AD 99-07-05 ACTIVE

This amendment adopts a new airworthiness directive (AD), applicable to all Lockheed Model L-1011-385 series airplanes, that requires repetitive external visual inspections and internal borescope inspections to detect discrepancies of the elevator assembly; and either repair or repair/modification of certain identified discrepancies. This amendment is prompted by a report of fretting at the diagonal truss to web joint of the elevator and cracking in the cap fillet radius adjacent to the joint, apparently due to loose fasteners as a result of local vibration. The actions specified by this AD are intended to detect and correct such fretting and cracking, which could result in reduced structural integrity of the elevator and consequent flutter instability if coupled with other structural failures.

Final Rule

99-07-05 LOCKHEED: Amendment 39-11090. Docket 96-NM-256-AD.

Applicability: All Model L-1011-385 series airplanes, certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (d) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To detect and correct fretting at the diagonal truss to web joint of the elevator, and cracking in the cap fillet radius adjacent to the joint, which could result in reduced structural integrity of the elevator and consequent flutter instability if coupled with other structural failures, accomplish the following:

Initial and Repetitive Inspections
(a) Within 12 months after the effective date of this AD, perform an external visual inspection and internal borescope inspection to detect discrepancies (i.e., loose/missing fasteners or rivets, sponginess, sheared rivets, fretting, damage, and cracking) of the elevator assembly, in accordance with Part I of the Accomplishment Instructions of Lockheed L-1011 Service Bulletin 093-55-031, dated April 26, 1996. Repeat the inspections thereafter at intervals not to exceed 18 months.

Repair or Repair/Modification
(b) If any discrepancy described in paragraph (a) of this AD is detected during any inspection required by this AD, prior to further flight, accomplish either the repair in accordance with the applicable sections of the Lockheed L-1011 Structural Repair Manual, or the repair/modification in accordance with Part II of the Accomplishment Instructions of Lockheed L- 1011 Service Bulletin 093-55-031, dated April 26, 1996. Repeat the inspections required by paragraph (a) of this AD thereafter at intervals not to exceed 18 months.

NOTE 2: This AD requires repetitive inspections after accomplishment of either the repair or the repair/modification.

Correct Part Number
(c) Part II A. (3) of the Accomplishment Instructions of Lockheed L-1011 Service Bulletin 093-55-031, dated April 26, 1996, incorrectly specifies the part number to be used as a replacement for 1/8-inch-diameter rivets as "HLT319-5." The correct part number and description are identified as "HLT318-5 protruding head Hi-lok." Where there are differences between the AD and the service bulletin, the AD prevails.

Alternative Methods of Compliance
(d) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Atlanta Aircraft Certification Office (ACO), FAA, Small Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Atlanta ACO.

NOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Atlanta ACO.

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

Incorporation by Reference
(f) Except as provided by paragraph (b) of this AD, the actions shall be done in accordance with Lockheed L-1011 Service Bulletin 093-55-031, dated April 26, 1996. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Lockheed Martin Aircraft & Logistics Center, 120 Orion Street, Greenville, South Carolina 29605. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Atlanta Aircraft Certification Office, One Crown Center, 1895 Phoenix Boulevard, suite 450, Atlanta, Georgia; or at the Office of the Federal Register, 800 North Capitol Street, NW, suite 700, Washington, DC.

(g) This amendment becomes effective on April 30, 1999.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to all Lockheed Model L-1011-385 series airplanes was published in the Federal Register on May 9, 1997 (62 FR 25565). That action proposed to require repetitive external visual inspections and internal borescope inspections to detect discrepancies of the elevator assembly; and repair/modification of any discrepancy.

Comments
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

Support for the Proposal
One commenter supports the proposed AD.

Request to Revise the Cost Estimate
One commenter states that inspection and modification of the elevator, in accordance with Part II of the Accomplishment Instructions of Lockheed L-1011 Service Bulletin 093-55-031, dated April 26, 1996, requires approximately 320 work hours instead of the 20 work hours specified in the service bulletin. The FAA infers that the commenter considers that the cost estimate included in the proposed AD is too low and should be revised.

The FAA does not concur. The economic analysis of the AD is limited only to the cost of actions actually required by the rule. It does not consider the costs of an "on condition" action, such as either the repair or repair/modification specified by paragraph (b) of this AD, which is required to be accomplished only if any discrepancy is detected during the required inspection. In light of this, the FAA considers that the cost estimate provided in the proposed AD is appropriate. No change has been made to this estimate in the final rule.

Request to Change the Inspection Requirements
One commenter requests that a one-time inspection be accomplished on all elevators, unless previously accomplished within the last 24 months in accordance with Lockheed L-1011 Service Bulletin 093-55-031, dated April 26, 1996. The commenter states that, because no damage has been found outboard of elevator station (ES) 187.5 by either the commenter or the manufacturer, inspection outside that area is unnecessary. The commenter adds that no damage has been found on airplanes having an elevator previously modified to incorporate larger (5/32-inch) fasteners in accordance with Lockheed L-1011 Service Bulletin 093-55-018, Revision 1, dated July 12, 1990. Based on these findings, the commenter maintains that those airplanes should not be subject to the inspection requirements of the proposed AD.

The FAA does not concur that a one-time inspection, instead of the repetitive inspections required by paragraphs (a) and (b) of this AD, would be adequate to detect and correct the unsafe condition. Although the FAA agrees that elevator damage has been limited to elevators on which the smaller fasteners are installed, and to the truss structure inboard of ES 187.5,Service Bulletin 093-55-031 describes only possible sources of such damage. While it appears that loose fasteners are the cause, the FAA has determined that it is possible that other factors could be involved. In light of that possibility and until the exact cause has been identified, the FAA has determined that mandating repetitive inspections is the only means to detect future damage to the elevator assembly, regardless of the fastener configuration of the truss structure. No change has been made to the repetitive inspections required by paragraph (a) of the final rule.

Requests to Change Repair/Modification Requirements
One commenter requests removal of the words "any discrepancy" from paragraph (b) of the proposed AD, because such wording would require accomplishment of the Part II inspection/modification [i.e., repair/modification] of the referenced service bulletin, even if the noted discrepancy is outside the scope of interest of this proposed AD. The commenter adds that the restriction should be limited to the repair of damages detected during inspections.

The FAA concurs and agrees that the term "any discrepancy" is too broad and needs clarification. The FAA has revised paragraph (b) of this final rule to specify that corrective action is required only for those discrepancies identified in paragraph (a) of this AD.

That same commenter requests that the repair of all damage found during inspections be accomplished prior to further flight, in accordance with the Lockheed L-1011 Structural Repair Manual (SRM), or instructions approved by a designated engineering representative (DER).

The FAA partially concurs. The FAA concurs with the commenter s request to allow repairs in accordance with the Lockheed L-1011 SRM. The FAA has reviewed the SRM procedure and finds that it may be used as an acceptable means of compliance for the repair required by paragraph (b) of this AD. However, the FAA has determined that the repair/modification (if accomplished) must be accomplished in accordance with Lockheed L-1011 Service Bulletin 093-55-031. Paragraph (b) of the final rule has been changed accordingly.

The FAA does not concur with the commenter s request to allow repair in accordance with DER-approved instructions. The FAA does not consider it appropriate for a DER to approve the repairs required by this AD. While DER s are authorized to approve certain repairs for cracking found during routine maintenance inspections or other types of inspections, the FAA considers that any cracking detected in the principal structural elements (PSE) during an inspection required by this AD indicates an airworthiness concern of a complex nature. Therefore, such cracking does not warrant "routine" handling, but requires expeditious action or a special approach to address the unsafe condition. In light of this, the FAA has determined that DER approval of repairs for AD-mandated discrepancy findings is not appropriate in this AD; therefore, DER approval is not included as an alternative source of information for accomplishing the repairs required by paragraph (b) of the final rule.

The same commenter states that modification of the elevator, in accordance with Part II of the Accomplishment Instructions of the referenced service bulletin, should not be required because the modification requires 320 work hours per "set" (two elevators) to accomplish, and that repairs with repetitive inspections would provide an equivalent level of safety.

The FAA partially concurs. The FAA agrees that the operator may have the option of accomplishing either the repair or the repair/modification, with continued inspections thereafter, and that accomplishment of either of these actions will provide an adequate level of safety. The final rule has been changed accordingly.

The FAA points out that Service Bulletin 093-55-031 specifies that accomplishment of the Part II repair/modification procedure closes out the inspection requirements. However, paragraph (a) of the final rule requires repetitive inspections after accomplishment of either the repair or the repair/modification. NOTE 2 has been added to the final rule to clarify that the inspections are to be continued after accomplishment of either of these actions.
Request to Correct the Part Number Specified in the Service Bulletin

One commenter notes that Part II A.(3) of the Accomplishment Instructions of Lockheed L-1011 Service Bulletin 093-55-031, dated April 26, 1996, incorrectly specifies part number (P/N) HLT319-5 flush head Hi-loks as alternative parts to MS20470AD5 rivets. The commenter states that the correct specification should be "P/N HLT318-5 protruding head Hi-loks," which has been confirmed by the manufacturer.

The FAA concurs that clarification of the specified part number is necessary, based on information received from the manufacturer. The correct part number has been added to paragraph (c) in the final rule.

Request to Add a Reporting Requirement
One commenter recommends mandatory reporting of damages found during the initial inspection because the manufacturer has not yet determined the cause and extent of failures of the inboard ribs.

The FAA does not concur. Although the FAA agrees that mandatory reporting could help identify the extent of the cracking found in the elevator truss structure, it is unlikely that such reports could identify the root cause. For this reason, the FAA has not added a reporting requirement to the final rule. However, if the commenter or other operators wish to obtain the results of such inspections and provide findings to the FAA, the FAA would consider further analysis of such data.

Conclusion
After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

Cost Impact
There are approximately 235 Lockheed Model L-1011-385 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 117 airplanes of U.S. registry will be affected by this AD, that it will take approximately 20 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $140,400, or $1,200 per airplane.

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted.

Regulatory Impact
The regulations adopted herein will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES."

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39 - AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.

39.13 [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive:

The service information referenced in this AD may be obtained from Lockheed Martin Aircraft & Logistics Center, 120 Orion Street, Greenville, South Carolina 29605. This information may be examined at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Small Airplane Directorate, Atlanta Aircraft Certification Office, One Crown Center, 1895 Phoenix Boulevard, suite 450, Atlanta, Georgia; or at the Office of the Federal Register, 800 North Capitol Street, NW, suite 700, Washington, DC.

Thomas Peters, Aerospace Engineer, Systems and Flight Test Branch, ACE-116A, FAA, Small Airplane Directorate, Atlanta Aircraft Certification Office, One Crown Center, 1895 Phoenix Boulevard, suite 450, Atlanta, Georgia 30349; telephone (770) 703-6063; fax (770) 703-6097.