AD 99-24-08

This amendment supersedes an existing airworthiness directive (AD), applicable to all Boeing Model 737-100, - 200, -300, -400, and -500 series airplanes, that currently requires, for certain airplanes, repetitive replacements of the airplane battery with a new or reconditioned battery and replacement of the battery charger with a new or serviceable battery charger; performing repetitive tests to determine the condition of a certain diode of the Generator Control Units (GCU); and corrective actions, if necessary. This amendment adds, for certain other airplanes, a requirement for repetitive replacements of the airplane battery with a new or reconditioned battery, and clarifies a diode test requirement. This amendment is prompted by an incident during which all electrical power was lost due to a combination of a weak or depleted battery and the failure of a certain diode of the GCU. The actions specified in this AD are intended to prevent failure of all electrically powered airplane systems, which could result in the inability to continue safe flight and landing.

Final rule; request for comments

99-24-08 BOEING: Amendment 39-11432. Docket 99-NM-260-AD. Supersedes AD 99-18-17, Amendment 39-11283. \n\n\tApplicability: All Model 737-100, -200, -300, -400, and -500 series airplanes; certificated in any category. \n\n\tNOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (h)(1) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo prevent failure of all electrically powered airplane systems, which could result in the inability to continue safe flight and landing, accomplish the following: \n\nRESTATEMENT OF THE REQUIREMENTS OF AD 99-18-17 \n\n\t(a)\tFor Model 737-100 and -200 series airplanes equipped with battery charger Boeing part number (P/N) 10-60701-1: Within 90 days after September 16, 1999 (the effective date of AD 99-18-17, amendment 39-11283), accomplish the requirements of paragraphs (a)(1) and (a)(2) of this AD. \n\n\t\t(1)\tReplace the airplane battery charger with a new or serviceable airplane battery charger, Boeing P/N 10-60701-3, in accordance with Chapter 20-10-111 of the Boeing 737 Airplane Maintenance Manual (AMM); and \n\n\t\t(2)\tReplace the airplane battery with a new or reconditioned airplane battery in accordance with Chapter 24-31-11 of the Boeing 737 AMM. Thereafter, replace the airplane battery with a new or reconditioned airplane battery at intervals not to exceed 750 flight hours, until the accomplishment of paragraph (f) of this AD. \n\n\t(b)\tFor Model 737-300, -400, and -500 series airplanes: Within 90 days after September 16, 1999, replace the airplane battery with a new or reconditioned airplane battery in accordance with Chapter 24-31-11 of the Boeing 737 AMM. Thereafter, replace the airplane battery with a new or reconditioned airplane battery at intervals not to exceed 750 flight hours. \n\n\t(c)\tFor all airplanes: Within 90 days after September 16, 1999, perform a test to determine the condition of diode CR910 of the Generator Control Units (GCU), in accordance with Boeing Telex Message M-7200-99-01528, dated March 5, 1999. \n\n\t\t(1)\tIf all diodes pass the test, repeat the diode test thereafter at intervals not to exceed 600 flight hours, until the accomplishment of paragraph (g) of this AD. \n\n\t\t(2)\tIf any diode fails the test: Prior to further flight, replace the GCU with a new or serviceable GCU, and the airplane battery with a new or reconditioned airplane battery, and repeat the diode test for the replaced GCU in accordance with the telex message until successful completion of the test is achieved. Repeat the diode test thereafter, at intervals not to exceed 600 flight hours, until the accomplishment of paragraph (g) of this AD. \n\n\t(d)\tAs of September 16, 1999, no person shall install a battery charger having Boeing P/N 10-60701-1 on any Model 737 series airplane. \n\n\t(e)\tWithin 10 days after accomplishing the initial diode test required by paragraph (c) of this AD, submit a report of the test results (negative findings, i.e., test failures) to the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; fax (425) 227-1181. Information collection requirements contained in this regulation have been approved by the Office of Management and Budget (OMB) under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-0056. \n\nNEW REQUIREMENTS OF THIS AD: \n\n\t(f)\tFor Model 737-100 and -200 series airplanes equipped with battery charger Boeing P/N 10-60701-3: Within 90 days after the effective date of this AD, or within 750 flight hours after the last battery replacement accomplished in accordance with paragraph (a)(2) of this AD, whichever occurs later, replace the airplane battery with a new or reconditioned airplane battery in accordance with Chapter 24-31-11 of the Boeing 737 AMM. Thereafter, replace the airplane battery with a new or reconditioned airplane battery at intervals not to exceed 750 flight hours. Accomplishment of this replacement constitutes terminating action for the requirements of paragraph (a)(2) of this AD. \n\n\t(g)\tFor all airplanes: Within 90 days after the effective date of this AD, or within 90 days after accomplishment of the test required by paragraph (c) of this AD, whichever occurs later, determine the condition of diode CR910 of the GCU, in accordance with the "Alternative Test of Diode CR910," as specified in Boeing Telex Message M-7200-99-01528, dated March 5, 1999. Accomplishment of this action constitutes terminating action for the requirements of paragraph (c) of this AD. \n\n\tNOTE 2: Any tests performed prior to September 16, 1999, in accordance with Boeing Telex Message M-7200-99-01528, dated February 19, 1999, or dated March 4, 1999, are not considered acceptable for compliance with the applicable action specified by this AD. \n\n\t(1)\tIf all diodes pass the test, repeat the diode test thereafter at intervals not to exceed 600 flight hours.\n \n\t(2)\tIf any diode fails the test: Prior to further flight, replace the GCU with a new or serviceable GCU, and the airplane battery with a new or reconditioned airplane battery, and repeat the "Alternative Test of Diode CR910" for the replaced GCU in accordance with the telex message until successful completion ofthe test is achieved. Repeat the diode test thereafter, at intervals not to exceed 600 flight hours. \n\nAlternative Methods of Compliance \n\n\t(h)(1)\tAn alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle ACO. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO. \n\n\t(h)(2)\tAlternative methods of compliance with paragraphs (a)(1), (a)(2), or (b) of this AD, approved previously in accordance with AD 99-18-17, amendment 39-11283, are approved as alternative methods of compliance with paragraphs (a)(1), (a)(2), or (b) of this AD. \n\n\tNOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. \n\nSpecial Flight Permits \n\n\t(i)\tSpecial flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished. \n\nIncorporation by Reference \n\n\t(j)\tExcept as provided by paragraphs (a)(1), (a)(2), (b), and (f) of this AD, the actions shall be done in accordance with Boeing Telex Message M-7200-99-01528, dated March 5, 1999. This incorporation by reference was approved previously by the Director of the Federal Register as of September 16, 1999 (64 FR 47656, September 1, 1999). Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. \n\n\t(k)\tThis amendment becomes effective on December 13, 1999.

On August 24, 1999, the FAA issued AD 99-18-17, amendment 39-11283 (64 FR 47656, September 1, 1999), applicable to all Boeing Model 737-100, -200, -300, -400, and -500 series airplanes, to require repetitive replacements of the airplane battery with a new or reconditioned battery and, for certain airplanes, replacement of the battery charger with a new or serviceable battery charger. That action also requires performing repetitive tests to determine the condition of a certain diode of the Generator Control Units (GCU); and corrective actions, if necessary. That action was prompted by an incident during which all electrical power was lost due to a combination of a weak or depleted battery and the failure of a certain diode of the GCU. The actions required by that AD are intended to prevent failure of all electrically powered airplane systems, which could result in the inability to continue safe flight and landing. \n\nActions Since Issuance of Previous Rule \n\n\tFollowing the incident described previously in which all electrical power was lost due to a weak or depleted battery and the failure of certain GCU diodes, an assessment of airplane battery maintenance was conducted. As a result, it was determined that some operators have extended maintenance intervals beyond those recommended by the airplane manufacturer, which increases the likelihood of allowing an airplane to operate with a weak or depleted airplane battery. In addition, the risk associated with the use of such a battery is greater on Model 737-100 and -200 series airplanes because some of these airplanes use an older version of battery charger. The older version has charging characteristics that are not compatible with the extended airplane battery maintenance intervals. \n\n\tSince the issuance of AD 99-18-17, the FAA has determined that it is necessary to revise certain requirements of that AD. \n\n\tThe FAA points out that its intent in that AD was to require operators of Model 737-100 and -200 series airplanes equipped with battery chargers having Boeing part number (P/N) 10-60701-3, as well as P/N 10-60701-1, to replace the airplane battery with a new or reconditioned airplane battery. However, the replacement requirement for airplanes equipped with a battery charger having Boeing P/N 10-60701-3 was inadvertently omitted from paragraph (a) of the AD. That requirement is included in paragraph (f) of this AD.\n \n\tThe FAA also has determined that it is necessary to clarify its intent in AD 99-18-17 regarding the test required to determine the condition of diode CR910 of the GCU. Although that AD only specifies that "a test" is required, this AD clarifies that the required test is the "Alternative Test of Diode CR910," which is specified along with various other tests included in Boeing Telex Message M-7200-99-01528, dated March 5, 1999. This change is necessary because the test requirement specified in AD 99-18-17 unintentionally allows operators the discretion to select from any of the various tests specified in the Boeing telex message. The FAA has determined that all other test methods referenced in that Boeing telex message are unacceptable as methods of complying with the requirements of this amendment. \n\nExplanation of Requirements of Rule \n\n\tSince an unsafe condition has been identified that is likely to exist or develop on other airplanes of this same type design, this AD supersedes AD 99-18-17 to continue to require, for certain airplanes, repetitive replacements of the airplane battery with a new or reconditioned battery, and replacement of the battery charger with a new or serviceable battery charger; performing repetitive tests to determine the condition of a certain diode of the GCU; and corrective actions, if necessary. This amendment adds, for certain airplanes, a requirement for repetitive replacement of the airplane battery for Models 737-100 and -200 series airplanes equipped with battery charger Boeing P/N 10-60701-3 with a new or reconditioned battery, and clarifies a diode test requirement. The battery replacement is required to be accomplished in accordance with Chapter 20-20-111 of the Boeing 737 Airplane Maintenance Manual; and the diode test is required to be accomplished in accordance with the "Alternative Test of Diode CR910," as specified in Boeing Telex Message M-7200-99-01528, dated March 5, 1999. \n\nInterim Action \n\n\tSince the cause of the failures of the GCU's is under investigation, this is considered to be interim action until final action is identified, at which time the FAA may consider further rulemaking. \n\nDetermination of Rule's Effective Date \n\n\tSince a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days. \n\nComments Invited \n\n\tAlthough this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed. \n\n\tComments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. Allcomments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket. \n\n\tCommenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 99-NM-260-AD." The postcard will be date stamped and returned to the commenter. \n\nRegulatory Impact \n\n\tThe regulations adopted herein will not have substantial direct effects 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. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. \n\n\tThe FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES." \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\n\tAccordingly, pursuant to 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\n PART 39 - AIRWORTHINESS DIRECTIVES \n\n\t1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. § 39.13 (Amended) \n\t2. Section 39.13 is amended by removing amendment 39-11283 (64 FR 47656, September 1, 1999), and by adding a new airworthiness directive (AD), amendment 39-11432, to read as follows: