Federal Register: PROPOSED RULES Airworthiness Directives: [14 CFR Part 39]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

CFR Citation: 14 CFR Part 39

Docket ID: [Docket No. FAA-2008-0520; Directorate Identifier 2008-NM-018-AD]

RIN ID: RIN 2120-AA64

NOTICE: PROPOSED RULES

ACTION: Airworthiness Directives:

DOCUMENT ACTION: Notice of proposed rulemaking (NPRM).

SUBJECT CATEGORY: Airworthiness Directives; Boeing Model 777-200 Series Airplanes

DATES: We must receive comments on this proposed AD by June 23, 2008.

DOCUMENT SUMMARY: We propose to adopt a new airworthiness directive (AD) for certain Boeing Model 777200 series airplanes. This proposed AD would require repetitive inspections for any wrinkle in certain external skin panels, and for cracking at the fuselage bulkhead shear tie end fastener locations at certain stations of section 48 of the fuselage; and doing related investigative and corrective actions if necessary. This proposed AD results from a report of cracks found in the external skin on the left and right sides of the Section 48 panel of the fuselage on two airplanes with skin wrinkles found at two of the external crack locations. We are proposing this AD to detect and correct wrinkles and cracks in certain external skin panels of Section 48, which could join together and result in reduced structural integrity of support structure for the vertical and horizontal stabilizers and inability of the airplane to sustain limit loads.

SUMMARY: Boeing Model 777-200 Series Airplanes,

SUPPLEMENTAL INFORMATION

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include ``Docket No. FAA20080520; Directorate Identifier 2008NM018AD'' at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD because of those comments.

We will post all comments we receive, without change, to http:// www.regulations.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this proposed AD.

Discussion

We have received a report of cracks found in the external skin on the left and right sides of the section 48 panel of the fuselage on two airplanes. There were ten external skin cracks on one airplane with 22,732 total flight hours and 20,286 total flight cycles; the cracks were 0.20 to 0.50 inch in length at
[[Page 25600]]
Stations 2195.75 and 2221.65, between Stringers 6 to 10 on the left and right sides. In addition, skin wrinkles 4.5 and 5.0 inches long and 1.0 inch wide and 0.014 inch deep were found at two of the external skin crack locations. A second report indicated that three external skin cracks, 0.12 to 0.20 inches in length were found at Station 2195.75, above Stringer 7 on the left side, on an airplane with 22,147 total flight hours and 19,281 total flight cycles. This condition, if not corrected, could result in reduced structural integrity of support structure for the vertical and horizontal stabilizers and inability of the airplane to sustain limit loads.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 77753A0051, dated November 8, 2007. The alert service bulletin describes procedures for repetitive general visual inspections for any wrinkle of the external skin at Stations 2195.75, 2221.65, and 2245.70 of the Section 48 panel of the fuselage, between stringers 5 and 10 on the left and right sides. The service bulletin also describes procedures for repetitive high frequency eddy current (HFEC) and detailed inspections for cracking at the fuselage bulkhead shear tie end fastener locations of the external skin at Stations 2195.75, 2221.65, and 2245.70 of the section 48 panel of the fuselage; between stringers 5 and 10 on the left and right sides. In addition, the service bulletin describes performing related investigative and corrective actions if necessary. The corrective actions include removing any skin wrinkle, repairing any skin crack, and installing a skin repair if any wrinkle or crack is found. The related investigative actions include an internal HFEC inspection of the repair doubler edge row fasteners for cracking if a skin repair is installed. The service bulletin also recommends contacting Boeing for repair data if any crack is found that is 1.0 or more inches in length.

The compliance times for the inspections specified in the service bulletin are as follows:

General visual and external HFEC inspections for any wrinkle and cracking of the skin panels and bulkhead shear tie end fastener locations at Stations 2195.75, 2221.65, and 2245.70 of the Section 48 panel of the fuselage, between stringers 5 and 10: Before 16,000 total flight cycles or within 2,300 flight cycles after the date on the service bulletin, whichever occurs later. If no wrinkle or skin crack is found, the service bulletin specifies repeating the inspections thereafter at intervals not to exceed 4,500 flight cycles.

Internal HFEC inspection of the repair doubler shear tie end fasteners and external and internal detailed inspection of the tripler, doubler, skin, shear tie, stringer, or fuselage bulkhead (fastener locations): Within 30,000 flight cycles after installation of the repair.

Internal HFEC inspection of the repair doubler edge row fasteners and external and internal detailed inspection of the tripler, doubler, skin, shear tie, stringer or fuselage bulkhead within the repair area: Before 30,000 total flight cycles, or within 16,000 flight cycles after installation of the repair, whichever occurs first. If no cracking is found, the service bulletin describes repeating the inspections thereafter at intervals not to exceed 16,000 flight cycles. If any crack is found, the service bulletin recommends contacting Boeing for repair data and repairing.

FAA's Determination and Requirements of This Proposed AD

We are proposing this AD because we evaluated all relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design. This proposed AD would require accomplishing the actions specified in the service information described previously, except as discussed under ``Difference Between the Proposed AD and Service Information.'' Difference Between the Proposed AD and Service Information

The alert service bulletin specifies to contact the manufacturer for instructions on how to repair certain conditions, but this proposed AD would require repairing those conditions in one of the following ways:

Using a method that we approve; or

Using data that meet the certification basis of the airplane, and that have been approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization whom we have authorized to make those findings. Costs of Compliance

We estimate that the inspections in this proposed AD would affect 13 airplanes of U.S. registry. We also estimate that it would take about 15 workhours per product to comply with this proposed AD. The average labor rate is $80 per workhour. Based on these figures, we estimate the cost of this proposed AD to the U.S. operators to be $15,600, or $1,200 per product, per inspection cycle.

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 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 this 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.

You can find our regulatory evaluation and the estimated costs of compliance in the AD Docket.

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 39AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows: [[Page 25601]]

Authority: 49 U.S.C. 106(g), 40113, 44701.

Sec. 39.13 [Amended]

2. The FAA amends Sec. 39.13 by adding the following new AD: Boeing: Docket No. FAA20080520; Directorate Identifier 2008NM 018AD.
Comments Due Date
(a) We must receive comments by June 23, 2008.
Affected ADs
(b) None.
Applicability
(c) This AD applies to Boeing Model 777200 series airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 77753A0051, dated November 8, 2007.
Unsafe Condition
(d) This AD results from a report of cracks found in the external skin on the left and right sides of the section 48 fuselage panel on two airplanes with skin wrinkles found at two of the external crack locations. We are issuing this AD to detect and correct wrinkles and cracks in certain external skin panels of section 48, which could join together and result in reduced structural integrity of support structure for the vertical and horizontal stabilizers and inability of the airplane to sustain limit loads.
Compliance
(e) Comply with this AD within the compliance times specified, unless already done.
Repetitive Inspections/Investigative and Corrective Actions (f) At the applicable compliance times specified in paragraph 1.E., ``Compliance'' of Boeing Alert Service Bulletin 77753A0051, dated November 8, 2007, except as provided by paragraph (g) of this

FOR FURTHER INFORMATION CONTACT Duong Tran, Aerospace Engineer, Airframe Branch, ANM120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 980573356; telephone (425) 9176452; fax (425) 9176590.