SUPPLEMENTARY INFORMATION:

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-2005-20970; Directorate Identifier 2004-NM-53-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.

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 (800) 647-5227) is 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 chafing can exist between the submerged electrical wiring harness on the wing fuel boost pump and an aluminum fuel line inside the wing fuel tank. When troubleshooting a tripped circuit breaker for the fuel boost pump on a Cessna Model 550 airplane, technicians discovered that the electrical wiring harness of the wing fuel boost pump had chafed through the wire bundle insulation and was arcing on an aluminum fuel line inside the wing fuel tank. Subsequent inspections of additional airplanes revealed similar wire chafing on nearly half the inspected airplanes. The resulting potential for arcing and fuel vapor ignition, if not corrected, could result in explosion and loss of the airplane.

The design of the wire routing installation, the type and spacing of electrical wire clamps or lack of clamping, and the fuel pump wire type in the area of the wing fuel boost pump on Model 550 airplanes are the same on Cessna Model 500, 501, S550, 551, and 560 airplanes; therefore, the unsafe condition could exist on all of these airplanes.

Relevant Service Information

We have reviewed the Cessna service bulletins listed in the following table:

The service bulletins describe procedures for:

• Revising the Limitations section of the airplane flight manual (AFM) to prohibit use of the wing fuel boost pumps for defueling if the individual fuel load in each wing is less than a specified weight;
• Installing a placard that advises the flightcrew of the minimum fuel weight requirements; and
• Inspecting the full length of the wiring of the wing fuel boost pumps to detect chafing through the outer jackets, through the wire braid (shielding), and into the wire insulation.

The service bulletins also describe procedures for corrective and other specified actions, depending on the inspection results, as follows:

• Applying sealant to any damaged areas of the wing fuel boost pump wiring;
• Installing spiral wrap on fuel boost pump wiring; and
• Replacing the fuel boost pump with a new pump, if the wire conductor is exposed and chafing is found through the outer jacket, wire braid, and insulation.

In addition, the service bulletins describe procedures for inspecting for damage of the fuel tube and wing structure, replacing damaged fuel tubes with new fuel tubes, and replacing or repairing damaged wing structure.

The service bulletins also describe procedures for modifying the wing fuel boost pumps by installing clamps on certain tube assemblies and on the boost pump wiring, and ensuring that the wires will not contact any fuel lines or the airplane structure.

The service bulletins specify removing the AFM revision and placard after doing the inspection, corrective and other specified actions, and modification.

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 the actions specified in the service information described previously, except as discussed under “Differences Between the Proposed AD and the Service Information.”

Differences Between the Proposed AD and the Service Information

This proposed AD specifies the placard text size, which is not provided in the service bulletins. We find it necessary to require this minimum standard on the placard to ensure its readability.

The service bulletins specify revising the AFM immediately (after receipt of the service bulletin), but this proposed AD would allow up to 25 flight hours for this action. In developing an appropriate compliance time for this action, we considered the safety implications and operators' typical maintenance schedules and determined that 25 flight hours will have minimal effect on operators, and no adverse effect on safety.

Although the Accomplishment Instructions of the referenced service bulletins describe procedures for submitting a sheet recording compliance with the service bulletin, this proposed AD would not require that action. We do not need this information from operators.

Costs of Compliance

This proposed AD would affect about 2,397 airplanes worldwide. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

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 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.

The Proposed Amendment

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