Discussion
Cessna issued Service Bulletin SB525B-24-02, dated January 10, 2007, to add fuses to the emergency electrical power relay circuits to protect aircraft wiring left unprotected in the original design. Since issuance of that service bulletin, the FAA received a report from Cessna of a Model 525B airplane experiencing an in-flight direct short between aircraft direct current (DC) power and ground with loss of numerous systems, tripped circuit breakers, and burned wiring adjacent to the power distribution panel.
Cessna determined that a wiring alteration done following Cessna Citation Service Bulletin SB525B-24-02, dated January 10, 2007, contributed to this direct short between aircraft DC power and ground. The service bulletin had incorrect alteration instructions, which if implemented, could cause a direct short between aircraft DC power and ground.
Failure or opening of power bus limiters in conjunction with incorporation of thatservice bulletin may result in loss of numerous systems and burned aircraft wiring. The instructions and wiring diagrams call for incorrectly connecting 28V DC to an annunciator panel where there should be a ground. Terminal 2 of circuit breaker HZ050 is left with no wiring connected. This results in a direct short.
Cessna revised the service bulletin to include correct alteration instructions that would fully address the unsafe condition of unprotected wiring in the original design.
This condition, if not corrected, could result in burned wiring and loss of various aircraft electrical systems.
Relevant Service Information
We reviewed Cessna Citation Service Bulletin SB525B-24-02, Revision 1, dated October 4, 2007. The service information describes procedures for incorporating electrical power relay circuit protection kit P/N SB525B-24-02. The manufacturer intends that the actions specified in the service information adequately address the unsafe condition.
FAA'sDetermination and Requirements of this AD
We are issuing this AD because we evaluated all the information and determined the unsafe condition described previously is likely to exist or develop on other products of the same type design. This AD requires you to incorporate electrical power relay circuit protection kit P/N SB525B-24-02.
In preparing this rule, we contacted type clubs and aircraft operators to get technical information and information on operational and economic impacts. We did not receive any information through these contacts. If received, we would have included a discussion of any information that may have influenced this action in the rulemaking docket.
FAA's Determination of the Effective Date
An unsafe condition exists that requires the immediate adoption of this AD. The FAA has found that the risk to the flying public justifies waiving notice and comment prior to adoption of this rule because this condition, if not corrected, could result in burnedwiring and loss of various aircraft electrical systems. Therefore, we determined that notice and opportunity for public comment before issuing this AD are impracticable and that good cause exists for making this amendment effective in fewer than 30 days.
Comments Invited
This AD is a final rule that involves requirements affecting flight safety, and we did not precede it by notice and an opportunity for public comment. We invite you to send any written relevant data, views, or arguments regarding this AD. Send your comments to an address listed under the ADDRESSES section. Include the docket number "FAA-2007-0198; Directorate Identifier 2007-CE-085-AD'' at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the AD. We will consider all comments received by the closing date and may amend the 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 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 determined that this AD will not have federalism implications under Executive Order 13132. This AD will 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 this AD:
(1) Is not a "significant regulatory action'' under Executive Order 12866;
(2) Is not a "significant rule'' under 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 AD and placed it in the AD docket.
Examining the AD Docket
You may examine the AD docket thatcontains the 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.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
Adoption of the Amendment
Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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.
Sec. 39.13 [Amended]
2. The FAA amends Sec. 39.13 by adding the following new airworthiness directive (AD):