[Federal Register Volume 64, Number 193 (Wednesday, October 6, 1999)]
[Proposed Rules]
[Pages 54237-54238]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-26087]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-223-AD]
RIN 2120-AA64


Airworthiness Directives; Short Brothers Model SD3-60 SHERPA, 
SD3-SHERPA, and SD3-30 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, SD3-SHERPA, and SD3-30 series airplanes. This proposal would 
require replacement of existing oxygen system ``O'' rings with improved 
wear-resistant ``O'' rings. 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 the loss of oxygen from the aircraft oxygen system, 
which could result in an insufficient supply of oxygen being provided 
to the airplane flight crew and passengers in the event of an 
emergency.

DATES: Comments must be received by November 5, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-223-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.
    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 99-NM-223-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. 99-NM-223-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The Civil Aviation Authority (CAA), which is the airworthiness 
authority for the United Kingdom, recently notified the FAA that an 
unsafe condition may exist on all Short Brothers Model SD3-60 SHERPA, 
SD3-SHERPA, and SD3-30 series airplanes. The CAA advises that service 
experience has shown that certain ``O'' rings of the airplane oxygen 
system are prone to unexpected deterioration. This condition, if not 
corrected, could result in an insufficient supply of oxygen being 
provided to the airplane flight crew and passengers in the event of an 
emergency.

Explanation of Relevant Service Information

    Short Brothers has issued Service Bulletins SD360 Sherpa-35-2, 
dated February 25, 1999 (for Model SD3-60 Sherpa series airplanes); SD3 
Sherpa-35-3, Revision 1, dated May 5, 1999 (for

[[Page 54238]]

Model SD3 Sherpa series airplanes); and SD330-35-1, dated February 25, 
1999 (for Model SD3-30 series airplanes). These service bulletins 
describe procedures for replacement of existing oxygen system ``O'' 
rings with improved wear-resistant ``O'' rings. Accomplishment of the 
actions specified in the service bulletins is intended to adequately 
address the identified unsafe condition. The CAA classified these 
service bulletins as mandatory and issued British airworthiness 
directives 007-02-99 (for Model SD3-60 Sherpa series airplanes), 006-
02-99 (for Model SD3 Sherpa series airplanes), and 008-02-99 (for Model 
SD3-30 series airplanes), 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.

Cost Impact

    The FAA estimates that 62 airplanes of U.S. registry would be 
affected by this proposed AD, that it would take approximately 50 work 
hours per airplane to accomplish the proposed actions, and that the 
average labor rate is $60 per work hour. Required parts would be 
provided by the manufacturer at no cost to operators. Based on these 
figures, the cost impact of the proposed AD on U.S. operators is 
estimated to be $186,000, or $3,000 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.

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 99-NM-223-AD.

    Applicability: All Model SD3-60 SHERPA, SD3-SHERPA, and SD3-30 
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 (c) 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 the loss of oxygen from the aircraft oxygen system, 
accomplish the following:
    (a) Within 24 months after the effective date of this AD, 
replace oxygen system ``O'' rings, part number (P/N) MS28778, with 
improved wear-resistant ``O'' rings, P/N MS9068, in accordance with 
Shorts Service Bulletins SD360 Sherpa-35-2, dated February 25, 1999 
(for Model SD3-60 Sherpa series airplanes); SD3 Sherpa-35-3, 
Revision 1, dated May 5, 1999 (for Model SD3 Sherpa series 
airplanes), and SD330-35-1, dated February 25, 1999 (for Model SD3-
30 series airplanes); as applicable.
    (b) As of the effective date of this AD, no person shall install 
an oxygen system ``O'' ring, P/N MS28778, on any airplane.

Alternative Methods of Compliance

    (c) 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, FAA, 
Transport Airplane Directorate. 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

    (d) 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 directives 007-02-99 (for Model SD3-60 Sherpa series 
airplanes), 006-02-99 (for Model SD3 Sherpa series airplanes), and 
008-02-99 (for Model SD3-30 series airplanes).

    Issued in Renton, Washington, on September 30, 1999.
D. L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-26087 Filed 10-5-99; 8:45 am]
BILLING CODE 4910-13-P