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Proposed Rule

Airworthiness Directives; Boeing Model 777 Airplanes

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Information about this document as published in the Federal Register.

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AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 777 airplanes. This proposed AD would require repetitive measurements of the freeplay of certain joints of the trailing edge flap supports; repetitive lubrication of the support joints; and related investigative and corrective actions if necessary. The proposed AD also provides for modifying certain components of the trailing edge flap supports, which would extend the intervals for the repetitive measurements, and revising the maintenance practices of the maintenance planning data document. This proposed AD results from reports of excessive wear of the pins, bushings, and bearings, and corrosion at the joints of the outboard trailing edge flap supports. We are proposing this AD to prevent wear and corrosion at the flap support joints, which could result in loss of the trailing edge flap and possible loss of control of the airplane.

DATES:

We must receive comments on this proposed AD by May 4, 2007.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD.

  • DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
  • Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
  • Mail: Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, room PL-401, Washington, DC 20590.
  • Fax: (202) 493-2251.
  • Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207, for the service information identified in this proposed AD.

Start Further Info

FOR FURTHER INFORMATION CONTACT:

Gary Oltman, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6443; fax (425) 917-6590.

End Further Info End Preamble Start Supplemental Information

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed in the ADDRESSES section. Include the docket number “FAA-2007-27619; Directorate Identifier 2005-NM-164-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of that Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov.

Examining the Docket

You may examine the AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the Docket Management System receives them.

Discussion

We have received reports of excessive wear of the pins, bushings, and bearings, and corrosion at certain support joints on Boeing Model 777 airplanes. An operator investigating an unrelated issue during heavy maintenance first discovered these discrepancies. In addition, some flap support joints were completely dry due to blocked grease paths, and many pins were seized in the fittings. Inadequate lubrication and the use of clay-based lubricants can accelerate pin wear. The pins are made of titanium and coated with D-gun coating for wear resistance. The wear characteristics of titanium pins are unknown, so if the wear progresses through the D-gun coating, the pins could eventually crack and then fracture. Moreover, undetected wear of the joint bushings results in freeplay-induced dynamic loading of the pin that is in excess of design loads. Wear and corrosion at the flap support joints, if not corrected, could result in loss of the trailing edge flap and possible loss of control of the airplane.

Relevant Service Information

We have reviewed Boeing Service Bulletin 777-27A0066, Revision 1, dated May 18, 2006. The service bulletin describes procedures for repetitive measurements of the freeplay of support joints A, B, C, and D of the trailing edge flap supports, numbers 1 through 3 inclusive and 6 through 8 inclusive; and of joint B of the trailing edge flap supports, numbers 4 and 5. The service bulletin also describes procedures for disassembling any joint that exceeds the freeplay limits specified in the service bulletin, and doing the related investigative and corrective actions in the “support teardown inspection.” The related Start Printed Page 13049investigative and corrective actions are doing a detailed inspection of the joint for worn pins, bearings, and bushings, and for blocked lubrication paths; doing a dye penetrant inspection for cracks of pins with an acceptable surface finish; and replacing worn or cracked parts and unblocking the lubrication path if necessary.

As an option to the support teardown inspection, for certain airplanes, the service bulletin describes procedures for a “temporary return to service” inspection. The temporary return to service inspection is similar to the support teardown inspection, except inspection for wear of the bearings and bushings may be accomplished without removing the flap from the airplane by insuring that joint freeplay is limited to temporarily acceptable levels when combined with frequent repetitive freeplay inspections. Doing the temporary return to service inspection extends the compliance time before the service bulletin specifies the support teardown inspection should be done. The service bulletin notes that certain pins identified during the support teardown inspection or temporary return to service inspection are acceptable for continued, time-limited use if the wear is within certain limits specified in the service bulletin.

The service bulletin also describes procedures for repetitive lubrications of certain joints of the trailing edge flap supports, using Boeing Material Standard (BMS) 3-33 grease. The service bulletin specifies that part of this lubrication is verifying that grease emerges from the interface common to the pin outer diameter. If grease does not emerge, the service bulletin describes procedures for doing the following related investigative and corrective actions:

  • Removing the pin and doing the detailed and dye penetrant inspection procedures described in the support teardown inspection, and replacing excessively worn or cracked parts if necessary;
  • Inspecting for a blocked lubrication path, and clearing it if necessary; and
  • Doing a detailed inspection for wear of the interfacing bearings and bushings and replacing them if necessary.

The service bulletin also refers to Boeing Alert Service Bulletin 777-27A0071, Revision 1, dated October 16, 2006 (described below), which eliminates the need for the repetitive measurements and lubrications of certain trailing edge flap supports after accomplishing the specified actions.

We have also reviewed Boeing Alert Service Bulletin 777-27A0071, Revision 1, dated October 16, 2006. The service bulletin describes procedures for modifying certain components of the trailing edge flap supports. The modification includes replacing the pins, ball sets, and bushings on the joints of the trailing edge flap at support numbers 1 through 8 inclusive, with new, improved components; doing a detailed inspection of the components that interface with the flap support pins for discrepancies (corrosion, damage, or excessive wear); doing a general visual inspection of those components for any blocked lubrication paths; and doing corrective actions if necessary. If any discrepancies are found, the corrective actions include replacing the components and clearing any blocked lubrication paths. The service bulletin also describes procedures for revising the maintenance practices of the Boeing 777 Maintenance Planning Data (MPD) Document to update certain lubrication and inspection intervals. Accomplishing these actions extends the intervals for the repetitive measurement of certain trailing edge flap supports specified in Boeing Service Bulletin 777-27A0066, Revision 1.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other airplanes of this same type design. For this reason, we are proposing this AD, which would require accomplishing the actions specified in the service information described previously, except as discussed under “Differences Between the Proposed AD and the Service Bulletins.”

Differences Between the Proposed AD and the Service Bulletins

Note (b) in Table 1 of Paragraph 1.E. “Compliance” of Boeing Service Bulletin 777-27A0066, Revision 1, recommends repeating the freeplay measurement every 6,000 flight cycles if the joints can be proven to have been lubricated with only BMS 3-33 grease every 1,000 flight cycles or every 240 days, whichever occurs first, after the airplane delivery or the last support teardown inspection. However, this proposed AD would require repeating the freeplay measurement under those conditions at intervals not to exceed 6,000 flight cycles, as specified in the service bulletin, but would add a compliance time of 120 months (whichever occurs first).

Note (c) in Table 1 of Paragraph 1.E. “Compliance” of Boeing Service Bulletin 777-27A0066, Revision 1, specifies that freeplay levels greater than 0.020 inch are not recommended later than 30 months after release of the service bulletin. This proposed AD would require the initial measurement of the freeplay, for airplanes that have accumulated 6,000 total flight cycles or more on or before the effective date of this AD or on which a teardown inspection has not been accomplished before the effective date of this AD; at the earlier of the following compliance times.

  • Prior to the accumulation of 10,000 total flight cycles, or within 9 months after the effective date of this AD, whichever occurs later.
  • Within 30 months after the effective date of this AD.

Boeing Alert Service Bulletin 777-27A0071 specifies revising the maintenance practices for performing periodic inspections and maintenance of the support joints of the trailing edge flap for the maintenance inspection program of the Boeing 777 MPD Document by doing the actions specified in Part 7 of the Accomplishment Instructions of the service bulletin. However, this proposed AD would mandate only the maintenance actions specified in paragraphs 1 and 3 of Part 7 of the service bulletin. Parts 3, 4, and 6 of the service bulletin include optional actions for certain structure in order to increase the interval of the repetitive freeplay measurement.

These differences have been coordinated with Boeing.

Costs of Compliance

There are about 546 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs for U.S. operators to comply with this proposed AD. Start Printed Page 13050

Estimated Costs

ActionWork hoursAverage labor rate per hourParts costCost per airplaneNumber of U.S.-registered airplanesFleet cost
Freeplay measurement, per cycle28$80$0$2,240, per cycle145$324,800, per cycle.
Lubrication, per cycle2800$160, per cycle145$23,200 per cycle.
Modification for flap support No. 3 and 61358058,521$69,321145$10,051,545.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, Section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, “General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would 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.

For the reasons discussed above, I certify that the proposed regulation:

1. Is not a “significant regulatory action” under Executive Order 12866;

2. Is not a “significant rule” under the 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.

We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD and placed it in the AD docket. See the ADDRESSES section for a location to examine the regulatory evaluation.

Start List of Subjects

List of Subjects in 14 CFR Part 39

End List of Subjects

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

Start Part

PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Start Authority

Authority: 49 U.S.C. 106(g), 40113, 44701.

End Authority
[Amended]

2. The Federal Aviation Administration (FAA) amends § 39.13 by adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2007-27619; Directorate Identifier 2005-NM-164-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by May 4, 2007.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Boeing Model 777-200, -200LR, -300, and -300ER series airplanes, certificated in any category; as identified in Boeing Service Bulletin 777-27A0066, Revision 1, dated May 18, 2006.

Unsafe Condition

(d) This AD results from reports of excessive wear of the pins, bushings, and bearings, and corrosion at the joints of the outboard trailing edge flap supports. We are issuing this AD to prevent wear and corrosion at the flap support joints, which could result in loss of the trailing edge flap and possible loss of control of the airplane.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Initial Freeplay Measurement

(f) At the applicable time in paragraph (f)(1) or (f)(2) of this AD: Measure the freeplay of support joints A, B, C, and D of the trailing edge flap supports, numbers 1 through 3 inclusive and 6 through 8 inclusive, and of joint B of the trailing edge flap supports, numbers 4 and 5; in accordance with the Accomplishment Instructions of Boeing Service Bulletin 777-27A0066, Revision 1, dated May 18, 2006.

(1) For airplanes that have accumulated 6,000 total flight cycles or more on or before the effective date of this AD or on which a teardown inspection has not been accomplished before the effective date of this AD: At the earlier of the times in paragraph (f)(1)(i) or (f)(1)(ii) of this AD.

(i) Prior to the accumulation of 10,000 total flight cycles, or within 9 months after the effective date of this AD, whichever occurs later.

(ii) Within 30 months after the effective date of this AD.

(2) For airplanes that have accumulated fewer than 6,000 total flight cycles on or before the effective date of this AD: At the later of the times in paragraph (f)(2)(i) or (f)(2)(ii) of this AD.

(i) Prior to the accumulation of 6,000 total flight cycles, or within 120 months after the date of issuance of the original standard airworthiness certificate or the date of issuance of the original export certificate of airworthiness, whichever occurs first.

(ii) Within 30 months after the effective date of this AD.

Repetitive Intervals if the Freeplay Measurement Is Less Than 0.020 Inch

(g) If, during any freeplay measurement required by paragraph (f), (g), or (h) of this AD, the freeplay measurement is less than 0.020 inch: Repeat the freeplay measurement required by paragraph (f) of this AD at the applicable interval in paragraph (g)(1) or (g)(2) of this AD. Accomplishing the actions specified in paragraph (j) or (k) of this AD, as applicable, extends the intervals for the repetitive measurements for the associated flap support only.

(1) At intervals not to exceed 1,000 flight cycles.

(2) At intervals not to exceed 6,000 flight cycles or 120 months, whichever occurs first, if a review of airplane maintenance records can conclusively determine that the joints have been lubricated with only BMS 3-33 grease at the earlier of intervals not to exceed 1,000 flight cycles or 240 days since the last support teardown inspection, or since the date of issuance of the original standard airworthiness certificate or the date of issuance of the original export certificate of airworthiness. Start Printed Page 13051

Related Investigative and Corrective Actions, and Repetitive Intervals if the Freeplay Measurement Is 0.020 Inch or Greater

(h) If, during any freeplay measurement required by paragraph (f), (g), or (h) of this AD, the freeplay measurement is 0.020 inch or greater: Do the applicable action in paragraph (h)(1), (h)(2), or (h)(3) of this AD. Accomplishing the actions specified in paragraph (j) or (k) of this AD, as applicable, extends the intervals for repetitive measurements for the associated flap support only. Do all actions in accordance with the Accomplishment Instructions of Boeing Service Bulletin 777-27A0066, Revision 1, dated May 18, 2006, and note (e) of Table 1 in paragraph 1.E., “Compliance.”

(1) For airplanes that have accumulated 6,000 total flight cycles or more as of the effective date of this AD, and for which the freeplay measurement is 0.020 inch to 0.100 inch inclusive: Repeat the freeplay measurement required by paragraph (f) of this AD thereafter at intervals not to exceed 500 flight cycles until the support teardown inspection in paragraph (h)(1)(i) or (h)(1)(ii) of this AD is done.

(i) Within 12 months after the first freeplay measurement of 0.020 inch to 0.100 inch inclusive, do the applicable related investigative and corrective actions specified in the service bulletin as the “Support Teardown Inspection,” and repeat the freeplay measurement required by paragraph (f) of this AD thereafter at intervals not to exceed 6,000 flight cycles or 120 months, whichever occurs first.

(ii) Before further flight after the first freeplay measurement of 0.020 inch to 0.100 inch inclusive, do the applicable related investigative and corrective actions specified in the service bulletin as the “Temporary Return to Service Inspection” and, within 24 months after the first freeplay measurement of 0.020 inch to 0.100 inch inclusive, do the applicable related investigative and corrective actions specified in the service bulletin as the “Support Teardown Inspection.” Repeat the freeplay measurement required by paragraph (f) of this AD thereafter at intervals not to exceed 6,000 flight cycles, or 120 months, whichever occurs first.

(2) For airplanes that have accumulated 6,000 total flight cycles or more as of the effective date of this AD, and the freeplay measurement is greater than 0.100 inch: Do the action in paragraph (h)(2)(i) or (h)(2)(ii) of this AD.

(i) Before further flight after the first freeplay measurement of greater than 0.100 inch, do the applicable related investigative and corrective actions specified in the service bulletin as the “Support Teardown Inspection.” Repeat the freeplay measurement required by paragraph (f) of this AD thereafter at intervals not to exceed 6,000 flight cycles or 120 months, whichever occurs first.

(ii) Before further flight after the first freeplay measurement of greater than 0.100 inch, do applicable related investigative and corrective actions in the “Temporary Return to Service Inspection,” and within 6 months after the first freeplay measurement of greater than 0.100 inch, do the applicable related investigative and corrective actions in the “Support Teardown Inspection.” Repeat the freeplay measurement required by paragraph (f) of this AD thereafter at intervals not to exceed 6,000 flight cycles or 120 months, whichever occurs first.

(3) For airplanes that have accumulated fewer than 6,000 total flight cycles as of the effective date of this AD: Before further flight after the first freeplay measurement of 0.020 inch or greater, do the related investigative and corrective actions specified in the service bulletin as the “Support Teardown Inspection.” Repeat the freeplay measurement required by paragraph (f) of this AD thereafter at intervals not to exceed 6,000 flight cycles or 120 months, whichever occurs first.

Repetitive Lubrications

(i) Within 12 months after the effective date of this AD: Lubricate the joints of the trailing edge flap supports using BMS 3-33 grease. Repeat the lubrication thereafter at intervals not to exceed 1,000 flight cycles, or 240 days, whichever occurs first. Do all actions in accordance with the Accomplishment Instructions, and note (d) of Table 1 in paragraph 1.E., “Compliance” of Boeing Service Bulletin 777-27A0066, Revision 1, dated May 18, 2006.

Modification/Repetitive Freeplay Measurements

(j) Before the accumulation of 23,000 total flight cycles or within 24 months after the effective date of this AD, whichever is later: Replace the pins, ball sets, and bushings on the joints of the trailing edge flap at support numbers 3 and 6 with new, improved components by doing all the applicable actions, including all applicable corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 777-27A0071, Revision 1, dated October 16, 2006. Before further flight after doing the actions, do a detailed inspection of the components that interface with the flap support pins for discrepancies (corrosion, damage, or excessive wear), and a general visual inspection for any blocked lubrication paths; and do all applicable corrective actions. Repeat the freeplay measurements for the associated flap support at intervals not to exceed 16,000 flight cycles in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 777-27A0071, Revision 1, dated October 16, 2006. Accomplishing the actions in this paragraph constitutes terminating action for the actions specified in paragraphs (f), (g), (h), and (i) of this AD, for the associated trailing edge flap support only.

Optional Modification

(k) Accomplishing the actions specified in paragraph (j) of this AD at support numbers 1, 2, 4, 5, 7, and 8, extends the intervals for the repetitive measurements required by paragraph (g) of this AD for the associated flap support only.

Revise Maintenance Planning Data (MPD) Document

(l) Within 12 months after the effective date of this AD: Revise the maintenance practices for performing periodic inspections and maintenance of the support joints of the trailing edge flap for the maintenance inspection program of the Boeing 777 MPD Document by doing the actions specified in paragraphs 1 and 3 only of Part 7 of the Accomplishment Instructions of Boeing Alert Service Bulletin 777-27A0071, Revision 1, dated October 16, 2006.

Actions Accomplished Previously

(m) Actions done before the effective date of this AD in accordance with Boeing Alert Service Bulletin 777-27A0066, dated July 28, 2005, are acceptable for compliance with paragraphs (f), (g), (h), and (i) of this AD, as applicable. Actions done before the effective date of this AD in accordance with Boeing Alert Service Bulletin 777-27A0071, dated March 30, 2006, are acceptable for compliance with paragraphs (j), (k), and (l) of this AD, as applicable.

Alternative Methods of Compliance (AMOCs)

(n)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

(2) Before using any AMOC approved in accordance with § 39.19 on any airplane to which the AMOC applies, notify the appropriate principal inspector in the FAA Flight Standards Certificate Holding District Office.

(3) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD, if it is approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization who has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD.

Start Signature

Issued in Renton, Washington, on March 9, 2007.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

End Signature End Part End Supplemental Information

[FR Doc. E7-5013 Filed 3-19-07; 8:45 am]

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