Airworthiness Directives; Slingsby Aviation Limited Models Dart T.51, Dart T.51/17, and Dart T.51/17R Sailplanes

[Federal Register Volume 63, Number 211 (Monday, November 2, 1998)]
[Rules and Regulations]
[Pages 58624-58625]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-28966]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-CE-67-AD; Amendment 39-10863; AD 98-22-15]
RIN 2120-AA64


Airworthiness Directives; Slingsby Aviation Limited Models Dart 
T.51, Dart T.51/17, and Dart T.51/17R Sailplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
applies to all Slingsby Aviation Limited (Slingsby) Models Dart T.51, 
Dart T.51/17, and Dart T.51/17R sailplanes that are equipped with 
aluminum alloy spar booms. This AD requires repetitively inspecting the 
aluminum alloy spar booms and the wing attach fittings for delamination 
or corrosion damage, and repairing any delamination or corrosion damage 
found. This AD is the result of mandatory continuing airworthiness 
information (MCAI) issued by the airworthiness authority for the United 
Kingdom. The actions specified by this AD are intended to prevent 
failure of the spar assembly and adjoining structure caused by 
delamination or corrosion damage to the aluminum alloy spar booms or 
the wing attach fittings, which could result in reduced controllability 
or loss of control of the sailplane.

DATES: Effective December 14, 1998.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of December 14, 1998.

ADDRESSES: Service information that applies to this AD may be obtained 
from Slingsby Aviation Ltd., Kirbymoorside, York Y06 6EZ England; 
telephone: +44(0)1751 432474; facsimile: +44(0)1751 431173. This 
information may also be examined at the Federal Aviation Administration 
(FAA), Central Region, Office of the Regional Counsel, Attention: Rules 
Docket No. 98-CE-67-AD, Room 1558, 601 E. 12th Street, Kansas City, 
Missouri 64106; or at the Office of the Federal Register, 800 North 
Capitol Street, NW, suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Mr. Mike Kiesov, Aerospace Engineer, 
FAA, Small Airplane Directorate, 1201 Walnut, suite 900, Kansas City, 
Missouri 64106; telephone: (816) 426-6934; facsimile: (816) 426-2169.

SUPPLEMENTARY INFORMATION:

Events Leading to the Issuance of This AD

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to include an AD that would apply to all Slingsby Models 
Dart T.51, Dart T.51/17, and Dart T.51/17R sailplanes that are equipped 
with aluminum alloy spar booms was published in the Federal Register as 
a notice of proposed rulemaking (NPRM) on July 15, 1998 (63 FR 38126). 
The NPRM proposed to require repetitively inspecting the aluminum alloy 
spar booms and the wing attach fittings for delamination or corrosion 
damage, and repairing any delamination or corrosion damage found. 
Accomplishment of the proposed action as specified in the NPRM would be 
in accordance with Slingsby Technical Instruction (TI) No. 109/T51, 
Issue No. 2, dated October 7, 1997.
    The NPRM was the result of mandatory continuing airworthiness 
information (MCAI) issued by the airworthiness authority for the United 
Kingdom.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. No comments were received on the 
proposed rule or the FAA's determination of the cost to the public.

The FAA's Determination

    After careful review of all available information related to the 
subject presented above, the FAA has determined that air safety and the 
public interest require the adoption of the rule as proposed except for 
minor editorial corrections. The FAA has determined that these minor 
corrections will not change the meaning of the AD and will not add any 
additional burden upon the public than was already proposed.

Compliance Time of This AD

    The unsafe condition specified by this AD is caused by corrosion. 
Corrosion can occur regardless of whether the aircraft is in operation 
or is in storage. Therefore, to assure that the unsafe condition 
specified in this AD does not go undetected for a long period of time, 
the compliance is presented in calendar time instead of hours time-in-
service (TIS).

Differences Between the British AD, the Technical Instruction, and 
This AD

    Both Slingsby TI No. 109/T51, Issue No. 2, dated October 7, 1997, 
and British AD 005-09-97, dated October 3, 1997, specify the initial 
inspection prior to further flight.
    The FAA does not have justification through its regulatory process 
to require the initial inspection prior to further flight. To assure 
that no affected sailplanes are inadvertently grounded, the FAA is 
utilizing a compliance time of 6 calendar months for the initial 
inspection.

Cost Impact

    The FAA estimates that 3 sailplanes in the U.S. registry will be 
affected by this AD, that it will take approximately 40 workhours per 
sailplane to accomplish the initial inspection, and that the average 
labor rate is approximately $60 an hour. Based on these figures, the 
total cost impact of the initial inspection specified in this AD on 
U.S. operators is estimated to be $7,200, or $2,400 per sailplane.
    These figures only take into account the costs of the initial 
inspection and do not take into account the costs of repetitive 
inspections and the costs associated with any repair that will be 
necessary if corrosion or delamination damage is found. The FAA has no 
way of determining the number of repetitive inspections an owner/
operator will incur over the life of the sailplane, or the number of 
sailplanes that will need repairs.

Regulatory Impact

    The regulations adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    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 copy of the final

[[Page 58625]]

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, Incorporation by 
reference, 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 a new airworthiness directive 
(AD) to read as follows:

98-22-15  Slingsby Aviation Limited (Type Certificate No. G5EU 
formerly held by Slingsby Sailplanes Ltd.): Amendment 39-10863; 
Docket No. 98-CE-67-AD.

    Applicability: Models Dart T.51, Dart T.51/17, and Dart T.51/17R 
sailplanes, all serial numbers, certificated in any category, that 
are equipped with aluminum alloy spar booms.

    Note 1: This AD applies to each sailplane 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 sailplanes 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 (d) 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 in the body of this AD, unless 
already accomplished.
    To prevent failure of the spar assembly and adjoining structure 
caused by delamination or corrosion damage to the aluminum alloy 
spar booms or the wing attach fittings, which could result in 
reduced controllability or loss of control of the sailplane, 
accomplish the following:
    (a) Within the next 6 calendar months after the effective date 
of this AD and thereafter at intervals not to exceed 5 years, 
inspect the aluminum alloy spar booms and the wing attach fittings 
for delamination or corrosion damage. Accomplish this inspection in 
accordance with Slingsby Technical Instruction (TI) No. 109/T51, 
Issue No. 2, dated October 7, 1997.

    Note 2: Slingsby TI No. 109/T51, Issue No. 2, dated October 7, 
1997, includes guidance to determine whether an affected sailplane 
is equipped with aluminum alloy spar booms.

    (b) If any corrosion or delamination damage is found during any 
inspection required by paragraph (a) of this AD, prior to further 
flight, accomplish the following:
    (1) Obtain a repair scheme from the manufacturer through the 
FAA, Small Airplane Directorate, at the address specified in 
paragraph (d) of this AD; and
    (2) Incorporate this scheme and continue to repetitively inspect 
as required by paragraph (a) of this AD, unless specified 
differently in the instructions to the repair scheme.
    (c) 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 sailplane to a location where 
the requirements of this AD can be accomplished.
    (d) An alternative method of compliance or adjustment of the 
initial or repetitive compliance times that provides an equivalent 
level of safety may be approved by the Manager, Small Airplane 
Directorate, FAA, 1201 Walnut, suite 900, Kansas City, Missouri 
64106. The request shall be forwarded through an appropriate FAA 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Small Airplane Directorate.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Small Airplane Directorate.

    (e) Questions or technical information related to Slingsby TI 
No. 109/T51, Issue No. 2, dated October 7, 1997, should be directed 
to Slingsby Aviation Ltd., Kirbymoorside, York Y06 6EZ England; 
telephone: +44(0)1751 432474; facsimile: +44(0)1751 431173. This 
service information may be examined at the FAA, Central Region, 
Office of the Regional Counsel, Room 1558, 601 E. 12th Street, 
Kansas City, Missouri 64106.
    (f) The inspection required by this AD shall be done in 
accordance with Slingsby Technical Instruction No. 109/T51, Issue 
No. 2, dated October 7, 1997. This incorporation by reference was 
approved by the Director of the Federal Register in accordance with 
5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from 
Slingsby Aviation Ltd., Kirbymoorside, York Y06 6EZ England. Copies 
may be inspected at the FAA, Central Region, Office of the Regional 
Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri, or at 
the Office of the Federal Register, 800 North Capitol Street, NW, 
suite 700, Washington, DC.

    Note 4: The subject of this AD is addressed in British AD 005-
09-97, dated October 3, 1997.

    (g) This amendment becomes effective on December 14, 1998.

    Issued in Kansas City, Missouri, on October 22, 1998.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 98-28966 Filed 10-30-98; 8:45 am]
BILLING CODE 4910-13-U

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