SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments regarding this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include the docket number, “FAA-2007-28956; Directorate Identifier 2007-CE-068-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://www.regulations.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive concerning this proposed AD.

Discussion

Cessna reported wing skin corrosion in a Model 525 and belly skin corrosion in several Model 525A airplanes. Cessna received information on more than 18 cases of significant corrosion. Cessna also received information on 42 cases of some corrosion on Models 525, 525A, and 525B airplanes. Corrosive fluids leaked after use of the cockpit mounted pilot relief tube and caused corrosion of the fuselage skins, fairings, fairing support structure, and wing structure.

This condition, if not corrected, could result in structural degradation and lead to structural failure of the airplane with consequent loss of control.

Relevant Service Information

We have reviewed the following Cessna service information for this AD:

• Service Bulletin SB525-53-20, dated April 30, 2007;
• Service Bulletin SB525A-53-01, dated April 30, 2007;
• Service Bulletin SB525B-53-01, dated April 30, 2007;
• Alert Service Letter ASL525-53-04, Revision 2, dated August 19, 2007;
• Alert Service Letter ASL525A-53-05, Revision 2, dated July 25, 2007; and
• Alert Service Letter ASL525B-53-02, Revision 2, dated July 25, 2007.

The service information describes procedures for the following actions:

• Inspecting the lower wing skin structure, forward wing spars, lower fuselage skin, fairings, and external fairing frames for corrosion;
• Repairing corrosion by blending within specified limits or by contacting the manufacturer to obtain an FAA-approved repair scheme if corrosion damage can not be repaired within the limits specified;
• Doing a surface eddy current inspection or a dye-penetrant inspection on the repaired blended areas for cracks, and contacting the manufacturer to obtain an FAA-approved repair scheme if cracks are found;
• Applying a corrosion inhibitive sealant to the fuselage fairings before reinstalling; and
• Disabling the cockpit mounted relief tube.

FAA's Determination and Requirements of the Proposed AD

We are proposing this AD because we evaluated all information and determined the unsafe condition described previously is likely to exist or develop on other products of the same type design. This proposed AD would require you to inspect the lower wing skin structure, forward wing spar, lower fuselage skin, fairings, and the external fairing frames for corrosion; repair any damage found; apply a corrosion inhibitive sealant to the fuselage fairings before reinstalling; and disable the cockpit mounted pilot relief tube.

Costs of Compliance

We estimate that this proposed AD would affect 261 airplanes in the U.S. registry.

We estimate the following costs to do the proposed inspection:

We have no way of determining the number of airplanes that may need repair or further inspection based on the results of the proposed inspection, or the costs associated with such repair or inspection.

We estimate the following costs to do the proposed disabling of the cockpit mounted pilot relief tube:

Cessna will provide warranty credit to the extent specified in Cessna Citation Service Bulletin SB525-53-20, dated April 30, 2007; Service Bulletin SB525A-53-01, dated April 30, 2007; Service Bulletin SB525B-53-01, dated April 30, 2007; Alert Service Letter ASL525-53-04, Revision 2, dated August 19, 2007; Alert Service Letter ASL525A-53-05, Revision 2, dated July 25, 2007; and Alert Service Letter ASL525B-53-02, Revision 2, dated July 25, 2007.

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 ( printed page 60792) 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 and placed it in the AD docket.

Examining the AD Docket

You may examine the AD docket that contains the proposed AD, the regulatory evaluation, any comments received, and other information on the Internet at http://www.regulations.gov; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Office (telephone (800) 647-5527) is located at the street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows: