[Federal Register Volume 69, Number 58 (Thursday, March 25, 2004)]
[Proposed Rules]
[Pages 15266-15268]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-6680]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2003-NM-200-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 repetitive 
inspections and torque tests for discrepancies of certain bolts and 
rivets; and related investigative and corrective actions. This action 
is necessary to detect and correct loose bolts that attach the vertical 
stabilizer to the horizontal stabilizer, and pulled or loose rivets in 
the upper shear angles, which could result in reduced structural 
integrity of the vertical stabilizer. This action is intended to 
address the identified unsafe condition.

DATES: Comments must be received by April 26, 2004.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2003-NM-

[[Page 15267]]

200-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments 
may be inspected at this location between 9 a.m. and 3 p.m., Monday 
through Friday, except Federal holidays. Comments may be submitted via 
fax to (425) 227-1232. Comments may also be sent via the Internet using 
the following address: [email protected]. Comments sent via fax 
or the Internet must contain ``Docket No. 2003-NM-200-AD'' in the 
subject line and need not be submitted in triplicate. Comments sent via 
the Internet as attached electronic files must be formatted in 
Microsoft Word 97 or 2000 or ASCII text.
    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: Todd Thompson, Aerospace Engineer, 
International Branch, ANM-116, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-1175; 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 action may be changed in 
light of the comments received.
    Submit comments using the following format:
     Organize comments issue-by-issue. For example, 
discuss a request to change the compliance time and a request to change 
the service bulletin reference as two separate issues.
     For each issue, state what specific change to 
the proposed AD is being requested.
     Include justification (e.g., reasons or data) 
for each request.
    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 action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2003-NM-200-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. 2003-NM-200-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 during an unscheduled inspection of an 
SD3-60 SHERPA airplane, some of the bolts that attach the vertical 
stabilizer to the horizontal stabilizer were found to be loose. This 
condition, if not corrected, could result in reduced structural 
integrity of the vertical stabilizer.

Explanation of Relevant Service Information

    Short Brothers has issued Service Bulletin SD3-60 Sherpa-55-1, 
dated June 6, 2003, which describes procedures for inspecting and 
performing torque tests to detect the following discrepancies: Loose 
bolts that attach the vertical stabilizer to the horizontal stabilizer; 
and loose or pulled rivets in the upper shear angles. The service 
bulletin recommends repeating these inspections and torque tests every 
1,500 flight hours, and reporting all findings to the manufacturer.
    If any discrepancy is found during any inspection, the service 
bulletin describes the procedures for related investigative and 
corrective actions. The related investigative action is a further 
inspection to detect worn or distorted bolts, and worn or elongated 
bolt holes. The related corrective actions are:
     Fitting a new bolt with a new stiffnut and 
sufficient washers to ensure that the nut does not neck at full torque. 
This includes opening up a worn or elongated hole to oversize diameter, 
if necessary; and reporting any elongated holes that cannot be removed 
by oversizing to Short Brothers PLC.
     Replacing any discrepant shear angle using 
oversize rivets.
    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 001-06-2003 to ensure 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 AD

    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.

Differences Between the Proposed AD and the Service Bulletin

    Although the service bulletin specifies that operators may contact 
the manufacturer for disposition of certain repair conditions, this 
proposal would require operators to repair those conditions per 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 
unsafe condition, and consistent with existing bilateral airworthiness 
agreements, we have 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.
    Operators should note that, although the Accomplishment 
Instructions of the referenced service bulletin describe procedures for 
submitting findings to the manufacturer, this proposed AD would not 
require those actions.

[[Page 15268]]

Clarification Between the Proposed AD and the Service Bulletin

    Although the service bulletin does not specify the type of 
inspection, this proposed AD would require a ``detailed inspection.'' 
We have included a note in the proposed AD to clarify the definition of 
a detailed inspection.

Cost Impact

    The FAA estimates that 27 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 inspections and torque 
tests, and that the average labor rate is $65 per work hour. Based on 
these figures, the cost impact of the proposed AD on U.S. operators is 
estimated to be $8,775, or $325 per airplane, per inspection/test 
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. The cost impact figures 
discussed in AD rulemaking actions represent only the time necessary to 
perform the specific actions actually required by the AD. These figures 
typically do not include incidental costs, such as the time required to 
gain access and close up, planning time, or time necessitated by other 
administrative actions.

Regulatory Impact

    The regulations proposed herein would 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 proposal would not have federalism implications 
under Executive Order 13132.
    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.

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 2003-NM-200-AD.

    Applicability: All Short Brothers Model SD3-60 SHERPA series 
airplanes, certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To detect and correct loose bolts that attach the vertical 
stabilizer to the horizontal stabilizer, and pulled or loose rivets 
in the upper shear angles, which could result in reduced structural 
integrity of the vertical stabilizer, accomplish the following:

Repetitive Inspections and Torque Tests and Related Investigative 
Action

    (a) Prior to the accumulation of 1,500 total flight hours, or 
within 2 months after the effective date of this AD, whichever 
occurs later: Perform a detailed inspection, including a torque 
test, to detect discrepancies in the bolts or bolt holes that attach 
the vertical stabilizer to the horizontal stabilizer; and to detect 
loose or pulled rivets in the upper shear angles. Repeat the 
detailed inspection and torque test at intervals not to exceed 1,500 
flight hours. If any discrepancy is found in the bolts or bolt 
holes, do the related investigative action before further flight. 
Accomplish all actions in accordance with the Accomplishment 
Instructions of Short Brothers Service Bulletin SD3-60 Sherpa-55-1, 
dated June 6, 2003.

    Note 1: For the purposes of this AD, a detailed inspection is 
defined as: ``An intensive visual examination of a specific 
structural area, system, installation, or assembly to detect damage, 
failure, or irregularity. Available lighting is normally 
supplemented with a direct source of good lighting at intensity 
deemed appropriate by the inspector. Inspection aids such as mirror, 
magnifying lenses, etc., may be used. Surface cleaning and elaborate 
access procedures may be required.''

Related Corrective Actions

    (b) If any discrepancy is found during any inspection or torque 
test required by paragraph (a) of this AD: Before further flight, 
repair in accordance with the Accomplishment Instructions of Short 
Brothers Service Bulletin SD3-60 Sherpa-55-1, dated June 6, 2003. 
Where the service bulletin specifies to contact the manufacturer for 
disposition of certain repair conditions: Before further flight, 
repair per a method approved by either the Manager, International 
Branch, ANM-116, FAA, Transport Airplane Directorate; or the Civil 
Aviation Authority or its delegated agent.

No Reporting Requirement

    (c) Although the service bulletin referenced in this AD 
specifies to submit certain information to the manufacturer, this AD 
does not include such a requirement.

Alternative Methods of Compliance

    (d) In accordance with 14 CFR 39.19, the Manager, International 
Branch, ANM-116, is authorized to approve alternative methods of 
compliance for this AD.

    Note 2: The subject of this AD is addressed in British 
airworthiness directive 001-06-2003.


    Issued in Renton, Washington, on March 19, 2004.
Kevin M. Mullin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-6680 Filed 3-24-04; 8:45 am]
BILLING CODE 4910-13-P