04-27329. Airworthiness Directives; Boeing Model 737-600, -700, and -800 Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 737-600, -700, and -800 series airplanes. This proposed AD would require doing a general visual inspection for sealant at the interface of the upper spar fittings, strut side skins, and the fittings of the thrust reverser strut fairing on the engine struts; and applying an injection seal or silicone sponge rubber with fillet seal if necessary. This proposed AD is prompted by a report that an injection seal in the engine strut area may not have been properly completed or installed during production. We are proposing this AD to prevent flammable fluid (such as fuel or hydraulic fluid) from leaking onto a hot engine exhaust nozzle or into the engine core fire zone, and consequently cause an uncontrolled fire or explosion.

DATES:

We must receive comments on this proposed AD by January 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.
• By fax: [phone].
• 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.

FOR FURTHER INFORMATION CONTACT:

Technical information: Doug Pegors, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

Plain language information: Marcia Walters, [e-mail].

SUPPLEMENTARY INFORMATION:

Docket Management System (DMS)

The FAA has implemented new procedures for maintaining AD dockets electronically. As of May 17, 2004, new AD actions are posted on DMS and assigned a docket number. We track each action and assign a corresponding directorate identifier. The DMS AD docket number is in the form “Docket No. FAA-2004-99999.” The Transport Airplane Directorate identifier is in the form “Directorate Identifier 2004-NM-999-AD.” Each DMS AD docket also lists the directorate identifier (“Old Docket Number”) as a cross-reference for searching purposes.

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-2004-19810; Directorate Identifier 2004-NM-119-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 website, 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.

We are reviewing the writing style we currently use in regulatory documents. We are interested in your comments on whether the style of this document is clear, and your suggestions to improve the clarity of our communications that affect you. You can get more information about plain language at http://www.faa.gov/​language and http://www.plainlanguage.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 [phone]) 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 the injection seal at the interface of the upper spar fittings, strut side skins, and thrust reverser strut fairing fittings may not have been completed during production on certain Boeing Model 737-600, -700, and -800 series airplanes. The affected area is in a flammable fluid leakage zone, which requires absolute sealing of all openings. This condition, if not corrected, could result in flammable fluid (such as fuel or hydraulic fluid) leaking onto a hot engine exhaust nozzle or into the engine core fire zone, and consequently cause an uncontrolled fire or explosion.

Relevant Service Information

We have reviewed Boeing Special Attention Service Bulletin 737-54-1040, dated November 14, 2002; and Revision 1, dated August 14, 2003. The service bulletins describe procedures for doing a general visual inspection for sealant at the interface of the upper spar fittings, strut side skins, and the fittings of the thrust reverser strut fairing on the engine struts; and applying an injection seal or silicone sponge rubber with fillet seal if necessary. 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.

Costs of Compliance

This proposed AD would affect about 257 airplanes worldwide and 99 airplanes of U.S. registry. The proposed inspection would take about 2 work hours per airplane, at an average labor rate of $65 per work hour. Based on these figures, the estimated cost of the proposed AD for U.S. operators is $12,870, or $130 per airplane.

Authority for This Rulemaking

The FAA's authority to issue rules regarding aviation safety is found in Title 49 of the United States Code. 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.

This rulemaking is promulgated under the authority described in subtitle VII, part A, subpart III, section 44701, “General requirements.” Under that section, the FAA is charged with promoting safety 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 proposed AD.

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.

§ 39.13

[Amended]

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

Boeing: Docket No. FAA-2004-19810; Directorate Identifier 2004-NM-119-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this AD action by January 28, 2005.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Boeing Model 737-600, -700, and -800 series airplanes, as listed in Boeing Special Attention Service Bulletin 737-54-1040, Revision 1, dated August 14, 2003; certificated in any category.

Unsafe Condition

(d) This AD was prompted by a report that an injection seal in the engine strut area may not have been properly completed or installed during production. We are issuing this AD to prevent flammable fluid (such as fuel or hydraulic fluid) leaking onto a hot engine exhaust nozzle or into the engine core fire zone, and consequently cause an uncontrolled fire or explosion.

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.

Inspection and Corrective Action

(f) Within 18 months or 3,500 flight cycles after the effective date of this AD, whichever occurs first: Do a general visual inspection for sealant at the interface of the upper spar fittings, strut side skins, and the fittings of the thrust reverser strut fairing on the engine struts, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-54-1040, dated November 14, 2002; or Revision 1, dated August 14, 2003.

(1) If the injection seal is found to properly seal the entire gap, no further action is required by this AD.

(2) If the injection seal is not found to properly seal the entire gap or if the injection seal is found to be missing, before further flight, apply an injection seal or silicone sponge rubber with fillet seal in accordance with the Accomplishment Instructions of the service bulletin.

Alternative Methods of Compliance (AMOCs)

(g) 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.

Issued in Renton, Washington, on December 1, 2004.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.