[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.

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    (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