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Proposed Rule

Airworthiness Directives; Boeing Model 747 and 767 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 747 and 767 airplanes. This proposed AD would require reworking the electrical bonding between the airplane structure and the pump housing of the outboard boost pumps in the main fuel tank of certain Boeing Model 747 airplanes, and between the airplane structure and the pump housing of the override/jettison pumps in the left and right wing center auxiliary fuel tanks of certain Boeing Model 767 airplanes. This proposed AD would also require related investigative actions and corrective actions if necessary. This proposed AD is prompted by the results of fuel system reviews conducted by the manufacturer. We are proposing this AD to prevent insufficient electrical bonding, which could result in a potential of ignition sources inside the fuel tanks, and which, in combination with flammable fuel vapors, could result in fuel tank explosions and consequent loss of the airplane.

DATES:

We must receive comments on this proposed AD by August 15, 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-2005-21701; the directorate identifier for this docket is 2005-NM-086-AD.

Start Further Info

FOR FURTHER INFORMATION CONTACT:

Diane Pagel, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6488; 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-2005-21701; Directorate Identifier 2005-NM-086-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 Start Printed Page 37294site, 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 Docket Management System (DMS) receives them.

Discussion

The FAA has examined the underlying safety issues involved in recent fuel tank explosions on several large transport airplanes, including the adequacy of existing regulations, the service history of airplanes subject to those regulations, and existing maintenance practices for fuel tank systems. As a result of those findings, we issued a regulation titled “Transport Airplane Fuel Tank System Design Review, Flammability Reduction and Maintenance and Inspection Requirements” (67 FR 23086, May 7, 2001). In addition to new airworthiness standards for transport airplanes and new maintenance requirements, this rule included Special Federal Aviation Regulation No. 88 (“SFAR 88,” Amendment 21-78, and subsequent Amendments 21-82 and 21-83).

Among other actions, SFAR 88 requires certain type design (i.e., type certificate (TC) and supplemental type certificate (STC)) holders to substantiate that their fuel tank systems can prevent ignition sources in the fuel tanks. This requirement applies to type design holders for large turbine-powered transport airplanes and for subsequent modifications to those airplanes. It requires them to perform design reviews and to develop design changes and maintenance procedures if their designs do not meet the new fuel tank safety standards. As explained in the preamble to the rule, we intended to adopt airworthiness directives to mandate any changes found necessary to address unsafe conditions identified as a result of these reviews.

In evaluating these design reviews, we have established four criteria intended to define the unsafe conditions associated with fuel tank systems that require corrective actions. The percentage of operating time during which fuel tanks are exposed to flammable conditions is one of these criteria. The other three criteria address the failure types under evaluation: Single failures, single failures in combination with another latent condition(s), and in-service failure experience. For all four criteria, the evaluations included consideration of previous actions taken that may mitigate the need for further action.

We have received a report indicating that the outboard boost pumps in the main fuel tank of certain Boeing Model 747 airplanes, and the override/jettison pumps in the left and right wing center auxiliary fuel tanks of certain Boeing Model 767 airplanes, have insufficient electrical bonding between the pump housing and the airplane structure. This condition, if not corrected, could result in an ignition source inside the fuel tanks, which, in combination with flammable fuel vapors, could result in fuel tank explosions and consequent loss of the airplane.

Relevant Service Information

We have reviewed Boeing Special Attention Service Bulletin 747-28-2259, dated November 4, 2004 (for Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes). This service bulletin describes procedures for reworking the electrical bonding between the airplane structure and the pump housing of the outboard boost pumps in the main fuel tank, and related investigative and corrective actions. The rework consists of replacing the four mounting fasteners on each of the pump housings with rivets, stenciling each new rivet with the statement: “CAUTION—BONDING RIVET,” and, when the related investigative actions are completed, sealing the new rivets as specified in the airplane maintenance manual. The related investigative actions are measuring the electrical resistance of the new rivets, and doing an open-hole high-frequency eddy current (HFEC) inspection for cracks, corrosion, and damage. If the resistance is greater than the maximum allowable resistance specified in the service bulletin, the procedures include reworking the bonding as necessary according to the standard wiring practices manual, until the resistance is within allowable limits.

We have also reviewed Boeing Special Attention Service Bulletin 767-57-0092, dated November 4, 2004 (for Boeing Model 767-200, -300, and -300F series airplanes); and Boeing Special Attention Service Bulletin 767-57-0093, dated November 4, 2004 (for Boeing Model 767-400ER series airplanes). These service bulletins describe procedures for reworking the electrical bonding between the airplane structure and the pump housing of the override/jettison pumps in the left and right wing center auxiliary fuel tanks, and related investigative actions and corrective actions. The rework consists of cleaning the wing rib/ground bracket bonding surface, installing new fasteners for the ground brackets of the fuel override/jettison pump, using new bonding processes during the installation, and sealing the ground brackets. The related investigative actions are measuring the electrical resistance at specified points in the re-work process. If the electrical resistance is greater than the maximum allowable resistance specified in the service bulletin, the corrective action specified in the procedures includes repeating the applicable corrective actions and the applicable related investigative actions until the resistance is within allowable limits.

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, except as discussed under “Difference Between the Proposed AD and Special Attention Service Bulletin 747-28-2259.”

Difference Between the Proposed AD and Special Attention Service Bulletin 747-28-2259

Although Boeing Special Attention Service Bulletin 747-28-2259 does not specify an action to take if any crack, corrosion, or damage is found during the open-hole HFEC inspection, this proposed AD would require operators to repair those conditions in one of the following ways:

  • Using a method that we approve; or Start Printed Page 37295
  • Using data that meet the certification basis of the airplane, and that have been approved by an Authorized Representative for the Boeing Delegation Option Authorization Organization whom we have authorized to make those findings.

Costs of Compliance

There are about 3,401 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

ActionWork hourAverage labor rate pere hourCost per airplaneNumber of U.S.-registered airplanesFleet cost
Rework electrical bonding for Boeing Model 747 airplanes10$65$6501,115$724,750
Rework electrical bonding for Boeing Model 767 airplanes965585921538,785

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

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The Proposed Amendment

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

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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.

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[Amended]

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

Boeing: Docket No. FAA-2005-21701; Directorate Identifier 2005-NM-086-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this AD action by August 15, 2005.

Affected ADs

(b) None.

Applicability

(c) This AD applies to the Boeing airplane models identified in Table 1 of this AD, certificated in any category.

Table 1.—Airplanes Affected by This AD

Model—As identified in Boeing special attention service bulletin—
747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes747-28-2259, dated November 4, 2004.
767-200, -300, and -300F series airplanes767-57-0092, dated November 4, 2004.
767-400ER series airplanes767-57-0093, dated November 4, 2004.

Unsafe Condition

(d) This AD was prompted by the results of fuel system reviews conducted by the manufacturer. We are issuing this AD to prevent insufficient electrical bonding, which could result in a potential of ignition sources inside the fuel tanks, and which, in combination with flammable fuel vapors, could result in fuel tank explosions and consequent loss of the airplane.

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.

Rework Electrical Bonding

(f) Within 60 months after the effective date of this AD: Do the actions specified in paragraph (f)(1) or (f)(2) of this AD, as applicable, by accomplishing all the actions specified in the Accomplishment Instructions of the applicable service bulletin in Table 1 of this AD. Do any related investigative and corrective actions before further flight.

(1) For Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes: Rework the electrical bonding between the airplane structure and the pump housing of the outboard boost pumps in the main fuel tank, and do related investigative and Start Printed Page 37296applicable corrective actions. If any crack, corrosion, or damage is found during the open-hole high-frequency eddy current inspection specified in Boeing Special Attention Service Bulletin 747-28-2259, dated November 4, 2004: Before further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or in accordance with data meeting the certification basis of the airplane approved by an Authorized Representative for the Boeing Delegation Option Authorization Organization who has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the approval must specifically reference this AD.

(2) For Boeing Model 767-200, -300, -300F, and -400ER series airplanes: Rework the electrical bonding between the airplane structure and the pump housing of the override/jettison pumps in the left and right wing center auxiliary fuel tanks, and do the related investigative and applicable corrective actions.

Alternative Methods of Compliance (AMOCs)

(g) The Manager, Seattle 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 June 21, 2005.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

End Signature End Part End Supplemental Information

[FR Doc. 05-12840 Filed 6-28-05; 8:45 am]

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