02-12323. Airworthiness Directives; Boeing Model 737-300, -400, -500, -600, -700, -700C, -800, -900; 747-400; 757; 767; and 777 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 737-300, -400, -500, -600, -700, -700C, -800, -900; 747-400; 757; 767; and 777 series airplanes. This proposal would require modifying the static inverter by relocating resistor R170 of the static inverter bridge assembly. This action is necessary to prevent a standby static inverter from overheating, which could result in smoke in the flight deck and cabin and loss of the electrical standby power system. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by July 1, 2002.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2002-NM-12-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to [phone]. Comments may also be sent via the Internet using the following address: [e-mail]. Comments sent via fax or the Internet must contain “Docket No. 2002-NM-12-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

Binh V. Tran, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed 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 above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this action may be changed in light of the comments received.

Submit comments using the following format:

• 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.
• For each issue, state what specific change to the proposed AD is being requested.
• Include justification (e.g., reasons or data) for each request.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket 2002-NM-12-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket 2002-NM-12-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received reports that static inverters had overheated on several Boeing airplanes. In one incident, smoke entered the flight deck and the cabin, and the captain declared an emergency. The smoke was traced to the static inverter unit, a critical piece of equipment that converts battery power during a standby condition. The type of static inverter involved in this incident is used on the affected Boeing airplane models. Analysis conducted by the manufacturer indicates that the proximity of resistor R170 to capacitors C50 and C51 in the static inverter could lead to overheating and consequent damage or failure of those capacitors. The results of the analysis suggest that the combination of obstructed convection cooling and localized heat dissipation from resistor R170 resulted in sufficient energy to damage the adjacent capacitors. These conditions, if not corrected, could result in smoke in the flight deck and cabin and loss of the electrical standby power system.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Service Letters 737-SL-24-165, 747-SL-24-058, 757-SL-24-069, 767-SL-24-047, and 777-SL-24-028; dated October 3, 2000. The service letters describe procedures for modifying the static inverter by relocating resistor R170 of the static inverter bridge assembly and reidentifying the static inverter to indicate the new modification level. Accomplishment of the actions specified in the service letters is intended to adequately address the identified unsafe condition.

The service letters refer to Avionic Instruments Inc. Service Bulletin 1-002-0102-1000-24-24, dated July 19, 1999, as an additional source of service information for relocating R170 and reidentifying the static inverter.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would require accomplishment of the actions specified in the service letters.

Cost Impact

There are approximately 3,832 airplanes of the affected design in the worldwide fleet. The FAA estimates that 1,882 airplanes of U.S. registry would be affected by this proposed AD.

The cost impact discussed in ADs is based on assumptions that no operator has yet accomplished any of the proposed requirements, and that no operator would accomplish those actions in the future if the proposed AD were not adopted. However, the FAA has been advised that manufacturer warranty remedies are available for the cost of modified replacement parts and labor associated with accomplishing the actions specified by this proposed AD. Therefore, the economic cost impact of this proposed AD on U.S. operators may be minimal. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations proposed herein would 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. Therefore, it is determined that this proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this proposed regulation (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

§ 39.13

[Amended]

2. Section 39.13 is amended by adding the following new airworthiness directive:

Boeing: Docket 2002NM-12AD.

Applicability: The following airplanes, certificated in any category:

Table 1.—Applicability

Model/series	Equipped with Avionic Instruments Inc. static inverters having any of the following part numbers (P/Ns)—	Which correspond to Boeing P/Ns—
737-300, -400, -500, -600, -700, -800, -900	1-002-0102-0265	S282T004-5
747-400	1-002-0102-0714	S282T004-7
757	1-111-0102-0714	S282T004-8
767	1-002-0102-1000	S282T004-10
777

Note 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.

Compliance: Required as indicated, unless accomplished previously.

To prevent a standby static inverter from overheating, which could result in smoke in the flight deck and cabin and loss of the electrical standby power system, accomplish the following:

Modification

(a) Within 18 months after the effective date of this AD: Modify the static inverter by relocating resistor R170 of the static inverter bridge assembly and reidentifying the static inverter to indicate the new modification level, in accordance with Boeing Service Letters 737-SL-24-165, 747-SL-24-058, 757-SL-24-069, 767-SL-24-047, and 777-SL-24-028; dated October 3, 2000.

Note 2:

The Boeing service letters refer to Avionic Instruments Inc. Service Bulletin 1-002-0102-1000-24-24, dated July 19, 1999, as an additional source of service information for the modification required by paragraph (a) of this AD.

Spare Parts

(b) As of the effective date of this AD, no person may install, on any airplane, a static inverter having a part number listed in the applicability section of this AD, unless the static inverter has been modified in accordance with the requirements of this AD.

Alternative Methods of Compliance

(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.

Note 3:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

Special Flight Permits

(d) Special 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.

Issued in Renton, Washington, on May 10, 2002.

Ali Bahrami,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.