[Federal Register Volume 63, Number 152 (Friday, August 7, 1998)]
[Rules and Regulations]
[Pages 42208-42210]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-20970]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-NM-227-AD; Amendment 39-10694; AD 98-16-18]
RIN 2120-AA64
Airworthiness Directives; Learjet Model 60 Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
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SUMMARY: This amendment adopts a new airworthiness directive (AD) that
is applicable to certain Learjet Model 60 airplanes. This action
requires repetitive measurements of the brake wear dimension between
the housing subassembly and the pressure plate that is adjacent to the
top pistons of the brake assembly; and follow-on corrective actions, if
necessary. This amendment is prompted by reports of abnormal (uneven)
brake wear. The actions specified in this AD are intended to detect and
repair an abnormal brake wear condition, which could result in loss of
brake effectiveness and cause the airplane to leave the runway surface.
DATES: Effective August 24, 1998.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of August 24, 1998.
Comments for inclusion in the Rules Docket must be received on or
before October 6, 1998.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 98-NM-227-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056.
The service information referenced in this AD may be obtained from
Aircraft Braking Systems Corporation, 1204 Massillon, Akron, Ohio
44306. This information may be examined at the FAA, Transport Airplane
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA,
Small Airplane Directorate, Wichita Aircraft Certification Office, 1801
Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas; or at
the Office of the Federal Register, 800 North Capitol Street, NW.,
suite 700, Washington, DC.
FOR FURTHER INFORMATION CONTACT: Paul C. DeVore, Aerospace Engineer,
Systems and Propulsion Branch, ACE-116W, FAA, Small Airplane
Directorate, Wichita Aircraft Certification Office, 1801 Airport Road,
Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone (316)
946-4142; fax (316) 946-4407.
SUPPLEMENTARY INFORMATION: The FAA has received reports from Learjet of
an abnormal brake wear condition on certain Learjet Model 60 airplanes.
Subsequent investigation, conducted by Aircraft Braking Systems
Corporation (ABS) (the manufacturer of the brakes), revealed an
abnormal (uneven) brake
[[Page 42209]]
wear condition of the friction material (friction mix) on the rotating
disks. The uneven wear has been attributed to thermal gradients within
the brake stack of the ABS brake assembly. Such abnormal brake wear, if
not corrected, could result in loss of brake effectiveness, which could
cause the airplane to leave the runway surface.
Explanation of Relevant Service Information
The FAA has reviewed Aircraft Braking Systems Service Bulletin
LEAR60-32-03, dated March 5, 1998, which describes procedures for
repetitive measurements of the brake wear dimension between the housing
subassembly and the pressure plate that is adjacent to the top pistons
of the brake assembly; and follow-on corrective actions, if necessary.
These follow-on actions include performing a visual inspection to
detect abnormal wear of the friction mix on the rotating disks, and
replacing both rotating disks with new disks, if necessary; and
replacing the disk stack with a new disk stack or overhauling it.
Accomplishment of certain actions specified in the service bulletin is
intended to adequately address the identified unsafe condition.
Explanation of the Requirements of the Rule
Since an unsafe condition has been identified that is likely to
exist or develop on other airplanes of the same type design, this AD is
being issued to detect and repair an abnormal (uneven) brake wear
condition, which could result in loss of brake effectiveness and cause
the airplane to leave the runway surface. This AD requires
accomplishment of certain actions specified in the service bulletin
described previously.
Operators should note that the service bulletin lists other actions
in addition to those described previously. The FAA considers these
additional actions to be routine maintenance and therefore has not
specified their performance in this AD.
Determination of Rule's Effective Date
Since a situation exists that requires the immediate adoption of
this regulation, it is found that notice and opportunity for prior
public comment hereon are impracticable, and that good cause exists for
making this amendment effective in less than 30 days.
Comments Invited
Although this action is in the form of a final rule that involves
requirements affecting flight safety and, thus, was not preceded by
notice and an opportunity for public comment, comments are invited on
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All
communications received on or before the closing date for comments will
be considered, and this rule may be amended in light of the comments
received. Factual information that supports the commenter's ideas and
suggestions is extremely helpful in evaluating the effectiveness of the
AD action and determining whether additional rulemaking action would be
needed.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the rule that might
suggest a need to modify the 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 that
summarizes each FAA-public contact concerned with the substance of this
AD will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this rule must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 98-NM-227-AD.'' The postcard will be date stamped and
returned to the commenter.
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.
The FAA has determined that this regulation is an emergency
regulation that must be issued immediately to correct an unsafe
condition in aircraft, and that it is not a ``significant regulatory
action'' under Executive Order 12866. It has been determined further
that this action involves an emergency regulation under DOT Regulatory
Policies and Procedures (44 FR 11034, February 26, 1979). If it is
determined that this emergency regulation otherwise would be
significant under DOT Regulatory Policies and Procedures, a final
regulatory evaluation will be prepared and placed in the Rules Docket.
A copy of it, if filed, 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:
98-16-18 Learjet: Amendment 39-10694. Docket 98-NM-227-AD.
Applicability: Model 60 airplanes equipped with Aircraft Braking
Systems (ABS) brake assemblies having part number 5003096-7,
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 (c) 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 repair an abnormal (uneven) brake wear condition,
which could result in loss of brake effectiveness and cause the
airplane to leave the runway surface, accomplish the following:
(a) Within 10 flight hours after the effective date of this AD,
measure the brake wear dimension between the housing subassembly and
the pressure plate that is adjacent to the top pistons of the brake
assembly, in accordance with ABS Service Bulletin LEAR60-32-03,
dated March 5, 1998.
(1) If the dimension is less than 0.359 inch (9.12 mm),
thereafter repeat the measurement at intervals not to exceed 25
flight cycles.
[[Page 42210]]
(2) If the dimension is equal to or greater than 0.359 inch
(9.12 mm) and less than 0.464 inch (11.79 mm), prior to further
flight, perform a visual inspection to detect abnormal wear of the
friction mix on the rotating disks, in accordance with the service
bulletin.
(i) If the friction mix is not worn to the disk cores on either
disk, thereafter repeat the measurement at intervals not to exceed
25 flight cycles.
(ii) If the friction mix is worn to the disk core on either
disk, replace both rotating disks with new disks in accordance with
the service bulletin. Thereafter, repeat the measurement at
intervals not to exceed 25 flight cycles.
(3) If the dimension is greater than or equal to 0.464 inch
(11.769 mm), replace the disk stack with a new disk stack or
overhaul it, in accordance with the service bulletin. Thereafter,
repeat the measurement at intervals not to exceed 25 flight cycles.
(b) As of the effective date of this AD, no person shall install
on any airplane a used ABS brake assembly, part number 5003096-7,
unless it has been inspected and applicable corrective actions have
been performed in accordance with the requirements of this AD.
(c) 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, Wichita 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, Wichita ACO.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Wichita ACO.
(d) 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.
(e) The actions shall be done in accordance with Aircraft
Braking Systems Corporation Service Bulletin LEAR60-32-03, dated
March 5, 1998. 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 Learjet, Inc., One
Learjet Way, Wichita, Kansas 67209-2942. Copies may be inspected at
the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW.,
Renton, Washington; or at the FAA, Small Airplane Directorate,
Wichita Aircraft Certification Office, 1801 Airport Road, Room 100,
Mid-Continent Airport, Wichita, Kansas; or at the Office of the
Federal Register, 800 North Capitol Street, NW., suite 700,
Washington, DC.
(f) This amendment becomes effective on August 24, 1998.
Issued in Renton, Washington, on July 30, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 98-20970 Filed 8-6-98; 8:45 am]
BILLING CODE 4910-13-P