05-6251. Airworthiness Directives; Boeing Model 707-300B, -300C, and -400 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 all Boeing Model 707-300B, -300C, and -400 series airplanes. This proposed AD would require repetitive inspections to detect cracked or broken hinge fitting assemblies of the inboard leading edge slats, and corrective action if necessary. This proposed AD would provide as an option a preventive modification, which would defer the repetitive inspections. This proposed AD also would provide an option of replacing all hinge fitting assemblies with new, improved parts, which would terminate the repetitive inspection requirements. This proposed AD is prompted by results of a review to identify and implement procedures to ensure the continued structural airworthiness of aging transport category airplanes. We are proposing this AD to detect and correct fatigue cracking of the hinge fitting assembly of the inboard leading edge slats, which could result in reduced structural integrity of the slat system. This condition could result in loss of the inboard leading edge slat and could cause the flightcrew to lose control of the airplane.

DATES:

We must receive comments on this proposed AD by May 16, 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.

You can get the service information identified in this proposed AD from Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

You may 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-2005-20725; Directorate Identifier 2003-NM-250-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 may review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may 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 may 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

The Air Transport Association (ATA) of America and the Aerospace Industries Association (AIA) of America agreed to undertake the task of identifying and implementing procedures to ensure the continued structural airworthiness of aging transport category airplanes. An Airworthiness Assurance Working Group (AAWG) was established in August 1988, with members representing aircraft manufacturers, operators, regulatory authorities, and other aviation industry representatives worldwide. The objective of the AAWG was to sponsor “Task Groups” to:

1. Select service bulletins, applicable to each airplane model in the transport fleet, to be recommended for mandatory modification of aging airplanes;

2. Develop corrosion-directed inspections and prevention programs;

3. Review the adequacy of each operator's structural maintenance program;

4. Review and update the Supplemental Inspection Documents (SID); and

5. Assess repair quality.

Based on the results of this review, the task group for Boeing Model 707 series airplanes recommended replacing all hinge fitting assemblies on Boeing Model 707-300B, -300C, and -400 series airplanes to prevent fatigue cracking of the hinge fitting assembly of the inboard leading edge slats, which could result in reduced structural integrity of the slat system. This condition could result in loss of the inboard leading edge slat, which could cause the flightcrew to lose control of the airplane.

We partially agree with the task group's recommendation. We agree that corrective action is necessary to address the identified unsafe condition. However, we do not agree with the recommendation to mandate the replacement of all hinge fitting assemblies for the following reasons:

1. Accessing the hinge fitting assemblies for inspection is easily accomplished; and

2. Cracked or broken assemblies are easily detectable by means of a visual inspection.

Relevant Service Information

We have reviewed Boeing Service Bulletin 2982, Revision 2, dated October 7, 1977. This service bulletin describes procedures for doing repetitive dye penetrant inspections to detect cracked or broken hinge fitting assemblies of the inboard leading edge slats, and corrective action if necessary. The corrective action replaces any cracked or broken hinge fitting assembly with the following:

• A like serviceable part;
• A like serviceable part on which the preventative modification (described below) has been done. This replacement defers the repetitive inspections for 1.5 times the total flight hours at the time of modification for that hinge fitting assembly; or
• A new, improved part. This replacement ends the repetitive inspections for that hinge fitting assembly.

As an option to the repetitive dye penetrant inspections, this service bulletin also describes procedures for a preventive modification, which consists of a magnetic particle inspection and rework of the hinge fitting assembly. This preventive modification provides a new threshold for doing the repetitive dye penetrant inspections of the hinge fitting assemblies. This service bulletin also describes procedures for replacing all hinge fitting assemblies with new, improved parts, which ends the repetitive inspections. We have determined that accomplishment of 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 dye penetrant inspections of the hinge fitting assemblies of the inboard leading edge slats to detect cracks or broken parts of the hinge fitting assemblies of the inboard leading edge, and corrective action if necessary. This proposed AD would provide as an option a preventive modification, which would defer the repetitive dye penetrant inspections. This proposed AD also would provide an option of replacing all hinge fitting assemblies with new, improved parts, which would terminate the repetitive inspection requirements. 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

The service bulletin gives a new inspection threshold following a preventive modification that is “equal to 1.5 times the accumulated flight hours at the time of the modification.” This preventive modification is included in paragraph (i) of this proposed AD. Instead of allowing a threshold that multiplies the current number of flight hours, paragraph (i) proposes to limit the inspection threshold to 15,000 flight hours following the preventive modification. We have made this change to the inspection threshold because, when the service bulletin was originally released in 1970, the affected airplanes had relatively few total flight hours. All affected airplanes now have significantly more total flight hours—in one case, more than 90,000. We find that allowing a threshold of 1.5 times the flight hours of any airplane in the current fleet would not provide an adequate level of safety.

This proposed AD also differs from the service bulletin in that it applies to Boeing Model 707-400 series airplanes as well as the Boeing Model 707-300B and -300C series airplanes specified in the service bulletin. As stated earlier in this proposed AD, the inboard leading edge slats on the Model 707-400 series airplanes have the same configuration as that on the affected Model 707-300B and -300C series airplanes. Therefore, those Model 707-400 series airplanes may be subject to the same unsafe condition as the Model -300B, and -300C series airplanes. In addition, the procedures in the service bulletin also address the unsafe condition on the Model 707-400 series airplanes.

The service bulletin does not provide procedures for repairing any crack found during the magnetic particle inspection (part of the preventative modification). This proposed AD would require you to do the corrective action specified in paragraph (h) of the proposed AD.

We have coordinated the differences discussed above with the airplane manufacturer.

Clarification Between the Proposed AD and the Service Bulletin

The service bulletin allows operators to use a “like serviceable part.” For this proposed AD, we have defined “like serviceable part” as a serviceable part listed in the “Existing” part number column of Table II of the service bulletin that has been inspected and found to be crack free in accordance with paragraph (g) of this AD before installation. A “new part” is a part listed in the “Replacement” or “Optional” part number column of Table II of the service bulletin.

Costs of Compliance

This proposed AD would affect about 189 Boeing Model 707-300B, -300C, and -400 series airplanes worldwide. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Estimated Costs

Action	Work hours	Average labor rate per hour	Parts	Cost per airplane	Number of U.S.-registered airplanes
Dye Penetrant Inspection	3	$65	None	$195 (per inspection cycle)	16
Preventive Modification (Optional)	10	65	None	650 (per inspection)	16
Terminating Action (Optional)	10	65	$8,220	8,870	16

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, 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 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-2005-20725; Directorate Identifier 2003-NM-250-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this AD action by May 16, 2005.

Affected ADs

(b) None.

Applicability

(c) This AD applies to all Boeing Model 707-300B, -300C, and -400 series airplanes, certificated in any category.

Unsafe Condition

(d) This AD was prompted by results of a review to identify and implement procedures to ensure the continued structural airworthiness of aging transport category airplanes. We are proposing this AD to detect and correct fatigue cracking of the hinge fitting assembly of the inboard leading edge slats, which could result in reduced structural integrity of the slat system. This condition could result in loss of the inboard leading edge slat and could cause the flightcrew to lose control 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.

Service Bulletin Reference

(f) In this AD, the term “service bulletin” means the Accomplishment Instructions of Boeing Service Bulletin 2982, Revision 2, dated October 7, 1977.

Repetitive Inspections

(g) Before the accumulation of 10,000 total flight hours, or within 1,500 flight hours after the effective date of this AD, whichever occurs later, do a dye penetrant inspection to detect cracked or broken hinge fitting assemblies of the inboard leading edge slats in accordance with Part I, “Inspection Data,” of the service bulletin. Repeat the inspection at intervals not to exceed 1,500 flight hours, except as provided by paragraph (i) or (k) of this AD.

Corrective Action

(h) If any crack or broken assembly is found during any inspection required by paragraph (g) of this AD, before further flight, do the action specified in paragraph (h)(1), (h)(2), or (h)(3) of this AD.

(1) Replace the hinge fitting assembly with like serviceable part in accordance with Part I of the service bulletin.

(2) Replace the hinge fitting assembly with like serviceable part on which the preventative modification specified in paragraph (i) of this AD has been done, in accordance with Part II of the service bulletin. This replacement defers the repetitive inspection requirements of paragraph (g) of this AD for 15,000 flight hours for that hinge fitting assembly.

(3) Replace the hinge fitting assembly with a new, improved part in accordance with Part III of the service bulletin. This replacement terminates the repetitive inspection requirements of paragraph (g) of this AD for that hinge fitting assembly.

Note 1:

For this AD, a “like serviceable part” is a serviceable part listed in the “Existing” part number column of Table II of the service bulletin that has been inspected and found to be crack free in accordance with paragraph (g) of this AD before installation. A “new part” is a part listed in the “Replacement” or “Optional” part number column of Table II of the service bulletin.

Optional Preventative Modification (Defers Repetitive Inspections)

(i) Do a preventative modification by accomplishing all the procedures in Part II of the service bulletin, except as required by paragraph (j) of this AD. Within 15,000 flight hours after the preventive modification, do the repetitive inspections in paragraph (g) of this AD at intervals not to exceed 1,500 flight hours.

(j) If any crack is found during the preventative modification specified in paragraph (i) of this AD, before further flight, do the action specified in paragraph (h) of this AD.

Optional Terminating Action

(k) Replacement of a hinge fitting assembly with a new, improved part terminates the repetitive inspection requirements of paragraph (g) of this AD for that assembly. Replacement of all hinge fitting assemblies with new, improved parts terminates the repetitive inspection requirements of this AD. The replacement must be done in accordance with Part III of the service bulletin.

Actions Accomplished Using a Previous Issue of the Service Bulletin

(l) Actions accomplished before the effective date of this AD using Boeing Service Bulletin 2982, Revision 1, dated June 29, 1970, are considered acceptable for compliance with the corresponding action in this AD.

Alternative Methods of Compliance (AMOCs)

(m)(1) The Manager, Seattle Aircraft Certification Office (ACO) has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19.

(2) An AMOC that provides an acceptable level of safety may be used for a preventive modification of hinge fitting assemblies of the inboard leading edge slat if it is 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 repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD.

Issued in Renton, Washington, on March 17, 2005.

Jeffery E. Duven,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.