Discussion
We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to the specified products. That NPRM was published in the Federal Register on July 10, 2008 (73 FR 39628). That NPRM proposed to correct an unsafe condition for the specified products. The MCAI states:
Analysed in-service events revealed that corrosion of pressure relief valves in wing fuel tanks was likely to occur well before reaching their Time Between Overhaul (TBO) and could make the valves stick in the closed position.
Therefore some aircraft could have experienced wing overpressure consecutive to the latent failure of both valve units. Overpressure although not sufficient to cause static damages could have impaired the fatigue damage tolerance of the wing structure. Consequently this Airworthiness Directive (AD) mandates introduction of a new repetitive inspection of the wing structure.
The repetitive ultrasonic inspection is intended to detect incipient cracking on the stiffeners of the right-hand and left-hand wing lower panels between ribs 13 and 17 (the inspection area extends to just beyond rib 16). The corrective actions if any cracking is found include contacting Dassault for repair instructions, and doing the repair. You may obtain further information by examining the MCAI in the AD docket.
Comments
We gave the public the opportunity to participate in developing this AD. We considered the comment received.
Request to Change the Inspection Interval for the "Valve Boxes''
Jim Sparks, a private citizen, requests that a more practical solution to this subject would be to change the interval of inspections for the "valve boxes.'' He states that the reliability of the "valve boxes'' has not been stellar. The commenter explains that Model Mystere-Falcon 50 airplanes have two independent wing fuel tank "valve boxes'' that incorporate over-pressure relief valves coupled with a stand-alone wing tank pressure reducing/overpressure relief valve. The commenter states that because of the commonality in the system, both overpressure relief valves and the regulating valve would have to fail before any overpressure would occur. The commenter also states that the pressure relief valves, along with the entire system, do have manufacturer's recommended intervals for both operational and functional testing and that a more practical solution would be to require a change to the inspection interval for those "valve boxes.''
We disagree with the request to require a change to the repetitive inspection interval of the "valve boxes.'' The purpose of this AD is to address the unsafe condition, which is possible damage to the wing structure due to over-pressurization. Therefore, we will be mandating only the inspections of the lower panel stiffeners. We are aware that the manufacturer has made changes to the design of the "valve boxes'' and the inspection interval for them. Weagree with the recommended changes from the manufacturer in modifying the design and inspection interval of the "valve boxes'' and acknowledge that they could result in fewer overpressure occurrences leading to the unsafe condition of damage to the wing structure. However, the intent of this AD is to detect any cracking of the wing structure that might have a root cause in an overpressure event. We have not changed the AD in this regard.
Explanation of Updated Service Information
Since we issued the NPRM, Dassault has issued Falcon 50/50EX Maintenance Manual, Maintenance Procedure 57-401, "Non-Destructive Check of the Wing Lower Panels Stiffeners Between Ribs 13 and 17 (ATA 57-00-21),'' dated July 2008. (We referred to Temporary Revision 74, dated November 2007, to the Dassault Falcon 50/50EX Maintenance Manual, Maintenance Procedure 57-401, "Non-Destructive Check of the Wing Lower Panels Stiffeners Between Ribs 13 and 16 (ATA 57-00-21),'' as the appropriate source of serviceinformation in the NPRM.) Maintenance Procedure 57-401, Revision July 2008, refers to "Between Ribs 13 and 17'' rather than "Between Ribs 13 and 16.'' The change to refer to Rib 17 and the corresponding change in certain sections of the maintenance procedure more accurately reflect the inspection area required by this AD and specified in the MCAI.
We have revised paragraph (f) of this AD to include two separate paragraphs.
The new paragraph (f)(1) refers to Dassault Falcon 50/50EX Maintenance Manual, Maintenance Procedure 57-401, "Non-Destructive Check of the Wing Lower Panels Stiffeners Between Ribs 13 and 17 (ATA 57-00-21),'' dated July 2008, as the appropriate source of service information for doing the actions required by this AD. The new paragraph (f)(2) gives credit to operators who accomplished the actions before the effective date of this AD in accordance with Dassault Temporary Revision 74, dated November 2007.
Conclusion
We reviewed the available data, including the comment received, and determined that air safety and the public interest require adopting the AD with the changes described previously. We determined that these changes will not increase the economic burden on any operator or increase the scope of the AD.
Differences Between This AD and the MCAI or Service Information
We have reviewed the MCAI and related service information and, in general, agree with their substance. But we might have found it necessary to use different words from those in the MCAI to ensure the AD is clear for U.S. operators and is enforceable. In making these changes, we do not intend to differ substantively from the information provided in the MCAI and related service information.
We might also have required different actions in this AD from those in the MCAI in order to follow our FAA policies. Any such differences are highlighted in a NOTE within the AD.
Costs of Compliance
We estimate that this AD will affect 247 products of U.S. registry. We also estimate that it will take about 6 work-hours per product to comply with the basic requirements of this AD. The average labor rate is $80 per work-hour. Based on these figures, we estimate the cost of this AD to the U.S. operators to be $118,560, or $480 per product.
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 this AD:
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 withthis AD and placed it in the AD docket.
Examining the AD Docket
You may examine the AD docket on the Internet at http:// www.regulations.gov; or in person at the Docket Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains the NPRM, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (telephone (800) 647-5527) is 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 AD: