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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-233-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 supersedure of an existing

airworthiness directive (AD), applicable to certain Lockheed Model L-

1011-385 series airplanes, that currently requires repetitive

inspections to detect cracking of the canted pressure bulkhead at

fuselage station (FS) 1212, and repetitive inspections to detect

cracking of the web at the fastener rows of the vertical stiffener-to-

web; and repair or replacement of the web with a new web, if necessary.

This action would require that the initial inspections be accomplished

at a reduced threshold. This proposal is prompted by a report of

fatigue cracking of the canted pressure bulkhead at FS 1212. The

actions specified by the proposed AD are intended to detect and correct

fatigue cracking of the canted pressure bulkhead at FS 1212, which

could result in blowout of a panel between adjacent stiffeners and

consequent cabin depressurization.

DATES: Comments must be received by November 22, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-114,

Attention: Rules Docket No. 99-NM-233-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, Program Manager,

[[Page 54231]]

Program Management and Services Branch, ACE-118A, 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 99-NM-233-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. 99-NM-233-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

On September 26, 1996, the FAA issued AD 96-20-10, amendment 39-

9776 (61 FR 53044, October 10, 1996), applicable to certain Lockheed

Model L-1011-385 series airplanes, to require inspections to detect

cracking of the canted pressure bulkhead at fuselage station (FS) 1212,

and inspections to detect cracking of the web at the fastener rows of

the vertical stiffener-to-web; and repair or replacement of the web

with a new web, if necessary. That action was prompted by a report of

fatigue cracking of the canted pressure bulkhead at FS 1212. The

requirements of that AD are intended to detect and correct fatigue

cracking of the canted pressure bulkhead at FS 1212, which could result

in blowout of a panel between adjacent stiffeners and consequent cabin

depressurization.

Actions Since Issuance of Previous Rule

Since the issuance of that AD, the FAA has received an additional

report of fatigue cracking in the subject area on one of these

airplanes. The airplane on which the cracking occurred had accumulated

fewer flight cycles at the time the cracking was detected than the

number of flight cycles specified as the inspection threshold in AD 96-

20-10.

Explanation of Relevant Service Information

The FAA has reviewed and approved Lockheed L-1011 Service Bulletin

093-53-277, Revision 1, dated November 19, 1998, which describes

procedures for repetitive detailed visual inspections to detect

cracking of the entire aft surface of the canted pressure bulkhead at

FS 1212 between left buttock line (LBL) 103 and right buttock line

(RBL) 103, and repetitive optical inspections (i.e., using a borescope

or mirror) to detect cracking of the web at the fastener rows of the

vertical stiffener-to-web; and repair or replacement of the web with a

new web, if necessary. 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 supersede AD 96-20-10 to continue to require

repetitive inspections to detect cracking of the canted pressure

bulkhead at FS 1212, and repetitive inspections to detect cracking of

the web at the fastener rows of the vertical stiffener-to-web; and

repair or replacement of the web with a new web, if necessary. The

proposed AD would require that the initial inspections be accomplished

at a reduced threshold. The actions would be required to be

accomplished in accordance with the service bulletin described

previously.

Explanation of Changes Made to Requirements of AD 96-20-10

The FAA has restated the compliance time in terms of flight cycles,

instead of landings. This is consistent with the compliance times

stated in the service bulletin. In addition, the inspection identified

in AD 96-20-10 as a ``close visual inspection'' is identified in this

proposed AD as a ``detailed visual inspection.'' Furthermore, the FAA

has added a note to the proposed AD to clarify the definition of a

detailed visual inspection.

Cost Impact

There are approximately 235 airplanes of the affected design in the

worldwide fleet. The FAA estimates that 116 airplanes of U.S. registry

would be affected by this proposed AD. The requirements of this

proposed AD would not add any new additional economic burden on

affected operators, other than the costs that are associated with

beginning the inspections at an earlier time than would have been

required by AD 96-20-10 (initial inspection is now required within

18,000 flight cycles, rather than 20,000 flight cycles).

The inspections that are currently required by AD 96-20-10, and

retained in this proposed AD, take approximately 5 work hours per

airplane to accomplish, at an average labor rate of $60 per work hour.

Based on these figures, the cost impact of the currently required

actions on U.S. operators is estimated to be $34,800, or $300 per

airplane, per inspection cycle.

The cost impact figure discussed above is based on assumptions that

no operator has yet accomplished any of the current or 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 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

proposal would not have sufficient federalism implications to warrant

the preparation of a Federalism Assessment.

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

[[Page 54232]]

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 removing amendment 39-9776 (61 FR

53044, October 10, 1996), and by adding a new airworthiness directive

(AD), to read as follows:

Lockheed: Docket 99-NM-233-AD. Supersedes AD 96-20-10, Amendment 39-

9776.

Applicability: Model L-1011-385 series airplanes; serial numbers

1013 through 1250 inclusive; 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 (c)(1)

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 fatigue cracking of the canted pressure

bulkhead at fuselage station (FS) 1212, which could result in

blowout of a panel between adjacent stiffeners and consequent cabin

depressurization, accomplish the following:

Repetitive Inspections

(a) Perform a detailed visual inspection to detect cracking of

the entire aft surface of the canted pressure bulkhead at FS 1212

between left buttock line (LBL) 103 and right buttock line (RBL)

103; and perform an optical inspection using a borescope or other

optical device to detect cracking of the web at the fastener rows of

the vertical stiffener-to-web; in accordance with Lockheed L-1011

Service Bulletin 093-53-277, dated July 2, 1996, or Revision 1,

dated November 19, 1998; at the earlier of the times specified in

paragraphs (a)(1) and (a)(2) of this AD. Thereafter, repeat these

inspections at intervals not to exceed 1,000 flight cycles.

(1) Prior to the accumulation of 20,000 total flight cycles, or

within 60 days after October 25, 1996 (the effective date of AD 96-

20-10), whichever occurs later; or

(2) Prior to the accumulation of 18,000 total flight cycles, or

within 60 days after the effective date of this AD, whichever occurs

later.

Note 2: For the purposes of this AD, a detailed visual

inspection is defined as: ``An intensive visual examination of a

specific structural area, system, installation, or assembly to

detect damage, failure, or irregularity. Available lighting is

normally supplemented with a direct source of good lighting at

intensity deemed appropriate by the inspector. Inspection aids such

as mirror, magnifying lenses, etc., may be used. Surface cleaning

and elaborate access procedures may be required.''

Repair

(b) If any cracking is found during any inspection required by

paragraph (a) of this AD, prior to further flight, accomplish either

paragraph (b)(1) or (b)(2) of this AD.

(1) Accomplish either paragraph (b)(1)(i) or (b)(1)(ii) of this

AD, as applicable.

(i) If the cracking is found in an area that is specified in

Lockheed Repair Drawing LCC-7622-385, repair in accordance with

Lockheed L-1011 Service Bulletin 093-53-277, dated July 2, 1996, or

Revision 1, dated November 19, 1998. Accomplishment of a repair

constitutes terminating action for the repetitive inspections

required by paragraph (a) of this AD at the repaired location only.

Or

(ii) If the cracking is found in an area that is not specified

in Lockheed Repair Drawing LCC-7622-385, repair in accordance with a

method approved by the Manager, Atlanta Aircraft Certification

Office (ACO), FAA, Small Airplane Directorate.

(2) Replace the entire web with a new web in accordance with

Lockheed L-1011 Service Bulletin 093-53-277, dated July 2, 1996, or

Revision 1, dated November 19, 1998. Such replacement constitutes

terminating action for the repetitive inspections required by

paragraph (a) of this AD.

Alternative Methods of Compliance

(c)(1) 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.

(c)(2) Alternative methods of compliance, approved previously in

accordance with AD 96-20-10, amendment 39-9776, are approved as

alternative methods of compliance with paragraph (b) of this AD.

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

(d) 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 September 29, 1999.

D.L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 99-25934 Filed 10-5-99; 8:45 am]

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