E7-11679. Airworthiness Directives; Boeing Model 777 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 all Boeing Model 777-200, -300, and -300ER series airplanes. The original NPRM would have required, for the drive mechanism of the horizontal stabilizer, repetitive detailed inspections for discrepancies; repetitive lubrication of the ballnut and ballscrew; repetitive measurements of the freeplay between the ballnut and the ballscrew; and corrective action if necessary. The original NPRM resulted from a report of extensive corrosion of a ballscrew in the drive mechanism of the horizontal stabilizer on a Boeing Model 757 airplane, which is similar in design to the ballscrew on Model 777 airplanes. This action revises the original NPRM by adding airplanes to the applicability. We are proposing this supplemental NPRM to prevent an undetected failure of the primary load path for the ballscrew in the horizontal stabilizer and subsequent wear and failure of the secondary load path, which could lead to loss of control of the horizontal stabilizer and consequent loss of control of the airplane.

DATES:

We must receive comments on this supplemental NPRM by July 13, 2007.

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 the service information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT:

Kelly McGuckin, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, 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 “FAA-2006-24270; Directorate Identifier 2005-NM-200-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 all 777-200, -300, and -300ER series airplanes. The original NPRM was published in the Federal Register on March 30, 2006 (71 FR 16061). The original NPRM proposed to require, for the drive mechanism of the horizontal stabilizer, repetitive detailed inspections for discrepancies; repetitive lubrication of the ballnut and ballscrew; repetitive measurements of the freeplay between the ballnut and the ballscrew; and corrective action if necessary.

Actions Since Original NPRM Was Issued

Since we issued the original NPRM, we have determined that all Model 777 airplanes may be subject to the unsafe condition specified in the original NPRM. Therefore, we are issuing this supplemental NPRM to revise the applicability of the original NPRM to identify all Model 777 airplanes.

Comments

We have considered the following comments on the original NPRM.

Request To Remove Unnecessary Instruction

Two commenters, Boeing and Air Transport Association (ATA) on behalf of its member United Airlines (UAL), assert that the added instruction in paragraph (h) of the original NPRM regarding changing the position of the horizontal stabilizer to permit inspecting the entire ballscrew is not necessary as the Boeing 777 Aircraft Maintenance Manual and task cards already require such a change of position as part of the ballscrew inspection. A third commenter, British Airways (BA), also notes that the required instruction already exists as described. Boeing requests that we revise the description of the detailed inspection in the original NPRM as the specified instruction is unnecessary. UAL states that the phrase “or in the referenced AMM sections” is incorrect and requests that it be deleted from the first paragraph under the heading “Differences Between the Proposed AD and Service Information” in the original NPRM.

We agree. The instruction to move the horizontal stabilizer is sufficiently addressed as part of the required inspection in the Boeing 777 Aircraft Maintenance Manual and task cards and need not be repeated in the AD. Since the “Differences Between the Proposed AD and Service Information” section of the original NPRM is not carried forward, there is no need to change the paragraph specified by UAL. However, we have removed the unnecessary instruction “changing the position of the horizontal stabilizer as needed to allow inspecting the entire ballscrew” from paragraph (h) of the supplemental NPRM.

Request To Revise Maintenance Records Check

Boeing requests that we change the maintenance records check. Boeing states that, as written, the original NPRM would require production airplanes delivered after the effective date of the AD to have a maintenance records check within 6 months after the effective date. Further, Boeing states, airplanes delivered 6 months after the effective date would immediately be out of compliance. Boeing requests, therefore, that paragraph (g) of the original NPRM be revised to include the following statement: “This paragraph applies only to those airplanes delivered prior to the effective date of this AD.”

We agree. We have determined that the maintenance records check should apply only to airplanes that received a standard airworthiness certificate or original export certificate of airworthiness prior to the effective date of the AD. We have revised paragraphs (g), (h), (i), and (j) of the supplemental NPRM to reflect this. We have also revised the Cost of Compliance of the supplemental NPRM to reflect the cost of the maintenance records check.

Request To Revise Prior Replacement of Actuator

ATA, on behalf of UAL, requests certain relief from the repetitive inspections of the horizontal stabilizer ballscrew. UAL states that paragraph (l) of the original NPRM does not state requirements for operators who have replaced actuators with new or overhauled actuators. UAL states it has “hard-timed” its actuators at 9 years to be removed and overhauled per original equipment manufacturer (OEM) component maintenance manual (CMM) specifications. UAL requests that credit for repetitive inspections be given to operators who have a stabilizer trim actuator overhaul maintenance program in place.

We agree. Any hard-time program that involves removing, overhauling, and re-installing the stabilizer trim actuator accomplishes the intent of performing one freeplay inspection, one detailed inspection, and one lubrication of the stabilizer ballscrew assembly, provided that the stabilizer ballscrew sub-assembly is removed from the trim actuator and overhauled. We find that removing, disassembling, and overhauling the stabilizer ballscrew sub-assembly in accordance with OEM CMM specifications provides a thorough detailed inspection and measurement of the condition of the stabilizer actuator and ballscrew. Therefore, we have revised paragraph (l) of the supplemental NPRM to give credit for accomplishing the actions required by paragraphs (h), (i), and (j) of this AD for actuators which have been overhauled as part of a hard-time program in accordance with OEM CMM specifications.

Request To Revise Description of Affected Airplanes

Boeing requests that certain language of the original NPRM be revised to clarify the extent to which Model 777 airplanes are affected. Boeing states that, at this time, Alert Service Bulletin 777-27A0059 applies to all Model 777 airplanes, current and future. Boeing requests that the original NPRM be changed as follows:

• That the Costs of Compliance be changed from “there are about 582 airplanes” to “there are currently 582 airplanes” and from “would affect about” to “would currently affect about”; and
• That paragraph (c) Applicability be changed from “Boeing Model 777-200, -300, and -300ER series airplanes” to “all Boeing Model 777 series airplanes.”

We partially agree. The costs of compliance estimate is understood to be based on the best information about affected airplanes currently in operation. There is no need to add “currently” to the costs of compliance. However, in reviewing this comment, we determined that there are about 596 airplanes in the worldwide fleet rather than 582 such airplanes, and about 203 airplanes of U.S. registry rather than 130 such airplanes. Further, we have determined that, as Alert Service Bulletin 777-27A0059 applies to future Model 777 airplanes, the applicability of the AD should be changed. Therefore, in this supplemental NPRM, we have revised the Costs of Compliance to reflect the increased number of airplanes and revised paragraph (c) to read “all Boeing Model 777 airplanes.”

Suggestion To Change Governance of Maintenance Program

ATA, on behalf of its member American Airlines (AAL), suggests a change of governance for the maintenance program. AAL has no objections to the maintenance actions described in the original NPRM, but believes the maintenance program should be governed and dictated through the maintenance review board report (MRBR) prepared by the FAA airplane evaluation groups (AEG), with proper oversight by the FAA Flight Standards Office, not via ADs. AAL asserts that implementation and oversight of ADs is costly to airlines, especially ADs which have no terminating action.

We do not agree. We have determined that the maintenance actions and intervals described in the original NPRM for the horizontal stabilizer ballscrew can directly affect the safety of the airplane and should be mandated because of the identified unsafe condition. To prevent escalation of the intervals of maintenance tasks that are directly linked both to airplane safety and to an accident, we found it necessary to mandate these actions by issuance of the proposed AD. We have not changed the supplemental NPRM in this regard.

Request To Change Intervals of Repetitive Actions

Two commenters, BA and Air France, do not agree with the repeat intervals specified in the original NPRM for the lubrication; and BA also does not agree with the repeat intervals specified in the original NPRM for the detailed inspection and freeplay measurement. BA states that the 777 Industry Steering Committee/Maintenance Review Board (ISC/MRB) meeting, held in February 2004, produced the “Re-analysis of the Horizontal Stabilizer Control System MSG-3.” BA asserts that this re-analysis took into account Boeing's safety analysis, and the suggested alternative repeat intervals were agreed to by numerous attendees at the meeting, including Boeing, Boeing's designated engineering representative (DER), the FAA Seattle Aircraft Evaluation Group (AEG), and Model 777 operators. In addition, BA asserts that the use of an improved synthetic oil-based grease (conforming to Boeing material specification BMS3-33) and 10 years of operating experience support the alternative repeat intervals. BA further asserts that Boeing's safety analysis of the Model 777 stabilizer drive mechanism revealed no problems with the configuration of that mechanism. BA therefore requests that the repeat intervals of the original NPRM be revised as follows:

• Detailed inspection—6,000 flight hours or 400 days, whichever comes first;
• Freeplay inspection—25,000 flight hours or five years, whichever comes first;
• Lubrication—2,000 flight hours or 400 days, whichever comes first.

Air France explains that its request is based on information from the MRB Report revision of March 3, 2006, and the maintenance planning document (MPD) revision of May 5, 2006. In addition, Air France states that a decision was made at the ISC meeting of January 2006 to revise the lubrication interval from 2,000 flight hours/400 days to 3,000 flight hours/400 days, based on in-service experience. Air France further states that it has never found any applicable corrosion or damage during 8 years of 777 operating experience. Air France states, therefore, that it does not agree with the lubrication interval specified in the original NPRM and requests that the interval be changed to 3,000 flight hours or 400 days, whichever comes first.

We do not agree with this request. Consistent with our response shown above to the comment regarding a change of governance for the maintenance program, we have identified an unsafe condition and are proposing an AD to control the tasks and intervals needed to address this condition. The commenters assert that alternative repeat intervals were agreed to by numerous attendees at the February 2004 ISC/MRB meeting, however, those intervals are inconsistent with the intervals developed by Boeing's safety organization and transmitted via letter to the Seattle Aircraft Certification Office (ACO) in support of development of this AD. The intervals for lubrication, detailed inspection, and freeplay inspection that appear in the FAA-approved Boeing service bulletin were determined from the results of a safety review by means of testing, failure mode analysis, and fault tree analysis and are based upon using BMS 3-33 grease or acceptable substitute. Boeing has not revised those intervals, and the intervals suggested by BA and Air France do not meet the requirements identified by the safety review. Further, Boeing has advised us that it intends to pursue revising the MPD task to reflect the compliance times specified in this AD at the next revision cycle of the document. Task intervals specified in maintenance programs may be increased based on positive results obtained from previous repetitions of the task. We are concerned with the practice of escalating safety related maintenance intervals until negative findings are discovered. We have not changed the supplemental NPRM as requested by the commenters. However, to obtain longer compliance times, anyone may request approval of an alternative method of compliance (AMOC) as specified in paragraph (n) of this supplemental NPRM, provided data are submitted to demonstrate that an acceptable level of safety will be maintained.

FAA's Determination and Proposed Requirements of the 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.

Costs of Compliance

There are about 596 airplanes of the affected design in the worldwide fleet. This proposed AD would affect about 203 airplanes of U.S. registry.

The proposed maintenance records check would take about 1 work hour per airplane, at an average labor rate of $80 per work hour. Based on these figures, the estimated cost of the proposed inspection for U.S. operators is $16,240, or $80 per airplane, per inspection cycle.

The proposed detailed inspection would take about 1 work hour per airplane, at an average labor rate of $80 per work hour. Based on these figures, the estimated cost of the proposed inspection for U.S. operators is $16,240, or $80 per airplane, per inspection cycle.

The proposed freeplay measurement would take about 5 work hours per airplane, at an average labor rate of $80 per work hour. Based on these figures, the estimated cost of the proposed freeplay measurement for U.S. operators is $81,200, or $400 per airplane, per measurement cycle.

The proposed lubrication would take about 1 work hour per airplane, at an average labor rate of $80 per work hour. Based on these figures, the estimated cost of the proposed lubrication for U.S. operators is $16,240, or $80 per airplane, per lubrication cycle.

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-2006-24270; Directorate Identifier 2005-NM-200-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by July 13, 2007.

Affected ADs

(b) None.

Applicability

(c) This AD applies to all Boeing Model 777 airplanes, certificated in any category.

Unsafe Condition

(d) This AD results from a report of extensive corrosion of a ballscrew in the drive mechanism of the horizontal stabilizer of a Boeing Model 757 airplane, which is similar in design to the ballscrew on Model 777 airplanes. We are issuing this AD to prevent an undetected failure of the primary load path for the ballscrew in the drive mechanism of the horizontal stabilizer and subsequent wear and failure of the secondary load path, which could lead to loss of control of the horizontal stabilizer and consequent 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.

Service Bulletin Reference

(f) The term “service bulletin,” as used in this AD, means Boeing Alert Service Bulletin 777-27A0059, Revision 1, dated August 18, 2005.

Note 1:

The service bulletin refers to the Boeing 777 Aircraft Maintenance Manual (AMM), subjects 12-21-05, 27-41-13, and 29-11-00, as additional sources of service information for accomplishing the actions required by this AD.

Maintenance Records Check

(g) For airplanes that have received a certificate of airworthiness prior to the effective date of this AD: Within 180 days or 3,500 flight hours after the effective date of this AD, whichever occurs first, perform a maintenance records check or inspect to determine whether any horizontal stabilizer trim actuator has been replaced for any issue described in the service bulletin with a serviceable actuator that was not new or overhauled, and has not received a detailed inspection and freeplay measurement since the replacement.

Detailed Inspection

(h) Within the compliance times specified in paragraph (h)(1) or (h)(2) of this AD, as applicable: Perform a detailed inspection for discrepancies of the horizontal stabilizer trim actuator ballnut and ballscrew in accordance with Part 1 of the Accomplishment Instructions of the service bulletin. Repeat the detailed inspection thereafter at intervals not to exceed 3,500 flight hours or 12 months, whichever occurs first. If any discrepancy is found during any inspection required by this AD, before further flight, replace the actuator with a new or serviceable actuator in accordance with the service bulletin.

(1) For airplanes identified in paragraph (g) of this AD on which the actuator has not been replaced: Before the accumulation of 15,000 total flight hours, or within 18 months after the effective date of this AD, whichever occurs later.

(2) For airplanes identified in paragraph (g) of this AD on which the actuator has been replaced, and for airplanes having received a certificate of airworthiness after the effective date of this AD: Before the accumulation of 3,500 flight hours or within 24 months after the effective date of this AD, whichever occurs later.

Freeplay Measurement (Inspection)

(i) Within the compliance times specified in paragraph (i)(1) or (i)(2) of this AD, as applicable: Perform a freeplay measurement of the ballnut and ballscrew in accordance with Part 2 of the Accomplishment Instructions of the service bulletin. Repeat the freeplay measurement thereafter at intervals not to exceed 18,000 flight hours or 60 months, whichever occurs first. If the freeplay is found to exceed the limits specified in the service bulletin during any measurement required by this AD, before further flight, replace the actuator with a new or serviceable actuator in accordance with the service bulletin.

(1) For airplanes identified in paragraph (g) of this AD on which the actuator has not been replaced: Before the accumulation of 15,000 total flight hours, or within 18 months after the effective date of this AD, whichever occurs later.

(2) For airplanes identified in paragraph (g) of this AD on which the actuator has been replaced, and for airplanes having received a certificate of airworthiness after the effective date of this AD: Before the accumulation of 3,500 flight hours or within 24 months after the effective date of this AD, whichever occurs later.

Lubrication

(j) Within the compliance times specified in paragraph (j)(1) or (j)(2) of this AD, as applicable: Lubricate the ballnut and ballscrew in accordance with Part 3 of the Accomplishment Instructions of the service bulletin. Repeat the lubrication thereafter at intervals not to exceed 2,000 flight hours or 12 months, whichever occurs first.

(1) For airplanes identified in paragraph (g) of this AD on which the actuator has not been replaced: Before the accumulation of 15,000 total flight hours, or within 18 months after the effective date of this AD, whichever occurs later.

(2) For airplanes identified in paragraph (g) of this AD on which the actuator has been replaced, and for airplanes having received a certificate of airworthiness after the effective date of this AD: Before the accumulation of 3,500 flight hours or within 24 months after the effective date of this AD, whichever occurs later.

Credit for Using Original Issue of Service Bulletin

(k) Actions performed prior to the effective date of this AD in accordance with Boeing Alert Service Bulletin 777-27A0059, dated September 18, 2003, are considered acceptable for compliance with the corresponding actions of this AD.

Credit for Hard-time Replacement of Actuator

(l) Any actuator overhauled within the compliance times specified for paragraphs (h), (i), and (j) of this AD or before the effective date of this AD—as part of a “hard-time” replacement program that includes removal of the stabilizer actuator from the airplane and overhaul of the stabilizer ballscrew in accordance with original equipment manufacturer (OEM) component maintenance manual (CMM) instructions—meets the intent of one detailed inspection, one freeplay inspection, and one lubrication of the stabilizer ballscrew. Therefore, any such actuator is considered acceptable for compliance with the initial accomplishment of paragraphs (h), (i), and (j) of this AD, and repetitions of those paragraphs may be determined from the performance date of that overhaul.

Parts Installation

(m) As of the effective date of this AD, no person may install, on any airplane, a horizontal stabilizer trim actuator that is not new or overhauled, unless a detailed inspection, freeplay measurement, and lubrication of that actuator have been performed in accordance with paragraphs (h), (i), and (j) of this AD.

Alternative Methods of Compliance (AMOCs)

(n)(1) The Manager, Seattle Aircraft Certification Office, 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.

Issued in Renton, Washington, on June 8, 2007.

Stephen P. Boyd,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.