AD 98-24-02

This amendment adopts a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model MD-11 series airplanes. This action requires a one-time inspection to identify the part numbers of two dimmer controls for the overhead instrument panel light and circuit breaker lightplate located in the flight compartment. For airplanes on which a dimmer control having an incorrect part number is installed, this action also requires replacing the dimmer control with a new part; modifying and reinstalling the existing dimmer control; or reinstalling a dimmer control following modification of the part by the part manufacturer. This amendment is prompted by reports of smoke emitting from the overhead panels in the cockpit area. The actions specified in this AD are intended to prevent an electrical failure in the overhead dimmer control due to overheating of a printed circuit board capacitor in the dimmer control, which could result in rupture of the capacitor andsmoke in the flight compartment.

Final rule; request for comments.

98-24-02 MCDONNELL DOUGLAS: Amendment 39-10889. Docket 98-NM-304-AD. \n\n\tApplicability: Model MD-11 series airplanes, serial numbers 447 through 597 inclusive; 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 an electrical failure in the dimmer control for the overhead instrument panel light and circuit breaker lightplate due to overheating of a printed circuit board (PCB) capacitor in the dimmer control, which could result in rupture of the capacitor and smoke in the flight compartment, accomplish the following: \n\n\t(a)\tWithin 30 days after the effective date of this AD, perform a one-time visual inspection of the two dimmer controls for the overhead instrument panel light and circuit breaker lightplate located in the flight compartment to identify the part numbers of the dimmer controls. \n\n\t\t(1)\tIf all dimmer controls are identified as part number (P/N) 263-2, no further action is required by this AD. \n\n\t\t(2)\tIf any dimmer control is identified as P/N 263-1, within 30 days after accomplishing the inspection specified by paragraph (a) of this AD, accomplish the actions required by paragraph (a)(2)(i), (a)(2)(ii), or (a)(2)(iii) of this AD, in accordance with McDonnell Douglas Service Bulletin MD11-33-045, dated June 14, 1995. \n\n\t\t\t(i)\tReplace any dimmer control, P/N 263-1, with a new dimmer control, P/N 263-2. Or \n\n\t\t\t(ii)\tModify any dimmer control, P/N 263-1, and reinstall the modified and reidentified dimmer control in the flight compartment. Or \n\n\t\t\t(iii)\tRemove any dimmer control, P/N 263-1; return it for modification and reidentification to Olin Aerospace Company, 11441 Willows Road NE, Redmond, Washington, 98073-9745; and reinstall the modified and reidentified dimmer control in the flight compartment. \n\n\t(b)\tAs of the effective date of this AD, no person shall install on any McDonnell Douglas Model MD-11 series airplane, a dimmer control, P/N 263-1, unless that dimmer control has been modified and reidentified to P/N 263-2 in accordance with McDonnell Douglas Service Bulletin MD11-33-045, dated June 14, 1995. \n\n\t(c)\tAn alternative method of compliance or adjustment of the compliance time that provides an acceptable levelof safety may be used if approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Los Angeles ACO. \n\n\tNOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO. \n\n\t(d)\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\n\t(e)\tExcept as provided by paragraph (a) of this AD, the actions shall be done in accordance with McDonnell Douglas Service Bulletin MD11-33-045, dated June 14, 1995. 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 The Boeing Company, Douglas Products Division, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Technical Publications Business Administration, Dept. C1-L51 (2-60). Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Transport Airplane Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. \n\n\t(f)\tThis amendment becomes effective on November 30, 1998.

As part of its practice of re-examining all aspects of the service experience of a particular aircraft whenever an accident occurs, the FAA has become aware of several incidents of dimmer switches overheating and emitting smoke. These incidents occurred on McDonnell Douglas Model MD-11 series airplanes. \n\n\tInvestigation has revealed that, when a need for higher lighting in the cockpit occurs (such as during a thunderstorm) and increased voltage is required, a strong burning odor could occur due to overheating of a capacitor within the dimmer unit. The dimmer unit is located in the overhead switch panel to the rear of the firewall shut off handles. This component is well protected by a unit housing and additional cover that separates the unit from other components in the cockpit overhead compartment. \n\n\tThere is no evidence from any of the in-service events that any overheated capacitor has led to further aircraft damage beyond the capacitor. These incidents are not considered to be related to a recent accident that occurred off the coast of Nova Scotia involving a McDonnell Douglas Model MD-11 series airplane. The cause of that accident is still under investigation. \n\n\tOverheating of a capacitor inside the dimmer controls of the overhead instrument panel light and circuit breaker lightplate in the cockpit could cause an electrical failure in the overhead dimmer control, and consequent rupture of the PCB capacitor and smoke in the flight compartment. \n\nExplanation of Relevant Service Information \n\n\tThe FAA has reviewed and approved McDonnell Douglas Service Bulletin MD11-33-045, dated June 14, 1995, which describes the following procedures: \n\nReplacing any dimmer control, part number (P/N) 263-1, of the overhead instrument panel light and circuit breaker lightplate in the flight compartment with a new dimmer control, P/N 263-2. \n\nModifying any dimmer control, P/N 263-1, of the overhead instrument panel light and circuitbreaker lightplate to improve reliability and to extend the service life of dimmer controls by replacing one capacitor (C2) of the PCB assembly with a new, higher voltage capacitor that is more thermal resistant, reidentifying the existing dimmer control, and installing a new unit nameplate; and reinstalling the modified part. \n\nReturning the incorrect dimmer control, P/N 263-1, to the manufacturer of the part for modification and reidentification, and reinstalling the modified part. \n\n\tAccomplishment of either the replacement or modification 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 is being issued to prevent an electrical failure in the overhead dimmer control due to overheating of a PCB capacitor in the dimmer control, which could resultin rupture of the capacitor and smoke in the flight compartment. This AD requires a one- time visual inspection to identify the part numbers of two dimmer controls for the overhead instrument panel light and circuit breaker lightplate located in the flight compartment. For airplanes on which a dimmer control having a certain part number installed, this action also requires replacing the dimmer control with a new part; or replacing the existing dimmer control with a modified dimmer control. \n\n\tThe FAA has been notified by the manufacturer that a 30-day lead time for obtaining the required parts will be required, following the 30 days specified for inspection of the dimmer controls. The FAA considers that the 30-day lead time will accommodate the time necessary for affected operators to order and obtain the necessary parts required for the replacement of the dimmer controls, without adversely affecting safety. \n\nDetermination of Rule's Effective Date \n\n\tSince a situation existsthat 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. 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 98-NM-304-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 relationshipbetween 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\n Adoption 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\nAuthority: 49 U.S.C. 106(g), 40113, 44701. § 39.13 (Amended) \n\n\t2. Section 39.13 is amended by adding the following new airworthiness directive: