[Federal Register Volume 65, Number 32 (Wednesday, February 16, 2000)]
[Proposed Rules]
[Pages 7801-7803]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-3689]



[[Page 7801]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-311-AD]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to all Lockheed Model L-1011-385 
series airplanes. This proposal would require repetitive inspections to 
detect cracking of the fuselage skin in the areas of the left- and 
right-hand stringerless sidewall window belts, and repair, if 
necessary. This proposal is prompted by reports of fatigue cracks found 
in the fuselage skin where the skin thickness steps from 0.40 to 0.23 
inch. The actions specified by the proposed AD are intended to detect 
and correct cracking of the fuselage skin, which could result in 
reduced structural integrity of the airplane.

DATES: Comments must be received by April 3, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-311-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays.
    The service information referenced in the proposed rule may be 
obtained from Lockheed Martin Aircraft & Logistics Center, 120 Orion 
Street, Greenville, South Carolina 29605. This information may be 
examined at the FAA, Transport Airplane Directorate, 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.

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:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications shall identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 98-NM-311-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules 
Docket No. 98-NM-311-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received a report indicating that an 8-inch crack in 
the fuselage skin was found on a Model L-1011 series airplane in the 
stringerless sidewall window belt at fuselage station (FS) 1283 on the 
left-hand side. The fatigue crack occurred along a machined radius in 
the area where the sidewall skin thickness decreases from 0.40 inch to 
0.23 inch. This condition, if not corrected, could result in cracking 
of the fuselage skin, which could result in reduced structural 
integrity of the airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Lockheed Service Bulletin 093-53-
279, dated May 6, 1998, which describes procedures for repetitive 
ultrasonic and low frequency eddy current inspections to detect 
cracking of the fuselage skin in the areas of the left-hand and right-
hand stringerless sidewall window belts. Repair for cracking consists 
of installing external skin doublers (on the fuselage outer skin) and 
internal straps and angle fittings. The service bulletin describes 6 
inspection zones, which are located at FS 1243, 1263, and 1283, and 
between waterlines 224.5 and 253, on the left-hand and right-hand sides 
of the fuselage. The specific areas of inspection are the radii on both 
the forward and aft sides of the machined cutout where the fuselage 
skin steps from 0.40 to 0.23 inch. Accomplishment of the actions 
specified in the service bulletin is intended to adequately address the 
identified unsafe condition.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would require accomplishment of the actions specified in 
the service bulletin described previously.
    This AD specifies that flight with a crack is allowed, provided 
that cracking is within prescribed limits. The FAA has determined that 
this allowance provides an acceptable level of safety because (1) the 
crack growth is easily detectable, and (2) the established repetitive 
inspection procedures would detect cracked structure at an interval 
that would permit repairs to be accomplished before the structure's 
strength falls below ultimate load carrying capability.

Differences Between the Proposed AD and the Service Bulletin

    Operators should note that, although the service bulletin 
recommends that operators contact Lockheed Martin Engineering for 
assistance in the event that crack repair is required in two adjacent 
frames, this proposal would require the repair of those conditions to 
be accomplished in accordance with a method approved by the FAA. The 
generic repairs specified by the service bulletin may not be adequate 
if they are installed in two adjacent locations. Therefore, the FAA has 
determined that a unique repair would be necessary under these 
circumstances.
    Further, unlike the procedures described in the service bulletin, 
this proposed AD would provide for terminating action for the 
repetitive inspections for repaired inspection zones.

[[Page 7802]]

Cost Impact

    There are approximately 235 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 117 airplanes of U.S. registry 
would be affected by this proposed AD, that it would take approximately 
48 work hours per airplane to accomplish the proposed inspection, and 
that the average labor rate is $60 per work hour. Based on these 
figures, the cost impact of the proposed AD on U.S. operators is 
estimated to be $336,960, or $2,880 per airplane.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the proposed 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 proposed herein 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. Therefore, it 
is determined that this proposal would not have federalism implications 
under Executive Order 13132.
    For the reasons discussed above, I certify that this 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) if promulgated, 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 copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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:

    Lockheed: Docket 98-NM-311-AD.

    Applicability: Model L-1011-385 series airplanes, as listed in 
Lockheed Service Bulletin 093-53-279, dated May 6, 1998; 
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 (f) 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 cracking of the fuselage skin, which could 
result in reduced structural integrity of the airplane, accomplish 
the following:
    (a) Perform an ultrasonic inspection on the fuselage skin in the 
area of the stringerless sidewall window belts, at the radii on both 
the forward and aft sides of the machined cutout where the fuselage 
skin steps from 0.40 to 0.23 inch, to detect cracking in the base of 
the radii. Accomplish the inspection in accordance with Lockheed 
Service Bulletin 093-53-279, dated May 6, 1998, at each of the 6 
specific inspection zones identified in the service bulletin at the 
later of the times specified in paragraphs (a)(1) and (a)(2) of this 
AD.
    (1) Prior to the accumulation of 20,000 total flight cycles; or
    (2) Within 600 flight cycles or 6 months after the effective 
date of this AD, whichever occurs first.
    (b) For readings of less than 20 percent obtained at all 6 
inspection zones during the ultrasonic inspection required by 
paragraph (a) of this AD: Repeat the ultrasonic inspection 
thereafter at intervals not to exceed 1,500 flight cycles.
    (c) Except as provided by paragraph (e) of this AD: For any 
reading of 20 percent or greater and less than or equal to 50 
percent obtained at any inspection zone during the ultrasonic 
inspection required by paragraph (a) of this AD, prior to further 
flight, perform a low frequency eddy current (LFEC) inspection to 
measure the depth of the cracking, in accordance with Lockheed 
Service Bulletin 093-53-279, dated May 6, 1998.
    (1) If the results of the LFEC inspection are outside the reject 
zone, as defined in the service bulletin: Within 1,500 flight 
cycles, repeat both the ultrasonic and LFEC inspections specified by 
paragraphs (a) and (c), respectively, of this AD.
    (i) If the results of the LFEC inspection specified by paragraph 
(c)(1) of this AD are outside the reject zone: Within 1,800 flight 
cycles after the initial crack finding, as detected during the 
ultrasonic inspection specified in paragraph (a) of this AD, repair 
any affected inspection zone in accordance with Part II of the 
Accomplishment Instructions of the service bulletin. Such repair 
constitutes terminating action for the repetitive inspection 
requirements of this AD for the repaired inspection zone only.
    (ii) If the results of the LFEC inspection specified by 
paragraph (c)(1) of this AD are within the reject zone: Prior to 
further flight, repair any affected inspection zone in accordance 
with Part II of the Accomplishment Instructions of the service 
bulletin. Such repair constitutes terminating action for the 
repetitive inspection requirements of this AD for the repaired 
inspection zone only.
    (2) If the results of the LFEC inspection are within the reject 
zone, as defined in the service bulletin: Prior to further flight, 
repair any affected inspection zone in accordance with Part II of 
the Accomplishment Instructions of the service bulletin. Such repair 
constitutes terminating action for the repetitive inspection 
requirements of this AD for the repaired inspection zone only.
    (d) Except as provided by paragraph (e) of this AD: For any 
reading of 50 percent or greater obtained at any inspection zone 
during the ultrasonic inspection required by paragraph (a) of this 
AD, prior to further flight, perform a LFEC inspection to measure 
the depth of the cracking, in accordance with Lockheed Service 
Bulletin 093-53-279, dated May 6, 1998.
    (1) If the results of the LFEC inspection are outside the reject 
zone, as defined in the service bulletin: Within 300 flight cycles, 
repeat both the ultrasonic and LFEC inspections specified in 
paragraphs (a) and (c), respectively, of this AD.
    (i) If the results of the LFEC inspection specified by paragraph 
(d)(1) of this AD are outside the reject zone: Within 600 flight 
cycles after the initial crack finding, as detected during the 
ultrasonic inspection specified in paragraph (a) of this AD, repair 
any affected inspection zone in accordance with Part II of the 
Accomplishment Instructions of the service bulletin. Such repair 
constitutes terminating action for the repetitive inspection 
requirements of this AD for the repaired inspection zone only.
    (ii) If the results of the LFEC inspection specified by 
paragraph (d)(1) of this AD are within the reject zone: Prior to 
further flight, repair any affected inspection zone in accordance 
with Part II of the Accomplishment Instructions of the service 
bulletin. Such repair constitutes terminating action for the 
repetitive inspection requirements of this AD for the repaired 
inspection zone only.
    (2) If the results from the LFEC inspection are within the 
reject zone, as defined in the service bulletin: Prior to further 
flight, repair any affected inspection zone in accordance with Part 
II of the Accomplishment Instructions of the service bulletin. Such 
repair constitutes terminating action for the repetitive inspection 
requirements of this AD for the repaired inspection zone only.

[[Page 7803]]

    (e) For any inspection results that require repair in two 
adjacent zones: Prior to further flight, repair in accordance with a 
method approved by the Manager, Atlanta Aircraft Certification 
Office (ACO), FAA, Small Airplane Directorate.

Alternative Methods of Compliance

    (f) 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 ACO. 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 2: 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

    (g) 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.

    Issued in Renton, Washington, on February 10, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.

[FR Doc. 00-3689 Filed 2-15-00; 8:45 am]
BILLING CODE 4910-13-P