E7-22543. Airworthiness Directives; Boeing Model 767-200, -300, -300F, and -400ER Series Airplanes

AGENCY:

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

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to supersede an existing airworthiness directive (AD) that applies to certain Boeing Model 767-200, -300, and -300F series airplanes. The existing AD currently requires reworking the surface of the ground stud bracket of the left and right transformer rectifier units (TRUs) and the airplane structure mounting surface, and measuring the resistance from the bracket to the structure and the ground lugs to the bracket using a bonding meter. This proposed AD would revise the applicability of the existing AD to include additional airplanes and would also require, among other actions, installation of a new ground stud bracket using faying surface bonding. This proposed AD results from a report of loss of all direct current (DC) power generation during a flight, due to inadequate electrical ground path between the ground bracket of the TRUs/main battery charger (MBC) and the structure. We are proposing this AD to prevent depletion of the main battery while in flight, resulting from the loss of both TRUs and the MBC, and consequent loss of all DC power, which could impact the safe flight and landing of the airplane due to the loss of function or malfunction of essential/critical systems and displays in the cockpit.

DATES:

We must receive comments on this proposed AD by January 3, 2008.

ADDRESSES:

You may send comments by any of the following methods:

• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
• Fax: [phone].
• Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.
• Hand Delivery: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

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

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov;​; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Office (telephone [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Louis Natsiopoulous, 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

We invite you to send any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSE section. Include “Docket No. FAA-2007-0203; Directorate Identifier 2007-NM-105-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD because of those comments.

We will post all comments we receive, without change, to http://www.regulations.gov,, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this proposed AD.

Discussion

On November 3, 2004, we issued AD 2004-23-14, amendment 39-13869 (69 FR 67043, November 16, 2004), for certain Boeing Model 767-200, -300, and -300F series airplanes. That AD requires reworking the surface of the ground stud bracket of the left and right transformer rectifier units (TRUs) and the airplane structure mounting surface, and measuring the resistance from the bracket to the structure and the ground lugs to the bracket using a bonding meter. That AD resulted from a report of loss of all direct current (DC) power generation during a flight, due to inadequate electrical ground path between the ground bracket of the TRUs and the structure. We issued that AD to prevent depletion of the main battery and consequent loss of all DC power, which could cause the loss of flight critical systems.

Actions Since Existing AD Was Issued

The preamble to AD 2004-23-14 explains that we consider the requirements “interim action” and were considering further rulemaking to add a redundant TRU ground bracket on all 767 airplanes. We now have determined that further rulemaking is indeed necessary, and this proposed AD follows from that determination.

In addition, Boeing has informed us that additional airplanes are subject to the identified unsafe condition (i.e., depletion of the main battery while in flight, resulting from the loss of both TRUs and the MBC, and consequent loss of all DC power, which could impact the safe flight and landing of the airplane due to the loss of function or malfunction of essential/critical systems and displays in the cockpit).

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 767-24A0162, dated May 30, 2006. The service information describes the following major procedures, depending on the airplane configuration:

• Reworking the existing ground stud bracket of the TRUs/MBC and structure mounting surface.
• Measuring the resistance from that bracket to the structure and from the ground lugs to that bracket using a bonding meter.
• Installing a new ground stud bracket using faying surface bonding.

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 develop on other airplanes of the same type design. For this reason, we are proposing this AD, which would supersede AD 2004-23-14 and would retain the requirements of the existing AD. This proposed AD also would require accomplishing the applicable actions specified in service information described previously. In addition, this proposed AD would expand the applicability of the existing AD to include additional airplanes.

Costs of Compliance

There are about 932 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Estimated Costs

Action	Work hours	Average labor rate per hour	Parts	Cost per airplane	Number of U.S.-registered airplanes	Fleet cost
Rework and Measurement (required by AD 2004-23-14)	1	$80	$4	$84	262	$22,008.
New proposed actions	1 or 2 1	80	208	$288 or $368 1	412	$118,656 or $151,616 1.
1 Depending on the airplane configuration.

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 and placed it in the AD docket. See the ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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. The Federal Aviation Administration (FAA) amends § 39.13 by removing amendment 39-13869 (69 FR 67043, November 16, 2004) and adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2007-0203; Directorate Identifier 2007-NM-105-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by January 3, 2008.

Affected ADs

(b) This AD supersedes AD 2004-23-14.

Applicability

(c) This AD applies to Boeing Model 767-200, -300, -300F, and -400ER series airplanes, certificated in any category, as identified in Boeing Alert Service Bulletin 767-24A0162, dated May 30, 2006.

Unsafe Condition

(d) This AD results from a report of loss of all direct current (DC) power generation during a flight, due to inadequate electrical ground path between the ground bracket of the left and right transformer rectifier unit (TRUs)/main battery charger (MBC) and the structure. We are issuing this AD to prevent depletion of the main battery while in flight, resulting from the loss of both TRUs and the MBC, and consequent loss of all DC power, which could impact the safe flight and landing of the airplane due to the loss of function or malfunction of essential/critical systems and displays in the cockpit.

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.

Requirements of AD 2004-23-14

Rework and Measure Resistance

(f) For Model 767-200, -300, and -300F series airplanes, as listed in Boeing Alert Service Bulletin 767-24A0119, Revision 2, dated August 19, 2004; on which the actions of Boeing Service Bulletin 767-24-0119, dated May 14, 1998, and/or Revision 1, dated December 16, 1999, have been done: Within 45 days after December 1, 2004 (the effective date of AD 2004-23-14), rework the ground stud bracket of the TRUs and structure mounting surface, and measure the resistance from the bracket to the structure and the grounding lug to the bracket using a bonding meter, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 767-24A0119, Revision 2, dated August 19, 2004, as revised by Boeing Information Notice 767-24A0119 IN 01, dated October 21, 2004, except as provided by paragraph (g) of this AD.

(g) Step 4, Sheet 3 of Figure 1 in the Accomplishment Instructions of the service bulletin only specifies to install one collar with part number (P/N) BACC30M6. However, a collar with P/N BACC30BL6 (as listed in paragraph 2.C., “Parts Necessary for Each Airplane” of the service bulletin) may be used as an alternative method of compliance (AMOC).

New Actions Required by This AD

Rework, Installation, Measurement, as Applicable

(h) For all airplanes: Within 36 months after the effective date of this AD, rework the existing ground stud bracket of the TRUs/MBC, measure the resistance, and install a new ground stud bracket of the TRUs by doing all the applicable actions specified in the Accomplishment Instructions of Boeing Alert Service Bulletin 767-4A0162, dated May 30, 2006.

AMOCs

(i)(1) The Manager, Seattle Aircraft Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

(2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO.

Issued in Renton, Washington, on November 7, 2007.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.