E6-16198. Airworthiness Directives; Boeing Model 777-200, 777-300, and 777-300ER Series Airplanes

AGENCY:

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

ACTION:

Supplemental notice of proposed rulemaking (NPRM); reopening of comment period.

SUMMARY:

The FAA is revising an earlier proposed airworthiness directive (AD) for certain Boeing Model 777-200 and 777-300 series airplanes. The original NPRM would have required repetitive inspections for discrepancies of the splined components that support the inboard end of the inboard trailing edge flap; related investigative, corrective, and other specified actions if necessary; a one-time modification of the inboard support of the inboard trailing edge flap by installing a new isolation strap and attachment hardware; and repetitive replacement of the torque tube assembly. The original NPRM resulted from reports of corrosion on the torque tube and closeout rib fittings that support the inboard end of the inboard trailing edge flap, as well as a structural reassessment of the torque tube joint that revealed the potential for premature fatigue cracking of the torque tube that would not be detected using reasonable inspection methods. This action revises the original NPRM by providing the terminating action for the repetitive inspections of modifying the inboard main flap. This action also revises the original NPRM by specifying prior or concurrent accomplishment, for certain Boeing Model 777-200 series airplanes, of one-time inspections of the flap seal panels for cracking and minimum clearances, and of the torque tubes for damage; and related investigative and corrective actions if necessary. We are proposing this supplemental NPRM to detect and correct corrosion or cracking of the torque tube and closeout rib fittings that support the inboard end of the inboard trailing edge flap. Cracking in these components could lead to a fracture, which could result in loss of the inboard trailing edge flap and consequent reduced controllability of the airplane.

DATES:

We must receive comments on this supplemental NPRM by October 30, 2006.

ADDRESSES:

Use one of the following addresses to submit comments on this supplemental NPRM.

• 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: [phone].
• 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 service information identified in this proposed AD.

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 [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any relevant written data, views, or arguments regarding this supplemental NPRM. Send your comments to an address listed in the ADDRESSES section. Include the docket number “Docket No. FAA-2006-23842; Directorate Identifier 2005-NM-145-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this supplemental NPRM. We will consider all comments received by the closing date and may amend this supplemental NPRM in light of those comments.

We will post all comments submitted, 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 supplemental NPRM. 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 the 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 [phone]) is located on the plaza level in the Nassif Building at the DOT street address stated in ADDRESSES. Comments will be available in the AD docket shortly after the Docket Management System receives them.

Discussion

We proposed to amend 14 CFR part 39 with a notice of proposed rulemaking (NPRM) for an AD (the “original NPRM”) for certain Boeing Model 777-200 and 777-300 series airplanes. The original NPRM was published in the Federal Register on February 9, 2006 (71 FR 6687). The original NPRM proposed to require repetitive inspections for discrepancies of the splined components that support the inboard end of the inboard trailing edge flap; related investigative, corrective, and other specified actions if necessary; a one-time modification of the inboard support of the inboard trailing edge flap by installing a new isolation strap and attachment hardware; and repetitive replacement of the torque tube assembly.

Actions Since Original NPRM Was Issued

In the original NPRM we stated that we considered the proposed actions to be interim. We stated that the manufacturer was currently developing a new, improved torque tube made from corrosion-resistant steel with thicker walls; and that installing this new, improved torque tube was expected to address the unsafe condition identified in theoriginal NPRM and eliminate the need for the repetitive inspections and torque tube assembly replacements. Since we issued the original NPRM, the manufacturer has developed the improved torque tube and made it available. We have approved the improved torque tube, and this action follows that approval.

Relevant Service Information

We have reviewed Boeing Service Bulletin 777-57-0054, dated February 23, 2006. The service bulletin describes procedures for modifying the inboard main flap by installing a new corrosion-resistant (CRES) closeout rib fitting assembly; a new CRES torque tube; a new CRES torque tube retainer fitting; certain new components such as isolation straps, washers, and nuts; and assembling the parts using corrosion-inhibiting compound in lieu of grease. The service bulletin also specifies updating the maintenance practices for performing periodic inspections and maintenance of the torque tube splined joints, as given in the Boeing 777 Maintenance Planning Document (MPD) D622W001, Section 2, MPD Item 57-521-00, and Boeing 777 MPD D622W001, Section 9, Structural Significant Items (SSI) 57-53-I10 and SSI 57-53-I11.

Boeing Service Bulletin 777-57-0054 states that, for certain airplanes, the actions specified in Boeing Service Bulletin 777-27-0034, Revision 1, dated April 20, 2006, must be done prior to or concurrently with the modification of the inboard main flap. These prior/concurrent actions are a visual inspection of the flap seal panels for cracking and a measurement for minimum clearances; a close visual inspection of the torque tubes of the main flap for damage (breaks in the finish or finish that is not intact); and corrective actions if necessary. The corrective actions include:

• For the flap seal panels: Replacing the panel or doing a permanent repair and trim of the panel before further flight. If the cracking is within certain limits specified in the service bulletin, the service bulletin specifies the option of an immediate temporary repair followed by eventual permanent repair and trim, or replacement of the panel within 6 months after the temporary repair. If the cracking is outside certain limits specified in the service bulletin, the option for a temporary or permanent repair is not specified; instead, the panel must be replaced. The replacement includes measurement for minimum clearances.
• For the torque tubes: Replacing the torque tube or repairing before further flight. The service bulletin specifies doing either a permanent repair or an immediate temporary repair, depending on the extent of the damage. The temporary repair includes the related investigative action of a visual inspection for corrosion, pitting, or cracks; and repair if necessary. If the temporary repair is done, the service bulletin specifies that it must be followed by eventual permanent repair or replacement of the torque tube within 6 months after the temporary repair. If the damage is outside certain limits specified in the service bulletin, the service bulletin states that the torque tube must be replaced rather than repaired, and that the replacement may be done in accordance with the service bulletin or in accordance with instructions given by Boeing.

Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition.

Comments

We have considered the following comments on the original NPRM.

Support for the Original NPRM

Boeing reviewed the contents of the original NPRM and concurs with the contents.

Request to Allow Credit for Original Revision of Service Bulletin

Air Transport Association (ATA), on behalf of American Airlines, and British Airways request that we state that the original issue of Boeing Alert Service Bulletin 777-57A0048, dated September 9, 2004, is acceptable for compliance with the actions in the original NPRM. American Airlines points out that, according to Boeing, either release of the service bulletin is satisfactory.

We agree. We cited only Boeing Service Bulletin 777-57A0048, Revision 1, dated June 9, 2005, as the appropriate source of service information for accomplishing the required actions. Revision 1 of the service bulletin provides additional flexibility in accomplishing the modification specified in the original NPRM, and provides improvements in the procedure to determine the condition of the spline interface. However, actions accomplished in accordance with the original release of the service bulletin are also acceptable for compliance. We have added paragraph (n) to this supplemental NPRM to give credit for actions accomplished in accordance with the original release of the service bulletin.

Request To Revise Cost Estimate

British Airways states that the statement in the original NPRM that the work hours are negligible provided Boeing Service Bulletin 777-57A0048, Revision 1, is carried out at a scheduled inspection is incorrect because there is no scheduled inspection that calls for the torque tube to be disturbed. British Airways points out that the Boeing figures for accomplishing this service bulletin are 138 hours minimum per airplane.

We infer that British Airways would like us to revise the cost estimate. We disagree. The cost information below describes only the direct costs of the specific action proposed in the original NPRM, which is the detailed inspection for discrepancies of the splined components. In this case, the installation of the isolation strap and the replacement of the torque tube assembly are done during the detailed inspection, when the entire assembly has been completely disassembled. Therefore, the replacement of the torque tube assembly will take less time because no inspections of the originally installed torque tube are required if it is simply being replaced. We recognize that, in doing the actions required by an AD, 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, time necessary for planning, or time necessitated by other administrative actions. Those incidental costs, which may vary significantly among operators, are almost impossible to calculate. There is no need to revise the original NPRM in this regard.

Request To Clarify Alternative Methods of Compliance (AMOCs)

British Airways states that, presumably, an AMOC will need to be requested to cover those airplanes on which torque tube rework has been undertaken outside the scope of the instructions given in Boeing Service Bulletin 777-57A0048, Revision 1.

We agree that an AMOC will need to be requested. Paragraph (l) of the original NPRM (new paragraph (o) of this supplemental NPRM) gives procedures for requesting an AMOC. There is no need to revise the original NPRM in this regard.

FAA's Determination and Proposed Requirements of This Supplemental NPRM

Certain changes discussed above expand the scope of the original NPRM; therefore, we have determined that it is necessary to reopen the comment period to provide additional opportunity for public comment on this supplemental NPRM.

Difference Between This Supplemental NPRM and Boeing Service Bulletin 777-27-0034

Where Boeing Service Bulletin 777-27-0034 specifies to replace the torque tube in accordance with that service bulletin (or instructions from Boeing), this supplemental NPRM would require replacing the torque tube with a new CRES torque tube in accordance with the procedures in Boeing Service Bulletin 777-57-0054.

Clarification of Inspection Terminology

Boeing Service Bulletin 777-27-0034 specifies a visual inspection of the flap seal panels for cracking and measurement for minimum clearances; in this supplemental NPRM we refer to that inspection as a general visual inspection. That service bulletin also specifies a close visual inspection of the torque tubes of the main flap for damage. In this supplemental NPRM we refer to that inspection as a detailed inspection. We have included a definition of both inspection types in notes in this supplemental NPRM.

Explanation of Change to Costs of Compliance

After the original NPRM was issued, we reviewed the figures we have used over the past several years to calculate AD costs to operators. To account for various inflationary costs in the airline industry, we find it necessary to increase the labor rate used in these calculations from $65 per work hour to $80 per work hour. The cost impact information, below, reflects this increase in the specified hourly labor rate.

Costs of Compliance

There are about 353 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, at an average labor rate of $80 per work hour.

Estimated Costs

Action	Work hours	Parts	Cost per airplane	Number of U.S.-registered airplanes	Fleet cost
Detailed inspection for discrepancies of the splined components	20	None	$1,600, per inspection cycle	132	$211,200, per inspection cycle.
Modification (installing isolation strap and hardware)	Negligible	$17,156	$17,156	132	$2,264,592.
Replacement of torque tube assembly	Negligible 1	$24,230	$24,230	132	$3,198,360, per replacement cycle.
Modification (terminating action)	32 to 36, depending on airplane configuration	$145,659	$148,219 to $148,539	132	$19,564,908 to $19,607,148.
Prior/concurrent inspection	1	None	$80	Up to 132	As much as $10,560.
1 Provided that the replacement is performed at the same time as a scheduled inspection.

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 supplemental NPRM and placed it in the AD docket. See the ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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. The Federal Aviation Administration (FAA) amends § 39.13 by adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2006-23842; Directorate Identifier 2005-NM-145-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by October 30, 2006.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Boeing Model 777-200, -300, and -300ER series airplanes, certificated in any category, as identified in Boeing Service Bulletin 777-57-0054, dated February 23, 2006.

Unsafe Condition

(d) This AD results from reports of corrosion on the torque tube and closeout rib fittings that support the inboard end of the inboard trailing edge flap, as well as a structural reassessment of the torque tube joint that revealed the potential for premature fatigue cracking of the torque tube that would not be detected using reasonable inspection methods. We are issuing this AD to detect and correct corrosion or cracking of the torque tube and closeout rib fittings that support the inboard end of the inboard trailing edge flap. Cracking in these components could lead to a fracture, which could result in loss of the inboard trailing edge flap and consequent reduced controllability 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.

Service Bulletin Reference

(f) The term “service bulletin,” as used in paragraphs (g), (h), (i), (j), and (k) of this AD, means Boeing Service Bulletin 777-57A0048, Revision 1, dated June 9, 2005.

(g) Where the service bulletin specifies a compliance time after the issuance of the service bulletin, this AD requires compliance within the specified compliance time after the effective date of this AD.

Initial Inspection

(h) For all airplanes: Do a detailed inspection for any discrepancy of the splined components of the inboard trailing edge flap, in accordance with the Accomplishment Instructions of the service bulletin. The splined components of the inboard trailing edge flap include the torque tube, closeout rib fitting assembly, carrier beam pillow block fitting assembly, and drive crank support. Discrepancies of the torque tube and closeout rib fitting include light contact wear, corrosion pits, corrosion, cracking, or fracture. Discrepancies of the carrier beam pillow block fitting assembly and drive crank support consist of light contact wear and damage to the cadmium plating. Do the initial inspection at the applicable time specified in Table 7 under paragraph 1.E., “Compliance,” of the service bulletin, except as provided by paragraph (g) of this AD.

Note 1:

For the purposes of this AD, a detailed inspection is: “An intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate. Inspection aids such as mirror, magnifying lenses, etc., may be necessary. Surface cleaning and elaborate procedures may be required.”

No Discrepancy/Other Specified Actions

(i) If no discrepancy is found during the inspection required by paragraph (h) of this AD, perform all applicable specified actions, including the modification to install a new isolation strap and attachment hardware, in accordance with the Accomplishment Instructions of the service bulletin. Then, repeat the inspection at the applicable time specified in Table 7 under paragraph 1.E., “Compliance,” of the service bulletin. Doing the modification in paragraph (l)(1) of this AD terminates the repetitive inspection requirements of this paragraph.

Related Investigative/Corrective/Other Specified Actions and Repetitive Inspections

(j) For any discrepancy found during any inspection required paragraphs (h) and (i) of this AD: Before further flight, accomplish all applicable investigative, corrective, and other specified actions, including the modification to install a new isolation strap and attachment hardware, in accordance with the Accomplishment Instructions of the service bulletin. Then, evaluate the spline rework to determine the appropriate repetitive interval, in accordance with the Accomplishment Instructions of the service bulletin. Thereafter, repeat the inspection at the applicable interval specified in Table 7 under paragraph 1.E., “Compliance,” of the service bulletin. Doing the modification in paragraph (l)(1) of this AD terminates the repetitive inspection requirements of this paragraph.

Replacement of Torque Tube Assembly

(k) For all airplanes: Replace the torque tube assembly with a new torque tube assembly, in accordance with the Accomplishment Instructions of the service bulletin. Do the initial replacement at the applicable compliance time specified in Notes (c) and (d), as applicable, of Table 7 in paragraph 1.E., “Compliance,” of the service bulletin, except as provided by paragraph (g) of this AD. Repeat the replacement thereafter at the applicable interval specified in Notes (c) and (d), of Table 7 under paragraph 1.E., “Compliance,” of the service bulletin. Doing the modification in paragraph (l)(1) of this AD terminates the repetitive replacement requirements of this paragraph.

Modification

(l) For all airplanes: Within 60 months after the effective date of this AD, do the actions in paragraphs (l)(1) and (l)(2) of this AD.

(1) Modify the inboard main flap in accordance with the Accomplishment Instructions of Boeing Service Bulletin 777-57-0054, dated February 23, 2006. Doing this modification terminates the repetitive requirements of paragraphs (i), (j), and (k) of this AD.

(2) Revise the FAA-approved maintenance inspection program for performing periodic inspections and maintenance of the torque tube splined joints in accordance with the Accomplishment Instructions of Boeing Service Bulletin 777-57-0054, dated February 23, 2006.

Concurrent Requirement

(m) For Boeing Model 777-200 series airplanes, as identified in Boeing Service Bulletin 777-27-0034, Revision 1, dated April 20, 2006: Prior to or concurrently with the actions in paragraph (l) of this AD, do a general visual inspection of the flap seal panels for cracking and minimum clearances, and a detailed inspection of the torque tubes for damage; and do all applicable related investigative and corrective actions before further flight. Do all actions in accordance with the Accomplishment Instructions of Boeing Service Bulletin 777-27-0034, Revision 1, dated April 20, 2006; except where the service bulletin specifies the corrective action of replacing the torque tube, the replacement must be done in accordance with the Accomplishment Instructions of Boeing Service Bulletin 777-57-0054, dated February 23, 2006.

Note 2:

For the purposes of this AD, a general visual inspection is: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to ensure visual access to all surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplight 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.”

Actions Done In Accordance With Previous Issues of Service Bulletins

(n) Actions done before the effective date of this AD in accordance with Boeing Service Bulletin 777-27-0034, dated February 11, 1999; or Boeing Service Alert Bulletin 777-57A0048, dated September 9, 2004; are acceptable for compliance with the corresponding actions of this AD.

Alternative Methods of Compliance (AMOCs)

(o)(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.

Issued in Renton, Washington, on September 22, 2006.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.