[Federal Register Volume 64, Number 219 (Monday, November 15, 1999)]
[Proposed Rules]
[Pages 61796-61798]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-29743]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 99-NM-220-AD]
RIN 2120-AA64
Airworthiness Directives; Fokker Model F.28 Mark 1000, 2000,
3000, and 4000 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 certain Fokker Model F.28 Mark
1000, 2000, 3000, and 4000 series airplanes. This proposal would
require an eddy current inspection to detect cracks in the upper girder
of the two main landing gear (MLG) brackets; and repair of a cracked
bracket followed by repetitive inspections, or replacement of a cracked
MLG bracket with an improved bracket, as applicable. This proposal also
provides for optional terminating action for certain requirements of
this proposed AD. 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
detect and correct cracks in the upper girder of the MLG bracket, which
could progress into the vertical stiffeners of the MLG bracket and
result in reduced structural integrity of the landing gear.
DATES: Comments must be received by December 15, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 99-NM-220-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 Fokker Services B.V., P.O. Box 231, 2150 AE Nieuw-Vennep,
the Netherlands. 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-220-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
[[Page 61797]]
FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket
No. 99-NM-220-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.
Discussion
The Rijksluchtvaartdienst (RLD), which is the airworthiness
authority for the Netherlands, notified the FAA that an unsafe
condition may exist on certain Fokker Model F.28 Mark 1000, 2000, 3000,
and 4000 series airplanes. The RLD advises that cracks have been
discovered in the upper girder of the main landing gear (MLG) bracket,
between the stringer fitting bolts attaching the MLG bracket and
fitting to the wing upper skin. Crack surface investigation has shown
that the cracking occurred due to stress corrosion. The affected MLG
brackets are made of 7079T6 aluminum, which is known to be sensitive to
this type of cracking. Such cracking, if not corrected, could progress
into the vertical stiffeners of the MLG bracket, and result in an
insufficient load transfer from the MLG aft pintle pin into the
auxiliary wing spar structure, and consequent reduced structural
integrity of the landing gear.
Explanation of Relevant Service Information
Fokker has issued Service Bulletin F28/57-90, dated March 1, 1999,
which contains procedures for an eddy current inspection to detect
cracks in the upper girder of the two MLG brackets; and repair of a
cracked bracket, with follow-on repetitive eddy current inspections, or
replacement of a cracked bracket with an improved bracket, as
applicable. The RLD classified Service Bulletin F28/57-90 as mandatory,
and issued Dutch airworthiness directive 1999-045, dated March 31,
1999, in order to assure the continued airworthiness of these airplanes
in the Netherlands.
Fokker has also issued Fokker Proforma Service Bulletin F28/57-92,
dated July 1, 1999, which describes the procedures for replacement of
the existing MLG bracket with an improved bracket. The improved bracket
is made of 7175T7 aluminum, which is not as sensitive to stress
corrosion cracking as the material of the existing bracket. The
accomplishment instructions of the proforma service bulletin reference
an appendix to the proforma service bulletin that will include specific
instructions on accomplishing the replacement on a specific operator's
fleet. Procedures for the replacement include measuring the position of
the existing MLG bracket, removing the existing bracket and attachment
fittings, checking alignment of the fastener holes, measuring gaps,
installing a shim, aligning the new bracket, and installing the new
bracket and attachment fittings.
Accomplishment of the actions specified in these service bulletins
is intended to adequately address the identified unsafe condition.
FAA's Conclusions
This airplane model is manufactured in the Netherlands 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 RLD has kept the FAA informed of
the situation described above. The FAA has examined the findings of the
RLD, 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,
except as noted below.
Operators should note that, in consonance with the findings of the
RLD, the FAA has determined that, in certain cases, the repair and
repetitive inspections proposed by this AD can be allowed to continue
in lieu of accomplishment of a terminating action. In making this
determination, the FAA considers that, in certain cases, long-term
continued operational safety will be adequately assured by
accomplishing the repetitive inspections to detect cracking before it
represents a hazard to the airplane.
The proposed AD also would require that, regardless of the results
of the inspections, operators report all inspection findings to the
airplane manufacturer.
Differences Between Proposed Rule, Foreign Airworthiness Directive,
and Service Bulletin
The proposed AD would differ from Fokker Service Bulletin F28/57-90
and the parallel Dutch airworthiness directive in that it would
require, prior to further flight, replacement of a cracked MLG bracket
with an improved bracket, if a crack exceeds 0.0591 inch (15 mm) in
length. The service bulletin and the Dutch airworthiness directive
specify replacement of a cracked MLG bracket prior to further flight
only if a crack exceeds 1.576 inch (40 mm) in length. The FAA has
determined that, because of the safety implications and consequences
associated with such cracking, any subject MLG bracket that is found to
have a crack that exceeds 0.0591 (15 mm) in length must be replaced
prior to further flight.
Operators should note that Fokker Service Bulletin F28/57-90 and
the Dutch airworthiness directive specify to replace a cracked MLG
bracket in accordance with Fokker Proforma Service Bulletin F28/57-92,
or to contact the manufacturer for replacement instructions. However,
this proposed AD would require replacement of a cracked MLG bracket to
be accomplished in accordance with Fokker Proforma Service Bulletin
F28/57-92.
Operators also should note that, although Fokker Proforma Service
Bulletin F28/57-92, including any appendix referenced in that proforma
service bulletin, may specify that the manufacturer may be contacted if
any discrepancies are found during the replacement of the MLG bracket,
this proposal would require correction of the discrepancies in
accordance with a method approved by the FAA, or the RLD (or its
delegated agent). In light of the type of corrective action that would
be required to address the identified unsafe condition, and in
consonance with existing bilateral airworthiness agreements, the FAA
has determined that, for this proposed AD, corrective action approved
by either the FAA or the RLD would be acceptable for compliance with
this proposed AD.
Cost Impact
The FAA estimates that 6 airplanes of U.S. registry would be
affected by this proposed AD, that it would take approximately 2 work
hours per airplane to accomplish the proposed inspection, and that the
average labor rate is $60 per work hour. Based on these figures, the
cost impact of the proposed AD on U.S. operators is estimated to be
$720, or $120 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
[[Page 61798]]
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:
Fokker Services B.V.: Docket 99-NM-220-AD.
Applicability: Model F.28 Mark 1000, 2000, 3000 and 4000 series
airplanes; serial numbers 11003 through 11091 inclusive, 11094
through 11171 inclusive, 11991, and 11992; 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 (f) 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 cracks in the upper girder of the main
landing gear (MLG) bracket, which could progress into the vertical
stiffeners of the MLG bracket and result in reduced structural
integrity of the landing gear, accomplish the following:
One-Time Inspection and Corrective Actions
(a) Within 12 months after the effective date of this AD,
perform a one-time eddy current inspection of the upper girder of
the MLG brackets on the left and right sides of the airplane for
cracks, in accordance with the Accomplishment Instructions of Fokker
Service Bulletin F28/57-90, dated March 1, 1999.
(1) If no cracks are found, no further action is required by
this AD.
(2) Except as provided by paragraph (c) of this AD, if any crack
is found, prior to further flight, repair as specified in paragraph
C.(1) of the Accomplishment Instructions of the service bulletin, in
accordance with the service bulletin. Thereafter, repeat the eddy
current inspection at intervals not to exceed 1 year, until
accomplishment of paragraph (d) of this AD.
Reporting Requirement
(b) Within 10 days after accomplishing each inspection required
by paragraph (a) of this AD, submit a report of the inspection
results to: Fokker Services B.V., Technical Services, Attn: Manager
Airline Support, P.O. Box 231, 2150 AE Nieuw-Vennep, The
Netherlands. Information collection requirements contained in this
regulation have been approved by the Office of Management and Budget
(OMB) under the provisions of the Paperwork Reduction Act of 1980
(44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number
2120-0056.
Replacement
(c) For airplanes on which a crack greater than 0.591 inch (15
mm) in length is found: Except as provided by paragraph (e) of this
AD, prior to further flight, replace the cracked MLG bracket with a
new, improved bracket (including measuring the position of the
existing MLG bracket, removing the existing bracket and attachment
fittings, checking alignment of the fastener holes, measuring gaps,
installing a shim, and aligning the new bracket); in accordance with
Fokker Proforma Service Bulletin F28/57-92, dated July 1, 1999. Such
replacement constitutes terminating action for the repetitive
inspections required by paragraph (a)(2) of this AD.
Optional Terminating Action
(d) Except as provided by paragraph (e) of this AD, replacement
of the MLG bracket with a new, improved bracket (including measuring
the position of the existing MLG bracket, removing the existing
bracket and attachment fittings, checking alignment of the fastener
holes, measuring gaps, installing a shim, and aligning the new
bracket), in accordance with Fokker Proforma Service Bulletin F28/
57-92, dated July 1, 1999; constitutes terminating action for the
repetitive inspections specified in paragraph (a)(2) of this AD for
the replaced bracket.
(e) If any discrepancy is detected during accomplishment of the
replacement procedures, and the service bulletin or any appendix to
the service bulletin specifies to contact Fokker for appropriate
action: Prior to further flight, repair in accordance with a method
approved by either the Manager, International Branch, ANM-116, FAA,
Transport Airplane Directorate; or the Rijksluchtvaartdienst (or its
delegated agent). For a repair method to be approved by the Manager,
International Branch, ANM-116, as required by this paragraph, the
Manager's approval letter must specifically reference this AD.
Alternative Methods of Compliance
(f) 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
(g) 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 Dutch
airworthiness directive 1999-045, dated March 31, 1999.
Issued in Renton, Washington, on November 5, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-29743 Filed 11-12-99; 8:45 am]
BILLING CODE 4910-13-P
