757–27A0147, both dated October Flight Standards Certificate Holding District Street, SW., Room PL–401, Nassif Building, 14, 2004, describe procedures for submitting Office. a sheet recording accomplishment of the Washington, DC; on the Internet at http:// service bulletin, this AD does not require that Material Incorporated by Reference dms.dot.gov; or at the National Archives and action. (j) You must use the service information in Records Administration (NARA). For Table 2 of this AD to perform the actions that information on the availability of this Alternative Methods of Compliance are required by this AD, unless the AD material at the NARA, call (202) 741–6030, (AMOCs) specifies otherwise. The Director of the or go to http://www.archives.gov/ (i)(1) The Manager, Seattle Aircraft Federal Register approved the incorporation federal_register/code_of_federal_regulations/ Certification Office (ACO), FAA, has the by reference of these documents in ibr_locations.html.

TABLE 2.—MATERIAL INCORPORATED BY REFERENCE

Boeing Alert Service Bulletin Revision level Date

757–27A0146 ...... Original ...... October 14, 2004. 757–27A0147 ...... Original ...... October 14, 2004. 757–57A0058 ...... 1 ...... January 10, 2002.

Issued in Renton, Washington, on October at the upper attach hinge area, and other Discussion 31, 2006. reports of airplanes with loose hinges, On August 3, 2006, we issued a Kalene C. Yanamura, skin cracks, or signs of repairs to the proposal to amend part 39 of the Federal Acting Manager, Transport Airplane affected area. We are issuing this AD to Aviation Regulations (14 CFR part 39) to Directorate, Aircraft Certification Service. detect and correct loose fasteners; any include an AD that would apply to [FR Doc. E6–19164 Filed 11–15–06; 8:45 am] cracks in the or vertical fin skins, certain Air Tractor Models AT–502, BILLING CODE 4910–13–P spars, hinges or brackets; and/or AT–502A, AT–502B, AT–602, AT–802, corrosion of the rudder and vertical fin and AT–802A airplanes. This proposal hinge attaching structure. Hinge failure was published in the Federal Register DEPARTMENT OF TRANSPORTATION adversely affects ability to control yaw as a notice of proposed rulemaking and has led to the rudder folding over (NPRM) on August 3, 2006 (71 FR Federal Aviation Administration in flight. This condition could allow the 45451). The NPRM proposed to require rudder to contact the and affect you to repetitively visually inspect the 14 CFR Part 39 ability to control pitch with consequent rudder and vertical fin hinge attaching [Docket No. FAA–2006–25260; Directorate loss of control. structure for loose fasteners, any cracks Identifier 2006–CE–37–AD; Amendment 39– DATES: This AD becomes effective on in the rudder or vertical fin skins, spars, 14826; AD 2006–23–14] December 21, 2006. hinges or brackets, or corrosion. The AD RIN 2120–AA64 As of December 21, 2006, the Director would also require you to replace any of the Federal Register approved the damaged parts found as a result of the Airworthiness Directives; Air Tractor, incorporation by reference of certain inspection and install an external Inc. Models AT–502, AT–502A, AT– publications listed in the regulation. doubler at the upper rudder hinge. 502B, AT–602, AT–802, and AT–802A Installation of the external doubler at Airplanes ADDRESSES: To get the service the upper rudder hinge is terminating information identified in this AD, action for the repetitive inspection AGENCY: Federal Aviation contact Air Tractor, Inc., P.O. Box 485, requirements. Administration (FAA), DOT. Olney, Texas 76374; telephone: (940) ACTION: Final rule. 564–5616; fax: (940) 564–5612. Comments To view the AD docket, go to the We provided the public the SUMMARY: The FAA adopts a new Docket Management Facility; U.S. opportunity to participate in developing airworthiness directive (AD) for certain Department of Transportation, 400 this AD. The following presents the Air Tractor, Inc. (Air Tractor) Models Seventh Street, SW., Nassif Building, comments received on the proposal and AT–502, AT–502A, AT–502B, AT–602, Room PL–401, Washington, DC 20590 or FAA’s response to each comment: AT–802, and AT–802A airplanes. This on the Internet at http://dms.dot.gov. Comment Issue No. 1: Availability of AD requires you to repetitively visually The docket number is FAA–2006– inspect the rudder and vertical fin hinge Manufacturer Service Information for 25260; Directorate Identifier 2006–CE– the Proposed AD attaching structure (vertical fin skins, 37–AD. spars, hinges, and brackets) for loose Jack Buster with the Modification and fasteners, cracks, and/or corrosion. This FOR FURTHER INFORMATION CONTACT: Replacement Parts Association AD also requires you to replace any Andrew McAnaul, Aerospace Engineer, (MARPA) provides comments on the AD damaged parts found as a result of the ASW–150 (c/o MIDO–43), 10100 process pertaining to how the FAA inspection and install an external Reunion Place, Suite 650, San Antonio, addresses publishing manufacturer doubler at the upper rudder hinge. This Texas 78216; telephone: (210) 308– service information as part of a AD results from two reports of in-flight 3365; fax: (210) 308–3370. proposed AD action. Mr. Buster states rudder separation from the vertical fin SUPPLEMENTARY INFORMATION: that the proposed rule attempts to

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