AD 2001-02-08

[Federal Register Volume 66, Number 20 (Tuesday, January 30, 2001)]
[Rules and Regulations]
[Pages 8167-8168]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 01-2110]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-226-AD; Amendment 39-12092; AD 2001-02-08]
RIN 2120-AA64


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.

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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 (425) 
227-2110; fax (425) 227-1149.

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

[[Page 8168]]

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.


Sec. 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 
Secs. 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.
[FR Doc. 01-2110 Filed 1-29-01; 8:45 am]
BILLING CODE 4910-13-U