[Federal Register Volume 62, Number 9 (Tuesday, January 14, 1997)]
[Proposed Rules]
[Pages 1866-1868]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-883]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 96-NM-185-AD]
RIN 2120-AA64
Airworthiness Directives; Fokker Model F28 Mark 0100 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 F28 Mark 0100
series airplanes. This proposal would require repetitive inspections of
certain flanges and finger strips at rib 5.0 of the vertical stabilizer
to detect fatigue cracking, and repairs, if necessary. It also would
require modifications that would strengthen the torsion box at rib 5.0
and prevent fatigue cracking; one of these modifications would be
terminating action for the repetitive inspections. This proposal is
prompted by reports indicating that, during full-scale fatigue testing,
cracking has been found on the vertical stabilizer of the test article.
The actions specified by the proposed AD are intended to detect and
prevent fatigue cracking in the subject area, which, if not corrected,
could reduce the structural integrity of the vertical stabilizer.
DATES: Comments must be received by February 24, 1997.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 96-NM-185-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., Technical Support Department, P.O.
Box 75047, 1117 ZN Schiphol Airport, The Netherlands. This information
may be examined at the FAA, Transport Airplane Directorate, 1601 Lind
Avenue, SW., Renton, Washington.
FOR FURTHER INFORMATION CONTACT: Tim Dulin, Aerospace Engineer,
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate,
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206)
227-2141; fax (206) 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 96-NM-185-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-103, Attention: Rules
Docket No. 96-NM-185-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The Rijksluchtvaartdienst (RLD), which is the airworthiness
authority for the Netherlands, has notified the FAA that an unsafe
condition may exist on certain Fokker Model F28 Mark 0100 series
airplanes. The RLD advises that it has received reports indicating that
cracks have been found on the vertical stabilizer during the
manufacturer's full-scale fatigue tests on the Fokker Model F28 Mark
0100 test article. These fatigue cracks were detected at the bolt holes
of the right-hand flange of the torsion box, and in the finger strip on
the left-hand flange at rib 5.0 of the vertical stabilizer.
The RLD also advises that it has received reports indicating that
subsequent full-scale fatigue tests have detected additional cracks in
rib 5.0 of the vertical stabilizer after a stiffener had been added to
the torsion box in accordance with Fokker Service Bulletin SBF100-55-
018. Although this modification was performed to strengthen this area
against fatigue cracking, investigation has shown that the stiffener
produces a too-rapid change in the structural strength of the torsion
box, which may lead to fatigue cracking in an adjacent area.
Fatigue cracking in the subject area, if not prevented, could
reduce structural integrity of the vertical stabilizer.
Explanation of Relevant Service Information
Fokker has issued Service Bulletin SBF100-55-019, Revision 1, dated
May 19, 1993, which describes procedures for conducting repetitive eddy
current inspections of the flanges and finger strips at rib 5.0 of the
vertical stabilizers to detect fatigue cracking, and repair, if
necessary.
Fokker also has issued Service Bulletin SBF100-55-018, Revision 1,
dated December 27, 1993, which describes procedures for modifying the
torsion box at rib 5.0 of the vertical stabilizer by installing
stiffening to the rib web and flanges for added strength. This service
bulletin also describes procedures for a pre-modification eddy current
inspection of the vertical stabilizer to detect cracking, and repair,
if necessary, in accordance with Fokker Service Bulletin SBF100-55-019.
Accomplishment of this modification eliminates the need for repetitive
inspections to detect fatigue cracking.
Additionally, Fokker has issued Service Bulletin SBF100-55-023,
dated January 3, 1995, which describes procedures for another
modification to strengthen rib 5.0 of the vertical stabilizer. This
modification, which entails the cold expansion of holes in the torsion
box at rib 5.0, is intended to prevent additional fatigue cracking that
could be caused by the earlier installation of the torsion box
stiffener.
The RLD classified these service bulletins as mandatory and issued
Netherlands airworthiness directives (BLA) 93-069 (A), dated June 1,
1993, and BLA 1995-017 (A), dated February 28, 1995, in order to assure
the continued airworthiness of these airplanes in the Netherlands.
[[Page 1867]]
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 repetitive eddy
current inspections to detect fatigue cracking of the left-hand and
right-hand flanges and finger strips at rib 5.0 of the vertical
stabilizer, and repair, if necessary.
The proposed AD also would require modification of rib 5.0 by the
installation of a stiffener to the torsion box; this modification would
be preceded by an eddy current inspection to detect fatigue cracking,
and repair, if necessary. Accomplishment of this modification would
terminate the requirement for repetitive eddy current inspections.
In addition, the proposed AD would require another modification of
rib 5.0 by cold-expanding certain bolt holes on the torsion box.
These actions would be required to be accomplished in accordance
with the applicable service bulletins described previously.
Differences Between the Proposed Rule and the Service Bulletins
If any cracking is detected during an eddy current inspection of
the left-hand and right-hand flanges and finger strips at rib 5.0 of
the vertical stabilizer, the proposed rule would require that the
Manager, Standardization Branch, ANM-113, FAA, Transport Airplane
Directorate approve the method of repair. The applicable Fokker service
bulletins do not provide instructions for repair, but recommend that
Fokker be contacted prior to repairing fatigue cracks at rib 5.0.
Other Related Rulemaking Actions
The FAA has issued AD 91-18-15, amendment 39-8018 (56 FR 43548,
September 3, 1991), which requires reinforcement of the left-hand and
right-hand flanges of rib 5.0 of the vertical stabilizer by the
installation of reinforcing finger clips, in accordance with Fokker
Service Bulletin F100-55-014, dated November 29, 1990. That AD was
prompted by reports of cracking in the flange of the torsion box at the
junction of rib 5.0 and intermediate spar I; it is applicable to Fokker
Model F28 Mark 0100 series airplanes having serial numbers 11244
through 11335.
The reinforcement required by AD 91-18-15 is to be installed prior
to the accumulation of 6,000 total landings on the airplane, or within
100 days after October 8, 1991 (the effective date of that AD),
whichever is later. Under the proposed AD, however, this modification
would not have to be installed if the addition of steel reinforcement
to the torsion box [as specified in proposed paragraph (b)(2)] is
accomplished before an airplane has accumulated 6,000 total landings.
Cost Impact
The FAA estimates that 122 Fokker Model F28 Mark 0100 series
airplanes of U.S. registry would be affected by this proposed AD.
Approximately 77 airplanes would be required to conduct repetitive
inspections of the left-hand and right-hand flanges and finger strips
at rib 5.0 of the vertical stabilizer. It would take approximately 10
work hours per airplane to accomplish each proposed inspection. The
average labor rate is $60 per work hour. Based on these figures, the
cost impact of the proposed inspection requirement on U.S. operators of
these airplanes is estimated to be $46,200, or $600 per airplane, per
inspection.
Approximately 77 airplanes also would be required to accomplish the
proposed installation of steel reinforcement in the torsion box at rib
5.0 of the vertical stabilizer. It would take approximately 170 work
hours per airplane to accomplish this modification (including a pre-
modification inspection). The average labor rate is $60 per work hour.
Required parts would cost approximately $27,000. Based on these
figures, the cost impact of this proposed action on U.S. operators of
these airplanes is estimated to be $2,864,400, or $37,200 per airplane.
Approximately 122 airplanes would be required to accomplish the
proposed cold expansion of holes in the torsion box at rib 5.0 of the
vertical stabilizer. It would take approximately 17 work hours per
airplane to accomplish this modification, or approximately 8 work hours
per airplane if this proposed action is done at the same time as the
proposed installation of steel reinforcement. The average labor rate is
$60 per work hour. Required parts would cost approximately $206. Based
on these figures, the cost impact of this proposed action on U.S.
operators of these airplanes is estimated to be between $83,692 and
$149,572, or between $686 and $1,226 per airplane.
The cost impact figures discussed above are 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.
[[Page 1868]]
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
Fokker: Docket 96-NM-185-AD.
Applicability: Model F28 Mark 0100 series airplanes having the
serial numbers specified in Table 1 of this AD; certificated in any
category.
Table 1.--Serial Numbers of Airplanes Subject to This AD
11244 through 11460, inclusive
11463 through 11469, inclusive
11471
11474 through 11483, inclusive
11489 through 11491, inclusive
11497 through 11499, inclusive
11501
11502
11504
11506
11507
11512 through 11515, inclusive
11517
11520
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
otherwise 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 (e) 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 prevent fatigue cracking in the vertical
stabilizer, which consequently could reduce its structural
integrity, accomplish the following:
(a) For airplanes having serial numbers 11244 through 11419,
inclusive, and 11421: Except as provided by paragraph (c) of this
AD, prior to the accumulation of 8,500 total landings or within 30
days after the effective date of this AD, whichever occurs later,
perform an eddy current inspection to detect fatigue cracking in the
left-hand and right-hand flanges and finger strips at rib 5.0 of the
vertical stabilizer, in accordance with Fokker Service Bulletin
SBF100-55-019, Revision 1, dated May 19, 1993.
(1) If no cracking is detected, repeat this inspection
thereafter at intervals not to exceed 2,000 landings until the
requirements of paragraph (b) of this AD are accomplished.
(2) If any cracking is detected, prior to further flight, repair
in accordance with a method approved by the Manager, Standardization
Branch, ANM-113, FAA, Transport Airplane Directorate.
(b) For airplanes with serial numbers 11244 through 11419,
inclusive, and 11421, accomplish the requirements of both paragraphs
(b)(1) and (b)(2) of this AD:
(1) Except as provided by paragraph (c) of this AD, prior to the
accumulation of 13,500 total landings, or within 6 months after the
effective date of this AD, whichever occurs later, perform an eddy
current inspection to detect fatigue cracking in the left-hand and
right-hand flanges and finger strips at rib 5.0 of the vertical
stabilizer, in accordance with Part 1 of the Accomplishment
Instructions of Fokker Service Bulletin SBF100-55-018, Revision 1,
dated December 27, 1993.
(i) If no cracking is detected, prior to further flight,
accomplish the requirements of paragraph (b)(2) of this AD.
(ii) If any cracking is detected, prior to further flight,
repair in accordance with a method approved by the Manager,
Standardization Branch, ANM-113, and accomplish the requirements of
paragraph (b)(2) of this AD.
(2) After accomplishing the requirements of paragraph (b)(1) of
this AD, modify rib 5.0 of the vertical stabilizer by installing new
stiffening, in accordance with Part 2 of the Accomplishment
Instructions of Fokker Service Bulletin SBF100-55-018, Revision 1,
dated December 27, 1993. Accomplishment of this modification
constitutes terminating action for the repetitive inspections
required by paragraph (a) of this AD.
(c) The following exceptions apply with regard to the
requirements of paragraphs (a) and (b) of this AD:
(1) Accomplishment of the inspection specified in paragraph (a)
and (b)(1) of this AD is not required if the modification specified
in paragraph (b)(2) is accomplished prior to the accumulation of
7,300 total landings on the airplane.
(2) Compliance with AD 91-18-15, amendment 39-8018, is not
required if the requirements of paragraph (b)(2) of this AD are
accomplished prior to the accumulation of 6,000 total landings on
the airplane.
(d) For all airplanes: At the applicable times specified in
paragraph (d)(1) or (d)(2), modify the Hi-lok bolt holes at rib 5.0
of the vertical stabilizer by cold expansion, in accordance with
Fokker Service Bulletin SBF100-55-023, dated January 3, 1995.
(1) For airplanes that have been modified in accordance with the
requirements of paragraph (b) of this AD prior to the effective date
of this AD: Modify prior to the accumulation of either 10,000
landings after in-service modification, or 10,000 landings after
delivery with factory modification, as applicable; or within 30 days
after the effective date of this AD, whichever occurs later.
(2) For all other airplanes: Modify concurrent with
accomplishing the requirements of paragraph (b) of this AD.
(e) 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, Standardization Branch, ANM-113.
Operators shall submit their requests through an appropriate FAA
Principal Maintenance Inspector, who may add comments and then send
it to the Manager, Standardization Branch, ANM-113.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Standardization Branch, ANM-113.
(f) Special flight permits may be issued in accordance with
Secs. 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.
Issued in Renton, Washington, on January 8, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 97-883 Filed 1-13-97; 8:45 am]
BILLING CODE 4910-13-U
