04-21821. Airworthiness Directives; Boeing Model 747-100, -100B, -100B SUD, -200B, -200C, -200F, and -300 Series Airplanes; and Model 747SP and 747SR Series Airplanes; Equipped with Pratt & Whitney JT9D-3, and -7 (except -70) Series Engines or ...

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 airplanes listed above. This proposed AD would require repetitive detailed inspections of the midspar web of the inboard and/or outboard struts for cracking, disbonding, or buckling; repetitive detailed inspections of the midspar stiffeners for any crack or fracture; related investigative actions; and corrective actions, if necessary. This proposed AD is prompted by reports of cracking in the midspar web. We are proposing this AD to detect and correct cracking in the midspar assembly, which could result in the loss of the midspar assembly load path, and could, combined with the loss of the Nacelle Station 180 bulkhead load path, lead to the separation of the engine from the airplane.

DATES:

We must receive comments on this proposed AD by November 15, 2004.

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 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:

Candice Gerretsen, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

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 written relevant data, views, or arguments regarding this proposed AD. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2004-19200; Directorate Identifier 2003-NM-195-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.

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 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 reports of cracking in the midspar web, and one report of a fractured stiffener on certain Boeing Model 747 series airplanes with Pratt & Whitney Model JT9D-7 series engines. The cracking/fracture was caused by fatigue and sonic-induced vibration. This condition, if not detected and corrected, could result in the loss of the midspar assembly load path, and could, combined with the loss of the Nacelle Station 180 bulkhead load path, lead to the separation of the engine from the airplane.

Similar Design

The subject area on Boeing Model 747 series airplanes with Pratt & Whitney Model JT9D-3 series engines or General Electric Model CF6-50 series engines with modified JT9D-7 inboard struts is identical to that on the affected Model 747 series airplanes with JT9D-7 series engines. Therefore, those Model 747 series airplanes with JT9D-3 series engines or CF6-50 series engines with modified JT9D-7 inboard struts may be subject to the same unsafe condition revealed on the Model 747 series airplanes with JT9D-7 series engines.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 747-54A2219, dated September 4, 2003, which describes the following procedures:

• For Group 1 and 2 airplanes: Performing repetitive detailed inspections of the midspar web of the inboard struts for cracking, disbonding, or buckling.
• For Group 1 airplanes: Performing repetitive detailed inspections of the midspar web of the outboard struts for cracking, disbonding, or buckling.
• For Group 1 and 2 airplanes: Performing repetitive detailed inspections of the midspar stiffeners of the inboard struts for any crack or fracture.
• For Group 1 airplanes: Performing repetitive detailed inspections of the midspar stiffeners of the outboard struts for any crack or fracture.
• For Group 1 and 2 airplanes: Performing related investigative actions. The related investigative actions include performing a high frequency eddy current (HFEC) or penetrant inspection for cracking of any buckle found on the midspar web and performing an ultrasonic inspection for disbonding of any buckle found on the midspar web.
• For Group 1 and 2 airplanes: Performing corrective actions, if necessary. The corrective actions include repairing the midspar web or replacing the midspar stiffener with a new midspar stiffener (includes an HFEC inspection of the stiffener hole for any crack), and contacting Boeing if any crack is found in the stiffener hole or if any buckle is found that does not have any cracking and the web is not disbonded.

We have determined that accomplishing the actions specified in the service bulletin will 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 repetitive detailed inspections of the midspar web of the inboard and/or outboard struts for cracking, disbonding, or buckling; repetitive detailed inspections of the midspar stiffeners for any crack or fracture; related investigative actions; and corrective actions, if necessary. The proposed AD would require you to use the service information described previously to perform these actions, except as discussed under “Differences Between the Proposed AD and the Service Bulletin.”

Differences Between the Proposed AD and the Service Bulletin

Operators should note that, although the service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, this proposal would require the repair of those conditions to be accomplished per a method approved by the FAA, or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the FAA to make such findings.

Costs of Compliance

This proposed AD would affect about 78 airplanes of U.S. registry and 228 airplanes worldwide. The proposed actions would take about 6 to 13 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 between $30,420 and $65,910, or between $390 and $845 per airplane, per inspection cycle.

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-2004-19200; Directorate Identifier 2003-NM-195-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this AD action by November 15, 2004.

Affected ADs

(b) None.

Applicability: (c) This AD applies to Boeing Model 747-100, -100B, -100B SUD, -200B, -200C, -200F, and -300 series airplanes; and Model 747SP and 747SR series airplanes; certificated in any category; equipped with Pratt & Whitney JT9D-3, and -7 (except-70) series engines or General Electric CF6-50 series engines with modified JT9D-7 inboard struts; as listed in Boeing Alert Service Bulletin 747-54A2219, dated September 4, 2003.

Unsafe Condition

(d) This AD was prompted by reports of cracking in the midspar web. We are issuing this AD to detect and correct cracking in the midspar assembly, which could result in the loss of the midspar assembly load path, and could, combined with the loss of the Nacelle Station 180 bulkhead load path, lead to the separation of the engine from 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.

Compliance Times

(f) Within 18 months after the effective date of this AD, do the actions in paragraphs (g) and (h) of this AD, as applicable. Repeat the actions thereafter at intervals not to exceed 1,200 flight cycles.

Inboard Strut Midspar Inspection

(g) For Group 1 and 2 airplanes specified in paragraph 1.A.1. of Boeing Alert Service Bulletin 747-54A2219, dated September 4, 2003: Perform a detailed inspection of the midspar web of the inboard struts for cracking, disbonding, or buckling; a detailed inspection of the midspar stiffeners for any crack or fracture; related investigative actions; and any applicable corrective actions; in accordance with “Part 1” of the Work Instructions of Boeing Alert Service Bulletin 747-54A2219, dated September 4, 2003; except as required by paragraph (i) of this AD. Perform any related investigative actions and any applicable corrective actions before further flight.

Outboard Strut Midspar Inspection

(h) For Group 1 airplanes specified in paragraph 1.A.1. of Boeing Alert Service Bulletin 747-54A2219, dated September 4, 2003: Perform a detailed inspection of the midspar web of the outboard struts for cracking, disbonding, or buckling; a detailed inspection of the midspar stiffeners for any crack or fracture; related investigative actions; and any applicable corrective actions; in accordance with “Part 2” of the Work Instructions of Boeing Alert Service Bulletin 747-54A2219, dated September 4, 2003; except as required by paragraph (i) of this AD. Perform any related investigative actions and any applicable corrective actions before further flight.

Contact the FAA/Designated Engineering Representative

(i) Where Boeing Alert Service Bulletin 747-54A2219, dated September 4, 2003, specifies to contact Boeing for appropriate action: Before further flight, repair per a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved, the approval must specifically reference this AD.

Alternative Methods of Compliance (AMOCs)

(j)(1) 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.

(2) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD, if it is approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the approval must specifically refer to this AD.

Issued in Renton, Washington, on September 21, 2004.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.