01-2110. Airworthiness Directives; Short Brothers Model SD3-60 SHERPA, SD3-SHERPA, SD3-30, and SD3-60 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Final rule.

SUMMARY:

This amendment adopts a new airworthiness directive (AD), applicable to all Short Brothers Model SD3-60 SHERPA, SD3-SHERPA, SD3-30, and SD3-60 series airplanes, that requires replacement of the existing pneumatic de-icing boot pressure indicator switch with a newly designed switch. This amendment is prompted by an occurrence on a similar airplane model in which the pneumatic de-icing boot indication light may have provided the flightcrew with misleading information as to the proper functioning of the de-icing boots. The actions specified by this AD are intended to prevent ice accumulation on the airplane leading edges, which could reduce controllability of the airplane.

DATES:

Effective February 20, 2001.

ADDRESSES:

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

FOR FURTHER INFORMATION CONTACT:

Norman B. Martenson, Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

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.

Comments

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.

Request To Extend the Comment Period

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.

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

Cost Impact

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.

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:

2001-02-08 Short Brothers PLC: Amendment 39-12092. Docket 99-NM-226-AD.

Applicability: All Model SD3-60 SHERPA, SD3-SHERPA, SD3-30, and SD3-60 series airplanes; certificated in any category.

Note 1:

This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (b) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent ice accumulation on the airplane leading edges, which could reduce controllability of the airplane, accomplish the following:

Modification

(a) Within 1 year after the effective date of this AD, replace the flight deck pneumatic de-icing boot pressure indicator switch with a switch that activates the flight deck indicator light at 15 pounds per square inch gage, in accordance with a method approved by the Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate.

Alternative Methods of Compliance

(b) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, International Branch, ANM-116. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, International Branch, ANM-116.

Note 2:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116.

Special Flight Permits

(c) Special flight permits may be issued in accordance with §§ 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

Effective Date

(d) This amendment becomes effective on February 20, 2001.

Issued in Renton, Washington, on January 18, 2001.

Dorenda D. Baker,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.