[Federal Register Volume 63, Number 135 (Wednesday, July 15, 1998)]
[Proposed Rules]
[Pages 38126-38128]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-18869]


-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-CE-67-AD]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: This document proposes to adopt a new airworthiness directive 
(AD) that would apply to all Slingsby Sailplanes Ltd. (Slingsby) Models 
Dart T.51, Dart T.51/17, and Dart T.51/17R sailplanes that are equipped 
with aluminum alloy spar booms. The proposed AD would 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. The proposed AD is the result 
of mandatory continuing airworthiness information (MCAI) issued by the 
airworthiness authority for the United Kingdom. The actions specified 
by the proposed 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: Comments must be received on or before August 14, 1998.

ADDRESSES: Submit comments in triplicate to 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. Comments may be inspected at this location 
between 8 a.m. and 4 p.m., Monday through Friday, holidays excepted.
    Service information that applies to the proposed 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 also may be examined at the Rules Docket at the address 
above.

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

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 should 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 that summarizes 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 No. 98-CE-67-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, 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.

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 Slingsby Models Dart T.51, Dart T.51/17, and 
Dart T.51/17R sailplanes that are equipped with aluminum alloy spar 
booms. The CAA reports an incident of glue joint failure on a starboard 
wing caused by water entering the area of the airbrake box. 
Investigation of this incident revealed delamination and corrosion in 
the area of the aluminum alloy spar booms and the wing attach fittings.
    These conditions, if not detected and corrected, could result in 
failure of the spar assembly and adjoining structure with possible 
reduced controllability or loss of control of the sailplane.

Relevant Service Information

    Slingsby has issued Technical Instruction (TI) No. 109/T51, Issue 
No. 2, dated October 7, 1997, which specifies procedures for inspecting 
the aluminum alloy spar booms and the wing attach fittings for 
delamination or corrosion damage.
    The CAA classified this service bulletin as mandatory and issued 
British AD 005-09-97, dated October 3, 1997, in order to assure the 
continued airworthiness of these sailplanes in the United Kingdom.

The FAA's Determination

    These sailplane 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, including the service information referenced 
above; and determined that AD action is necessary for products of this 
type design that are certificated for operation in the United States.

Explanation of the Provisions of the Proposed AD

    Since an unsafe condition has been identified that is likely to 
exist or develop in other Slingsby Models Dart T.51, Dart T.51/17, and 
Dart T.51/17R sailplanes equipped with aluminum alloy spar booms of the 
same type design registered in the United States, the FAA is proposing 
AD action. The proposed AD would 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 inspection would be in accordance 
with Slingsby TI No. 109/T51, Issue No. 2, dated October 7, 1997.

[[Page 38127]]

Compliance Time of the Proposed AD

    The unsafe condition specified by the proposed 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 the proposed 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 Proposed 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 
proposing a compliance time of 6 calendar months for the initial 
inspection.

Cost Impact

    The FAA estimates that 3 sailplanes in the U.S. registry would be 
affected by the proposed AD, that it would take approximately 40 
workhours per sailplane to accomplish the proposed 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 proposed 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 proposed 
initial inspection and do not take into account the costs of repetitive 
inspections and the costs associated with any repair that would 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 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 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) 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 has been placed 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 a new airworthiness directive 
(AD) to read as follows:

Slingsby Sailplanes Ltd.: 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 Small Airplane Directorate.

    (e) Questions or technical information related to Slingsby 
Technical Instruction 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.

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


[[Page 38128]]


    Issued in Kansas City, Missouri, on July 8, 1998.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 98-18869 Filed 7-14-98; 8:45 am]
BILLING CODE 4910-13-U