AD 2001-02-08

Effective February 20, 2001.

Information concerning this AD may be examined at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington.

Norman B. Martenson, Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2110; fax (425) 227-1149.

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 all Short Brothers Model SD3-60 SHERPA, SD3-SHERPA, SD3-30, and SD3-60 series airplanes, was published in the Federal Register on October 6, 1999 (64 FR 54239). That action proposed to require replacement of the existing pneumatic de-icing boot pressure indicator switch with a newly designed switch.

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the two comments received.

The commenters request that the comment period for the proposed AD be extended by 2 to 3 months to give the manufacturer additional time to develop a warning system that would adequately address the identified unsafe condition. The commenters consider replacing the existing pressure indicator switch with a higher-value switch—without revising the system logic—to be insufficient to ensure a fully effective de-icing system. One commenter requests this extension of time to better define the appropriate pressure threshold for inflating the de-icing boots, which the commenter estimates to be 12 pounds per square inch gage (psig), rather than 15 psig as stated in the proposed AD. The commenters add that replacing the switch as proposed could generate a large number of false warnings. The manufacturer states that it is in the process of completing additional testing and data analysis for use in developing an appropriate modification.

The FAA does not concur with the request to extend the comment period. The manufacturer has had ample time (more than a year) since the issuance of the proposed rule to develop an appropriate modification. In accordance with the requirements of this AD, the manufacturer may submit a modification for approval by the FAA. Modifications (including those incorporating the installation of a lower pressure switch) that positively address the identified unsafe condition may be considered as alternative means of compliance. In addition, if such a modification is developed, approved, and available, the FAA may consider additional rulemaking.

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 published. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

The FAA estimates that 89 airplanes of U.S. registry will be affected by this AD. Since the manufacturer has not yet developed one specific modification commensurate with the requirements of this AD, the FAA is unable at this time to provide specific information as to the number of work hours or cost of parts that would be required to accomplish the required modification.

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.

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:

1. The authority citation for part 39 continues to read as follows:

2. Section 39.13 is amended by adding the following new airworthiness directive: