Discussion \n\n\tWe issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an airworthiness directive (AD) that would apply to all Boeing Model 757-200, -200CB, -200PF, and -300 series airplanes. That NPRM was published in the Federal Register on July 9, 2007 (72 FR 37132). That NPRM proposed to require installation of an automatic shutoff system for the center tank fuel boost pumps, and installation of a placard in the airplane flight deck if necessary. That NPRM also proposed to require revisions to the Limitations and Normal Procedures sections of the airplane flight manual to advise the flightcrew of certain operating restrictions for airplanes equipped with an automated center tank fuel pump shutoff control. That NPRM also proposed to require a revision to the Airworthiness Limitations (AWLs) section of the Instructions for Continued Airworthiness (ICA) to incorporate AWLs No. 28-AWL-20 and No. 28-AWL-26. That NPRM also proposed to require replacement of the fuel control panel assembly with a modified part, installation of two secondary pump control relays for the center tank fuel pumps, other specified actions, and concurrent modification of the fuel control panel assembly. \n\nActions Since NPRM Was Issued \n\n\tOn April 29, 2008, we issued AD 2008-10-11, amendment 39-15517, that applies to all Model 757 airplanes. AD 2008-10-11, among other actions, requires revising the AWLs section of the ICA by incorporating AWLs No. 28-AWL-01 through No. 28-AWL-24 of Section 9 of the Boeing 757 Maintenance Planning Document (MPD) Document D622N001-9, Revision March 2008. AD 2008-10-11 also provides the optional action of incorporating AWL No. 28-AWL-26. This AD, however, requires the incorporation of AWLs No. 28-AWL-20 and No. 28-AWL-26 in accordance with paragraphs (j) and (m) of this AD, respectively. Therefore, we have added a new paragraph (q) to this AD specifying that incorporating AWLs No. 28-AWL-20 and No. 28-AWL-26 into the AWLs section of the ICA in accordance with paragraph (g)(3) of AD 2008-10-11 terminates the corresponding actions required by this AD. \n\nComments \n\n\tWe gave the public the opportunity to participate in developing this AD. We considered the comments received from the four commenters. \n\nRequest To Revise the Unsafe Condition \n\n\tBoeing requests that we clarify the unsafe condition in the summary and in paragraph (d) of the NPRM. Boeing states that the unsafe condition exists when continuous low pressure is indicated during pump operation with no fuel available to cover the pump inlet, and that it does not exist when there is fuel available to cover the pump inlet during pump operation. Boeing suggests using the following statement: \n\n\tWe are issuing this AD to prevent center tank fuel pump operation with continuous low pressure (with no fuel passing through the pump), which could lead to friction sparks or overheating in the fuel pump inlet that could create a potential ignition source inside the center fuel tank. These conditions, in combination with flammable fuel vapors, could result in a center fuel tank explosion and consequent loss of the airplane. \n\n\tWe agree that the unsafe condition is present only when there is no fuel available to cover the pump inlet. When fuel is not covering the pump inlet, the "continuous low pressure'' indication will be present. Therefore, we have not added the phrase "with no fuel passing through the pump'' to this AD in this regard, since the continuous low pressure indication is integral to describing the unsafe condition. We have, however, revised the summary and paragraph (d) of this AD by replacing "or'' with "that'' to specify "* * * overheating in the fuel pump inlet that could create a potential ignition source * * * '' \n\nRequest To Explain Policy for Alternative Methods of Compliance (AMOCs) \n\n\tTDG Aerospace requests that we explain our criteria in determining which FAA-approved solutions arespecified as a primary means of compliance as opposed to being identified as an AMOC and listed in the AMOC paragraph of an AD. TDG Aerospace states that it would be logical to include all solutions that exist and address an unsafe condition in an AD as a primary means of compliance. TDG Aerospace asserts that, by not doing so, we are failing to provide operators with a comprehensive discussion of the cost and scheduling impact associated with compliance, and that this practice could misrepresent ongoing maintenance and airworthiness limitation requirements. TDG Aerospace also asserts that it appears that preferential bias is shown towards one particular solution, even though two or more other equivalent solutions might exist. TDG Aerospace points to AD 2002-21-06, amendment 39-12912 (68 FR 12802, March 18, 2003), as an example of an AD that lists several equivalent solutions for addressing an unsafe condition. \n\tWe find that clarification of the AMOC process is necessary. An AMOC isissued only after an AD has been issued. AMOCs provide an alternative method of compliance to those methods that are cited in the associated AD. \n\tWhen an unsafe condition is identified, the burden of developing a means for correcting the unsafe condition is placed on the original equipment manufacturer (OEM). Usually, no means for correcting an unsafe condition other than those provided by the OEM exist when we issue an AD. We agree that if multiple solutions exist that have fleet- wide application, such solutions may be cited in an AD. However, such solutions would be included in the AD only as methods of compliance with the requirements of the AD--not as AMOCs. \n\tIn cases where a non-OEM solution does not have fleet-wide application, it would not be appropriate to include the solution in the AD. Such solutions are best addressed by requesting approval as AMOCs after the AD has been issued. We disagree that this approach undermines the efficacy of those alternative methods, or shows bias towards the OEM's method. A key aspect of the notice of proposed rulemaking process is to do specifically what the commenter is recommending, which is to provide an opportunity for us to become aware of other potential solutions to an unsafe condition. Any person who might be aware of another means to correct the unsafe condition is free to propose that means during the comment period to the proposed AD. We would then carefully consider the comment before issuing the AD. \n\tFurther, we have reviewed AD 2002-21-06, and that AD is in line with this practice. That AD refers to approved AMOCs; however, when a new AD supersedes a previously issued AD, we make an assessment of any AMOCs that may have been approved for the previously issued AD. If appropriate, we include a reference to those AMOCs in the new AD to preclude an affected operator from having to re-apply for AMOC approval. \n\tIn this case, we have determined that installing and maintaining TDG Aerospace Universal Fault Interrupter (UFI), in accordance with Supplemental Type Certificate (STC) ST01950LA, would also address the unsafe condition on Model 757-200 and -300 series airplanes. Therefore, we have deleted paragraph (p)(3) of the NPRM and added a new paragraph (p) to this AD specifying that incorporating STC ST01950LA terminates the requirements of paragraphs (g) through (m) of this AD. We have also added a concurrent requirement to paragraph (p) of this AD to install a placard on all airplanes in the operator's fleet not equipped with a UFI or automatic shutoff system. \n\nRequest To Clarify the Summary \n\n\tBoeing requests that we add a statement to the NPRM specifying that this AD will not be extended to the main wing tanks, as discussed in meetings between Boeing and the Seattle Aircraft Certification Office, FAA. Boeing states that AD 2002-24-51, amendment 39-12992 (68 FR 10, January 2, 2003), was based upon discrepancies in the manufacturing process, and that AD 2002-24-51 was later expandedbecause inspection of in-service units showed that the units could possibly overheat in service or during manufacture. Boeing further states that there is no service history of incidents or accidents on the main wing tanks on Model 757 airplanes to support this AD. \n\tAlthough we agree that the scope of this AD is not being expanded to address the main wing tanks, revising the summary of this AD is not necessary because it only discusses the center fuel tanks. We have not changed this AD in this regard. \n\nRequest To Allow Use of Existing AMOC \n\n\tBoeing requests that we revise the NPRM to specify that operators may continue using the procedures in the following documents as an AMOC, until an operator has inspected all center tank fuel pumps and modified all airplanes in its fleet: AD 2002-19-52, amendment 39-12900 (67 FR 61253, September 30, 2002), and AD 2002-24-51; or FAA Approval Letter 140S-03-234, dated August 15, 2003. As justification, Boeing states that the AMOC has alreadybeen accepted as a valid means of fulfilling the intent of the AD pending hardware installation. \n\tWe agree that the procedures in AD 2002-19-52 and AD 2002-24-51, or the procedures approved by FAA Approval Letter 140S-03-234 as an AMOC to AD 2002-19-52 and AD 2002-24-51, continue to be acceptable until all airplanes in an operator's fleet are in compliance with all the requirements of this AD. As stated in the NPRM, installing a placard in accordance with paragraph (e) of AD 2002-19-52 is acceptable for compliance with paragraph (h) of this AD. Also, paragraph (n) of this AD states that accomplishing the actions specified in paragraphs (g), (h), (i), and (j) of this AD terminates the AFM revision specified in paragraph (e) of AD 2002-24-51 for Model 757-200, -200CB, -200PF, and - 300 series airplanes that have the automatic shutoff system installed. No change to this AD is necessary in this regard. \n\nRequest To Allow Use of an AMOC \n\n\tUPS requests that we revise the NPRM to allowAD 2002-24-51 as an AMOC and terminating action to the proposed requirements of the NPRM. As justification, UPS states that there is no opportunity for potential ignition sources to develop from the center tank fuel pump, since AD 2002-24-51 prohibits operating the fuel pumps when the center tank fuel quantity reaches 1,000 pounds; under this limitation, the fuel pump is submerged and always covered with fuel. UPS believes that the limitations required by AD 2002-24-51 provide a higher level of safety than the automatic shutoff system because the limitations of AD 2002- 24-51 always require the fuel pumps to be submerged in fuel, precluding the opportunity for dry running the pumps. UPS further states that, since Boeing Service Bulletin 757-28A0105, Revision 1, dated April 2, 2007, was issued to counteract the potential continued dry running of the fuel pump, it should not be required for operators who have accomplished AD 2002-24-51. \n\tWe do not agree to allow AD 2002-24-51 as an AMOC or terminating action for the requirements of this AD. The changes to the pump control system required by this AD address problems with the system, such as indication failures and power relay failures, that the limitations required by AD 2002-24-51 do not address. Further, the FAA Flight Standards Service has informed us that there are flights where the fuel pumps are not turned off as required by AD 2002-24-51 because of the lack of crew indication prompting early shutoff of the fuel pumps. AD 2002-24-51 was intended only to be an interim action until the pump power control system changes were developed and incorporated. We have determined that installing the automatic shutoff system provides a higher level of safety because it prevents extended dry running of the fuel pumps. Therefore, we have not changed this AD in this regard. \n\nRequest To Revise AWLs Intervals \n\n\tKLM Royal Dutch Airlines, on behalf of several operators, requests that we review a 45-page proposal to align certain Airworthiness Limitation Item (ALI) intervals with the applicable maintenance significant item (MSI) and enhanced zonal analysis procedure (EZAP) intervals, for Model 737, 747, 757, 767, and 777 airplanes. The recommendations in that proposal ensure that the ALI intervals align with the maintenance schedule of the operators. \n\tWe have reviewed the proposal and note that it recommends extending the inspection interval for AWL No. 28-AWL-20 from 1 year to 24 months. We infer that the operators request that we revise paragraph (m) of this AD to extend the inspection interval for AWL No. 28-AWL-20 of Boeing Temporary Revision (TR) 09-006, dated January 2007, to the Boeing 757 Maintenance Planning Document, D622N001-9. That 1-year interval was determined using a quantitative fault tree analysis. Given the confidence level of certain inputs into that analysis, it would not be appropriate to extend the inspection interval until sufficient reliability data is available to substantiate those assumptions. Therefore, we have determined that a 1-year interval is appropriate for ensuring an acceptable level of safety. No change to this AD is necessary in this regard. \n\nRequest To Explain Compliance With Industry Guidance \n\n\tTDG Aerospace requests that we specify whether the service bulletins referred to in the NPRM are in compliance with the requirements of section 25.981(a) and (b) of the Federal Aviation Regulations (14 CFR 25.981(a) and (b)) and with section 25.1309(c) of the Federal Aviation Regulations (14 CFR 25.1309(c)) with respect to latent failure conditions. If so, TDG Aerospace further requests that we discuss any inaccuracies between the service bulletins and FAA Advisory Circular (AC) 25.981-1B, "Fuel Tank Ignition Source Prevention Guidelines,'' dated April 18, 2001; AC 25.1309-1A, "System Design and Analysis,'' dated June 21, 1988; and MIL-HDBK-217F, "Reliability Prediction of Electronic Equipment.'' \n\tThe Boeing service bulletins referred to in thisAD are FAA- approved and were found to comply with the requirements of 14 CFR 25.981(a) and (b), amendment 25-102. In developing the service bulletins, Boeing followed the guidance cited by TDG Aerospace. Boeing's substantiation included other features with the fuel pump that contribute an additional condition probability to the latent failure cases referred to by TDG Aerospace. No change to this AD is necessary in this regard. \n\nRequest To Adopt an Industry-Collaborative Approach \n\n\tTDG Aerospace suggests that we use the regulatory docket as a tool to encourage industry participation in the pursuit of solutions to known deficiencies that we intend to address with an AD. TDG Aerospace suggests that such an approach would not only result in the most efficient and cost-effective solutions, but also reduce the delay in bringing viable corrective actions to the market. \n\tWe welcome any feedback that will improve the AD process for industry, while also ensuring that an unsafe conditionis adequately addressed in an appropriate amount of time. As stated previously, the burden of developing a means for correcting the unsafe condition is placed on the OEM. We have found that the comment period is most useful if we notify operators about the work required by a proposed AD, which is typically detailed in a service bulletin. Also, in determining the appropriate compliance time for an AD, we must consider both the risk and scope of work that would be required. Without service information, it would be difficult to set appropriate compliance times, or provide operators with an opportunity to comment on the merits of a corrective action. No change to this AD in necessary in this regard. \n\nConclusion \n\n\tWe reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting the AD with the changes described previously. We also determined that these changes will not increase the economic burden on any operatoror increase the scope of the AD. \n\nCosts of Compliance \n\n\tThere are about 1,094 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs, at an average labor rate of $80 per hour, for U.S. operators to comply with this AD. The estimated cost of parts in the following table depends on the airplane configuration. \n\n\tEstimated Costs\n\n\nModel\nAction\nWork hours\nParts\nCost per airplane\nNumber of U.S.-registered airplanes\nFleet cost\n757-200, -200CB, and -200PF, series airplanes\nInstallation of the automatic shutoff system\n91\n$8,309 to $9,194\n$15,589 to $16,474\n631\n$9,836,659 to $10,395,094\n757-300 series airplanes\nInstallation of the automatic shutoff system\n51\n$8,598 to $8,654\n$12,678 to $12,734\n75\n$950,850 to $955,050\n\nPlacard installation, if necessary\n1\n$10\n$90\n706\n$63,540\n\nAFM revision\n1\nNone\n$80\n706\n$56,480\n\nAWLs revision\n1\nNone\n$80\n706\n$56,480\n\nInstallation of secondary pump control relays\n29\n$2,097\n$4,417\n706\n$3,118,402\n757-200, -200CB, -200PF, and -300 series airplanes\nConcurrent modification of the fuel control panel assembly\n2\n$40\n$200\n706\n$141,200\n\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\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 developon products identified in this rulemaking action. \n\nRegulatory Findings \n\n\tThis 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\t(1) Is not a "significant regulatory action'' under Executive Order 12866, \n\t(2) Is not a "significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979), and \n\t(3) 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\tYou can find our regulatory evaluation and the estimated costs of compliance in the AD Docket. \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 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 adding the following new AD: