AD 2001-20-09

[Federal Register Volume 66, Number 197 (Thursday, October 11, 2001)]
[Rules and Regulations]
[Pages 51843-51849]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 01-25184]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-18-AD; Amendment 39-12457; AD 2001-20-09]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 727 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 all Boeing Model 727 series airplanes, that requires 
repetitive inspections of the bearing support fitting of the forward 
trunnion on the main landing gear (MLG) to detect corrosion and 
cracking; follow-on actions, if necessary; and repair/rework of the 
support fitting, or replacement with a new or repaired/reworked 
fitting. The actions specified by this AD are intended to prevent 
failure of the support fitting, which could result in collapse of the 
MLG during normal operations; consequent damage to the airplane 
structure; and injury to flight crew, passengers, or ground personnel. 
This action is intended to address the identified unsafe condition.

DATES: Effective November 15, 2001.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of November 15, 2001.

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, 
Washington 98124-2207. 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.

[[Page 51844]]


FOR FURTHER INFORMATION CONTACT: Walter Sippel, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington; telephone (425) 227-2028 or 
(425) 227-2774; 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 727 series 
airplanes was published in the Federal Register on August 10, 2000 (65 
FR 48943). That action proposed to require repetitive inspections of 
the bearing support fitting of the forward trunnion on the main landing 
gear (MLG) to detect corrosion and cracking; follow-on actions, if 
necessary; and rework of the support fitting.

Actions Since Issuance of Proposal

    Since the issuance of the notice of proposed rulemaking (NPRM), the 
FAA has reviewed and approved Boeing Service Bulletin 727-57A0179, 
Revision 5, dated December 20, 2000. Revision 5 revises certain actions 
regarding the support fitting. Such actions include the option of 
replacing a damaged fitting with a new fitting or with a repaired/
reworked fitting, reducing the amount of material removed from the 
holes in the fitting and from all faces of the support fitting common 
to the holes, and radius-boring the edges of the machined surfaces. 
Revision 5 also revises the effectivity, and changes the sequence of 
certain inspection and repair/rework instructions.

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.

Requests To Clarify the Rework Requirement

    The Air Transport Association (ATA) of America states that several 
operators have requested clarification of the term ``rework'' in the 
body of the NPRM, as follows:
    <bullet> One commenter states that the term ``rework'' needs to be 
defined, and that the service bulletins do not define the term. The 
commenter proposes that rework should be defined in paragraphs (a), 
(b), and (c) of the NPRM as the accomplishment of Part II of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 727-
57A0179, Revision 1, dated June 13, 1991; Revision 2, dated April 30, 
1992; Revision 3, dated September 2, 1999; or Revision 4, dated July 
13, 2000. Paragraph (c) of the NPRM is cited as paragraph (d) in the 
final rule.
    <bullet> Another commenter states that paragraph (a) of the NPRM 
should include a service bulletin reference similar to paragraph (b) of 
the NPRM. This reference would clarify the rework action required by 
the NPRM. The commenter states that the term ``rework,'' as used in the 
NPRM, is confusing and that the correct term is ``shop overhaul.'' In 
addition, paragraphs (b) and (c) of the NPRM should cite ``Part II'' of 
the Accomplishment Instructions of the applicable service bulletins. As 
stated previously, paragraph (c) of the NPRM is cited as paragraph (d) 
in the final rule.
    The FAA concurs that it is necessary to clarify the rework 
requirements and to cite specific paragraphs (parts) of the service 
bulletins, which specify the rework procedures. Boeing Service Bulletin 
727-57A0179, Revision 5, dated December 20, 2000, was issued to clarify 
the follow-on actions by specifying repair/rework of the support 
fitting, or replacement with a new or repaired/reworked fitting. In 
response, we have cited the specific part of the appropriate revision 
of the service bulletins in paragraphs (a), (b), and (d) of the final 
rule.

Requests To Extend the Rework Threshold

    Two commenters request that the FAA extend the compliance time in 
certain paragraphs of the NPRM. These requests and justifications are 
as follows:
    <bullet> One commenter requests extending the compliance time 
specified in paragraph (a) from 18 months to the ``next heavy 
maintenance visit (HMV).'' The commenter also requests changing the 
compliance time for the inspection/rework actions required by paragraph 
(c)(2) of the NPRM from 36 months to ``next gear change.'' The 
commenter justifies its request by stating that, since it began 
conducting ``on wing'' ultrasonic inspections of the subject fittings 
in 1993, no fitting has been found to be cracked and no overhaul has 
identified any potential fitting failures.
    <bullet> One commenter requests extending the compliance time 
specified in paragraph (a) from 18 to 24 months. The commenter states 
that the 18-month interval would present an undue economic burden 
because of the number of work hours and additional maintenance 
requirements, and would require airplanes to be removed from service 
for extended periods of time. The proposed extension would allow the 
rework to be performed during scheduled maintenance visits, such as a 
C-check. Such an extension would reduce the financial burden without 
compromising the safety of their fleet.
    In addition, another commenter states that the inventory and 
production of spare parts could not support the proposed insurance 
cuts, and that this could result in the unnecessary grounding of 
airplanes. The FAA infers that the commenter is requesting an extension 
of the compliance time for accomplishing the rework action.
    The FAA does not concur with the commenters' requests to extend the 
compliance times. We have determined that the proposed compliance times 
in paragraphs (a) and (c)(2) of the NPRM (cited as paragraph (d)(2) in 
the final rule) should not be extended for the following reasons, as 
listed below.
    <bullet> The proposal to use the terms ``HMV'' and ``next gear 
change'' instead of the specified compliance times is not specific 
enough to ensure when the action must be accomplished.
    <bullet> The service bulletin recommends accomplishment of the 
rework within the specified 18 months for those fittings that have not 
been reworked (overhauled) previously.
    <bullet> Revision 5 of the service bulletin allows operators the 
option of repairing/reworking damaged support fittings, or replacing 
the fittings with new fittings. Revision 5 also reduces the specified 
limits of the material removed from the faces common to the holes in 
the support fittings and the diameter of the holes in the fittings. 
Such a reduction will lengthen the time that the existing parts can be 
used, so the immediate purchase of a new part may not be necessary. The 
final rule includes Revision 5 of the service bulletin as an additional 
source of service information.
    <bullet> In developing the appropriate compliance times for the 
inspection and rework actions, the FAA considered the safety 
implications, parts availability, and normal maintenance schedules for 
timely accomplishment of the rework. In consideration of these items, 
as well as the reports of the collapse of the main landing gear on a 
number of airplanes, the FAA has determined that the 18-month 
compliance time specified in paragraph (a) of this AD, and the 36-month 
compliance time specified in paragraph (c)(2) of the NPRM (cited as 
paragraph (d)(2) in the final rule), represent the appropriate 
intervals of time allowable so that the specified actions can be 
accomplished during scheduled maintenance intervals for the majority of 
affected operators, and an acceptable level of safety can be 
maintained.
    <bullet> Although inspections will continue per paragraph (a) of 
this AD until

[[Page 51845]]

accomplishment of the rework per paragraph (d) of the NPRM (cited as 
paragraph (e) in the final rule), the inspections will not necessarily 
detect corrosion pitting, which also could lead to stress corrosion 
cracking of the fitting.
    For these reasons, the FAA has determined that the compliance times 
for the inspections and rework actions specified in the AD are 
appropriate. No changes are made to the final rule in this regard.

Request To Include a Rework Option

    One commenter requests the option of using chrome plate, not more 
than 0.010 inches thick, followed by a repair sleeve wet with primer, 
in lieu of the required cadmium plate/primer/sealant combination 
specified in Part II of Revision 4 of the previously referenced service 
bulletin. Service experience indicates that the use of chrome plate 
during rework provides superior corrosion protection.
    The FAA does not concur that it is necessary to change the rework 
requirement in the final rule to specify the proposed option. The 
commenter did not provide sufficient technical details for the proposed 
chrome plating process. However, we would consider this option under 
the provisions for requesting approval of an alternative method of 
compliance, as provided in paragraph (h) in the final rule (cited as 
paragraph (f) of the NPRM). No change is made to the final rule in this 
regard.

Requests To Delete or Modify the ``Insurance Cut'' Requirements

    Several commenters request deleting or modifying the requirement to 
do the insurance cut. The FAA infers that the insurance cut refers to 
the rework of the support fitting, which includes removing any damaged 
material from the face of the support fitting and from the holes of the 
fitting, and to increase the diameter of the holes in the fitting. The 
commenters' requests and justifications are as follows:
    Three of the commenters do not consider it necessary to do the 
insurance cuts on support fittings that do not show damage, such as 
corrosion or cracking. One of the commenters states that the Component 
Maintenance Manual (CMM) referenced in Revision 4 of the service 
bulletin specifies rework only if the fitting has corrosion or cracks, 
and that rework is unnecessary if the fitting is corrosion or crack 
free.
    Another commenter states that Revisions 3 and 4 of the referenced 
service bulletin are ambiguous if the insurance cut is required on 
support fittings that are corrosion or crack free. The FAA infers that 
the commenter considers that the insurance cut specified in Revisions 3 
and 4 of the service bulletins is unnecessary. The commenter also 
states that the root cause of the fractured fittings is the initiation 
of corrosion in the bore of the fitting, and that stress concentrations 
from corrosion pitting lead to cracking. Corrosion also can be 
controlled by regular overhaul of the subject fitting at the same time 
as the landing gear. Service records indicate that adequate safety was 
provided during previous overhauls that did not include insurance cuts 
and, until 1991, did not include protective sealant. Current overhaul 
procedures include additional improvements to further ensure safety.
    Another commenter states that insurance cuts for undamaged fittings 
should not be a requirement because the non-destructive tests (NDT) 
should be adequate. Another commenter states that insurance cuts are 
unnecessary after a magnetic particle inspection (MPI) because such 
action was not required in the past, and safety was not adversely 
affected. In addition, MPIs and a dedicated maintenance program provide 
adequate crack detection and a high level of safety throughout the life 
of the component. Another commenter states that MPI is one of the most 
sensitive and reliable methods for detecting shallow cracks and defects 
on steel parts.
    Another commenter, the manufacturer, states that it has further 
evaluated the insurance cut requirement, and has concluded that the 
size of the cut can be reduced without compromising safety. Such a 
reduction still allows adequate removal of nondetectable cracks not 
found during the MPI, and is a more practical approach to machining 
high-strength steel. Further, the depth of the insurance cut specified 
in earlier revisions of Boeing Alert Service Bulletin 727-57A0179 prior 
to the issuance of Revision 5 of the service bulletin is excessive and 
could lead to additional damage. Revision 5 has been issued to specify 
the recommended reduction in the size of the insurance cut.
    The FAA partially concurs with the commenters' suggestions to 
change the ``insurance cut'' requirements. The FAA does not concur that 
the insurance cut (rework) on undamaged support fittings is 
unnecessary, because certain cracks may remain undetected by the 
specified inspections. Although the referenced CMM specifies rework 
only if certain damage is found, we have determined that, even if the 
support fitting does not show damage, rework of the support fitting is 
necessary to address the identified unsafe condition. In addition, we 
have determined that even though an operator's service records show 
that adequate safety was provided during previous overhauls and that 
current overhaul procedures include improvements to ensure safety, the 
rework requirements specified by this AD are still necessary to ensure 
that all operators follow the same procedures in addressing the 
specified unsafe condition.
    The FAA does not concur that NDTs or MPIs are adequate to detect 
small cracks. Although we agree that an MPI is both sensitive and 
reliable, small cracks may remain following that inspection. For that 
reason, rework is necessary to ensure the removal of any cracking that 
remains undetected by the inspections.
    However, the FAA concurs with the commenters' requests to modify 
the insurance cut (rework) requirements for the support fitting. We 
consider that the sensitivity of the main particle inspection is 
sufficient to detect cracks of a smaller size than those specified in 
Revision 4 or earlier revisions of the service bulletins. As a result, 
we have determined that removing less material from the holes in the 
trunnion bearing support fitting is adequate to ensure the safety of 
the fleet. Although Revision 5 of the service bulletin specifies a 
further reduction in the size of the insurance cut specified in 
Revisions 3 and 4 (and earlier revisions) of the service bulletin, we 
consider that the repair/rework action accomplished per Revisions 3, 4, 
or 5 of the service bulletins, and the replacement action (i.e., 
replaced with a new or repair/reworked part) per Revision 5 of the 
service bulletin, are equally acceptable. Paragraph (e) in the final 
rule (cited as paragraph (d) of the NPRM) has been changed accordingly.

Requests To Revise the Inspections/Rework Intervals

    The ATA states that five member airlines request that the 
inspection/rework intervals specified in the NPRM be extended from 
12,000 flight cycles to a 10-year overhaul cycle. Several of the member 
airlines consider that the existing 10-year overhaul programs, combined 
with effective corrosion prevention programs, have prevented the unsafe 
condition identified in the NPRM. As a result, several commenters 
recommend that the inspections be performed on a 10-year overhaul 
cycle. Several commenters state that having a Corrosion Prevention and 
Control Program (CPCP), with a 10-year interval between rework 
(overhaul), is adequate in maintaining corrosion at an acceptable level 
of safety.

[[Page 51846]]

    Another commenter states that there are no data to support an 
interval of 12,000 flight cycles for reworking the subject fitting. The 
commenter states that all failures of the forward trunnion support 
fitting have occurred on fittings with extensive corrosion and long 
periods without overhaul. Such failures are not due to cyclic loading, 
but to intergranular stress corrosion cracking. The manufacturer 
(Boeing) confirms that the threshold of 12,000 flight cycles, cited in 
paragraphs (b)(1) and (c)(1) of the NPRM, is based on an industry 
average for D-checks and not on a damage tolerance assessment or other 
criteria.
    One commenter requests extending the 12,000 flight cycles specified 
in paragraphs (b)(1), (c)(1), and (d) of the NPRM to 16,000 flight 
cycles. The commenter indicates that its gear overhaul records show no 
failed fittings due to cracks or corrosion, and no corrosion in the 
large bore of the fittings in 12 out of 14 fittings. In addition, the 
fittings had bearings installed without faying surface sealant, 
although the current overhaul procedure requires such sealant, which 
will improve corrosion resistance.
    One commenter states that Boeing has identified the subject fitting 
as an ``on condition'' part, with no prescribed time limits for rework 
(overhaul). In addition, the Boeing 727 Maintenance Planning Document 
(MPD) recommends an inspection of the subject fitting at intervals not 
to exceed 16,000 flight cycles.
    The FAA does not concur with the requests to extend the 12,000-
flight-cycle intervals specified in paragraphs (b)(1), (c)(1), and (d) 
of the NPRM (cited as paragraphs (b)(1), (d)(1), and (e) in the final 
rule). Although a number of operators have implemented effective CPCPs 
per AD 90-25-03, amendment 39-6787 (55 FR 49258, November 5, 1990), 
fleet experience indicates that more rigorous inspections are required 
to detect and correct cracking of a bearing support fitting for the 
main landing gear. Preliminary data from the manufacturer indicate 
that, based on crack growth, 12,000 flight cycles is the correct 
interval for the inspections/rework. In addition, the inspection/rework 
intervals specified in certain earlier issues of the MPDs and CPCPs may 
not be adequate for detecting such cracking. Further, we have not 
received sufficient data from the commenters to determine what the 
acceptable 10-year overhaul requirements are for the specified support 
fitting.
    In view of this information, we find that the compliance times for 
the inspections and repair/rework actions cited in this AD are 
appropriate for ensuring an adequate level of safety. No change is made 
to the final rule in this regard. However, should an operator wish to 
gain approval for use of an alternate inspection schedule that provides 
an acceptable level of safety, the operator may submit a request for 
approval of an alternative method of compliance under paragraph (h) of 
this AD.

Request To Revise the Compliance Time in Paragraph (a)

    One operator requests revising paragraph (a) of the NPRM to require 
that operators accomplish the inspection ``at the later of'' rather 
than ``at the earlier of'' the times required in that paragraph. The 
commenter states that the earlier compliance time would not allow 
sufficient time for the inspection, and that qualified personnel or 
equipment would not be available. An estimated 6 hours would be 
required for the inspection instead of the 4 hours specified in the 
NPRM. In addition, the requested change would not adversely affect 
safety.
    The FAA does not concur with the request to make the proposed 
revision to the compliance time in paragraph (a) of this AD. Although 
the proposed change may be appropriate for the commenter, it may not be 
appropriate for other operators. We point out that corrosion is 
affected by time rather than flight cycles, and that the AD addresses 
both fatigue and corrosion factors. No change is made to the final rule 
in this regard.

Requests To Include a Replacement Option

    Two commenters request that the FAA revise the NPRM to specify that 
operators may either rework the support fitting or replace it with a 
new fitting. The commenters also request that the FAA revise paragraph 
(e) of the NPRM (cited as paragraph (g) in the final rule) to include 
the replacement option. The commenters contend that there is no 
justification to rework (shop overhaul) and ``insurance cut'' a new 
part that has not been subjected to cyclic loads and has no corrosion.
    The FAA concurs with the commenters' requests that this AD should 
include a replacement option, which allows operators to either repair/
rework a damaged support fitting, or replace it with a new or reworked 
fitting. We also agree that it is not necessary for new parts to be 
reworked. While paragraph (e) of the final rule requires that operators 
repair/rework the support fitting, a new paragraph (f) allows an option 
for replacement of the fitting with a new fitting, followed by 
repetitive inspections of the new fitting. In addition, we have 
reformatted paragraph (g) of the final rule. Paragraph (g)(1) clarifies 
that a new fitting that has been received from the manufacturer and has 
not been previously installed on any airplane is acceptable for 
installation.

Request To Defer Action on New Support Fittings

    One commenter suggests revising the NPRM to defer action on new 
support fittings until the airplane reaches an initial threshold of 10 
years. The FAA concurs. Paragraph (f)(2) of the final rule is added to 
specify that new fittings, if installed, must be inspected at intervals 
not to exceed 12,000 flight cycles or 10 years, whichever occurs first.

Request To Clarify Paragraphs (b) and (c) of the Proposed Rule

    One commenter requests clarification of paragraph (b) of the NPRM 
by dividing it into two distinct categories. The commenter suggests 
changing the service bulletins referenced in the ``condition 
statement'' of paragraph (b) of the NPRM to specify only the original 
issue and Revisions 1 and 2, and changing the service bulletins 
referenced in the ``condition statement'' of paragraph (c) of the NPRM 
to specify only Revisions 3 and 4 of the service bulletins. The 
commenter considers that such clarification will assist operators in 
tracking the reworked support fittings.
    The FAA does not concur that the proposed clarifications to 
paragraphs (b) and paragraph (c) of the NPRM (cited as paragraphs (b) 
and (d) in the final rule) are necessary. The intent of the proposed 
rule was to have those paragraphs apply to airplanes reworked per any 
revision of the service bulletins. In the final rule, the intent of 
paragraph (b) is to require an interim inspection, until accomplishment 
of the inspections/rework actions required by paragraph (d), which 
specifies a grace period of 36 months for those airplanes that exceed 
12,000 flight cycles or 10 years after rework. Paragraph (d) requires 
the accomplishment of either the inspections and repair/rework actions 
in paragraph (e), or the alternative actions in the new paragraph (f) 
of the final rule. Because the commenter's proposed changes do not keep 
this intent, no changes are made to the final rule in this regard.

Requests To Clarify Paragraph (d) of the Proposed Rule

    One commenter states that paragraph (d) of the NPRM (cited as 
paragraph (e) in the final rule) should clarify that the repetitive 
inspections are ``detailed

[[Page 51847]]

visual and magnetic particle inspections.'' Another commenter states 
that paragraph (d) of the NPRM should clarify whether the repetitive 
inspections are ultrasonic inspections per Part I of the service 
bulletins, or detailed visual and magnetic particle inspections per 
Part II of the service bulletins.
    The FAA concurs with the commenters' requests. We have revised 
paragraph (e) in the final rule to specify repetitive detailed visual 
and magnetic particle inspections, and to clarify that those 
inspections are to be accomplished in accordance with Part II of the 
Accomplishment Instructions of Revisions 3, 4, or 5 of the previously 
referenced service bulletins. In addition, we have added that 
accomplishment of the inspections and repair/rework or replacement 
action specified by paragraph (e) of the final rule constitutes 
terminating action for the requirements in paragraphs (a) through (d) 
of this AD.

Request To Revise Cost Impact

    One commenter states that the cost estimate presented in the 
preamble to the NPRM is too low. The commenter states that its line 
maintenance personnel estimate that it will require a minimum of 6 
hours to do the ultrasonic inspection instead of the 4 hours specified 
in Boeing Alert Service Bulletin 727-57A0179, Revision 4, dated July 
13, 2000.
    The FAA does not concur that the cost estimate for the ultrasonic 
inspection proposed by the NPRM is too low for several reasons. First, 
the previously referenced service bulletins specify 4 hours for the 
ultrasonic inspection. Second, the commenter did not provide any 
substantiating data for the requested change. As stated in the preamble 
in the NPRM, our cost estimates typically do not include incidental 
costs, such as the time required to gain access and close up, planning 
time, or time necessitated by other administrative actions. As a 
result, no change to the final rule is necessary in this regard.

Request To Correct a Paragraph Reference

    One commenter requests that a paragraph reference specified in Note 
1 in the NPRM be changed from paragraph (e) to paragraph (f). The FAA 
concurs with the request to change the paragraph reference; however, 
the correct paragraph reference in Note 1 of the final rule is now 
paragraph (h). The final rule is changed accordingly.

Request To Issue a Supplemental NPRM

    One commenter, the ATA, requests that the FAA issue a supplemental 
NPRM in lieu of a final rule. The justification for this request is 
because of the comprehensive and detailed nature of the many comments 
received from the operators regarding the requirements of the NPRM and 
their recommended changes. The commenter advises that one operator has 
submitted a written proposal that includes suggested technical changes, 
which would provide a level of safety equivalent to that of the NPRM.
    The FAA does not concur that a supplemental NPRM should be issued 
in lieu of a final rule. We consider that all of the commenters' 
proposed changes are relieving or clarifying in nature and do not add 
any additional requirements. Issuance of a supplemental NPRM is 
necessary only if the commenters request substantive changes, and the 
FAA concurs with those commenters' requests. In this case, the FAA 
considers that issuance of the final rule is the appropriate rulemaking 
action.

Actions Since Issuance of the Proposed Rule

    Since the issuance of the proposed rule, the FAA has determined 
that the requirements for the follow-on actions/repetitive inspections 
specified in paragraphs (b)(2)(i) and (b(2)(ii) of the NPRM need to be 
clarified. We inadvertently specified the follow-on actions/repetitive 
inspections in paragraph (b)(2) of the NPRM. Those requirements, as 
specified in the service bulletin, also apply to paragraphs (a) and 
(b)(1) of the NPRM. To reflect this change, we have revised the final 
rule by including the follow-on actions/repetitive inspections, 
specified in paragraphs (b)(2)(i) and (b)(2)(ii) of the NPRM, as 
paragraphs (c), (c)(1), and (c)(2) in the final rule. We also have 
renumbered the succeeding paragraphs in the final rule accordingly.

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 1,375 Model 727 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 912 
airplanes of U.S. registry will be affected by this AD.
    Should an operator be required to accomplish the ultrasonic 
inspection, it will take approximately 4 work hours per airplane to 
accomplish the inspection, at an average labor rate of $60 per work 
hour. Based on these figures, the cost impact of the ultrasonic 
inspection on U.S. operators is estimated to be $240 per airplane, per 
inspection cycle.
    It will take approximately 6 work hours per airplane to accomplish 
the detailed visual and magnetic particle inspections, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact of the detailed visual and magnetic particle inspections on U.S. 
operators is estimated to be $328,320, or $360 per airplane, per 
inspection cycle.
    It will take approximately 108 work hours per airplane to 
accomplish the rework of the trunnion fitting, at an average labor rate 
of $60 per work hour. Based on these figures, the cost impact of the 
rework on U.S. operators is estimated to be $5,909,760, or $6,480 per 
airplane.
    The cost impact figures discussed above are 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. The cost impact figures discussed 
in AD rulemaking actions represent only the time necessary to perform 
the specific actions actually required by the AD. These figures 
typically do not include incidental costs, such as the time required to 
gain access and close up, planning time, or time necessitated by other 
administrative actions.

Regulatory Impact

    The regulations adopted herein will not have a substantial direct 
effect 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, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    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

[[Page 51848]]

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:

2001-20-09  Boeing: Amendment 39-12457. Docket 2000-NM-18-AD.

    Applicability: All Model 727 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 (h) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair of 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 bearing support fitting of the forward 
trunnion, which could result in collapse of the main landing gear 
during normal operations; consequent damage to the airplane 
structure; and injury to flight crew, passengers, or ground 
personnel; accomplish the following:

Interim Inspections/Follow-On Actions

    (a) For airplanes having a bearing support fitting of the 
forward trunnion installed that has NOT been repaired/reworked in 
accordance with Part II of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 727-57A0179, dated March 8, 1990; Revision 1, 
dated June 13, 1991; Revision 2, dated April 30, 1992; Revision 3, 
dated September 2, 1999; or Revision 4, dated July 13, 2000: Within 
1,500 flight cycles or 6 months after the effective date of this AD, 
whichever occurs first; perform an ultrasonic inspection of the 
bearing support fitting of the forward trunnion to detect corrosion 
and cracking in accordance with Part I of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 727-57A0179, Revision 
3, dated September 2, 1999; Revision 4, dated July 13, 2000; or 
Boeing Service Bulletin 727-57A0179, Revision 5, dated December 20, 
2000; and within 18 months after the effective date of this AD, 
accomplish the requirements in paragraph (e) or (f) of this AD.
    (b) For airplanes having a bearing support fitting of the 
forward trunnion installed that HAS been repaired/reworked in 
accordance with Part II of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 727-57A0179, dated March 8, 1990; Revision 1, 
dated June 13, 1991; Revision 2, dated April 30, 1992; Revision 3, 
dated September 2, 1999; or Revision 4, dated July 13, 2000: Perform 
an ultrasonic inspection of the bearing support fitting of the 
forward trunnion to detect corrosion and cracking in accordance with 
Part I of the Accomplishment Instructions of Boeing Alert Service 
Bulletin 727-57A0179, Revision 3, dated September 2, 1999; Revision 
4, dated July 13, 2000; or Boeing Service Bulletin 727-57A0179, 
Revision 5, dated December 20, 2000; at the latter of the times 
specified in paragraphs (b)(1) and (b)(2) of this AD.
    (1) Within 12,000 flight cycles or 10 years after repair/rework, 
whichever occurs first.
    (2) Within 1,500 flight cycles or 6 months after the effective 
date of this AD, whichever occurs first.

Follow-On Actions/Repetitive Inspections

    (c) Accomplish the actions required by either paragraph (c)(1) 
or (c)(2) of this AD, as applicable, in accordance with Part I of 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
727-57A0179, Revision 3, dated September 2, 1999; Revision 4, dated 
July 13, 2000; or Boeing Service Bulletin 727-57A0179, Revision 5, 
dated December 20, 2000.
    (1) If no corrosion or cracking is detected by the inspections 
required by paragraph (a) or (b) of this AD, prior to further 
flight, clean the fitting in accordance with the service bulletins. 
Repeat the inspection thereafter at intervals not to exceed 1,500 
flight cycles or 6 months, whichever occurs first.
    (2) If any corrosion or cracking is detected by the inspections 
required by paragraph (a) or (b) of this AD, prior to further 
flight, accomplish the requirements in paragraph (e) or (f) of this 
AD.

Inspections, Repair/Rework

    (d) For airplanes having a bearing support fitting of the 
forward trunnion installed that HAS been repaired/reworked in 
accordance with Part II of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 727-57A0179, dated March 8, 1990; Revision 1, 
dated June 13, 1991; Revision 2, dated April 30, 1992; Revision 3, 
dated September 2, 1999; Revision 4, dated July 13, 2000: Accomplish 
the requirements in paragraph (e) or (f) of this AD at the later of 
the times specified in paragraphs (d)(1) and (d)(2) of this AD.
    (1) Within 12,000 flight cycles or 10 years after rework, 
whichever occurs first.
    (2) Within 36 months after the effective date of this AD.

Inspections, Repair/Rework

    (e) At the applicable time specified in paragraph (a), (c)(2), 
or (d) of this AD, as applicable: Perform detailed visual and 
magnetic particle inspections to detect corrosion and cracking of 
the fitting, in accordance with Part II of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 727-57A0179, Revision 
3, dated September 2, 1999; Revision 4, dated July 13, 2000; or 
Boeing Service Bulletin 727-57A0179, Revision 5, dated December 20, 
2000; and repair/rework the support fitting in accordance with the 
service bulletins. Repeat the inspections at intervals not to exceed 
12,000 flight cycles or 10 years, whichever occurs first, in 
accordance with the service bulletins. Accomplishment of the 
requirements in this paragraph constitutes terminating action for 
the requirements in paragraphs (a), (b), (c), and (d) of this AD.

    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.''

Alternative Action

    (f) Accomplishment of the actions required by paragraphs (f)(1) 
and (f)(2) of this AD in accordance with Part II of the 
Accomplishment Instructions of Boeing Service Bulletin 72757A0179, 
Revision 5, dated December 20, 2000, is acceptable for compliance 
with the repair/rework requirements of paragraph (e) of this AD.
    (1) Replacement of the fitting with a new fitting, as specified 
in Part II of the Accomplishment Instructions of the service 
bulletin at the time specified in paragraph (e) of this AD.
    (2) Accomplishment of repetitive inspections of a new fitting 
thereafter at intervals not to exceed 12,000 flight cycles or 10 
years, whichever occurs first, in accordance with the service 
bulletin.

Spares

    (g) As of the effective date of this AD, no person shall install 
on any airplane any bearing support fitting of the forward trunnion 
identified in the ``Existing Part Number'' column of Paragraph 2.E. 
of Boeing Alert Service Bulletin 727-57A0179, Revision 3, dated 
September 2, 1999; Revision 4, dated July 13, 2000; or Boeing 
Service Bulletin 727-57A0179, Revision 5, dated December 20, 2000; 
unless that support fitting meets the criteria specified in 
paragraphs (g)(1), (g)(2), and (g)(3) of this AD.
    (1) The fitting has been repaired/reworked in accordance with 
Part II of the

[[Page 51849]]

Accomplishment Instructions of Revisions 3, 4, or 5 of the service 
bulletins, or the new fitting has been received from the 
manufacturer and has not been previously installed on any airplane.
    (2) The part number of the fitting has been verified in 
accordance with Revisions 4 or 5 of the service bulletins.
    (3) The maximum taxi gross weight (MTGW) limit of the fitting is 
greater than or equal to the MTGW of the airplane in accordance with 
Revisions 4 or 5 of service bulletins.

Alternative Methods of Compliance

    (h) 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. 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 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Special Flight Permit

    (i) 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

    (j) The actions shall be done in accordance with the service 
information included in Table 1, as follows:

                       Table 1.--Service Bulletins
------------------------------------------------------------------------
       Service bulletin           Revision               Date
------------------------------------------------------------------------
Boeing Alert Service Bulletin             3  September 2, 1999.
 727-57A0179.
Boeing Alert Service Bulletin             4  July 13, 2000.
 727-57A0179.
Boeing Service Bulletin 727-              5  December 20, 2000.
 57A0179.
------------------------------------------------------------------------

    This incorporation by reference is approved by the Director of 
the Federal Register in accordance with 5 U.S.C. 52(a) and 1 CFR 
part 51. Copies may be obtained from Boeing Commercial Airplane 
Group, P.O. Box 3707, Seattle, Washington 98124-2207. This 
information may be examined 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.

Effective Date

    (k) This amendment becomes effective on November 15, 2001.

    Issued in Renton, Washington, on October 2, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-25184 Filed 10-10-01; 8:45 am]
BILLING CODE 4910-13-U