[Federal Register Volume 64, Number 178 (Wednesday, September 15, 1999)]
[Rules and Regulations]
[Pages 49974-49977]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-23473]
[[Page 49974]]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-NM-261-AD; Amendment 39-11315; AD 99-19-28]
RIN 2120-AA64
Airworthiness Directives; Empresa Brasileira de Aeronautica S.A.
(EMBRAER) Model EMB-120RT and -120ER 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 EMBRAER Model EMB-120RT and -120ER series
airplanes, that requires repetitive detailed visual inspections to
detect discrepancies of the brake assemblies on the main landing gear
(MLG), and replacement of the brake assemblies with new or serviceable
brake assemblies, if necessary. This amendment is prompted by reports
of fatigue cracking or splitting of the brake stator disk at the
thermal expansion slots. The actions specified by this AD are intended
to prevent failure of the brake assemblies of the MLG due to cracking
or splitting of the stator disk, which could result in loss of brake
effectiveness and could cause the airplane to leave the runway surface.
DATES: Effective October 20, 1999.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of October 20, 1999.
ADDRESSES: The service information referenced in this AD may be
obtained from BFGoodrich, Aircraft Wheels and Brakes, P.O. Box 340,
Troy, Ohio, 45373. 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 FAA, Small
Airplane Directorate, Atlanta Aircraft Certification Office, One Crown
Center, 1895 Phoenix Boulevard, suite 450, Atlanta, Georgia; or at the
Office of the Federal Register, 800 North Capitol Street, NW., suite
700, Washington, DC.
FOR FURTHER INFORMATION CONTACT: Rob Capezzuto, Aerospace Engineer,
Systems and Flight Test Branch, ACE-116A, FAA, Small Airplane
Directorate, Atlanta Aircraft Certification Office, One Crown Center,
1895 Phoenix Boulevard, suite 450, Atlanta, Georgia 30349; telephone
(770) 703-6071; fax (770) 703-6097.
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 EMBRAER Model EMB-120RT
and -120ER series airplanes was published in the Federal Register on
October 14, 1998 (63 FR 55059). That action proposed to require
repetitive visual inspections to detect discrepancies of the brake
assemblies on the main landing gear (MLG), and replacement of the brake
assemblies with new brake assemblies, if necessary.
Comments
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the four comments received.
Request to Withdraw Proposed AD
One commenter, the manufacturer, states that it discussed
with the Brazilian airworthiness authority the ``cracked/splitted
stator brakes'' that were impairing the expected service life of the
brakes of Model EMB-120 series airplanes. Upon request by the Brazilian
airworthiness authority, the manufacturer incorporated the inspections
specified by BFGoodrich Service Bulletins 2-1585-32-1 and 2-1479-32-2
into the ``EMB-120 Maintenance Review Board (MRB)'' document, temporary
revision No. 3. The commenter contends that, since the MRB is an FAA-
approved document applicable to all U.S.-registered airplanes and
includes the same inspection procedures as the service bulletins,
issuance of the proposed AD would be a duplication and, therefore, is
unnecessary.
The FAA does not concur. Although the MRB is an FAA-approved
document, the procedures specified in that document are recommended
(rather than mandatory) for U.S. operators. The FAA finds that
accomplishment of the inspections as part of a recommended action in
the MRB report would not ensure an acceptable level of safety. In light
of this and the identified unsafe condition, the FAA has determined
that issuance of this AD is necessary in order to mandate repetitive
detailed visual inspections for discrepancies of the brake assemblies
on the MLG in paragraph (a) of this AD.
One commenter states that the proposed rule is not
justified because the actions required do not effectively prevent brake
rotor failure or promote safety. The commenter suggests that additional
research needs to be accomplished to determine answers to the following
questions. Why are some operators having problems with brake rotors
when others, such as the largest operator of Model EMB-120 series
airplanes in the world, are not? Is the problem of rotor breakage
associated with landing cycles, or is it associated with brake rotor
over-temperature situations? Have there been any runway excursions or
passenger injuries as a result of brake rotor failure on Model EMB-120
series airplanes?
The FAA does not concur that the proposed AD is not justified.
BFGoodrich's investigation of the brake stator rotors indicates that
fatigue cracking began to occur between 600 and 1,000 flight hours,
which clearly shows that a service difficulty does exist with the
rotors. To address this problem, BFGoodrich issued Service Bulletins 2-
1585-32-1 and 2-1479-32-2, both Revision 1, dated June 17, 1998.
Although the exact cause of the cracking is unknown at this time,
BFGoodrich has informed the FAA that the cracking and splitting [of the
brake stator disks] are due to overheat and thermal distortion of the
stator disks. The FAA considers that the number of landing cycles and
over-temperature conditions are related to the identified unsafe
condition. Although no runway excursions or passenger injuries have
been reported as a result of the identified unsafe condition to date,
the FAA has determined that the procedures required by this AD are
necessary to prevent an unsafe condition from occurring and to ensure
continued operational safety. No change to the final rule is necessary
in this regard.
Request to Increase the Compliance Time for the Inspections
Three commenters request that the compliance times for the initial
and repetitive inspections be increased.
One commenter requests revising the initial inspection in paragraph
(a) of the proposed AD to ``within 400 hours after the effective date
of this AD'' and repeating the inspections thereafter ``at an interval
not to exceed 400 hours.'' The commenter contends that such an
extension of the compliance time would allow accomplishment of these
inspection requirements during an operator's regularly scheduled ``A''
checks. The commenter adds that some operators do not have certified
inspectors at remote line stations to support a mandatory inspection
requirement to accomplish the repetitive inspections at each wheel
change, although it is preferred to have
[[Page 49975]]
line mechanics inspect the brakes at each wheel removal.
Another commenter states that the repetitive inspection interval
required by the proposed AD of ``300 landings'' would require very
labor intensive and costly tracking and planning, which would make
operators prone to ``overfly'' errors. The commenter contends that
repetitive inspection intervals should include the option of using
airframe hours and should be based on an operator's existing
maintenance/inspection program, as determined by each operator's
continuing analysis and surveillance system. Based on a sampling of
COEX brake removal data due to stator/disc breakage, an ``A-check''
interval of 400 hours would provide an equivalent level of safety for
our fleet.
Another commenter states that a ``300 cycle re-inspection
requirement'' is impractical and does not increase safety. There is no
documented time at which cracks appear, nor is there any documentation
of crack propagation rates. In addition, the ``300 cycle interval'' at
each wheel change required by the proposed AD appears to be arbitrary
with no supporting data.
The FAA concurs with the commenters' requests to extend the
compliance time for the inspections. Based on information provided by
one of the commenters, the FAA recognizes that ``400 flight hours''
corresponds more closely to the interval representative of most of the
affected operators' normal maintenance schedules, where special
equipment and trained maintenance personnel will be available if
necessary. The FAA does not consider that this extension will adversely
affect safety. Paragraph (a) of the final rule has been changed to
specify the compliance times for the initial detailed visual inspection
as: ``Within 400 flight hours after the effective date of this AD,''
and the repetitive inspections [in paragraphs (a) and (b)] as: ``at an
interval not to exceed 400 flight hours.''
Request to Change Brake Replacement Requirement
Three commenters request changing the proposed AD to require
replacement of the brake assembly with a ``serviceable'' rather than a
``new'' brake assembly. One commenter contends that it is doubtful the
brake manufacturer can maintain production levels to support Model EMB-
120 series airplanes with new replacement units. Another commenter
contends that there is no justification for requiring a new part to be
installed as a replacement because, in every instance, a
``serviceable'' part should be acceptable for replacement.
The FAA concurs that the replacement of discrepant brake assemblies
with serviceable parts is acceptable. The FAA has provided operators
with the option of replacing any discrepant brake assemblies with
either a new or serviceable brake assembly. This option provides
greater flexibility to the operators in meeting the requirements of
this AD and alleviates any problems regarding parts availability, while
still providing an acceptable level of safety for the fleet. The FAA
has revised the preamble and paragraph (b) of the final rule
accordingly.
Request to Consider Adding Brake Assemblies to the Applicability
One commenter requests that the FAA consider whether the
applicability of the proposed AD should include brake assemblies, part
numbers (P/N) 2-1585 and 2-1479-1, that have been modified with parts
manufacturer approval (PMA) heat sink components.
The FAA finds that this AD would apply to airplanes equipped with
brake assemblies having part number (P/N) 2-1585 or 2-1479-1, if those
assemblies have been modified with PMA heat sink components and if the
PMA approval was based on identicality. Such components are identical
to the original part in materials and dimensions and, therefore, may be
subject to the same identified unsafe condition. However, investigation
reveals that the only known PMA's to these brake assemblies were
obtained through test and computation. Because there are no known PMA's
to these brake assemblies that have been obtained through identicality,
no change to the applicability of the final rule is necessary.
Request to Revise the Preamble of the Proposal
One commenter requests revising the Summary of the proposed AD by
clarifying that the brake stator disk is located at the ``thermal
expansion slots'' rather than at the ``cut-out slots.'' The FAA concurs
and has changed the Summary of the final rule accordingly.
That same commenter also requests revising the ``Discussion''
paragraph of the proposed AD to clarify that the cause of the cracking
and splitting are the result of overheat and thermal distortion of the
stator disks, although the exact cause of these conditions have not
been determined at this time. The FAA recognizes that the suggested
change provides improved technical accuracy. However, since the
``Discussion'' paragraph of the preamble to the NPRM is not restated in
the final rule, no change to the final rule is necessary.
That same commenter also requests revising the ``Explanation of
Relevant Service Information'' paragraph of the proposed AD to change
one of the discrepancies listed in that paragraph from ``wear of
plates'' to ``excessive distortion of the wear plates.'' The FAA
acknowledges that the suggested change improves technical accuracy.
Even though the referenced paragraph does not appear in the final rule,
the FAA considers that the suggested change is appropriate for
paragraph (a) of the final rule and has changed that paragraph
accordingly.
Request to Revise the Cost Impact in the Proposed AD
One commenter requests revising the Cost Impact paragraph of the
proposed AD. The commenter states that the referenced service bulletins
estimate that the inspection at a tire change would be 15 minutes per
brake, or one hour per airplane. However, if the inspections were not
accomplished at a tire change, additional time and cost (approximately
2 hours per airplane) would be required to jack the airplane and remove
the wheel/tire assembly to enable the inspection.
The FAA does not concur. As explained earlier in this AD, no
additional time would be required for the inspections because the
compliance times are extended in the final rule, which should allow the
operator to perform the inspection during a tire change. No change to
the final rule was necessary in this regard.
Differences Between Service Bulletin and This AD
Operators should note that BFGoodrich Service Bulletins 2-1585-32-1
and 2-1479-32-2, both Revision 1, dated June 17, 1998, specify an
``examination'' of the brake assembly and a ``visual examination'' of
each stator disk expansion slot. However, this final rule requires a
``detailed visual inspection'' to determine the existence of any
discrepancies of the brake assemblies on the MLG. A note has been added
to the final rule to define that inspection.
Conclusion
After careful review of the available data, including the comment
noted above, the FAA has determined that air safety and the public
interest require the adoption of the rule with the changes previously
described. The FAA has determined that these changes will
[[Page 49976]]
neither increase the economic burden on any operator nor increase the
scope of the AD.
Interim Action
This is considered to be interim action until final action is
identified, at which time the FAA may consider further rulemaking.
Cost Impact
The FAA estimates that 227 Model EMB-120RT and -120ER series
airplanes of U.S. registry will be affected by this AD, that it will
take approximately 1 work hour 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 $13,620, or $60 per airplane, per inspection cycle.
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.
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:
99-19-28 Empresa Brasileira De Aeronautica S.A. (EMBRAER):
Amendment 39-11315. Docket 98-NM-261-AD.
Applicability: Model EMB-120RT and -120ER series airplanes,
equipped with BFGoodrich brake assemblies having part number (P/N)
2-1585 or 2-1479-1; 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 (d) 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 brake assemblies of the main landing
gear (MLG) due to cracking or splitting of the stator disk, which
could result in loss of brake effectiveness and could cause the
airplane to leave the runway surface, accomplish the following:
(a) Within 400 flight hours after the effective date of this AD,
perform a detailed visual inspection for discrepancies (e.g.,
locking or hanging up, broken or damaged stators, and excessive
distortion of the wear plates) of the brake assemblies on the MLG,
in accordance with paragraph (a)(1) or (a)(2) of this AD, as
applicable. Repeat the inspections thereafter at intervals not to
exceed 400 flight hours.
(1) For airplanes equipped with BFGoodrich main brake assemblies
having P/N 2-1479-1: Inspect in accordance with BFGoodrich Service
Bulletin 2-1479-32-2, Revision 1, dated June 17, 1998.
(2) For airplanes equipped with BFGoodrich main brake assemblies
having P/N 2-1585: Inspect in accordance with BFGoodrich Service
Bulletin 2-1585-32-1, Revision 1, dated June 17, 1998.
Note 2: For the purposes of this AD, a detailed visual
inspection is defined as: ``An intensive visual examination of a
specific structural area, system, installation, or assembly to
detect damage, failure, or irregularity. Available lighting is
normally supplemented with a direct source of good lighting at
intensity deemed appropriate by the inspector. Inspection aids such
as mirror, magnifying lenses, etc., may be used. Surface cleaning
and elaborate access procedures may be required.''
(b) If any discrepancy is detected during any inspection
required by paragraph (a) of this AD, prior to further flight,
replace the brake assembly with a new or serviceable brake assembly,
in accordance with section 32-41-05 of EMBRAER EMB-120 Brasilia
Maintenance Manual, dated April 30, 1992. Repeat the inspections
required by paragraph (a) of this AD thereafter at intervals not to
exceed 400 flight hours.
(c) Within 10 days after accomplishing any inspection required
by this AD, if a discrepant brake assembly is detected, submit a
report of the inspection results to BFGoodrich, Aircraft Wheels and
Brakes, P.O. Box 340 Troy, Ohio, 45373. 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.
Alternative Methods of Compliance
(d) 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, Atlanta Aircraft Certification
Office (ACO), FAA, Small 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, Atlanta ACO.
Note 3: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Atlanta ACO.
Special Flight Permits
(e) 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
(f) Except as provided by paragraph (b) of this AD, the
inspections and replacement shall be done in accordance with
BFGoodrich Service Bulletin 2-1479-32-2, Revision 1, dated June 17,
1998, and BFGoodrich Service Bulletin 2-1585-32-1, Revision 1, dated
June 17, 1998, as applicable. 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
BFGoodrich, Aircraft Wheels and Brakes, P.O. Box 340, Troy, Ohio
45373. Copies may be inspected at the FAA, Transport Airplane
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the
FAA, Small Airplane Directorate, Atlanta Aircraft Certification
Office, One Crown Center, 1895 Phoenix Boulevard, suite 450,
Atlanta, Georgia; or at the Office of the Federal Register, 800
North Capitol Street, NW, suite 700, Washington, DC.
[[Page 49977]]
(g) This amendment becomes effective on October 20, 1999.
Issued in Renton, Washington, on September 2, 1999.
Dorenda D. Baker,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-23473 Filed 9-14-99; 8:45 am]
BILLING CODE 4910-13-P
