[Federal Register Volume 64, Number 178 (Wednesday, September 15, 1999)]
[Rules and Regulations]
[Pages 49971-49973]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-23474]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-NM-251-AD; Amendment 39-11314; AD 99-19-27]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-100, -200, -300, -400,
and -500 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 Boeing Model 737-100, -200, -300, -400, and -500
series airplanes, that requires a one-time inspection of the main
landing gear (MLG) wheel assemblies to determine whether certain parts
are installed, and follow-on corrective actions, if necessary. For
certain airplanes, this amendment also requires eventual modification
of MLG wheel assemblies, which terminates the requirements of this AD.
This amendment is prompted by incidents of multiple tie bolt failures
on certain BFGoodrich wheel assemblies. The actions specified by this
AD are intended to prevent failure of multiple tie bolts of MLG wheel
assemblies, which could result in failure of the wheel rim, rapid
release of tire pressure, and possible consequent damage to the
airplane and injury to passengers and flightcrew.
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 Aerospace, 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
Office of the Federal Register, 800 North Capitol Street, NW., suite
700, Washington, DC.
FOR FURTHER INFORMATION CONTACT: Don Kurle, Senior Aerospace Engineer,
Systems and Equipment Branch, ANM-130S, FAA, Transport Airplane
Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue,
SW., Renton, Washington 98055-4056; telephone (425) 227-2798; fax (425)
227-1181.
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 all Boeing Model 737-100, -200, -
300, -400, and -500 series airplanes was published in the Federal
Register on November 18, 1998 (63 FR 64013). That action proposed to
require a one-time inspection of the main landing gear (MLG) wheel
assemblies to determine whether certain parts are installed, and
follow-on corrective actions, if necessary. For certain airplanes, that
action also proposed to require eventual modification of MLG wheel
assemblies, which would terminate the requirements of this AD.
Comments
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
Support for the Proposal
One commenter has no objection to the proposed AD.
Explanation of Change Made to Proposal
The FAA has clarified the inspection requirement contained in the
proposed AD. Whereas the proposed specified a visual inspection, the
FAA has revised paragraphs (b)(2)(i) and (b)(2)(ii) of this final rule
to clarify that its intent is to require a detailed visual inspection.
Additionally, Note 2 has been added to the final rule to define that
inspection.
Request to Revise Applicability
One commenter requests that the applicability of the proposed AD be
revised to read, ``All Model 737-100, -200, -300, -400, and -500 series
airplanes certificated in any category, having wheel assemblies
manufactured by BFGoodrich installed.'' In support of its request, the
commenter states that the current applicability does not exclude
airplanes that do not have BFGoodrich wheel and brake assemblies
installed.
The FAA does not concur. The purpose of the AD is to assure that
all operators verify part numbers, determine if BFGoodrich wheel
assemblies are installed, and if so, take appropriate action. No change
to the applicability section of the AD is made in this regard. However,
the FAA recognizes that a records review can verify part numbers, and
as discussed below, paragraph (a) of the AD has been revised to
essentially accomplish the result sought by the commenter.
Request to Revise Inspection Procedures
Several commenters request that the proposed inspection procedures
of the main landing gear (MLG) wheel assemblies be revised to allow for
a records review in lieu of a visual inspection to determine whether
certain parts are installed. In support of this request, the commenters
noted that other wheel assemblies (AlliedSignal) are not
interchangeable with BFGoodrich wheel assemblies, and since it is not
necessary to determine the type of wheel assemblies that are installed,
a review of records would be less expensive than a visual inspection.
The FAA concurs with the commenters' request to revise the
inspection procedures required by paragraph (a) of this AD. The FAA
recognizes that a visual inspection is not necessary to determine the
type of wheel assemblies that are installed. In light of this, the FAA
has revised paragraph (a) of this final rule to
[[Page 49972]]
require, ``an inspection of the MLG wheel assemblies or perform other
verifications (such as a records review) to determine the part number
(P/N) of each assembly.''
Request for Clarification of Discussion Section
One commenter requests that the FAA clarify the description in the
Discussion Section of the proposed AD of the tie bolt failures to
indicate that they occurred only on certain BFGoodrich wheel assemblies
that are installed on the main landing gear (MLG) of Boeing Model 737-
300 and -400 series airplanes.
The FAA agrees that the Discussion section of the proposed rule may
have been unclear regarding the incidents of tie bolt failures on
certain BFGoodrich wheel assemblies. The FAA acknowledges that no
reports of failures have been reported for Boeing Model 737-100, -200,
or -500 series airplanes. However, because the Discussion section is
not restated in the final rule, no change to this final rule is
necessary in this regard.
Request for Revision of Cost Impact Information
One commenter requests that the cost impact information of the
proposed AD be revised to clarify the usage of parts should an operator
elect to accomplish the replacement. The commenter requests adding a
phrase to clarify that if the same part number steel tie bolt fasteners
were used, such replacement will require no additional work hours if
accomplished during a regularly scheduled tire change.
The FAA concurs with the commenter's request. The cost impact
information, below, has been revised accordingly.
The same commenter requests that the cost impact information of the
proposed AD be revised to clarify the types of parts to be used. The
commenter requests adding a phrase to clarify that the modification of
the wheel assembly be accomplished by installing improved, Inconel tie
bolt fasteners, and that it would require no additional work hours per
airplane if the modification is accomplished during a regularly
scheduled tire change.
The FAA concurs with the commenter's request. The cost impact
information, below, has been revised accordingly.
Request for Clarification of Requirements
One commenter requests that the proposed rule be revised to clarify
certain requirements. The commenter suggests that additional
information be provided to clarify the visual inspections,
replacements, and terminating action.
The FAA does not concur. The FAA acknowledges the comment, however,
the commenter did not make any specific recommendations. Therefore, no
change to the final rule in this regard is necessary.
Conclusion
After careful review of the available data, including the comments
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 neither
increase the economic burden on any operator nor increase the scope of
the AD.
Cost Impact
There are approximately 460 Model 737-100, -200, -300, -400, and -
500 series airplanes of the affected design in the worldwide fleet. The
FAA estimates that 118 airplanes of U.S. registry will be affected by
this AD.
It will take approximately 1 work hour per airplane to accomplish
the required one-time inspection, at an average labor rate of $60 per
work hour. Based on these figures, the cost impact of the one-time
inspection required by this AD on U.S. operators is estimated to be
$7,080, or $60 per airplane.
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.
Should an operator elect to accomplish the repetitive visual
inspection, it would take approximately 1 work hour per airplane to
accomplish, at an average labor rate of $60 per work hour. Based on
these figures, the cost impact of the repetitive inspections, if
accomplished, is estimated to be $60 per airplane, per inspection
cycle.
Should an operator elect to accomplish the replacement using the
same part number steel tie bolt fasteners, such replacement would
require no additional work hours if accomplished during a regularly
scheduled tire change. Required parts would cost $2,840 per airplane
($710 per wheel). Based on these figures, the cost impact of the
replacement, if accomplished, is estimated to be $2,840 per airplane,
per replacement cycle.
Should an operator elect to accomplish the revisions to the FAA-
approved maintenance program, it would take approximately 1 work hour
per airplane to accomplish, at an average labor rate of $60 per work
hour. Based on these figures, the cost impact of the maintenance
program revision, if accomplished, is estimated to be $60 per airplane.
Should an operator be required to accomplish the necessary
modification of the wheel assembly by installing improved Inconel tie
bolt fasteners, it would require no additional work hours per airplane,
if the modification is accomplished during a regularly scheduled tire
change. Required parts would cost $4,848 per airplane ($1,212 per
wheel). Based on these figures, the cost impact of any necessary
modification is estimated to be $4,848 per airplane.
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:
[[Page 49973]]
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:
99-19-27 Boeing: Amendment 39-11314. Docket 98-NM-251-AD.
Applicability: Model 737-100, -200, -300, -400, and -500 series
airplanes, 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 (e) 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 multiple tie bolts of main landing gear
(MLG) wheel assemblies, which could result in failure of the wheel
rim, rapid release of tire pressure, and possible consequent damage
to the airplane and injury to passengers and flightcrew, accomplish
the following:
(a) Within 60 days after the effective date of this AD, perform
an inspection of the MLG wheel assemblies or perform other
verifications (such as a records review) to determine the part
number (P/N) of each assembly. If no wheel assembly manufactured by
BFGoodrich Aerospace and having P/N 3-1398-1, 3-1439-2, or 3-1439-3
is installed on the airplane, no further action is required by this
AD.
(b) Except as provided by paragraph (d) of this AD, if any MLG
wheel assembly manufactured by BFGoodrich Aerospace and having P/N
3-1398-1, 3-1439-2, or 3-1439-3 is installed on the airplane, within
60 days after the effective date of this AD, accomplish the actions
specified by paragraph (b)(1) or (b)(2) of this AD.
(1) Accomplish the actions specified by (b)(1)(i) or (b)(1)(ii)
of this AD.
(i) Replace all tie bolts, nuts, and washers of the MLG wheel
assembly with parts having the same P/N's, in accordance with the
BFGoodrich component maintenance manual. Thereafter, repeat the
replacement of tie bolts, nuts, and washers, at intervals not to
exceed 5 tire changes, until the actions specified by paragraph
(b)(2) or paragraph (c) of this AD have been accomplished. Or
(ii) Perform a detailed visual inspection to detect fractures of
any of the 16 tie bolts on each MLG wheel assembly, in accordance
with the Boeing 737 airplane maintenance manual. Thereafter, repeat
the inspection at intervals not to exceed 100 flight cycles until
the actions specified by paragraph (b)(2) or paragraph (c) of this
AD have been accomplished. If any fracture of any tie bolt is found
during any inspection performed in accordance with this requirement,
prior to further flight, replace the tie bolt, nut, and washer, in
accordance with the BFGoodrich component maintenance manual, with
new parts having the same P/N's.
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.''
(2) Revise the FAA-approved maintenance program as specified in
paragraph (b)(2)(i) or (b)(2)(ii) of this AD.
(i) Revise the FAA-approved maintenance program to require
replacement of all tie bolts, nuts, and washers of the MLG wheel
assembly with parts having the same P/N's, in accordance with the
BFGoodrich component maintenance manual, at intervals not to exceed
5 tire changes. Or
(ii) Revise the FAA-approved maintenance program to require a
detailed visual inspection to detect fractures of any of the 16 tie
bolts on each MLG wheel assembly, in accordance with the Boeing 737
airplane maintenance manual, at intervals not to exceed 100 flight
cycles. If any fracture of any tie bolt is found during any
inspection performed in accordance with this requirement, prior to
further flight, replace the tie bolt, nut, and washer, in accordance
with the BFGoodrich component maintenance manual, with new parts
having the same P/N's.
Note 3: After the maintenance program has been revised to
include the procedures specified in paragraph (b)(2)(i) or
(b)(2)(ii) of this AD, operators are not required to subsequently
record AD compliance each time the replacement or inspection is
performed.
(c) If any MLG wheel assembly manufactured by BFGoodrich
Aerospace and having P/N 3-1398-1, 3-1439-2, or 3-1439-3 is
installed on the airplane: Except as provided by paragraph (d) of
this AD, within 2 years after the effective date of this AD, modify
any BFGoodrich Aerospace wheel assembly, having P/N 3-1398-1, 3-
1439-2, or 3-1439-3; by replacing all existing tie bolts, nuts, and
washers, with new, improved parts; and by converting the P/N of the
MLG wheel assembly to 3-1398-2 (for BFGoodrich wheel assemblies
having the old P/N 3-1398-1), 3-1439-5 (for BFGoodrich wheel
assemblies having the old P/N 3-1439-2), or 3-1439-6 (for BFGoodrich
wheel assemblies having the old P/N 3-1439-3), as applicable; in
accordance with BFGoodrich Aerospace Service Bulletin 3-1439-32-13,
or BFGoodrich Aerospace Service Bulletin 3-1398-32-16, both dated
August 20, 1993, as applicable. Such modification constitutes
terminating action for the requirements of this AD, and the FAA-
approved maintenance program procedures specified by paragraph
(b)(2) of this AD may be removed following accomplishment of the
requirements of this paragraph.
(d) Airplanes on which the modification required by paragraph
(c) of this AD is accomplished within the compliance time specified
in paragraph (b) of this AD are not required to accomplish the
actions required by paragraph (b).
Alternative Methods of Compliance
(e) 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, Seattle Aircraft Certification
Office (ACO), 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, Seattle ACO.
Note 4: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
Special Flight Permits
(f) 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
(g) The modification shall be done in accordance with BFGoodrich
Aerospace Service Bulletin 3-1439-32-13, dated August 20, 1993; or
BFGoodrich Aerospace Service Bulletin 3-1398-32-16, dated August 20,
1993, 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
Aerospace, 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
Office of the Federal Register, 800 North Capitol Street, NW., suite
700, Washington, DC.
(h) 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. 99-23474 Filed 9-14-99; 8:45 am]
BILLING CODE 4910-13-P
