E7-16424. Airworthiness Directives; Boeing Model 767 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 767 airplanes. The original NPRM would have required the following actions for the drive mechanism of the horizontal stabilizer: Repetitive detailed inspections for discrepancies and loose ball bearings; 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 similar airplane model. This action revises the original NPRM by including additional initial and repetitive inspections of the ballscrew-to-ballnut freeplay for certain airplanes, and adding a new compliance time for those inspections. We are proposing this supplemental NPRM 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.

DATES:

We must receive comments on this supplemental NPRM by September 17, 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: U.S. Department of Transportation, Docket Operations, M-30, West Building, Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.
• Fax: [phone].
• Hand Delivery: Room W12-140 on the ground floor of the West Building, 1200 New Jersey Avenue, SE., 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:

Kelly McGuckin, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Airplane 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-2005-22623; Directorate Identifier 2004-NM-80-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 Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Operations office (telephone [phone]) is located on the ground floor of the West Building at the 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 proposed to amend 14 CFR part 39 with a notice of proposed rulemaking (NPRM) for an AD (the “original NPRM”) for all Boeing Model 767 airplanes. The original NPRM was published in the Federal Register on October 7, 2005 (70 FR 58620). The original NPRM proposed to require the following actions for the drive mechanism of the horizontal stabilizer: Repetitive detailed inspections for discrepancies and loose ball bearings; 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, Boeing has revised certain service information to add initial and repetitive inspections of the ballscrew-to-ballnut freeplay for certain airplanes, and to add a new compliance time for those inspections.

Relevant Service Information

We have reviewed the following service bulletins:

• Boeing Service Bulletin 767-27A0194, Revision 2, dated July 13, 2006 (for Model 767-200, -300, and -300F series airplanes); and
• Boeing Service Bulletin 767-27A0195, Revision 2, dated July 13, 2006 (for Model 767-400ER series airplanes).

The procedures in Revision 2 of the service bulletins are essentially the same as those in Revision 1 of the service bulletins, both dated July 21, 2005 (which were referenced in the NPRM as the appropriate sources of service information for accomplishing the specified actions); except Revision 2 includes additional requirements for airplanes on which the A55001-22 lock equipment was used to accomplish the ballscrew-to-ballnut freeplay inspection specified in Revision 1 of the service bulletins. For airplanes on which the ballscrew-to-ballnut freeplay inspection was done incorrectly, as specified in section 1.D. “Description” of the service bulletins, Revision 2 also adds a new compliance time for that additional ballscrew-to-ballnut freeplay inspection of within 60 months after the last inspection, or 60 months after the delivery date of the airplane, or 18 months after the date on the service bulletin, whichever occurs latest. Revision 2 also recommends repeating those inspections thereafter at intervals not to exceed 72 months. Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition. We added a new paragraph (g) to this AD to include these requirements.

Comments

We have considered the following comments on the original NPRM.

Request To Change Relevant Service Information Section

Boeing asks that we change the second paragraph of the Relevant Service Information section in the original NPRM to read “For airplanes on which an FAA-approved low utilization maintenance program is in effect * * *” We agree with Boeing that the second paragraph could be changed for clarification; however, that paragraph is not included in this supplemental NPRM. We have made no change to the supplemental NPRM in this regard.

Request To Change Additional Sources of Service Information Table

Boeing asks that we change the table in Note 1 of the original NPRM titled “Additional Sources of Service Information” to reflect that the airplane maintenance manual is applicable to all Model 767 airplanes, not just Model 767-200 airplanes. Boeing states that the original NPRM is applicable to all Model 767 airplanes. We agree with Boeing for the reason provided, and we have changed Note 1 of this supplemental NPRM accordingly.

Request To Change Compliance Time for Previously Accomplished Actions

Boeing asks that the compliance time specified in paragraph (g) of the original NPRM (paragraph (h) of the supplemental NPRM) be reduced from 4,000 to 3,500 flight hours. Boeing states that this compliance time is specified in section 1.D. “Description” of Service Bulletin 767-27A0194, Revision 1. We agree with Boeing for the reason provided. The compliance time specified in Service Bulletin 767-27A0195, Revision 1, is also 3,500 flight hours. The compliance time specified in the original NPRM was incorrect; therefore, we have changed the compliance time in paragraph (h) of this supplemental NPRM accordingly.

Request To Withdraw Original NPRM

Air Transport Association (ATA) on behalf of its member Delta Airlines, states that operators are already accomplishing the intent of the original NPRM and there are no instances of the underlying airworthiness concerns occurring on Model 767 airplanes.

Delta Airlines disagrees with the requirements in the original NPRM that would mandate what it considers routine maintenance program tasks. Delta states that it already performs all of these tasks and does not agree that the tasks should be mandated. Delta adds that the tasks and compliance intervals specified in the referenced service bulletins are similar to the tasks and intervals already defined in the Maintenance Planning Document (MPD). Delta notes that bundling these tasks allows efficiency, but mandating arbitrary limits through an AD significantly reduces operator scheduling flexibility and is not merited in this case.

We infer that the commenters are asking that the original NPRM be withdrawn; we do not agree. We have determined that a degraded stabilizer trim actuator can be a safety concern because each airplane has only one stabilizer trim actuator, which is both a critical system component and a critical structural component of the airplane. As we stated in the original NPRM, the unsafe condition is 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. The proposed maintenance tasks and intervals must be mandated because of the criticality of the horizontal stabilizer system, the consequences of not performing the maintenance tasks, and the adverse service history attributed to problems with the horizontal stabilizer system on other airplanes. These tasks and intervals were not chosen arbitrarily, but instead were based on the minimum maintenance requirements needed to maintain the integrity of the stabilizer trim system. Although the lubrication and inspection procedures are normally handled by the procedures in the maintenance program, these maintenance actions can affect the safety of the airplane if they are not performed in a timely manner. We do not mandate the implementation of MPD revisions, and we cannot control escalation of MPD intervals related to maintenance. We consider it unacceptable that maintenance intervals can be escalated for economic reasons when these maintenance actions directly affect the safety of the airplane. Failure to perform these maintenance tasks at the proper intervals can lead to an unsafe condition. Therefore, we consider that mandating the actions in this supplemental NPRM appropriate and necessary.

Requests To Extend Compliance Times

Delta states that there are no data provided in the original NPRM to support the proposed compliance time limits. Delta notes that both of these limits fall short of its C-check visit, and would impose significant down time and costs to accomplish tasks with such arbitrary limits. Delta recommends that, if the FAA decides to mandate these tasks, the limits be written in a manner that allows flexibility in scheduling, such as “the later of either (a) or (b), where (a) is 2,000 flight hours or 12 months, whichever occurs first; or (b) every C-check.”

United Parcel Service (UPS) asks that we consider revising the NPRM to specify accomplishment of the referenced time-controlled tasks within paragraph (g) of the original NPRM as follows: “For airplanes on which Boeing Maintenance Program Changes are in place to perform repetitive Inspections/Lubrications/Freeplay checks of the horizontal stabilizer, within 15,000 flight hours after the last Ballscrew-to-Ballnut Freeplay Inspection, or 24 months after the effective date, accomplish applicable actions required by paragraph (f) of this AD.” UPS states that the continuation of the referenced time-controlled tasks would provide an equivalent level of safety and relieve scheduling burdens that might be encountered during the accomplishment of proposed requirements.

We do not agree with allowing operators to perform the actions at later compliance times. We cannot specify a letter check for mandatory inspection intervals because letter checks vary among different operators and can be escalated. The inspection intervals were determined from the results of a safety review by means of testing, failure mode analysis, and fault tree analysis. In developing an appropriate compliance time for this action, we also considered the urgency associated with the subject unsafe condition, the practical aspect of accomplishing the required actions within an interval of time that corresponds to the normal scheduled maintenance for most affected operators, and the recommendation of the manufacturer. However, according to the provisions of paragraph (k) of this AD, we may approve requests to adjust the compliance time if the request includes data that substantiate that the new compliance time would provide an acceptable level of safety. We have made no change to the supplemental NPRM in this regard.

Request To Change Paragraph (i) of the Proposed AD

UPS states that no overhaul instructions are provided in the referenced service bulletins that are specified in paragraph (i) of the original NPRM, and adds that sufficient inspection requirements are given in the Component Maintenance Manual (CMM). Therefore, UPS recommends that paragraph (i) of the original NPRM (Parts Installation) specify that “* * * no person may install on any airplane a horizontal stabilizer trim actuator unless it is new or has been overhauled in accordance with the CMM; or has been inspected, lubricated, and measured in accordance with paragraph (f) of this AD.” UPS states that the referenced service bulletins do not provide any direction over and above the requirements of the associated CMM.

We disagree that the referenced service bulletins do not contain the overhaul instructions for the horizontal stabilizer trim actuator. Although the service bulletins do not list the detailed steps required to overhaul the stabilizer trim actuator, the bulletins do reference the appropriate CMM for accomplishing this task. We have made no change to the supplemental NPRM in this regard.

Request for Addition of Indication

The Air Line Pilots Association (ALPA) recommends that there be a clear indication to the operator when the primary load path has been compromised to the point of loading the secondary load path, so that corrective action can be taken immediately. The ALPA did not provide a specific reason for, or data to support, its recommendation.

We acknowledge ALPA's request; however, we do not agree with the need for this specific indication. The maintenance tasks and intervals identified in the service bulletins, and proposed by this supplemental NPRM, are intended to ensure proper operation and detect any degradation of the stabilizer trim actuator ballscrew and ballnut, without the need to provide a separate indication. Detection of any degradation of the primary load path, as detailed in the service bulletins, requires corrective action before further flight. The proposed maintenance interval limits are intended to detect any degradation of the primary load path in advance of loading the secondary load path. We have made no change to the supplemental NPRM in this regard.

Request To Notify Boeing of the Status of Original NPRM

Royal Brunei Airlines asks that Boeing be notified of the status of the original NPRM if the FAA's intent is to mandate Service Bulletin 767-27A0194, Revision 2 (the original NPRM is identified in Revision 2 as related information); then operators can eliminate unnecessary duplication of tasks. Royal Brunei Airlines states that the inspection and lubrication of the horizontal trim actuator are already called out in the relevant Boeing maintenance schedule. Royal Brunei Airlines adds that the Boeing maintenance schedule is approved and mandated by its local regulatory authority.

We acknowledge the commenter's request. However, it is not necessary that Boeing be notified of the status of the original NPRM. Boeing is aware that this supplemental NPRM to the original NPRM will be issued to include the procedures specified in Revision 2 of the referenced service bulletins. Boeing is also aware of the duplication of tasks between the MPD and Service Bulletin 767-27A0194, Revision 2. Although we agree that the inspection and lubrication tasks are duplicated, the requirements in this AD take precedence over the maintenance actions in the MPD. Boeing may, in a future revision to the MPD, align the MPD with the requirements of the service bulletin. We have made no change to the supplemental NPRM in this regard.

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.

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.

Clarification of Alternative Method of Compliance (AMOC) Paragraph

We have revised this action to clarify the appropriate procedure for notifying the principal inspector before using any approved AMOC on any airplane to which the AMOC applies.

Costs of Compliance

There are about 941 airplanes of the affected design in the worldwide fleet. This supplemental NPRM would affect about 411 airplanes of U.S. registry. The following table provides the estimated costs for U.S. operators to comply with this proposed AD, per cycle.

Estimated Costs

Repetitive actions	Work hours	Average labor rate per hour	Cost per airplane	Number of U.S.-registered airplanes	Fleet cost
Detailed inspection	1	$80	$80	411	$32,880
Lubrication	1	80	80	411	32,880
Freeplay measurement	3	80	240	411	98,640

The additional ballscrew-to-ballnut freeplay 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 new inspection on U.S. operators is $32,880, or $80 per airplane, per inspection 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-2005-22623; Directorate Identifier 2004-NM-80-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by September 17, 2007.

Affected ADs

(b) None.

Applicability

(c) This AD applies to all Boeing Model 767-200, -300, -300F, and -400ER series airplanes, certificated in any category.

Unsafe Condition

(d) This AD was prompted by a report of extensive corrosion of a ballscrew in the horizontal stabilizer of a similar airplane model. 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.

Repetitive Detailed Inspections/Lubrications/Freeplay Measurement/Corrective Action

(f) Do all the applicable actions, including any applicable corrective action, specified in Work Packages 1, 2, and 3 of the Accomplishment Instructions of Boeing Service Bulletin 767-27A0194 (for Model 767-200, -300, and -300F series airplanes) or Boeing Service Bulletin 767-27A0195 (for Model 767-400ER series airplanes), both Revision 1, both dated July 21, 2005, or Revision 2, both dated July 13, 2006, as applicable. Do the actions at the applicable compliance time specified in Table 1 of paragraph 1.E. “Compliance” of the service bulletins; except, where the service bulletins specify a compliance time relative to the original issue date of the service bulletin, this AD requires compliance relative to the effective date of this AD. Where the service bulletins specify a compliance time relative to the delivery date of the airplane, this AD requires compliance relative to the date of issuance of the original standard airworthiness certificate or the date of issuance of the original export certificate of airworthiness. Do all applicable corrective actions before further flight. Repeat the actions at the applicable repeat interval specified in Table 1 of paragraph 1.E “Compliance” of the service bulletins. As of the effective date of this AD only Revision 2 of the service bulletin may be used.

Repetitive Ballscrew-to-Ballnut Freeplay Inspections

(g) For airplanes on which the A55001-22 lock equipment was used to do the ballscrew-to-ballnut freeplay inspection, and the maintenance records do not show that the tool was correctly adjusted in accordance with Appendix A, step 1.E.3, of Boeing Service Bulletin 767-27A0194 or 767-27A0195, both Revision 1, both dated July 21, 2005: Do the ballscrew-to-ballnut freeplay inspection specified in Work Package 3, including any applicable corrective action, at the time specified in Table 1 of paragraph 1.E. “Compliance” of Boeing Service Bulletin 767-27A0194 or 767-27A0195, both Revision 2, both dated July 13, 2006, as applicable. Do all applicable corrective actions before further flight. Repeat the inspection thereafter at the intervals specified in Table 1 of paragraph 1.E “Compliance” of the service bulletins.

Previously Accomplished Actions

(h) For airplanes on which the drive mechanism of the horizontal stabilizer was replaced before the effective date of this AD with a drive mechanism that was not new or overhauled, and the detailed and freeplay inspections were not accomplished in accordance with Boeing Alert Service Bulletin 767-27A0194 or 767-27A0195, both dated August 21, 2003: Within 3,500 flight hours or 24 months after the effective date of this AD, whichever is first, accomplish the inspections and perform all applicable corrective actions before further flight in accordance with Work Package 3 of the Accomplishment Instructions of Boeing Service Bulletin 767-27A0194 or Boeing Service Bulletin 767-27A0195, both Revision 1, both dated July 21, 2005; or Revision 2, both dated July 13, 2006; as applicable. As of the effective date of this AD only Revision 2 of the service bulletin may be used.

(i) For Model 767 airplanes that have line numbers 002 through 175 inclusive: Accomplishing the initial inspection, applicable corrective action, and lubrication before the effective date of this AD in accordance with Boeing Alert Service Bulletin 767-27A0185, dated July 10, 2003; is considered acceptable for compliance with the applicable actions required by paragraph (f) of this AD.

Note 1:

Boeing Service Bulletins 767-27A0194 and 767-27A0195, both Revision 2, both dated July 13, 2006, refer to the applicable Boeing 767 Airplane Maintenance Manuals as additional sources of service information for accomplishing the detailed inspections, lubrications, freeplay measurements, and corrective action.

Parts Installation

(j) As of the effective date of this AD, no person may install on any airplane a horizontal stabilizer trim actuator unless it is new or has been overhauled as specified in Boeing Service Bulletins 767-27A0194 and 767-27A0195, both Revision 2, both dated July 13, 2006; or has been inspected, lubricated, and measured in accordance with paragraph (f) of this AD.

Alternative Methods of Compliance (AMOCs)

(k)(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) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO.

Issued in Renton, Washington, on July 31, 2007.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.