[Federal Register Volume 63, Number 152 (Friday, August 7, 1998)]
[Proposed Rules]
[Pages 42288-42290]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-21103]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-138-AD]
RIN 2120-AA64


Airworthiness Directives; Short Brothers Model SD3-60 SHERPA 
Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to all Short Brothers Model SD3-60 
SHERPA series airplanes. This proposal would require an initial 
cleaning and visual inspection of the distance piece and adjacent side 
plates of the fuselage wing strut pick-up of the left- and right-stub 
wings to detect corrosion; rework or replacement of damaged components; 
and, for certain conditions, follow-on repetitive cleaning and visual 
inspections of reworked components. This proposal is prompted by 
issuance of mandatory continuing airworthiness information by a foreign 
civil airworthiness authority. The actions specified by the proposed AD 
are intended to detect and correct corrosion of the distance piece and 
adjacent side plates, which could result in reduced strength of the 
wing strut attachment to the stub wing on the fuselage, and consequent 
reduced structural integrity of the main wing.

DATES: Comments must be received by September 8, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-138-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays.
    The service information referenced in the proposed rule may be 
obtained from Short Brothers, Airworthiness & Engineering Quality, P.O. 
Box 241, Airport Road, Belfast BT3 9DZ, Northern Ireland. This 
information may be examined at the FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Norman B. Martenson, Manager, 
International Branch, ANM-116, FAA,

[[Page 42289]]

Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2110; fax (425) 227-1149.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications shall identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 98-NM-138-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules 
Docket No. 98-NM-138-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The Civil Aviation Authority (CAA), which is the airworthiness 
authority for the United Kingdom, notified the FAA that an unsafe 
condition may exist on all Short Brothers Model SD3-60 SHERPA series 
airplanes. The CAA advises that corrosion has been detected on the 
horizontal leg of the distance piece and adjacent faces of the side 
plates of the wing strut pick-up on the left- and right-stub wing. This 
corrosion occurs from debris being thrown into pockets in the distance 
piece, which is adjacent to the main landing gear wheels. Such 
corrosion of the distance piece and adjacent side plates, if not 
corrected, could result in reduced strength of the wing strut 
attachment to the stub wing on the fuselage, and consequent reduced 
structural integrity of the main wing.

Explanation of Relevant Service Information

    Shorts has issued Service Bulletin SD3-60 SHERPA-53-2, dated 
November 4, 1997, which describes procedures for an initial cleaning 
and visual inspection of the distance piece and adjacent side plates of 
the fuselage wing strut pick-up of the left- and right-stub wings to 
detect corrosion; rework or replacement of damaged components, if 
necessary; and, for certain conditions, follow-on repetitive cleaning 
and visual inspections of reworked components. Accomplishment of the 
actions specified in the service bulletin is intended to adequately 
address the identified unsafe condition. The CAA classified this 
service bulletin as mandatory and issued British airworthiness 
directive 004-11-97 in order to assure the continued airworthiness of 
these airplanes in the United Kingdom.

FAA's Conclusions

    This airplane model is manufactured in the United Kingdom and is 
type certificated for operation in the United States under the 
provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 
21.29) and the applicable bilateral airworthiness agreement. Pursuant 
to this bilateral airworthiness agreement, the CAA has kept the FAA 
informed of the situation described above. The FAA has examined the 
findings of the CAA, reviewed all available information, and determined 
that AD action is necessary for products of this type design that are 
certificated for operation in the United States.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design registered 
in the United States, the proposed AD would require accomplishment of 
the actions specified in the service bulletin described previously, 
except as discussed below. The proposed AD also would require that 
operators report inspection findings to the manufacturer.

Differences between Proposed Rule and Service Bulletin

    Operators should note that, although the service bulletin specifies 
that the manufacturer may be contacted for disposition of corrosion 
that exceeds certain limits, this proposal would require the repair of 
those conditions to be accomplished in accordance with a method 
approved by either the FAA or the CAA (or its delegated agent). In 
light of the type of repair that would be required to address the 
identified unsafe condition, and in consonance with existing bilateral 
airworthiness agreements, the FAA has determined that, for this 
proposed AD, a repair approved by either the FAA or the CAA would be 
acceptable for compliance with this proposed AD.

Cost Impact

    The FAA estimates that 28 airplanes of U.S. registry would be 
affected by this proposed AD, that it would take approximately 5 work 
hours per airplane to accomplish the proposed inspection, and that the 
average labor rate is $60 per work hour. Based on these figures, the 
cost impact of the proposed AD on U.S. operators is estimated to be 
$8,400, or $300 per airplane, per inspection cycle.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the proposed 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 proposed herein would not have substantial direct 
effects 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, in 
accordance with Executive Order 12612, it is determined that this 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this proposed 
regulation (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) if promulgated, 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 copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

[[Page 42290]]

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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:

Short Brothers PLC: Docket 98-NM-138-AD.

    Applicability: All Model SD3-60 SHERPA 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 (e) 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 detect and correct corrosion of the distance piece and 
adjacent side plates of the fuselage wing strut pick-up of the left-
and right-stub wings, which could result in reduced strength of the 
wing strut attachment to the stub wing on the fuselage, and 
consequent reduced structural integrity of the main wing, accomplish 
the following:
    (a) Within 90 days after the effective date of this AD, clean 
the pockets in the horizontal and vertical legs of the distance 
piece and adjacent faces of the side plates at the wing strut pick-
up area on the stub wing, and perform a visual inspection to detect 
corrosion; in accordance with Shorts Service Bulletin SD3-60 SHERPA-
53-2, dated November 4, 1997.
    (b) If no corrosion is detected during the inspection required 
by paragraph (a) of this AD, prior to further flight, apply 
additional corrosion protection treatment in accordance with Shorts 
Service Bulletin SD3-60 SHERPA-53-2, dated November 4, 1997.
    (c) If any corrosion is detected, prior to further flight, after 
cleaning and removing the corrosion from the distance piece and side 
plates in accordance with Shorts Service Bulletin SD3-60 SHERPA-53-
2, dated November 4, 1997, accomplish paragraph (c)(1) or (c)(2) of 
this AD, as applicable.
    (1) If the depth of corrosion is within the limits specified in 
the service bulletin, apply additional corrosion protection 
treatment in accordance with the service bulletin.
    (2) If the depth of corrosion is outside the limits specified in 
the service bulletin, accomplish either paragraph (c)(2)(i) or 
(c)(2)(ii) of this AD. Thereafter, repeat the detailed visual 
inspection required by paragraph (a) of this AD at intervals not to 
exceed 600 hours time-in-service or 90 days, whichever occurs first.
    (i) Rework the damaged components in accordance with a method 
approved by either the Manager, International Branch, ANM-116, FAA, 
Transport Airplane Directorate; or the Civil Aviation Authority of 
the United Kingdom (or its delegated agent). Thereafter, repeat the 
detailed visual inspection required by paragraph (a) of this AD at 
intervals not to exceed 600 hours time-in-service or 90 days, 
whichever occurs first.
    (ii) Replace the damaged components with new components in 
accordance with Shorts SD3-60 Sherpa Maintenance Programme Manual, 
Section 5-26-57, page 9, dated July 17, 1995.
    (d) Within 10 days after accomplishing the initial cleaning and 
inspection required by paragraph (a) of this AD, submit a report of 
the inspection results (both positive and negative findings) to 
Short Brothers, PLC. Information collection requirements contained 
in this regulation have been approved by the Office of Management 
and Budget (OMB) under the provisions of the Paperwork Reduction Act 
of 1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control 
Number 2120-0056.
    (e) 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.

    (f) Special flight permits may be issued in accordance with 
sections 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.

    Note 3: The subject of this AD is addressed in British 
airworthiness directive 004-11-97.

    Issued in Renton, Washington, on July 31, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-21103 Filed 8-6-98; 8:45 am]
BILLING CODE 4910-13-P