AD 96-20-10

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Lockheed Model L-1011-385 series airplanes. This action requires 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. This amendment is prompted by a report of fatigue cracking of the canted pressure bulkhead at FS 1212. The actions specified in this AD are intended to detect and correct such fatigue cracking, which could result in blowout of a panel between adjacent stiffeners and consequent cabin depressurization.

Final Rule; Request for Comments

96-20-10 LOCKHEED: Amendment 39-9776. Docket 96-NM-240-AD.

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) 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:

(a) Prior to the accumulation of 20,000 total landings, or within 60 days after the effective date of this AD, whichever occurs later: Perform a close 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. Thereafter, repeat these inspections at intervals not to exceed 1,000 landings.

(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 the service bulletin. Accomplishment of a repair constitutes terminating action for the repetitive inspections required by paragraph (a) of this AD at the repaired location. 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 the service bulletin. Such replacement constitutes terminating action for the repetitive inspections required by paragraph (a) of this AD.

(c) An alternative method of compliance or adjustment ofthe 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.

(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.

(e) The actions shall be done in accordance with Lockheed Service Bulletin 093-53-277, dated July 2, 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 Aeronautical Systems Support Company (LASSC), Field Support Department, Dept. 693, Zone 0755, 2251 Lake Park Drive, Smyrna, Georgia. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Atlanta Aircraft Certification Office, Small Airplane Directorate, Campus Building, 1701 Columbia Avenue, suite 2-160, College Park, Georgia; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(f) This amendment becomes effective on October 25, 1996.

The FAA received a report indicating that fatigue cracking was found of the canted pressure bulkhead at fuselage station (FS) 1212 on a Lockheed Model L-1011-385 series airplane that had accumulated 31,749 total landings. Three vertical cracks, each approximately 11 inches long, were found in the areas of left buttock line (LBL) 30.0, LBL 10.0, and right buttock line (RBL) 22.5 along the fastener rows of the vertical stiffener-to-web. Subsequently, another operator found similar fatigue cracking on two other airplanes. Such fatigue cracking, if not detected and corrected in a timely manner, could result in blowout of a panel between adjacent stiffeners and consequent cabin depressurization.

Explanation of Relevant Service Information
The FAA has reviewed and approved Lockheed L-1011 Service Bulletin 093-53-277, dated July 2, 1996, which describes procedures for repetitive close visual inspections to detect cracking of the entire aft surface of the canted pressure bulkhead at FS 1212 between LBL 103 and RBL 103, and repetitive optical 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.

Explanation of the Requirements of the Rule
Since an unsafe condition has been identified that is likely to exist or develop on other Lockheed Model L-1011-385 series airplanes of the same type design, this AD is being issued 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. This AD requires repetitive close visual inspections to detect cracking of the entire aft surface of the canted pressure bulkhead at FS 1212 between LBL 103 and RBL 103, and repetitive optical inspections to detect cracking of the web at the fastener rows of the vertical stiffener-to-web; and repair or replacement of the webwith a new web, if necessary. The inspections, certain repairs, and replacement are required to be accomplished in accordance with the service bulletin described previously. Other repairs are required to be accomplished in accordance with a method approved by the FAA.

This is considered to be interim action until final action is identified, at which time the FAA may consider further rulemaking.

Determination of Rule's Effective Date
Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

Comments Invited
Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this 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 under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the 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 that summarizes each FAA-public contact concerned with the substance of this AD willbe filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 96-NM-240-AD." The postcard will be date stamped and returned to the commenter.

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.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, 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: