[Federal Register Volume 64, Number 120 (Wednesday, June 23, 1999)]
[Proposed Rules]
[Pages 33439-33441]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-15930]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-137-AD]
RIN 2120-AA64


Airworthiness Directives; Short Brothers Model SD3-30, SD3-60, 
SD3 SHERPA, and 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 SD3-30, 
SD3-60, SD3 SHERPA, and SD3-60 SHERPA series airplanes. This proposal 
would require a one-time borescope inspection to detect corrosion of 
the shear decks and ribs of the left and right stub wings, follow-on 
corrective actions, if necessary; and drilling of new drain holes in 
the lower shear decks. 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 prevent corrosion of the stub wing shear decks and ribs, 
which could result in cracking or failure of the stub wing structure.

DATES: Comments must be received by July 23, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-137-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, 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.

[[Page 33440]]

    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-137-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-137-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 SD3-30, SD3-60, SD3 
SHERPA, and SD3-60 SHERPA series airplanes. The CAA advises that 
corrosion has been found in the area of the upper and lower shear 
decks, and on the outer and inner ribs of the left and right stub 
wings. The corrosion is believed to have been caused by the ingress of 
water and debris into the area from the main landing gear wheels, and 
lack of follow-on maintenance in ensuring that the area is dry and 
clean. Corrosion of the stub wing shear decks and ribs, if not 
corrected, could result in cracking or failure of the stub wing 
structure.

Explanation of Relevant Service Information

    Shorts has issued the following service bulletins, all dated 
November 27, 1998:
     SD330-53-68 (for Model SD3-30 series airplanes);
     SD360-53-43, Revision 1 (for Model SD3-60 series 
airplanes);
     SD3 Sherpa-53-4 (for Model SD3 SHERPA series airplanes); 
and
     SD360-Sherpa-53-4 (for Model SD3-60 SHERPA series 
airplanes).
    These service bulletins describe procedures for a one-time 
borescope inspection to detect corrosion of the shear decks and ribs of 
the left and right stub wings, in the areas of the inner and outer 
ribs, front and rear web plates, strut support bracket, and upper and 
lower shear decks; and corrective actions, if necessary. The corrective 
actions include additional inspections for corrosion in other areas; 
removal of corrosion within acceptable limits; replacement of certain 
components with new components; and, follow-on repetitive inspections 
if corrosion is found. The service bulletins also describe procedures 
for drilling of new drain holes in the lower shear decks. Additionally, 
the service bulletins specify that operators are to report the results 
of the initial inspection to the manufacturer.
    Accomplishment of the actions specified in these service bulletins 
is intended to adequately address the identified unsafe condition. The 
CAA classified these service bulletins as mandatory and issued British 
airworthiness directives 006-11-97, 006-11-98, 007-11-98, and 008-11-98 
in order to assure the continued airworthiness of these airplanes in 
the United Kingdom.

FAA's Conclusions

    These airplane models are manufactured in the United Kingdom and 
are 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 bulletins described previously, 
except as discussed below.

Differences Between Proposed Rule and Service Bulletins

    Operators should note that, although the service bulletins specify 
that the manufacturer may be contacted for disposition of certain 
corrosion conditions, 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 112 airplanes of U.S. registry would be 
affected by this proposed AD, that it would take approximately 100 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 $672,000, or $6,000 per airplane.
    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.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

[[Page 33441]]

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-137-AD.

    Applicability: All Model SD3-30, SD3-60, SD3 SHERPA, and 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 prevent corrosion of the stub wing shear decks and ribs, 
which could result in cracking or failure of the stub wing 
structure, accomplish the following:

Inspection and Corrective Actions

    (a) Within 6 months after the effective date of this AD, perform 
a borescope inspection in the areas of the stub wing shear decks and 
ribs to detect corrosion, and drill new drain holes in the lower 
shear decks, in accordance with Part A of the Accomplishment 
Instructions of the applicable Shorts Service Bulletin specified 
below, all dated November 27, 1998 (hereinafter referred to as the 
applicable service bulletin):
     SD330-53-68 (for Model SD3-30 series airplanes);
     SD360-53-43, Revision 1 (for Model SD3-60 series 
airplanes);
     SD3 Sherpa-53-4 (for Model SD3 SHERPA series 
airplanes); and
     SD360-Sherpa-53-4 (for Model SD3-60 SHERPA series 
airplanes).

    Note 2: In the case where no corrosion is detected during the 
inspection described in Part A of the Accomplishment Instructions of 
the applicable service bulletin, the service bulletin specifies 
accomplishment of follow-on repetitive inspections of this area as 
specified in Short Brothers Aircraft Maintenance Programme, Chapter 
5-26-57.

    (b) Except as provided by paragraph (c) of this AD: If any 
corrosion is detected during the inspection required by paragraph 
(a) of this AD, prior to further flight, accomplish corrective 
actions (i.e., additional inspections, removal of corrosion, 
replacement of components), as applicable, in accordance with Part B 
of the Accomplishment Instructions of the applicable service 
bulletin. Thereafter, repeat the inspection required by paragraph 
(a) of this AD at intervals not to exceed 12 months.
    (c) If any corrosion condition is found for which the applicable 
service bulletin specifies that Short Brothers is to be contacted 
for an appropriate repair action: Prior to further flight, repair in 
accordance with a method approved by either the Manager, 
International Branch, ANM-116, FAA, Transport Airplane Directorate, 
or the Civil Aviation Authority (CAA) of the United Kingdom (or its 
delegated agent).

Reporting Requirement

    (d) Within 10 days after accomplishment of the initial 
inspection required by paragraph (a) of this AD, or within 30 days 
after the effective date of this AD, whichever occurs later, submit 
a report of the inspection findings (positive or negative) to: Team 
Leader, Service Engineering-Aerospace Customer Support Short 
Brothers plc, Belfast, N. Ireland. 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.

Alternative Methods of Compliance

    (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 3: 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

    (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 4: The subject of this AD is addressed in British 
airworthiness directives 006-11-97, 006-11-98, 007-11-98, and 008-
11-98.

    Issued in Renton, Washington, on June 17, 1999.
Vi L. Lipski,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-15930 Filed 6-22-99; 8:45 am]
BILLING CODE 4910-13-U