AD 2002-16-03

This amendment adopts a new airworthiness directive (AD) that is applicable to all Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes. This action requires determining exposure to runway deicing fluids containing potassium formate, and, for certain airplanes, repetitive inspections of certain electrical connectors in the wheel well of the main landing gear for corrosion, and follow-on actions. This action is necessary to prevent such corrosion, which could result in incorrect functioning of critical airplane systems essential to safe flight and landing of the airplane. This action is intended to address the identified unsafe condition.

Final rule; request for comments.

2002-16-03 Boeing: Amendment 39-12842. Docket 2002-NM-148-AD. \n\n\tApplicability: All Model 737-600, -700, -700C, -800, and -900 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 (c) 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 corrosion of the electrical connectors and contacts in the wheel well of the main landing gear (MLG), which could result in incorrect functioning of critical airplane systems essential to safe flight and landing of the airplane, accomplish the following: \n\nDetermination of Exposure/Inspections/Follow-On Actions \n\n\t(a) Within 90 days after the effective date of this AD, do the requirements specified in either paragraph (a)(1) or (a)(2) of this AD. \n\n\t\t(1) Determine airplane exposure to runway deicing fluids containing potassium formate by reviewing airport data on the type of components in the deicing fluid used at airports that support airplane operations. \n\n\t\t\t(i) For airplanes that have not been exposed: Repeat the requirements in paragraph (a)(1) of this AD at least every 12 months. \n\n\t\t\t(ii) For airplanes that have been exposed: Before further flight, do a detailed inspection of the line replaceable unit (LRU) electrical connectors (including the contacts and backshells) in the wheel well of the MLG for corrosion (the presence of moisture, corrosion pits, or white-colored material buildup), per Boeing Alert Service Bulletin 737-24A1148, dated December 6, 2001. Repeat the detailed inspection at least every 12 months. \n\n\tNote 2: For the purposes of this AD, a detailed inspection is defined as: "An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required." \n\n\t\t(2) Do a detailed inspection of the LRU electrical connectors (including the contacts and backshells) in the wheel well of the MLG for corrosion (the presence of moisture, corrosion pits, or white- colored material buildup), per the service bulletin.Repeat the detailed inspection at least every 12 months. \n\n\t(b) Before further flight after doing any inspection specified in paragraph (a)(1)(ii) or (a)(2) of this AD, as applicable; do the requirements specified in paragraphs (b)(1), (b)(2), and (b)(3) of this AD, as applicable, per Boeing Alert Service Bulletin 737- 24A1148, dated December 6, 2001. \n\n\t(1) If no corrosion is found, clean the LRU connector. \n\n\t(2) If any corrosion is found, replace the LRU connector with a new connector. \n\n\t(3) Apply D5026NS corrosion inhibiting compound, or equivalent, to the affected areas. \n\nAlternative Methods of Compliance \n\n\t(c) An 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 Aircraft Certification Office (ACO), FAA. 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\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(d) Special flight permits may be issued in accordance with §§ 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(e) Except as provided by paragraph (a)(1) of this AD: The actions shall be done in accordance with Boeing Alert Service Bulletin 737-24A1148, dated December 6, 2001. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. 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\nEffective Date \n\n\t(f) This amendment becomes effective on August 27, 2002.

The FAA has received reports indicating that significant corrosion of the electrical connectors located in the main wheel well was found on some Boeing Model 737 series airplanes. Those airplanes land on runways treated with deicing fluids containing potassium formate, which has been determined as the cause of the corrosion. Tests conducted by the airplane manufacturer revealed that corrosion inhibiting compounds (CIC) can be used to form a shield against such corrosion and will not affect the electrical components or the systems. Corrosion of the electrical connectors could result in incorrect functioning of critical airplane systems essential to safe flight and landing of the airplane. \n\nExplanation of Relevant Service Information \n\n\tWe have reviewed and approved Boeing Alert Service Bulletin 737- 24A1148, dated December 6, 2001, which recommends determining if airplanes have been exposed to runway deicing fluids containing potassium formate (by reviewing airport data on the type of components in deicing fluid used at airports that support their operations), and follow-on actions. If any airplane has been exposed, the service bulletin describes procedures for inspecting the line replaceable unit (LRU) electrical connectors (including the contacts and backshells) for corrosion. Signs of corrosion are the presence of moisture, corrosion pits, or white-colored material buildup on the connectors; black or reddish discoloration on the contacts; or loss of the olive-drab conversion coating on the backshells. The follow-on actions include cleaning the LRU connectors and applying CIC if no corrosion is found; and, if corrosion is found, replacing the LRU with a new LRU and applying CIC. The service bulletin also recommends an operational test of the affected systems after doing the applicable actions. Accomplishment of the inspections and follow-on actions specified in the service bulletin is intended to adequately address the identified unsafe condition. \n\nExplanation of the Requirements of the Rule \n\n\tSince an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design, this AD requires accomplishment of the actions specified in the service bulletin described previously, except as discussed below. \n\nDifferences Between Service Information and This AD \n\n\tThe service bulletin specifies an examination of the electrical connectors in the wheel well of the main landing gear for corrosion. For the purposes of this AD, we have determined that the procedures in the service bulletin constitute a "detailed inspection." Note 2 of this AD defines such an inspection. \n\n\tThe service bulletin specifies that no work is necessary for airplanes that have not been exposed to runways using deicing fluids containing potassium formate (this is determined by reviewing airport data, as specified previously). We have concluded that such airplanes, although not presently using those runways, could use them in the future due to changes in routes. Therefore, this AD requires operators of those airplanes to repeat the data review every 12 months. \n\n\tThe service bulletin states that airplane exposure to runway deicing fluids containing potassium format may be determined by reviewing airport data on the type of components in the deicing fluid used. This AD specifies that the determination be made in accordance with a review of the airport data, rather than specifying the determination in accordance with the service bulletin. \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\tSubmit comments using the following format: \n\n\t Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues. \n\n\t For each issue, state what specific change to the AD is being requested. \n\n\t Include justification (e.g., reasons or data) for each request. \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. All comments 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 2002-NM-148-AD." The postcard will be date stamped and returned to the commenter. \n\nRegulatory Impact \n\n\tThe regulations adopted herein will not have a substantial direct effect on the States, on the relationshipbetween the national Government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132. \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 14CFR 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\nPART 39--AIRWORTHINESS DIRECTIVES \n\n\t1. 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\n\t2. Section 39.13 is amended by adding the following new airworthiness directive: