[Federal Register Volume 61, Number 175 (Monday, September 9, 1996)]
[Proposed Rules]
[Pages 47462-47465]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-22920]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-NM-193-AD]
RIN 2120-AA64


Airworthiness Directives; Fokker Model F28 Mark 0100 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Supplemental notice of proposed rulemaking; reopening of 
comment period.

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SUMMARY: This document revises an earlier proposed airworthiness 
directive (AD) that is applicable to certain Fokker Model F28 Mark 0100 
series airplanes. That proposal would have required repetitive 
inspections to detect corrosion in the wheel axles of the main landing 
gear (MLG) sliding members; and rework of any corroded areas, an 
inspection to detect cracks in the wheel axles, and replacement of any 
cracked sliding member. That proposal was prompted by a report of 
failure of a MLG wheel axle during push back of an in-service airplane 
from the terminal. This action revises the proposed rule by providing 
for interim actions that may be accomplished in lieu of the repetitive 
inspections. This action also revises the proposed rule by requiring 
eventual modifications of the main wheel brake units and the MLG 
sliding members; when accomplished, these modifications terminate the 
repetitive inspections and interim actions. The actions specified by 
this proposed AD are intended to prevent failure of the MLG wheel axle 
due to problems associated with corrosion and cracking.

DATES: Comments must be received by October 3, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 93-NM-193-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 Aircraft USA, Inc., 1199 North Fairfax Street, 
Alexandria, Virginia 22314. This information may be examined at the 
FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Ruth E. Harder, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-1721; 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 93-NM-193-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. 93-NM-193-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to add an airworthiness directive (AD), applicable to 
certain Fokker Model F28 Mark 0100 series airplanes, was published as a 
notice of proposed rulemaking (NPRM) in the Federal Register on 
February 2, 1994 (59 FR 4875). That NPRM would have required repetitive 
inspections to detect corrosion in the wheel axles of the main landing 
gear (MLG) sliding members; and rework of any corroded areas, an 
inspection to detect cracks in the wheel axles, and replacement of any 
cracked sliding member. That NPRM was prompted by a report that a MLG 
wheel axle failed during push back of an in-

[[Page 47463]]

 service airplane from the terminal. That condition, if not corrected, 
could result in failure of the MLG wheel axle due to the problems 
associated with corrosion and cracking.

Actions Since Issuance of Previous Proposal

    Since the issuance of the NPRM, three new or revised service 
bulletins have been released. These service bulletins are described 
below.
    1. Dowty Aerospace has issued Service Bulletin F100-32-64, Revision 
1, dated February 18, 1994. The original issue of this service bulletin 
was cited in the NPRM as an appropriate source of service information 
for accomplishment of repetitive visual inspections to detect corrosion 
in the wheel axles of the MLG sliding members. Although Revision 1 is 
essentially the same as the original issue, it contains certain 
editorial changes; the technical content of the service bulletin has 
not been changed.
    2. Fokker has issued Service Bulletin SBF100-32-083, dated March 
23, 1994. This service bulletin describes procedures for interim 
actions that may be accomplished in lieu of the repetitive inspections 
described in Fokker Service Bulletin SBF100-32-080. Accomplishment of 
these interim actions would allow an operator to increase the 
repetitive inspection interval for its fleet from 3 months to one year 
until terminating modifications are accomplished. The interim actions 
include:

--Installation of main wheel brake units with chamfered and cadmium-
plated inboard bushings;
--Restoration of the protection scheme of the sliding members; and
--Inspections (also referred to as a ``sampling program'') to detect 
corrosion in the wheel axles of the MLG sliding members.

    This service bulletin recommends that if any sampling is 
unsatisfactory, the repetitive inspections described in Fokker Service 
Bulletin SBF100-32-080 should be resumed. (Additionally, this service 
bulletin references Part B of the Dowty service bulletin described 
previously as an additional source of service information for 
accomplishment of the interim actions.)
    3. Fokker also has issued Service Bulletin SBF100-32-081, dated 
March 23, 1994, which describes procedures for modifications of the 
main wheel brake units and the MLG sliding members. These modifications 
entail installing the main wheel brake units with chamfered and 
cadmium-plated inboard bushings, and installing landing gears with 
chromium or nickel plating on the brake abutment flange of the sliding 
member and restored cadmium plating and paint in the radius of the 
sliding member. Accomplishment of these modifications will prevent the 
development of corrosion in the radii of the wheel axles of the MLG 
sliding members. Accomplishment of the modifications eliminates the 
need for the repetitive inspections and the interim actions. 
(Additionally, the Fokker service bulletin references Part C of the 
Dowty service bulletin described previously as an additional source of 
service information for accomplishment of the modifications.)

Related Action by the Netherlands Authorities

    The Rijksluchtvaartdienst (RLD), which is the airworthiness 
authority for the Netherlands, has approved the Fokker service 
bulletins, and issued Netherlands airworthiness directive (BLA) 93-108/
3 (A), dated April 29, 1994, in order to assure the continued 
airworthiness of these airplanes in the Netherlands.
    The BLA requires the accomplishment of either the repetitive visual 
inspections for corrosion, or the interim actions (including the 
`sampling program'' inspections).

FAA's Findings; New Proposed Requirements

    The FAA examined the findings of the RLD, and reviewed the latest 
service information. The FAA finds that the previously issued NPRM must 
be revised to provide for interim actions that may be accomplished in 
lieu of the repetitive inspections, and to require the accomplishment 
of the modifications of the main wheel brake units and the MLG sliding 
members specified in Fokker Service Bulletin SBF100-32-081, dated March 
23, 1994. Two new paragraphs have been added to this supplemental NPRM 
to provide for these interim actions and to require the modifications 
that constitute terminating action for the inspections.
    The FAA also has revised the NPRM to cite the latest service 
bulletin revisions as the appropriate sources of service information.

Differences Between Proposed Rule and Netherlands Directive

    Although the Netherlands BLA does not mandate the accomplishment of 
the modifications, this proposed AD would require that those 
modifications be accomplished. The FAA has determined that long term 
continued operational safety will be better assured by design changes 
to remove the source of the problem, rather than by repetitive 
inspections. Long term inspections may not be providing the degree of 
safety assurance necessary for the transport airplane fleet. This, 
coupled with a better understanding of the human factors associated 
with numerous continual inspections, has led the FAA to consider 
placing less emphasis on inspections and more emphasis on design 
improvements. The proposed modification requirement is in consonance 
with these considerations.

Conclusion

    Since these changes expand the scope of the originally proposed 
rule, the FAA has determined that it is necessary to reopen the comment 
period to provide additional opportunity for public comment.

Cost Impact

    The cost impact information specified in the NPRM indicated that 
100 airplanes of U.S. registry would be affected by this proposed AD. 
The FAA has updated that information, below, to indicate that 125 
airplanes would be affected.
    In addition, the FAA has recently reviewed the figures it has used 
over the past several years in calculating the economic impact of AD 
activity. In order to account for various inflationary costs in the 
airline industry, the FAA has determined that it is necessary to 
increase the labor rate used in these calculations from $55 per work 
hour to $60 per work hour. The cost impact information also has been 
revised to reflect this increase in the specified hourly labor rate.
    The FAA estimates that 125 airplanes of U.S. registry would be 
affected by this proposed AD, that it would take approximately 14 work 
hours per airplane to accomplish the proposed visual inspections, and 
that the average labor rate is $60 per work hour. Based on these 
figures, the cost impact of the initial visual inspection of this 
proposed AD on U.S. operators is estimated to be $105,000, or $840 per 
airplane.
    The FAA estimates that it would take approximately 66 work hours 
per airplane to accomplished the proposed terminating modifications, at 
an average labor rate of $60 per work hour. The cost for required parts 
would be approximately $865 per airplane. Based on these figures, the 
cost impact of the proposed terminating action on U.S. operators is 
estimated to be $603,125, or $4,825 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

[[Page 47464]]

action, and that no operator would accomplish those actions in the 
future if this AD were not adopted.
    Should an operator elect to accomplish the repetitive visual 
inspections that would be provided by this AD action, it would take 
approximately 14 work hours to accomplish each repetitive inspection, 
at an average labor rate of $60 per work hour. The FAA estimates that 
these inspections would be accomplished four times per year. Based on 
these figures, the cost impact of the repetitive inspections on U.S. 
operators is estimated to be $3,360 per airplane, per year.
    Should an operator elect to accomplish the interim actions that 
would be provided by this AD action, it would take approximately 26 
work hours for the rework, and 26 work hours per airplane for the brake 
unit replacement. It would take between 28-168 work hours per year for 
the sampling program, depending on the size of an operator's fleet. The 
average labor rate is $60 per work hour. The cost for required parts 
would be approximately $865 per airplane. Additionally, once these 
interim actions are accomplished, the cost impact of the terminating 
modifications discussed previously would be reduced by $2,400 per 
airplane.

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.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

Fokker: Docket 93-NM-193-AD.

    Applicability: Model F28 Mark 0100 series airplanes equipped 
with Dowty Aerospace main landing gear (MLG) part number 201072011, 
201072012, 201072013, 201072014, 201072015, or 201072016; 
certificated in any category.

    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 (g) 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 prevent failure of the MLG wheel axle due to problems 
associated with corrosion and cracking, accomplish the following:
    (a) Within 30 days after the effective date of this AD, remove 
the MLG wheels and brakes and perform a visual inspection to detect 
corrosion and cracking in the wheel axles of the MLG sliding members 
in accordance with Fokker Service Bulletin F100-32-079, Revision 1, 
dated October 4, 1993, and paragraph 2.A. of the Accomplishment 
Instructions of Dowty Aerospace Service Bulletin F100-32-63, 
Revision 2, dated September 23, 1993.
    (b) Following accomplishment of the inspection required by 
paragraph (a) of this AD, accomplish either paragraph (b)(1) or 
(b)(2) of this AD.
    (1) Repeat the inspection required by paragraph (a) of this AD 
thereafter at intervals not to exceed 3 months in accordance with 
Fokker Service Bulletin SBF100-32-080, dated October 4, 1993, and 
Dowty Aerospace Service Bulletin F100-32-64, Revision 1, dated 
February 18, 1994, until the actions required by paragraph (e) of 
this AD are accomplished. Or
    (2) Accomplish paragraphs (b)(2)(i), (b)(2)(ii), and (b)(2)(iii) 
of this AD at the times specified in those paragraphs in accordance 
with Fokker Service Bulletin SBF100-32-083, dated March 23, 1994.
    (i) Within 3 months after the accomplishment of an inspection 
required by paragraph (a) or (b)(1) of this AD: Rework the axles in 
accordance with Part 2 of the Accomplishment Instructions of the 
service bulletin. Repeat this rework thereafter at intervals not to 
exceed 12 months or 2,200 landings, whichever occurs first. And
    (ii) Prior to or concurrent with accomplishing the initial 
rework specified in paragraph (b)(2)(i) of this AD: Replace the main 
wheel brake units in accordance with Part 1 of the Accomplishment 
Instructions of the service bulletin. And
    (iii) Within 3 months after the first accomplishment of the 
rework required by paragraph (b)(2)(i) of this AD: Begin performing 
interim inspections (``sampling program'') to detect corrosion and 
cracking in the wheel axles of the MLG sliding members, in 
accordance with Part 3 of the Accomplishment Instructions of the 
service bulletin. Perform these inspections at the intervals 
specified in the service bulletin until the actions required by 
paragraph (e) of this AD are accomplished.
    (c) If any corrosion is found during any inspection required by 
this AD, prior to further flight, rework the affected area and 
perform a non-destructive testing (NDT) inspection to detect cracks 
in the MLG wheel axles, in accordance with Appendix A of Dowty 
Aerospace Service Bulletin F100-32-63, Revision 2, dated September 
23, 1993 (if corrosion is found during the initial inspection 
required by this AD); or Dowty Aerospace Service Bulletin F100-32-
64, Revision 1, dated February 18, 1994 (if corrosion is found 
during a repetitive inspection required by this AD); as applicable. 
After rework, perform repetitive inspections of the affected area in 
accordance with paragraph (b)(1) of this AD until the actions 
required by paragraph (e) of this AD are accomplished.
    (d) If any crack is found during any inspection required by this 
AD, prior to further flight, replace the affected sliding member 
with a serviceable sliding member in accordance with Dowty Aerospace 
Service Bulletin F100-32-63, Revision 2, dated September 23, 1993 
(if any crack is found during the initial inspection required by 
this AD); or Dowty Aerospace Service Bulletin F100-32-64, Revision 
1, dated February 18, 1994 (if any crack is found during a 
repetitive inspection required by this AD); as applicable. After 
replacement of the affected sliding member, perform the repetitive 
inspections in accordance with paragraph (b)(1) of this AD until the 
actions required by paragraph (e) of this AD are accomplished.
    (e) At the next major gear overhaul, or within 4,400 landings 
after accomplishment of the initial inspection required by paragraph 
(a) of this AD, whichever occurs first: Rework the sliding member, 
and replace the main wheel brake units in accordance

[[Page 47465]]

with the Accomplishment Instructions of Fokker Service Bulletin 
SBF100-32-081, dated March 23, 1994. Accomplishment of these actions 
constitutes terminating action for the repetitive inspections and 
the interim actions specified in paragraph (b) of this AD.

    Note 2: Fokker Service Bulletin SBF100-32-081 references Dowty 
Aerospace Service Bulletin F100-32-64, Revision 1, dated February 
18, 1994, as an additional source of service information for 
accomplishment of the rework and replacement.

    (f) As of the effective date of this AD, no person shall install 
a Dowty Aerospace MLG, part number 201072011, 201072012, 201072013, 
201072014, 201072015, or 201072016, on any airplane unless the 
requirements of this AD have been accomplished on that MLG. 
Following its installation, the repetitive inspections required by 
paragraph (b) of this AD shall be accomplished on that MLG.
    (g) 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, 
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, 
Standardization Branch, ANM-113.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Standardization Branch, ANM-113.

    (h) 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.

    Issued in Renton, Washington, on September 3, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-22920 Filed 9-6-96; 8:45 am]
BILLING CODE 4910-13-U