Discussion \n\n\n\tOn February 1, 2013, we issued AD 2013-02-51, Amendment 39-17366 (78 FR 12231, February 22, 2013), for all The Boeing Company Model 787- 8 airplanes. That AD requires modification of the battery system, or other actions. That AD resulted from recent incidents involving lithium ion battery failures that resulted in release of flammable electrolytes, heat damage, and smoke on two Model 787-8 airplanes. We issued that AD to prevent damage to critical systems and structures and the potential for fire in the electrical compartment. \n\nActions Since AD 2013-02-51, Amendment 39-17366 (78 FR 12231, February 22, 2013), Was Issued \n\n\n\tSince we issued AD 2013-02-51, Amendment 39-17366 (78 FR 12231, February 22, 2013), the National Transportation Safety Board (NTSB) released an Interim Factual Report, NTSB Case Number DCA13IA037, on March 7, 2013, presenting its initial findings concerning a battery failure on a Model 787-8 airplane operated byJapan Airlines. That report can be found at: http://www.ntsb.gov/investigations/2013/boeing_787/interim_report_B787_3-7-13.pdf. \n\tThat report documents thermal and mechanical damage to the battery and the battery control units, and a lack of containment of the battery electrolytes, heat, and smoke from the battery case. The cause(s) of this battery failure incident has not yet been determined by the NTSB. Likewise, the cause(s) of the battery failure incident on a Model 787-8 airplane operated by All Nippon Airways has not yet been determined by the Japan Transport Safety Board (JTSB), which is the accident investigative authority for Japan. \n\tThe FAA has reviewed the NTSB's interim factual report, as well as information provided by the JTSB, Boeing, All Nippon Airways, and Japan Airlines. The main and APU batteries are identical, but perform different functions on the airplane. The main battery installed on Model 787-8 airplanes is used to provide power while the engines are off during ground maintenance operations (e.g., power-up, refueling, braking, and navigation lights during towing) and backup electrical power while airborne. The APU battery is required to start and operate the APU. The APU may be used on the ground, or in flight to generate backup electrical power. Each of the two engines drives two variable frequency starter generators (VFSGs) for a total of four VFSGs providing power to the airplane. Therefore, while in flight, the two generators driven by the APU provide the 5th and 6th layer of power generation for the airplane. \n\tOn March 12, 2013, the FAA approved a Boeing plan to mitigate the unsafe condition identified by AD 2013-02-51, Amendment 39-17366 (78 FR 12231, February 22, 2013). The plan resulted from a detailed review by Boeing and the FAA that considered all potential causal factors of the two recent battery incidents. The plan provides three layers of protection to improve the reliability of the battery and to prevent any hazardous effects on the airplane from a battery failure. Those layers are (1) measures to minimize the probability of a single battery cell failure, (2) measures to minimize the probability of any single battery cell failure from propagating to other cells in the battery, and (3) measures to preclude hazardous airplane-level safety effects of any battery failure that might occur. Details of these measures, which are mandated by this AD, are as follows: \n\tMinimize the Probability of a Single Battery Cell Failure--Each main and APU battery consists of a set of individual cells within a battery case. Each battery cell will be encapsulated to isolate the cell electrically. Locking nuts with specific torque values will be used on every cell terminal to prevent overheating of the terminal due to a loose electrical connection. Drainage within the battery case will be improved to remove any condensation within the battery. The battery monitoring and charging unit will be changed to reduce the operationalvoltage range to lessen electrical stress on the battery cell, and to enhance over-discharge protection. Boeing has also made mandatory changes to the battery manufacturing and acceptance testing processes to improve the overall quality of the battery. \n\tMinimize the Probability of Multiple Cell Failure Propagation--Additional insulation will be provided between each battery cell and between each cell and the battery case to thermally and electrically isolate the individual battery cells. High temperature sleeving will also be added to the battery internal wiring harness to protect against short circuits. In addition, cell venting will be added to the battery case to allow any cell gasses, including electrolytes, to escape into the battery enclosure to minimize heat build-up within the battery case. \n\tPreclude Hazardous Airplane-Level Safety Effects of a Battery Failure That Might Occur--As stated previously, each main and APU battery consists of a set of individual cells within a battery \n\n((Page 24675)) \n\ncase. The case containing the cells will be secured within a stainless steel, sealed enclosure. This enclosure will be connected to a titanium ECS duct that vents to the outside of the airplane. Should a battery failure occur, and generate significant heat, pressure, and gasses, a metallic frangible disc (also referred to as a vent burst disc) at the interface of the enclosure and vent duct will open and allow the heat, pressure, and gasses to safely vent overboard through the ECS duct. This will prevent the introduction of any heat, pressure, or gasses in the electronics equipment bays or any occupied area of the airplane. \n\nRelevant Service Information \n\n\n\tWe reviewed Boeing Alert Service Bulletin B787-81205-SB500003-00, Issue 001, dated April 19, 2013; and Section D, ''Airworthiness Limitations--Life Limits,'' of the Boeing 787 Airworthiness Limitations (AWLs) Document D011Z009-03-01, dated April 2013. For information on the procedures and compliance times, see this service information at http://www.regulations.gov by searching for Docket No. FAA-2013-0333. \n\nFAA's Determination \n\n\n\tWe are issuing this AD because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design. \n\nAD Requirements \n\n\n\tThis AD requires accomplishing the actions specified in the service information identified previously. \n\nChange to Applicability of AD 2013-02-51, Amendment 39-17366 (78 FR 12231, February 22, 2013) \n\n\n\tThis AD applies to The Boeing Company Model 787-8 airplanes, as identified in Boeing Alert Service Bulletin B787-81205-SB500003-00, Issue 001, dated April 19, 2013, instead of ''all'' airplanes, as specified in AD 2013-02-51, Amendment 39-17366 (78 FR 12231, February 22, 2013). The actions required by this AD address the identified unsafe condition for in-service airplanes. For all future delivered airplanes, the replacement batteries, their respective chargers, and enclosure and duct installations will be incorporated at the factory prior to delivery. \n\nFAA's Justification and Determination of the Effective Date \n\n\n\tAD 2013-02-51, Amendment 39-17366 (78 FR 12231, February 22, 2013), effectively grounded the Model 787-8 fleet and prevented delivery of new Model 787-8 airplanes because there was no design solution available. While necessary in the short term to address the unsafe condition, this caused a significant economic burden on domestic and international operators of Boeing Model 787-8 airplanes. The purpose of this AD is to allow the aircraft to return to service as soon as possible by mandating a modification that will address the unsafe condition. Therefore, we find that notice and opportunity for prior public comment are impracticable and would defeat the Agency's regulatory objective, and that good cause exists for making this amendment effective in less than 30 days. \n\nCommentsInvited \n\n\n\tThis AD is a final rule that involves requirements affecting flight safety, and we did not provide you with notice and an opportunity to provide your comments before it becomes effective. However, we invite you to send any written data, views, or arguments about this AD. Send your comments to an address listed under the ADDRESSES section. Include the docket number FAA-2013-0333 and Directorate Identifier 2013-NM-080- AD at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this AD. We will consider all comments received by the closing date and may amend this AD because of those comments. \n\tWe will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this AD. \n\nCosts of Compliance \n\n\n\tWe estimate that this AD affects 6 airplanes of U.S. registry. \n\tWe estimate the following costs to comply with this AD: \n\n\n\tEstimated Costs ---------------------------------------------------------------------------------------------------------------- \n\tCost per Cost on U.S. \n\tAction Labor cost Parts cost product operators ---------------------------------------------------------------------------------------------------------------- Installation and replacement.......... 112 work-hours x $85 per $455,158 $464,678 $2,788,068 \n\thour = $9,520. Revise maintenance program............ 1 work-hour x $85 per None 85 510 \n\thour = $85. ---------------------------------------------------------------------------------------------------------------- \n\n\n\tAccording to the manufacturer, some of the costs of this AD may be covered under warranty, thereby reducing the cost impact on affected individuals. We do not control warranty coverage for affected individuals. As a result, we have included all costs in our cost estimate. \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 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 rulemaking action. \n\nRegulatory Findings \n\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\n((Page 24676)) \n\n\n\t(2) Is not a ''significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979), \n\t(3) Will not affect intrastate aviation in Alaska, and \n\t(4) 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\nList of Subjects in 14 CFR Part 39 \n\n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.