Airworthiness Directives; Boeing Model 767 Series Airplanes

Summary:

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 767 series airplanes. For certain airplanes this AD requires rework of the bonding jumper assemblies on the drain tube assemblies of the slat track housing of the wings. For certain other airplanes, this AD requires repetitive inspections of the drain tube assemblies of the slat track housing of the wings to find discrepancies, and corrective actions, if necessary. This AD also provides for terminating action for the repetitive inspections. These actions are necessary to find and fix discrepancies of the bonding jumper assemblies, which could result in an in-tank ignition source due to electrostatic discharge or lightning. The actions also are necessary to find and fix discrepancies of the slat track drain tubes, which could result in fuel migrating into the tubes and leaking onto an engine or exhaust nozzle, and consequent risk of a fire when the airplane is stationary or during low speed taxiing. This action is intended to address the identified unsafe conditions.

Table of Contents

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:

Dennis Kammers, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2956; 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 certain Boeing Model 767 series airplanes was published in the Federal Register on December 22, 2000 (65 FR 80796). For certain airplanes that action proposed to require rework of the bonding jumper assemblies. For certain other airplanes, that action proposed to require repetitive inspections of the drain tube assemblies of the slat track housing ofthe wings to find discrepancies, and corrective actions, if necessary. That action also provides for terminating action for the repetitive inspections.

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.

Extend Compliance Time

Several commenters ask that the compliance time for doing the terminating action specified in paragraph (b) of the proposed rule be extended, as follows.

The first commenter states that the terminating action specified in paragraph (b) of the proposed rule requires compliance within 6,000 flight hours or 18 months after the effective date of the AD, whichever occurs first; but current Boeing delivery schedules forecast a 12-month delivery time for the required kits. The commenter further states that they have ordered the material (kits), but the kits have not yet arrived, which affects the commenter's ability to comply with the proposed rule. The commenter proposes to do the terminating action at a heavy maintenance visit as soon as the kits are delivered, but asks that the compliance time be changed to within 48 months after the effective date of the AD to allow time for delivery of the kits. The commenter adds that the repetitive visual inspections for the fuel leak specified in the service bulletin and a compliance time of 48 months provide an acceptable level of safety.

The second commenter states that the proposed rule, as written, does not take into consideration the amount of time needed to defuel and purge the fuel tanks. The commenter estimates that approximately 48 hours are needed to ensure adequate safety before maintenance personnel may enter the fuel tanks. The commenter does not specify a change to the compliance time, but states that the time given to do the terminating action should be extended to allow for proper airplane scheduling.

The third commenter states that the compliance time for doing the terminating action as specified in paragraph (b) of the proposed rule corresponds to a maintenance planning document “C” check interval, and is unreasonable. The commenter notes that the cracking of the slat track housing drain tubes is due to airframe vibration, which is related to flight hours, not calendar time. The commenter adds that the terminating action was considered optional based on ongoing inspections specified in the referenced service bulletin. The requirement to rework the drain tubes within 18 months after the effective date of the AD will not allow adequate time for airlines to obtain the necessary parts and do the rework within existing planned maintenance intervals, and does not allow for escalated maintenance programs. The commenter notes that the rework cannot be adequately done within planned maintenance outside of a “C” required to drain and vent the fuel tanks prior to tank entry. Additionally, there will be considerable impact on the airline operation when airplanes are scheduled for rework outside of routine maintenance checks. The commenter proposes that the calendar time limit for the terminating action specified in paragraph (b) of the proposed rule be extended to 24 months (the equivalent of a scheduled “C” check). The commenter wants the flight hour threshold specified in paragraph (b) to remain the same, which means the actual operating period for the airplane prior to rework is unchanged.

The fourth commenter states that they use Maintenance Planning Document MPD 57-50-00-A to inspect their airplanes at the enroute check before every flight. The commenter notes that this inspection is adequate to find fuel leaks, and no leaks have been found during these inspections. The commenter plans to do the terminating action specified in the proposed rule at the next heavy maintenance check per the normal defueling requirements of the MPD. The MPD task to defuel is at the 4C check, 72-month interval. The commenter adds that a 72-month compliance time could minimize their cost impact.

The fifth commenter states that since the terminating action in the proposed rule was optional in the service bulletin referenced in paragraph (b) of the proposed rule, kits were ordered only on demand as the operators planned their maintenance action. Since the proposed rule mandates that the terminating action be done within 18 months, there is a shortage of parts. The manufacturer has delivered 176 kits to date, and currently there are only 2 kits in supply, with 200 kits on order that are due to arrive in July 2001. The commenter adds that they will not be able to get enough kits for all 671 airplanes within the 18-month compliance time. The commenter also states that the repeat inspection at intervals not to exceed 500 flight hours, as specified in paragraph (a) of the proposed rule, maintains an adequate level of safety until the terminating action can be done. The commenter notes that there have not been any reported leaks at the slat track drain tube location since the proposed rule was issued. The commenter asks that the compliance time specified in paragraph (b) of the proposed rule be changed to within 6,000 flight hours or 36 months after the effective date of the AD, whichever comes first, to allow operators time to obtain the necessary parts.

The FAA concurs with the commenters that the compliance time required by paragraph (b) of the final rule should be extended somewhat to ensure that enough parts are available to do the required actions within the specified compliance time. In developing an appropriate compliance time for the terminating action required by the final rule, we considered not only the degree of urgency associated with addressing the unsafe condition, but the practical aspect of incorporating the required drain tube modification on the Model 767 fleet in a timely manner. Other factors included in the determination of an acceptable compliance time are that we informed the Air Transport Association in March 1998 of our plans to mandate appropriate service information to alleviate the unsafe condition, and affected operators have had access to the service bulletin that was revised to add the terminating modification since December 1998. Therefore, operators have had time to incorporate into their individual maintenance plans the inspections and terminating action required by this final rule.

It is our intent in this final rule to have the terminating action done within the time frame of a ‘C' check maintenance interval. We took the commenters' recommendations into account, as well as the time necessary to do the terminating action, and we find that a 24-month compliance time should correspond with the regular maintenance schedules of the majority of affected operators. An extension of the compliance time to 24 months will not adversely affect safety because the inspections required by paragraph (a) of the final rule will provide an acceptable level of safety until the terminating action required by paragraph (b) is done. Paragraph (b) of the final rule has been changed accordingly.

In response to the commenters' concerns that parts will not be available for installation within the compliance time required by the final rule, we have confirmed with the manufacturer that parts will be available to support a compliance time of 24 months after the effective date of this final rule.

In response to the third commenter's statement that the cracking of the slat track housing drain tubes is due to airframe vibration, which is related to flight hours, not calendar time; our determination is that the drain tubes failed in service due to corrosion.

Separate Rulemaking Actions

One commenter asks that Boeing Service Bulletins 767-57A0060, Revision 1, and 767-57-0068, referenced in the proposed rule as the appropriate sources of service information for accomplishment of the actions, be addressed in two separate rulemaking actions. The commenter states that these two service bulletins do not address the same discrepant condition and should not be grouped together in one proposed rule.

The FAA does not concur. We agree that two unsafe conditions do exist with the same drain tube installation, but we consider it acceptable to address both conditions in one rule. The reasons for this are as follows:

Boeing Service Bulletin 767-57A0060, Revision 1, provides procedures for repetitive visual inspections of the drain tube assemblies of the slat track housing of the wings to find discrepancies. Such discrepancies may lead to an airplane fire as a result of fuel leakage onto an engine or exhaust nozzle. The service bulletin also provides procedures for replacement of the existing drain tube assembly with a newly designed assembly that would constitute terminating action for the repetitive inspections.

Boeing Service Bulletin 767-57-0068 provides procedures for modification of the bonding jumper assembly on the drain tube assembly of the slat track housing of the wings. An earlier production installation of the bonding assembly on the newly designed drain tube assembly did not meet the current bonding specifications. Those airplanes with the earlier production installation must have the bonding provisions modified to protect against an in-tank ignition source due to electrostatic discharge or lightning. Incorporation of this service bulletin will bring affected airplanes into the same configuration as those airplanes modified by Service Bulletin 767-57A0060. Clarification of the related procedures in these two service bulletins was provided in the preamble of the proposed rule.

Revise Preamble Language

One commenter states that the Summary and Discussion sections of the proposed rule should be changed to explicitly state that only the numbers 5 and 8 inboard slat track housing drain locations are affected by the proposed rule. The commenter adds that it also should be explicitly stated that visual inspections are to be done at the exterior lower wing surface drain locations, as shown in Figure 2 of Boeing Service Bulletin 767-57A0060, Revision 1, located on page 21.

The FAA concurs with these comments and acknowledges that the description of the area (numbers 5 and 8 inboard) of the drain assembly of the slat track housing affected could have been more specific in the Summary and Discussion sections, but the Discussion section is not restated in this final rule. The intent of the Summary section of the final rule is to provide a brief explanation of the unsafe condition and the actions necessary to find and fix any discrepancies. We have revised the Summary section, as well as the other applicable sections in this final rule, to further clarify the unsafe condition and the specified actions.

One commenter asks that the Differences section of the proposed rule be changed. The commenter points out that there is a typographical error in the MPD section number that is specified in the Differences, the correct number is Section 57-50-00-A.

We concur that a typographical error in the Differences section resulted in an incorrect reference to Section 57-59-00-A of the MPD, instead of the correct reference to Section 57-50-00-A. But this final rule does not restate the Differences section of the proposed rule wherein the commenter has requested changes. That difference merely stated that the proposed rule would require accomplishment of the initial and repeat visual inspections regardless of earlier accomplishment of the inspection specified in the MPD.

Maintenance Planning Document (MPD)

One commenter states that Boeing Service Bulletin 767-57A0060, Revision 1, describes the Boeing 767 MPD, Section 57-50-00-A, as an acceptable means to inspect and detect damage and/or fuel leakage, as an alternative to the visual inspection specified in Part I of the service bulletin. The commenter asks that the FAA confirm that the MPD can be used instead of doing the visual inspection specified in paragraph (a) of the proposed rule.

The FAA does not concur. As stated in the Differences section of the proposed rule, discussed previously, the final rule requires accomplishment of the initial and repeat visual inspections regardless of earlier accomplishment of the inspection specified in the MPD. This is necessary because the inspection in the MPD does not require a minimum amount of fuel in each wing tank, but the visual inspections described in Part I of the service bulletin specify a minimum of 4,400 gallons of fuel in each wing tank to ensure adequate fuel coverage over the drain tubes during the fuel leakage check.

Cost Impact

One commenter states that the number of work hours estimated for doing the actions in the proposed rule, as specified in the service bulletins, are more accurate than the number of work hours specified in the cost impact section of the proposed rule. The commenter notes that the estimate for replacement of the drain tube assemblies as specified in the proposal is 12 work hours, but the estimate specified in the applicable service bulletin is 40 work hours for the replacement. The estimate for rework of the bonding jumper assemblies specified in the proposal is 4 work hours, but the estimate specified in the applicable service bulletin is 25 work hours. The commenter asks that the work hours estimated in the service bulletins be used in the Cost Impact section of the proposed rule.

The FAA does not concur. The cost impact information (below) estimates only the “direct” costs of the specific actions required by this final rule. The number of work hours necessary to do the required actions was provided to us by the manufacturer, based on the data available to date. We recognize that in doing the actions required by this final rule, operators may incur “incidental” costs in addition to the “direct” costs. The cost analysis in AD rulemaking actions, however, typically does not include incidental costs, such as the time required to gain access and close-up; planning time; or time necessitated by other administrative actions. Because incidental costs may vary significantly from operator to operator, they are almost impossible to calculate. Further, because ADs require specific actions to address specific unsafe conditions, they appear to impose costs that would not otherwise be incurred by operators. However, because of the general obligation of operators to maintain and operate airplanes in an airworthy condition, this cost estimate is inaccurate. Attributing those costs to the requirements of this final rule is unrealistic because in the interest of maintaining and operating safe airplanes, operators would do the required actions even if they were not required to do the final rule.

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 745 airplanes of the affected design in the worldwide fleet. The FAA estimates that 275 airplanes of U.S. registry will be affected by this AD.

For airplanes listed in Boeing Service Bulletin 767-57A0060, Revision 1 (228 U.S.-registered airplanes): It will take approximately 1 work hour per airplane to accomplish the required inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the required inspection on U.S. operators is estimated to be $13,680, or $60 per airplane, per inspection cycle.

It will take approximately 12 work hours per airplane to accomplish the required replacement of the drain tube assemblies specified in Boeing Service Bulletin 767-57A0060, Revision 1, at an average labor rate of $60 per work hour. Required parts will cost approximately $5,236 per airplane. Based on these figures, the cost impact of the required replacement on U.S. operators is estimated to be $1,357,968, or $5,956 per airplane.

For airplanes listed in Boeing Service Bulletin 767-57-0068, (47 U.S.-registered airplanes): It will take approximately 4 work hours per airplane to accomplish the required rework of the bonding jumper assemblies, at an average labor rate of $60 per work hour. Required parts will cost approximately $322 per airplane. Based on these figures, the cost impact of the required rework on U.S. operators is estimated to be $26,414, or $562 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 2. Section 39.13 is amended by adding the following new airworthiness directive:

2001-14-19Boeing: Amendment 39-12330. Docket 2000-NM-309-AD.

Applicability: Model 767 series airplanes, line numbers 1 through 757 inclusive, certificated in any category.

Note 1:

This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (d) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To find and fix discrepancies (bonding, loose fittings, cracking) of the bonding jumper assemblies, which could result in an in-tank ignition source due to electrostatic discharge or lightning; and of the slat track drain tubes, which could result in fuel migrating into the tubes and leaking onto an engine or exhaust nozzle, and consequent risk of a fire when the airplane is stationary or during low speed taxiing; accomplish the following:

Repetitive Inspections/Corrective Action

(a) For airplanes listed in Boeing Service Bulletin 767-57A0060, Revision 1, dated December 31, 1998; within 500 flight hours after the effective date of this AD: Do a general visual inspection of the drain tube assemblies of the slat track housings of the wings to find discrepancies (loose fittings, cracked tubes, fuel leaks), per Part I of the Accomplishment Instructions of the service bulletin.

(1) If any discrepancies are found, before further flight, rework the drain tube assembly per Part II of the Accomplishment Instructions of the service bulletin; repeat the inspection at intervals not to exceed 500 flight hours until accomplishment of the requirements in paragraph (b) of this AD.

(2) If no discrepancies are found, repeat the inspection thereafter at intervals not to exceed 500 flight hours, until accomplishment of the requirements in paragraph (b) of this AD.

Note 2:

For the purposes of this AD, a general visual inspection is defined as: “A visual examination of an interior or exterior area, installation, or assembly to find obvious damage, failure, or irregularity. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or drop-light and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”

Terminating Action for Repetitive Inspections

(b) For airplanes specified in paragraph (a) of this AD, within 6,000 flight hours or 24 months after the effective date of this AD, whichever occurs first: Replace the drain tube assemblies of the slat track housings of the wings (including general visual inspection and repair) per Part III of the Accomplishment Instructions of Boeing Service Bulletin 767-57A0060, Revision 1, dated December 31, 1998. Any applicable repair must be accomplished prior to further flight. Accomplishment of this paragraph terminates the repetitive inspections required by paragraph (a) of this AD.

Rework of Bonding Jumper Assemblies

(c) For airplanes listed in Boeing Service Bulletin 767-57-0068, dated September 16, 1999; within 5,000 flight cycles or 22 months after the effective date of this AD, whichever occurs first: Rework the bonding jumper assembly of the drain tube assemblies of the slat track housing of the wings (including general visual inspection and repair) per the Accomplishment Instructions of the service bulletin. Any applicable repair must be accomplished prior to further flight. Accomplishment of this paragraph terminates the requirements of this AD.

Alternative Methods of Compliance

(d) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA. Operators shall send 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

(e) Special flight permits may be issued per sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

Incorporation by Reference

(f) The actions shall be done in accordance with Boeing Service Bulletin 767-57A0060, Revision 1, dated December 31, 1998, and Boeing Service Bulletin 767-57-0068, dated September 16, 1999; 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 Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. 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.

Effective Date

(g) This amendment becomes effective on August 28, 2001.

Issued in Renton, Washington, on July 12, 2001. Vi L. Lipski,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

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