A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to Gulfstream Model G-159 series airplanes was published as a supplemental notice of proposed rulemaking (NPRM) in the Federal Register on November 18, 1999 (64 FR 62991). That action proposed to require an inspection to determine the type of pneumatic deicing boots, and an airplane flight manual (AFM) change only for those airplanes equipped with "modern" boots.
Since the Issuance of the NPRM
The FAA has received information indicating that natural ice shedding, melting, or sublimation from the protected areas of the pneumatic deicing boot system of the wing and tail leading edge will eliminate most residual ice. In light of that information, the FAA has determined that a revision of the last bulleted paragraph of the airplane flight manual revision specified in paragraph (a) of the NPRM is necessary. Consequently, that paragraph has been revised from, "The wing and tail leading edge pneumatic deicing boot system may be deactivated only after leaving icing conditions and after the airplane is determined to be clear of ice," to delete the phrase, "and after the airplane is determined to be clear of ice."
Comments
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.
Request to Add Further Requirements
The commenter, the United Kingdom Civil Aviation Authority, requests that the statement in the supplemental notice of proposed rulemaking (NPRM) advising that a potential for adverse aerodynamic effects of ice adhering to the airplane exists should be addressed in more detail. The commenter explains that icing boots contaminated with dirt or in a deteriorated condition can induce such ice adhering to the airplane. The commenter points out that various cleaning and protection fluids are available that provide extended life to the deicing boots, protection of the boots against ultraviolet (UV) rays, and assistance in maintaining the boots in a clean condition. However, the commenter notes that not all maintenance programs schedule tasks effectively for the use of such cleaning and protection fluids. Therefore, the commenter requests that the FAA consider mandating a specific schedule to use such cleaning and protection products. The commenter states that such a required schedule should be required for airplanes equipped with either the "modern" or "older" boots.
The FAA does not concur with the commenter's requests. The FAA considers that normal wear and tear on the deicing boot materials is to be expected, and that the adhesion characteristics of the boot increases as the boot surface degrades over time. Operators have the responsibility to monitor the performance of the deicing boots installed on their airplanes, and to perform maintenance asrequired.
The FAA acknowledges that use of certain ice-phobic chemicals may provide an additional safety benefit. However, a variety of factors (e.g., normal wear and tear, "patching," and oxidation of boot material) exist in varying degrees on individual airplanes. As a result, the optimum frequency of application will vary during the life of the boot. The FAA has received no quantitative data to demonstrate the adequacy of particular amounts of ice-phobic chemical sprays or to provide adequate intervals of application. Therefore, the FAA cannot establish an appropriate application interval at this time. However, if additional data becomes available, the FAA may consider further rulemaking.
Conclusion
After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed.
Cost Impact
The FAA estimates that 141 airplanes of U.S. registry will be affected by this AD.
The FAA estimates that it will take approximately 2 work hours per airplane to accomplish the AFM revision, at the average labor rate of $60 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $16,920, or $120 per airplane.
The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted.
Regulatory Impact
The regulations adopted herein 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. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132.
For the reasons discussed above, I certify that this action (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. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES."
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (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.
39.13 [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: