Airworthiness Directives; Boeing Model 777-200, -200ER, and -300 Series Airplanes

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 777-200, -200ER, and -300 series airplanes. This proposed AD would require modification of the splice plate assemblies installed under the floor panels at the forward and aft edges of the cabin aisle. This proposed AD is prompted by reports of cracking of the aluminum splice plates under the floor panels in the cabin aisle. We are proposing this AD to prevent loss of the capability of the cabin floor and seat track structure to support the airplane interior inertia loads under emergency landing conditions. Loss of this support could lead to galley or seat separation from attached restraints, which could result in blocking of the emergency exits and consequent injury to passengers and crew.

DATES:

We must receive comments on this proposed AD by April 18, 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-2005-20475; the directorate identifier for this docket is 2004-NM-157-AD.

FOR FURTHER INFORMATION CONTACT:

Gary Oltman, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6443; fax (425) 917-6590.

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-2005-20475; Directorate Identifier 2004-NM-157-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 reports indicating that cracking of the aluminum splice plates installed at the forward and aft edges under the floor panels in the cabin was found during routine maintenance on several Model 777 series airplanes. The floor panels are attached with fasteners that pass through the floor panel and connect to a threaded nut plate on the splice plate. The airplanes had accumulated between 1,375 and 14,614 total flight cycles. Analysis shows that the cracking of the splice plates is due to repeated bending from frequent traffic in the cabin aisle. This condition, if not corrected, could result in loss of the capability of the cabin floor and seat track structure to support the airplane interior inertia loads under emergency landing conditions. Loss of this support could lead to galley or seat separation from attached restraints, which could result in blocking of the emergency exits and consequent injury to passengers and crew.

Relevant Service Information

We have reviewed Boeing Special Attention Service Bulletin 777-53-0042, dated April 15, 2004. The service bulletin describes procedures for modification of the splice plate assemblies under the floor panels at the forward and aft edges of the cabin aisle. The modification involves replacing the existing aluminum splice plate assemblies with new fiberglass laminate assemblies; and marking the service bulletin number on the top of the floor panel. The modification also includes replacing any damaged fasteners with new fasteners. 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 “Differences Between the Proposed AD and Service Bulletin.”

Differences Between the Proposed AD and Service Bulletin

The service bulletin recommends accomplishing the modification at the next scheduled heavy maintenance check, not to exceed 72 months from the service bulletin release date. We have determined that, because maintenance schedules vary among operators, and in order to address the unsafe condition in a timely manner, this proposed AD would require compliance within 60 months after the effective date of this AD. In developing an appropriate compliance time for this proposed AD, we considered not only the manufacturer's recommendation, but the degree of urgency associated with addressing the subject unsafe condition, the average utilization of the affected fleet, and the time necessary to perform the modification. In light of all of these factors, we find a compliance time of 60 months for completing the modification to be warranted, in that it represents an appropriate interval of time for affected airplanes to continue to operate without compromising safety.

The applicability of the service bulletin inadvertently excluded Boeing Model 777-200ER series airplanes. Therefore, this proposed AD includes a requirement that the actions specified in the service bulletin be accomplished on those airplanes. This requirement would ensure that the actions specified in the service bulletin, and required by this proposed AD, are accomplished on all affected airplanes.

The service bulletin also recommends marking the service bulletin number on the top of the floor panel assembly, but this proposed AD would not require that action. We find that, with a variety of marking methods and panel locations, this marking could not be accurately verified.

These differences have been coordinated with the manufacturer.

Costs of Compliance

There are about 330 airplanes of the affected design in the worldwide fleet. This proposed AD would affect about 131 airplanes of U.S. registry. The proposed modification would take about 28 work hours per airplane, at an average labor rate of $65 per work hour. Required parts would cost between $4,717 and $9,099 per airplane. Based on these figures, the estimated cost of the proposed AD for U.S. operators is between $856,347 and $1,430,389, or between $6,537 and $10,919 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 will not have federalism implications under Executive Order 13132. This proposed AD will 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.

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.