[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