01-25184. Airworthiness Directives; Boeing Model 727 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Final rule.

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.

FOR FURTHER INFORMATION CONTACT:

Walter Sippel, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington; telephone [phone] or [phone]; fax [phone].

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:

• 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.
• 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:

• 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.
• 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.

• 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.
• The service bulletin recommends accomplishment of the rework within the specified 18 months for those fittings that have not been reworked (overhauled) previously.
• 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.
• 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.
• Although inspections will continue per paragraph (a) of this AD until 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.

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 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 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.

§ 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 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 727-57A0179	3	September 2, 1999.
Boeing Alert Service Bulletin 727-57A0179	4	July 13, 2000.
Boeing Service Bulletin 727-57A0179	5	December 20, 2000.

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.