[Federal Register Volume 64, Number 48 (Friday, March 12, 1999)]
[Rules and Regulations]
[Pages 12247-12249]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-5991]
[[Page 12247]]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-NM-106-AD; Amendment 39-11071; AD 99-06-07]
RIN 2120-AA64
Airworthiness Directives; Short Brothers Model SD3-60 and SD3-60
SHERPA Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment adopts a new airworthiness directive (AD),
applicable to all Short Brothers Model SD3-60 and SD3-60 SHERPA series
airplanes, that requires repetitive inspections to detect corrosion
and/or wear of the top and bottom shear decks of the left and right
stub wings in the area of the forward pintle pin of the main landing
gear (MLG), and repair, if necessary. This amendment is prompted by
issuance of mandatory continuing airworthiness information by a foreign
civil airworthiness authority. The actions specified by this AD are
intended to detect and correct corrosion and/or wear of the top and
bottom shear decks of the left and right stub wings in the area of the
forward pintle pin of the MLG, which could result in failure of the MLG
to extend or retract.
DATES: Effective April 16, 1999.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of April 16, 1999.
ADDRESSES: The service information referenced in this AD 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 Federal Aviation Administration
(FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue,
SW., Renton, Washington; or at the Office of the Federal Register, 800
North Capitol Street, NW., suite 700, Washington, DC.
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: A proposal to amend part 39 of the Federal
Aviation Regulations (14 CFR part 39) to include an airworthiness
directive (AD) that is applicable to all Short Brothers Model SD3-60
and SD3-60 SHERPA series airplanes was published as a supplemental
notice of proposed rulemaking (NPRM) in the Federal Register on July
24, 1998 (63 FR 39769). That action proposed to require repetitive
inspections to detect corrosion and/or wear of the top and bottom shear
decks of the left and right stub wings in the area of the forward
pintle pin of the main landing gear (MLG), and repair, if necessary.
That action also proposed to expand the applicability to include an
additional airplane model.
Comments Received
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
Support for the Proposal
One commenter supports the proposed rule.
Remove Repetitive Inspections or Extend Interval
One commenter, an operator, requests that the repetitive
inspections of the proposed AD be removed as a requirement when no
corrosion or wear is found during the initial inspection. The commenter
states that if no corrosion or wear is found during this initial
inspection, this would indicate that all surfaces are being adequately
protected and maintained by the present maintenance program. The
commenter also notes that repeated removals of parts for the
inspections will accelerate the wear of the alodine coating, increasing
the risk of corrosion. Additionally, the commenter states that, if a
repetitive inspection interval is required, the allowed interval should
be longer than for those airplanes on which corrosion is found. The
commenter suggests that existing inspection results be used to specify
longer intervals for remaining airplanes on which no corrosion is
found.
The FAA does not concur with the commenter's request. Corrosion has
been found to develop in the top and bottom shear decks of the left and
right stub wings in the area of the forward pintle pin of the MLG due
to migration of the retaining pin following the loss of the retaining
circlip. A single inspection of this area would be inadequate to detect
corrosion that could develop if the circlip is lost at a later time.
Further, in developing the repetitive inspection interval, the FAA
reviewed the available data regarding the existing circlip design and
considered the recommendations of the Civil Aviation Authority (CAA),
which is the airworthiness authority of the United Kingdom, and the
manufacturer. Therefore, the FAA has determined that repetitive
inspections are necessary at the specified intervals in order to
adequately address the identified unsafe condition, unless terminating
action is accomplished.
However, as provided for in paragraph (b) of this AD, operators may
elect to accomplish removal of corrosion and installation of bushings,
which would terminate the requirement for repetitive inspections.
Additionally, the FAA has reviewed Shorts Service Bulletin SD360-32-35,
dated September 1996, which describes procedures for installation of a
pin and nut in lieu of the retaining pin and circlip, and determined
that, for Model SD3-60 series airplanes, accomplishment of this
modification also is acceptable for terminating the repetitive
inspection requirements of this AD. Accordingly, this provision has
been added as a new paragraph (c) of the final rule.
Tracking of Inspections for Wear
The same commenter requests that the proposed inspection of the pin
and shear decks for wear be tracked separately from the inspection for
corrosion of the shear decks. The commenter notes that wear will occur
as a function of gear cycles, not calendar time, and is expected to
occur only if the circlip is missing. The commenter points out that the
AD requires operators to perform the wear inspection even if an
airplane has not flown during the 6-month interval between inspections.
The commenter suggests that the inspection for wear should be tracked
as a function of flight cycles, and if no wear is found during the
initial inspection, the repetitive inspection interval for that
inspection should be extended.
The FAA does not concur that the two inspections should be
separately tracked. Although wear of the top and bottom shear decks of
the left and right stub wings in the area of the forward pintle pin of
the MLG is expected to occur as a function of flight cycles, the
inspection for corrosion in this area must be accomplished at intervals
not to exceed six months. Since access to the same area is required to
accomplish both inspections, it is considered most cost effective for
operators to accomplish both inspections at the same time. However, if
operators wish to perform these inspections as two separate maintenance
actions, requests may be submitted under the provisions of paragraph
(d) of the final rule. The
[[Page 12248]]
FAA may approve requests for such an adjustment of the compliance time
if data are submitted to substantiate that such an adjustment would
provide an acceptable level of safety.
Manufacturer Repair Approvals
The same commenter requests that the proposed AD be revised to
allow repairs to be used if they have been approved by Shorts, rather
than requiring operators to request repair approvals through the
Manager, International Branch, ANM-116, FAA, Transport Airplane
Directorate, as specified in paragraph (a)(3)(ii)(B) of the AD. The
commenter states that, from previous experience, the ANM-116 Branch
Manager will require a Shorts-approved repair if such a request is
made. The FAA does not concur with the request to allow repair
approvals by Short Brothers, as the FAA cannot delegate authority for
general approval of repairs on the FAA's behalf to manufacturers.
However, in light of the type of repair that would be required to
address the identified unsafe condition, and in consonance with
existing bilateral airworthiness agreement with the United Kingdom, the
FAA has determined that, for this AD, a repair approved by either the
FAA or the CAA of the United Kingdom (or its delegated agent) is
acceptable for compliance with this AD. Paragraph (a)(3)(ii)(B) of the
final rule has been revised accordingly.
Replacement of Parts
The same commenter, also in reference to paragraph (a)(3)(ii)(B) of
the proposed AD, states that most operators will choose to replace the
part rather than repair it, and requests that the proposed AD be
revised to allow replacement of the part in accordance with the
Illustrated Parts Catalog (IPC), rather than requiring approval through
the Manager, ANM-116. The FAA does not concur with the request to allow
part replacement in accordance with the IPC, as the IPC is not an FAA-
approved document. However, the FAA has determined that replacement of
the pintle pin and sleeve with new or serviceable parts is an
acceptable method of compliance with paragraph (a)(3)(ii)(B). Paragraph
(a)(3)(ii)(B) of the final rule has been revised to also include the
replacement as an appropriate corrective action if accomplished in
accordance with an FAA-or CAA-approved method.
Inspection for Presence of Circlip
One commenter suggests that the proposed AD be revised to include
an inspection for the presence of the circlip, since it is the loss of
the circlip that causes the wear and corrosion to occur. The commenter
also recommends that this additional inspection be required to be
accomplished immediately, prior to the proposed inspection threshold of
90 days, if the presence of the circlip can be easily determined.
The FAA does not concur. Short Brothers Service Bulletins SD360-53-
42, dated September 1996, and SD3-60 SHERPA-53-3, dated November 4,
1997 (which are referenced in the AD as the appropriate source of
service information for accomplishment of the inspections for wear and
corrosion), describe procedures for installation of a circlip if the
part is not in position at the time of the inspection. Although an
inspection for the presence of the circlip is not specifically
described, the inspection procedures will ensure that the circlip is in
place following accomplishment of the initial inspection. Additionally,
in considering the compliance time of 90 days for the inspection, the
FAA cannot conclude that a reduction of the proposed compliance time,
without prior notice and opportunity for public comment, is warranted.
In developing an appropriate compliance time, the FAA considered the
safety implications, the manufacturer's recommendations, the average
utilization rate of the affected fleet, and the practical aspects of an
orderly inspection of the fleet during regular maintenance periods. No
change to the final rule is necessary in this regard.
Conclusion
After careful review of the available data, including the comments
noted above, the FAA has determined that air safety and the public
interest require the adoption of the rule with the changes described
previously. The FAA has determined that these changes will neither
increase the economic burden on any operator nor increase the scope of
the AD.
Cost Impact
The FAA estimates that 58 Model SD3-60 series airplanes and 28
Model SD3-60 SHERPA series airplanes of U.S. registry will be affected
by this AD, that it will take approximately 13 work hours per airplane
to accomplish the required actions, and that the average labor rate is
$60 per work hour. Based on these figures, the cost impact of the AD on
U.S. operators is estimated to be $67,080, or $780 per airplane, per
inspection cycle.
The cost impact figure discussed above is based on assumptions that
no operator has yet accomplished any of the 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 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 final evaluation has been prepared for this action
and it is contained in the Rules Docket. A copy of it may be obtained
from 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 the following new
airworthiness directive:
99-06-07 Short Brothers PLC: Amendment 39-11071. Docket 97-NM-106-
AD.
Applicability: All Model SD3-60 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
[[Page 12249]]
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 (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, unless accomplished
previously.
To detect and correct corrosion and/or wear of the top and
bottom shear decks of the left and right stub wings in the area of
the forward pintle pin of the main landing gear (MLG), which could
result in failure of the MLG to extend or retract, accomplish the
following:
(a) Within 90 days after the effective date of this AD, conduct
an inspection for corrosion of the top and bottom shear decks of the
left and right stub wings in the area of the forward pintle pin of
the MLG, and measure the retaining pin holes of the pintle pin for
wear; in accordance with Part A. of the Accomplishment Instructions
of Short Brothers Service Bulletin SD360-53-42, dated September 1996
(for Model SD3-60 series airplanes), or Short Brothers Service
Bulletin SD3-60 SHERPA-53-3, dated November 4, 1997 (for Model SD3-
60 SHERPA series airplanes), as applicable.
(1) If no corrosion, wear, or discrepancy of the measurement of
the holes for the retaining pin of the pintle pin is found, repeat
the inspection required by paragraph (a) of this AD thereafter at
intervals not to exceed 6 months.
(2) If any corrosion, wear, or measurement of the holes for the
retaining pin of the pintle pin is found that is within the limits
specified in Part A. of the Accomplishment Instructions of the
applicable service bulletin, prior to further flight, repair the
discrepancy in accordance with the applicable service bulletin.
Thereafter, repeat the inspection required by paragraph (a) of this
AD at intervals not to exceed 6 months.
(3) If any corrosion, wear, or measurement of the holes for the
retaining pin of the pintle pin is found that is beyond the limits
specified in Part A. of the Accomplishment Instructions of the
applicable service bulletin, prior to further flight, perform the
actions required by paragraph (a)(3)(i) and (a)(3)(ii) of this AD.
(i) Remove the corrosion and install bushings on the upper and
lower shear webs in the retaining pin holes for the pintle pin in
accordance with Part B. (left MLG) and/or Part C. (right MLG), as
applicable, of the Accomplishment Instructions of the applicable
service bulletin.
(ii) Perform a visual inspection of the pintle pin and the
sleeve for any discrepancy, in accordance with Part B. and/or Part
C., as applicable, of the Accomplishment Instructions of the
applicable service bulletin.
(A) If no discrepancy is detected, the pintle pin and the sleeve
of the pintle pin may be returned to service.
(B) If any discrepancy of the pintle pin and sleeve is detected,
prior to further flight, repair the pintle pin and sleeve or replace
the pintle pin and sleeve with new or serviceable parts, in
accordance with a method approved by either the Manager,
International Branch, ANM-116, FAA, Transport Airplane Directorate,
or the Civil Aviation Authority (CAA) (or its delegated agent).
(b) Removal of corrosion and installation of bushings in
accordance with Part B. and/or Part C., as applicable, of the
Accomplishment Instructions of Short Brothers Service Bulletin
SD360-53-42, dated September 1996 (for Model SD3-60 series
airplanes), or Short Brothers Service Bulletin SD3-60 HERPA-53-3,
dated November 4, 1997 (for Model SD3-60 SHERPA series airplanes),
as applicable, constitutes terminating action for the repetitive
inspection requirements of this AD.
(c) For Model SD3-60 series airplanes: Replacement of the pin
and circlip with a new pin and nut in accordance with Short Brothers
Service Bulletin SD360-32-35, dated September 1996, constitutes
terminating action for the repetitive inspection requirements of
this AD.
(d) 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 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.
(e) 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.
(f) Except as provided by paragraphs (a)(3)(ii)(B) and (c) of
this AD, the actions shall be done in accordance with Short Brothers
Service Bulletin SD360-53-42, dated September 1996, and Short
Brothers Service Bulletin SD3-60 SHERPA-53-3, dated November 4,
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 Short Brothers, Airworthiness &
Engineering Quality, P. O. Box 241, Airport Road, Belfast BT3 9DZ,
Northern Ireland. Copies may be inspected at the FAA, Transport
Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or
at the Office of the Federal Register, 800 North Capitol Street,
NW., suite 700,Washington, DC.
Note 3: The subject of this AD is addressed in British
airworthiness directives 005-09-96 and 005-11-97.
(g) This amendment becomes effective on April 16, 1999.
Issued in Renton, Washington, on March 4, 1999.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-5991 Filed 3-11-99; 8:45 am]
BILLING CODE 4910-13-P
