AD Amdt-39-11090

[Federal Register Volume 64, Number 58 (Friday, March 26, 1999)]
[Rules and Regulations]
[Pages 14580-14583]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 99-7116]


-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-256-AD; Amendment 39-11090; AD 99-07-05]
RIN 2120-AA64


Airworthiness Directives; Lockheed Model L-1011-385 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: 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.

DATES: Effective April 30, 1999.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of April 30, 1999.

ADDRESSES: 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.

FOR FURTHER INFORMATION CONTACT: 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.

SUPPLEMENTARY INFORMATION: 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

[[Page 14581]]

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,

[[Page 14582]]

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.


Sec. 39.13  [Amended]

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

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.

[[Page 14583]]

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.

    Issued in Renton, Washington, on March 17, 1999.
John J. Hickey,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-7116 Filed 3-25-99; 8:45 am]
BILLING CODE 4910-13-U