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Proposed Rule

Airworthiness Directives; Boeing Model 767-300 Series Airplanes

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 767-300 series airplanes. This proposed AD would require replacing the frequency converters used to supply power for medical outlets with modified frequency converters, and related actions. This proposed AD is prompted by a report indicating that a hard short circuit condition between the output of certain frequency converters and their downstream circuit breakers will produce a continuous output current that could cause the undersized output wiring to overheat when the frequency converters fail to shut off. We are proposing this AD to prevent overheating of the output wiring of the frequency converters, which could result in the failure of a wire bundle and consequent adverse effects on other systems sharing the affected wire bundle.

DATES:

We must receive comments on this proposed AD by May 2, 2005.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD.

  • DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
  • Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
  • Mail: Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, room PL-401, Washington, DC 20590.
  • By fax: (202) 493-2251.
  • Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this proposed AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

You can examine the contents of this AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., room PL-401, on the plaza level of the Nassif Building, Washington, DC. This docket number is FAA-2005-20629; the directorate identifier for this docket is 2004-NM-266-AD.

Start Further Info

FOR FURTHER INFORMATION CONTACT:

Binh Tran, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6485; fax (425) 917-6590.

End Further Info End Preamble Start Supplemental Information

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2005-20629; Directorate Identifier 2004-NM-266-AD” in the subject line of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments submitted by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of that Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You can review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you can visit http://dms.dot.gov.

Examining the Docket

You can examine the AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the DMS receives them.

Discussion

We have received a report indicating that analysis by the airplane manufacturer has shown that a hard short circuit condition between the output of certain frequency converters and their downstream, load circuit breakers will produce a continuous output current of 170—200 percent of nominal, on certain Boeing Model 747-200F and -400 series airplanes; Model 767-300 and -400ER series airplanes; and Model 777 series airplanes. The continuous current could cause the undersized output wiring to exceed its wire temperature rating of 150 degrees Celsius and consequently overheat when the frequency converters fail to shut off in response to a short circuit or overload. Overheating of the output wiring, if not corrected, could result in the failure of a wire bundle and consequent adverse effects on other systems sharing the affected wire bundle.

Other Related Rulemaking

On September 1, 2004, we proposed to amend 14 CFR part 39 with an AD for certain Boeing Model 747-200F and -400 series airplanes; Model 767-400ER series airplanes; and Model 777 series airplanes. That action, published in the Federal Register on September 13, 2004 (69 FR 55120), proposed to require replacing the frequency converter(s) used to supply electrical power for utility outlets (for the galley, medical equipment, or personal computers) with modified frequency converter(s). That action also proposed to require any specified action and related concurrent actions, as necessary. That proposed AD was prompted by a report that a hard short condition between the frequency Start Printed Page 12987converter's output and its downstream circuit breakers will produce a continuous circuit that could cause the undersized output wiring to overheat. The actions required by that proposed AD are intended to prevent the overheating of the frequency converter's undersized output wiring, which could lead to the failure of a wire bundle, and consequent adverse effects on other systems sharing the affected wire bundle.

Since issuance of that proposed AD, we have determined that the same unsafe condition addressed in that proposed AD also exists on certain Model 767-300 series airplanes. We have been advised that 54 Model 767-300 series airplanes were delivered with outlet installations using frequency converters affected by that proposed AD. Therefore, these additional airplanes are also subject to the same unsafe condition addressed in that proposed AD.

Relevant Service Information

We have reviewed Boeing Service Bulletin 767-25-0334, Revision 1, dated June 19, 2002. The service bulletin describes procedures for replacing the frequency converters used to supply power for medical outlets with modified frequency converters, and related actions. Replacement includes removing and sending the frequency converters to the vendor (Avionic Instruments, Inc.) for rework, and installing the reworked frequency converters. The other related actions include the following:

  • Collaring and labeling the circuit breaker(s) of the frequency converter input as “INOP” and removing the label(s) after installation of the modified frequency converters;
  • Capping and stowing the wire bundles of the frequency converters and reinstalling/connecting the wire bundles after installation of the modified frequency converters;
  • Installing a “DEACTIVATED” label on the frequency converter outlets and removing the labels after installation of the modified frequency converters;
  • Contacting the vendor for coordination of the rework; and
  • Doing a functional test of the replaced frequency converters.

Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other airplanes of this same type design. Therefore, we are proposing this AD, which would require accomplishing the actions specified in the service information described previously.

We have considered a number of factors in determining whether to issue a separate proposed AD or a supplemental notice of proposed rulemaking (NPRM) to the “related” NPRM (69 FR 55120, September 13, 2004). Although the 54 additional airplanes included in the applicability of this proposed AD were inadvertently omitted from the “related” NPRM, issuing a supplemental NPRM would require reopening the comment period of the “related” NPRM. However, to delay that action would be inappropriate, since we have determined that an unsafe condition exists and that modifications need to be made to ensure continued safety. We also have considered the entire fleet size that would be affected by issuing a supplemental NPRM and the fact that no new work would be required for airplanes affected by the “related” NPRM. In light of this, we have determined that a less burdensome approach is to propose a separate AD applicable only to the additional airplanes. This proposed AD would not reopen the comment period of the “related” NPRM; airplanes listed in the applicability of the “related” NPRM would be required to comply with the requirements of that proposed AD. This proposed AD is a separate AD action that is applicable only to certain Boeing Model 767-300 series airplanes, certificated in any category.

Costs of Compliance

There are about 55 airplanes of the affected design in the worldwide fleet. This proposed AD would affect about 54 airplanes of U.S. registry. The proposed actions would take about 1 work hour per frequency converter, at an average labor rate of $65 per work hour. There are about 2 frequency converters per airplane. Based on these figures, the estimated cost of the proposed AD for U.S. operators is $7,020, or $130 per airplane.

Authority for This Rulemaking

Title 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.

We 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.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD 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.

For the reasons discussed above, I certify that the 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. 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.

We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD. See the ADDRESSES section for a location to examine the regulatory evaluation.

Start List of Subjects

List of Subjects in 14 CFR Part 39

End List of Subjects

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

Start Part

PART 39—AIRWORTHINESS DIRECTIVES

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

Start Authority

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

End Authority
[Amended]

2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2005-20629; Directorate Identifier 2004-NM-266-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this AD action by May 2, 2005. Start Printed Page 12988

Affected ADs

(b) None.

Applicability

(c) This AD applies to certain Boeing Model 767-300 series airplanes, certificated in any category; as listed in Boeing Service Bulletin 767-25-0334, Revision 1, dated June 19, 2002.

Unsafe Condition

(d) This AD was prompted by a report indicating that a hard short circuit condition between the output of certain frequency converters and their downstream circuit breakers will produce a continuous output current that could cause the undersized output wiring to overheat when the frequency converters fail to shut off. We are issuing this AD to prevent overheating of the output wiring of the frequency converters, which could result in the failure of a wire bundle and consequent adverse effects on other systems sharing the affected wire bundle.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Replace Frequency Converters

(f) Within 18 months after the effective date of this AD, replace the frequency converters used to supply power for medical outlets with modified frequency converters, and do any related actions, by doing all of the actions specified in the Accomplishment Instructions of Boeing Service Bulletin 767-25-0334, Revision 1, dated June 19, 2002.

Credit for Previous Service Bulletin

(g) Actions done before the effective date of this AD in accordance with Boeing Service Bulletin 767-25-0334, dated November 7, 2002, are acceptable for compliance with the requirements of paragraph (f) of this AD.

Alternative Methods of Compliance (AMOCs)

(h) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

Start Signature

Issued in Renton, Washington, on March 8, 2005.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

End Signature End Part End Supplemental Information

[FR Doc. 05-5289 Filed 3-16-05; 8:45 am]

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