[Federal Register Volume 62, Number 229 (Friday, November 28, 1997)]
[Rules and Regulations]
[Pages 63262-63264]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-31029]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-185-AD; Amendment 39-10218; AD 97-24-11]
RIN 2120-AA64


Airworthiness Directives; Fokker Model F28 Mark 0100 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 certain Fokker Model F28 Mark 0100 series airplanes, that 
requires repetitive inspections of certain flanges and finger strips at 
rib 5.0 of the vertical stabilizer to detect fatigue cracking, and 
repairs, if necessary. This amendment also requires modifications that 
would strengthen the torsion box at rib 5.0 and prevent fatigue 
cracking; one of these modifications constitutes terminating action for 
the repetitive inspections. This amendment 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 this 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: Effective January 2, 1998.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of January 2, 1998.

ADDRESSES: The service information referenced in this AD 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 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: 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 certain Fokker Model F28 Mark 0100 
series airplanes was published in the Federal Register on January 14, 
1997 (62 FR 1866). That action proposed to 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. That action also proposed to 
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 constitutes terminating action for 
the repetitive inspection requirements. In addition, that action 
proposed to require another modification of rib 5.0 by cold-expanding 
certain bolt holes on the torsion box.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.
    One commenter supports the proposed rule.

Requests To Extend the Compliance Time

    Two commenters request that the compliance time for accomplishing 
the proposed eddy current inspection and modification of rib 5.0 of the 
vertical stabilizer [required by paragraphs (b)(1) and (b)(2) of the 
proposed AD, respectively] be extended from ``prior to the accumulation 
of 13,500 total landings, or within 6 months * * * '' to ``prior to the 
accumulation of 16,000 total landings or within 12 months.'' One of 
these commenters states that it is currently performing the subject 
inspection and modification during its F100 ``Q'' check visit, which is 
currently scheduled at 16,000 flight hours or 16,000 landings, 
whichever occurs first. The commenter also states that ten of its 
airplanes, which have accumulated between 10,972 and 14,976 flight 
cycles, have been inspected and modified. This commenter points out 
that no cracks have been detected on these airplanes. This commenter 
contends that accomplishment of the repetitive inspections required by 
paragraph (a) of the proposed AD at 2,000 flight cycle intervals will 
assure that the required level of safety is maintained.
    The FAA does not concur with the commenters' request to extend the 
compliance time. The FAA points out that the proposed compliance time 
of paragraphs (b)(1) and (b)(2) of the AD was developed in 
consideration of not only the degree of urgency associated with 
addressing the unsafe condition, but such factors as the manufacturer's 
and the foreign airworthiness authority's [i.e., Rijksluchtvaartdienst 
(RLD)] recommendations, the availability of required parts, and the 
practical aspect of installing the required modification within an 
interval of time that parallels normal scheduled maintenance for the 
majority of affected operators. The FAA also has consulted with the 
manufacturer and RLD and determined that 13,500 flight cycles 
represents the maximum number of flight cycles allowable for the 
affected airplanes to continue to operate prior to accomplishing the 
required inspections and modification without compromising safety. The 
proposed compliance times are based on results of fatigue tests and 
analysis of the effects of the thrust reverser loads on adjacent 
structure.
    In addition, the FAA finds that the commenters have not submitted 
any data to substantiate why a 2,500 flight-cycle extension of the 
compliance time would not compromise safety, nor have the commenters 
addressed whether further inspections would be necessary to ensure the 
long term operational safety. However, under the provisions of 
paragraph (e) of the final rule, the FAA may approve requests for 
adjustments to the compliance time if sufficient data are submitted to 
substantiate that such an adjustment would provide an acceptable level 
of safety.

Conclusion

    After careful review of the available data, including the comments 
noted

[[Page 63263]]

above, the FAA has determined that air safety and the public interest 
require the adoption of the rule as proposed.

Cost Impact

    The FAA estimates that 122 Fokker Model F28 Mark 0100 series 
airplanes of U.S. registry will be affected by this proposed AD.
    Approximately 77 airplanes will 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 will take approximately 10 
work hours per airplane to accomplish each required inspection. The 
average labor rate is $60 per work hour. Based on these figures, the 
cost impact of these inspections required by this AD on U.S. operators 
of these airplanes is estimated to be $46,200, or $600 per airplane, 
per inspection.
    Approximately 77 airplanes also will be required to accomplish the 
installation of steel reinforcement in the torsion box at rib 5.0 of 
the vertical stabilizer. It will 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 will cost approximately $27,000. Based on these figures, the cost 
impact of this modification required by this AD on U.S. operators of 
these airplanes is estimated to be $2,864,400, or $37,200 per airplane.
    Approximately 122 airplanes will be required to accomplish the cold 
expansion of holes in the torsion box at rib 5.0 of the vertical 
stabilizer. It will take approximately 17 work hours per airplane to 
accomplish this modification, or approximately 8 work hours per 
airplane if this modification is done at the same time as the 
installation of steel reinforcement. The average labor rate is $60 per 
work hour. Required parts will cost approximately $206. Based on these 
figures, the cost impact of this modification required by this AD 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 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:

97-24-11  Fokker: Amendment 39-10218. 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        
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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                                                                   
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    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, International 
Branch, ANM-116, 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, 
International Branch, ANM-116, and

[[Page 63264]]

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, 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.

    (f) 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.
    (g) The actions shall be done in accordance with the following 
Fokker service bulletins, which contain the following list of 
effective pages:

----------------------------------------------------------------------------------------------------------------
  Referenced service bulletin                             Revision level shown on                               
           and date                    Page No.                     page                  Date shown on page    
----------------------------------------------------------------------------------------------------------------
SBF100-55-018, Revision 1,      1-4, 8-16, 18, 19, 21-  1..........................  December 27, 1993.         
 December 27, 1993.              23, 25-28.                                                                     
                                5-7, 17, 20, 24, 29-31  Original...................  May 19, 1993.              
SBF100-55-019, Revision 1, May  1-3, 5, 9,............  1..........................  May 19, 1993.              
 19, 1993.                                                                                                      
                                4, 6-8, 10-12.........  Original...................  August 11, 1992.           
SBF100-55-023, January 3, 1995  1-17..................  Original...................  January 3, 1995.           
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    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 Fokker Services B.V., Technical 
Support Department, P.O. Box 75047, 1117 ZN Schiphol Airport, The 
Netherlands. 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 Dutch 
airworthiness directive (BLA) 93-069 (A), dated June 1, 1993.

    (h) This amendment becomes effective on January 2, 1998.

    Issued in Renton, Washington, on November 19, 1997.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-31029 Filed 11-26-97; 8:45 am]
BILLING CODE 4910-13-P