Airworthiness Directives; Fokker Model F.28 Mark 1000, 2000, 3000, and 4000 Series Airplanes

[Federal Register Volume 66, Number 197 (Thursday, October 11, 2001)]
[Rules and Regulations]
[Pages 51853-51856]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-25182]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-220-AD; Amendment 39-12456; AD 2001-20-08]
RIN 2120-AA64


Airworthiness Directives; Fokker Model F.28 Mark 1000, 2000, 
3000, and 4000 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 F.28 Mark 1000, 2000, 3000, and 4000 
series airplanes, that requires repetitive eddy current inspections 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 AD also provides for an optional 
terminating action for certain requirements of this AD. The actions 
specified by this 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. This action is intended to address the 
identified unsafe condition.

DATES: Effective November 15, 2001.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of November 15, 2001.

ADDRESSES: The service information referenced in this AD 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 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: Dan Rodina, Aerospace Engineer, 
International Branch, ANM-116, Transport Airplane Directorate, 1601 
Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-
2125; fax (425) 227-1149.

[[Page 51854]]


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 F.28 Mark 
1000, 2000, 3000, and 4000 series airplanes was published as a 
supplemental notice of proposed rulemaking (NPRM) in the Federal 
Register on May 4, 2001 (66 FR 22479). That action proposed to require 
repetitive eddy current inspections 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. That 
action also proposed to provide for optional terminating action for 
certain requirements of this AD.

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.

Requests To Allow Flight with Cracks

    One commenter requests that airplanes be allowed to fly with cracks 
within the range of 16 millimeters (mm) (0.630 inches) to 40 mm (1.575 
inches) on the MLG bracket, with repetitive inspections, for a period 
of six months or until the next heavy maintenance check, whichever 
occurs first. A second commenter requests that the replacement of the 
MLG bracket required by paragraph (b) of the proposed AD be required 
only when cracks exceed 40 mm (1.575 inches), as indicated in Dutch 
airworthiness directive 1999-045/2 dated October 31, 2000, and Fokker 
Service Bulletin F28/59-90, Revision 1, dated August 28, 2000. Both 
commenters point out that the proposed replacement of the MLG bracket 
would require extended downtime and would be a disruption to the 
operator's operating schedule if the repair cannot be accomplished in 
conjunction with a heavy maintenance check. The commenters state that 
requiring replacement of the MLG bracket with cracks between 15 mm 
(0.591 inches) and 40 mm (1.575 inches) could create severe logistical 
disturbances and a significant cost impact for the operators, with no 
added safety benefit.
    The FAA partially agrees with these commenters. The FAA 
acknowledges that if any crack is found, no matter what its length, the 
repair or replacement required by paragraph (a) or (c) of the AD 
requires a considerable number of work hours. We also acknowledge that 
unless the repetitive inspections required by paragraph (a) of this AD 
are scheduled during a heavy maintenance check, any crack finding could 
potentially remove the airplane from service and possibly result in a 
disruption to operating schedules.
    To address this issue, the Rijksluchtvaartdienst (RLD), the 
airworthiness authority for the Netherlands, has allowed a repeat 
inspection at intervals of 250 flight cycles, or one month, as an 
alternate to replacement. Neither Dutch airworthiness directive 1999-
045/2, dated October 31, 2000, nor Fokker Service Bulletin F28/59-90, 
Revision 1, dated August 28, 2000, puts a time limit on this 
replacement deferral. If the FAA were to allow for this reduced 
inspection cycle in lieu of repair, we would require a time limit.
    While recognizing that repair deferrals may be necessary at times, 
FAA policy is intended to minimize adverse human factors relating to 
the lack of reliability of long-term repetitive inspections, which may 
reduce the safety of the type certificated design if such repair 
deferrals are practiced routinely. Based upon correspondence with the 
manufacturer, the FAA has determined that no structural detrimental 
permanent deformation will occur in the MLG and surrounding structure 
under the full limit load when a stress corrosion crack with a length 
of 40 mm or less is present at the indicated location. In addition, no 
failure will occur in the MLG bracket or surrounding structure under 
the ultimate load. If the crack does not exceed 40 mm in length it will 
not cause loss of function or interfere with other necessary parts of 
the design. Experience supports the results of the theoretical analysis 
and the FAA has a high degree of confidence that operation with a known 
crack is safe as long as it is closely monitored.
    Consequently, paragraph (a) of the final rule has been revised to 
allow for a repair deferral period of not more than 18 months if a 
crack of 40 mm or less is detected, provided the crack is monitored at 
the reduced inspection interval specified in the service bulletin. In 
addition, paragraph (a) has been revised and reformatted to clarify 
that terminating action is not necessary; paragraph (c) has been 
removed; and subsequent paragraphs have been renumbered accordingly.
    Under the provisions of paragraph (e) of the final rule, the FAA 
may approve requests for adjustments to the compliance time if data are 
submitted to substantiate that such an adjustment would provide an 
acceptable level of safety.

Clarification of Service Bulletin Reference

    The FAA's intent in this rule was to require that repairs specified 
in paragraph (a) be performed in accordance with Part 3 (``The Repairs 
and the Repetitive Inspections'') of the Accomplishment Instructions of 
Fokker Service Bulletin F28/57-90, Revision 1, dated August 28, 2000. 
As issued, the supplemental notice of proposed rulemaking contained an 
incorrect reference to a service bulletin paragraph. The final rule has 
been revised to correct this error and to clarify the appropriate 
requirements.

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 8 Fokker Model F.28 Mark 1000, 2000, 3000, 
and 4000 series airplanes of U.S. registry will be affected by this AD, 
that it will take approximately 2 work hours per airplane to accomplish 
the required inspection, 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 $960, or $120 per airplane.
    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. The cost impact figures discussed 
in AD rulemaking actions represent only the time necessary to perform 
the specific actions actually required by the AD. These figures 
typically do not include incidental costs, such as the time required to 
gain access and close up, planning time, or time necessitated by other 
administrative actions.

Regulatory Impact

    The regulations adopted herein will not have a substantial direct 
effect 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, it 
is

[[Page 51855]]

determined that this final rule does not have federalism implications 
under Executive Order 13132.
    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:

2001-20-08  Fokker Services B.V.: Amendment 39-12456. 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 (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 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:

Repetitive Inspections and Corrective Actions

    (a) Within 12 months after the effective date of this AD, 
perform an 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, Revision 1, dated August 28, 2000.
    (1) If no cracks are found, repeat the inspection at least every 
18 months unless the terminating action in paragraph (c) of this AD 
has been accomplished.
    (2) Except as provided by paragraph (d) of this AD, if any crack 
is found, accomplish a repair as specified in Part 3, ``The Repairs 
and the Repetitive Inspections'', of the Accomplishment Instructions 
of the service bulletin, or accomplish the specified action at the 
time shown in paragraph (a)(2)(i), (a)(2)(ii), (a)(2)(iii), or 
(a)(2)(iv) of this AD, as applicable.
    (i) For airplanes on which a crack 15 millimeters (mm) in length 
or less is found: repair as specified in paragraph (a)(2) or, for a 
period of time not to exceed 18 months until accomplishment of a 
repair, repeat the inspection every 250 flight cycles or 1 month, 
whichever occurs first, in accordance with the service bulletin. 
After the repair has been accomplished, repeat the inspection 
required in paragraph (a) of this AD at least every 18 months unless 
the terminating action in paragraph (c) of this AD has been 
accomplished.
    (ii) For airplanes on which a crack greater than 15 mm but less 
than or equal to 25 mm in length is found: Within 18 months from the 
date of the inspection, accomplish the terminating action in 
paragraph (c) of this AD. From the date of the inspection until the 
accomplishment of the terminating action, repeat the inspection 
every 250 flight cycles or 1 month, whichever occurs first .
    (iii) For airplanes on which a crack greater than 25 mm but less 
than or equal to 40 mm in length is found: Within 18 months from the 
date of the inspection, accomplish the terminating action in 
paragraph (c) of this AD. From the date of the inspection until the 
accomplishment of the terminating action, repeat the inspection 
every 50 flight cycles or 1 week, whichever occurs first.
    (iv) For airplanes on which a crack greater than 40 mm in length 
is found: Prior to further flight, except as provided by paragraph 
(d) of this AD, accomplish the terminating action in paragraph (c) 
of this AD.

    Note 2: Inspections accomplished before the effective date of 
this AD in accordance with Fokker Service Bulletin F28/57-90, dated 
March 1, 1999, are considered acceptable for compliance with 
paragraph (a) 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.

Terminating Action

    (c) If required by paragraph (a) of this AD, except as provided 
by paragraph (d) 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) of this AD for the replaced bracket.
    (d) 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 it 
delegated agent).

Alternative Methods of Compliance

    (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, FAA. 
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 3: 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

    (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.

Incorporation by Reference

    (g) Except as provided by paragraph (d) of this AD, the actions 
shall be performed in accordance with Fokker Service Bulletin F28/
57-90, Revision 1, dated August 28, 2000; and Fokker Proforma 
Service Bulletin F28/57-92, dated July 1, 1999; as applicable. This 
incorporation by reference was approved by the Director of the 
Federal Register in accordance with 5 U.S.C. 552(a)

[[Page 51856]]

and 1 CFR part 51. Copies may be obtained from Fokker Services B.V., 
P.O. Box 231, 2150 AE Nieuw-Vennep, 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 4: The subject of this AD is addressed in Dutch 
airworthiness directive 1999-045/2, dated October 31, 2000.

Effective Date

    (h) This amendment becomes effective on November 15, 2001.

    Issued in Renton, Washington, on October 2, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-25182 Filed 10-10-01; 8:45 am]
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