Airworthiness Directives; Boeing Model 707 Airplanes and Model 720 and 720B Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to supersede an existing airworthiness directive (AD) that applies to certain Boeing Model 707 airplanes and Model 720 and 720B series airplanes. The existing AD currently requires a preventive modification of the front spar fitting on the outboard engine nacelle. This proposed AD would remove the requirement to do this preventive modification, and would require repetitive inspections for cracking of the front spar fitting of the inboard and outboard nacelle struts, and replacement of any cracked fitting with a new fitting. The proposed AD would also apply to more airplanes. This proposed AD is prompted by a report indicating that a crack was found in a front spar fitting that had been replaced as part of the modification required by the existing AD. We are proposing this AD to detect and correct this cracking, which could result in reduced structural integrity of the engine nacelle, and consequent separation of an engine from the airplane.

DATES:

We must receive comments on this proposed AD by February 28, 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.
• 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-2005-20023; the directorate identifier for this docket is 2004-NM-49-AD.

FOR FURTHER INFORMATION CONTACT:

Candice Gerretsen, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6428; 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-2005-20023; Directorate Identifier 2004-NM-49-AD” at the beginning 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 received 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 our docket 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 the 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

On August 20, 2001, we issued AD 2001-17-24, amendment 39-12415 (66 FR 45572, August 29, 2001), for certain Boeing Model 707 airplanes and 720 and 720B series airplanes. That AD requires a preventive modification of the front spar fitting on the outboard engine nacelle. That AD was prompted by reports indicating that fatigue cracks have been found in the front spar fitting on the outboard engine nacelle. We issued that AD to prevent this fatigue cracking, which could reduce the structural integrity of the nacelle and result in separation of the engine from the airplane.

Actions Since Existing AD Was Issued

Since we issued AD 2001-17-24, we have received a report indicating that a crack was found in a front spar fitting that had been previously modified as required by AD 2001-17-24. This report led to a determination that the currently required modification is not effective in preventing the previously identified unsafe condition.

Since we issued AD 2001-17-24, we have also determined that the front spar fitting on the inboard engine nacelle may also be subject to the same unsafe condition found on the outboard engine nacelle.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin A3514, dated July 29, 2004. The service bulletin describes procedures for performing repetitive detailed inspections for cracking of the upper surface of the front spar fitting of nacelle struts 1, 2, 3, and 4; and replacing any cracked fitting with a new fitting.

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 products of this same type design. This proposed AD would supersede AD 2001-17-24. This proposed AD would remove the requirement to do the preventive modification of the front spar fitting on the outboard engine nacelle. This proposed AD would require repetitive inspections for cracking of the front spar fitting of the inboard and outboard nacelle struts, and replacement of any cracked fitting with a new fitting. The proposed AD would also apply to more airplanes because it would apply to airplanes having front spar fittings previously modified during production.

Explanation of Change to Applicability

We have revised the applicability of the existing AD to identify model designations as published in the most recent type certificate data sheet for the affected models.

Costs of Compliance

There are about 290 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.

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.

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.