Airworthiness directives: Lockheed,
[Federal Register: September 11, 1998 (Volume 63, Number 176)]
[Proposed Rules]
[Page 48655-48658]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr11se98-31]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-NM-315-AD]
RIN 2120-AA64
Airworthiness Directives; Lockheed Model L-1011-385 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
SUMMARY: This document proposes the supersedure of an existing airworthiness directive (AD), applicable to all Lockheed Model L-1011- 385 series airplanes, that currently requires a one-time inspection to detect cracking of the bulkhead at fuselage station (FS) 1363 at butt line 42.5, and repair or additional inspections, if necessary. This action would add repetitive inspections to detect cracking of the bulkhead web and bulkhead cap (frame cap) at FS 1363, and repair, if necessary. This proposal is prompted by reports that additional, more extensive, fatigue cracking was found in the bulkhead web and cap. The actions specified by the proposed AD are intended to detect and correct cracking of the bulkhead web and cap, which could result in reduced structural integrity of the fuselage.
DATES: Comments must be received by October 26, 1998.
ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 97-NM-315-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 Aeronautical Systems Support Company (LASSC), Field Support Department, Dept. 693, Zone 0755, 2251 Lake Park Drive, Smyrna, Georgia 30080. 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
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proposal will be filedin 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 97-NM-315-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. 97-NM-315-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.
Discussion
On June 9, 1995, the FAA issued AD 95-12-24, amendment 39-9277 (60 FR 31624, June 16, 1995), applicable to all Lockheed Model L-1011-385 series airplanes, to require a one-time visual inspection to detect cracking of the bulkhead at fuselage station (FS) 1363 in the area of the stiffeners at left and right butt line 42.5, and repair or additional inspections, if necessary. That action was prompted by reports indicating that fatigue cracking was found in the rear bulkhead at FS 1363. The requirements of that AD are intended to detect and correct fatigue cracking of the pressure bulkhead, which could result in reduced structural integrity of the fuselage.
Actions Since Issuance of Previous Rule
Since the issuance of that AD, additional, more extensive, cracking has been found in the bulkhead web and cap in the area of FS 1363. Such cracking in the web has been attributed to high tension and shear stresses in the web and high tension loads in discontinuous stiffeners. Cracks initiated independently and concurrently at various locations in the web and cap. Cracks in the bulkhead cap initiated secondary fatigue cracks in the adjacent bulkhead web. Growth of such cracks could result in damage to the structure and consequent reduced structural integrity of the fuselage.
Further, in the preamble to AD 95-12-24, the FAA indicated that the actions required by that AD were considered ``interim action'' and that further rulemaking action was being considered. The FAA now has determined that further rulemaking action is indeed necessary, and this proposed AD follows from that determination.
Explanation of Relevant Service Information
The FAA has reviewed and approved Lockheed L-1011 Service Bulletin 093-53-268, Revision 1, dated July 2, 1996. That service bulletin describes procedures for repetitive visual and eddy current surface scan inspections to detect cracking of the bulkhead web at FS 1363, and repair, if necessary. The procedures include inspections for cracking of webs, web stiffeners, and fastener holes. Procedures for repair include installing web doublers and a splice. That service bulletin also specifies that repair of cracking may be deferred if the cracking meets certain conditions.
The service bulletin also describes an optional modification that involves removing fasteners; performing an eddy current bolt hole inspection; repair, if necessary; cold working of the fastener holes; and installation of new fasteners. The service bulletin specifies that this modification, if accomplished, would introduce a new threshold of 18,000 flight cycles for the repetitive inspections of the bulkhead web.
The FAA also has reviewed and approved Lockheed L-1011 Service Bulletin 093-53-272, dated November 12, 1996. That service bulletin describes procedures for repetitive visual, eddy current surface scan, eddy current bolt hole, and X-ray inspections to detect cracking of the bulkhead cap at FS 1363; and repair, if necessary. That service bulletin also describes an optional modification, which involves replacing the bulkhead cap, and cold working fastener holes. The service bulletin specifies that this modification, if accomplished, would introduce a new threshold of 18,000 flight cycles for the repetitive inspections of the bulkhead cap.
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 95-12-24 to continue to require a one- time visual inspection to detect cracking of the bulkhead at FS 1363 at butt line 42.5, and repair or additional inspections, if necessary. The proposed AD also would add repetitive visual and eddy current surface scan inspections to detect cracking of the bulkhead web at FS 1363; repetitive visual, eddy current bolt hole, eddy current surface scan, and X-ray inspections to detect cracking of the bulkhead cap at FS 1363; and repair, if necessary. The inspections would be required to be accomplished in accordance with the service bulletins described previously. This proposed AD also provides for modification of the bulkhead web or bulkhead cap, which, if accomplished, introduces a new threshold of 18,000 flight cycles for the repetitive inspections of the modified area.
This proposed AD specifies that flight with a crack in the bulkhead web is allowed, provided that (1) the crack does not extend beyond a certain area, (2) the crack does not exceed a certain maximum length, (3) the horizontal stiffeners above and below the web crack have no detectable cracks, and (4) inspections of the bulkhead are repeated on a more frequent basis until repair is accomplished.
Other Relevant Rulemaking
The FAA has previously issued AD 95-20-04 R1, amendment 39-9454 (60 FR 63414, December 12, 1995), applicable to all Lockheed Model L-1011- 385-1 series airplanes. That AD requires implementation of a Supplemental Inspection Document program of structural inspections to detect fatigue cracking; and repair, if necessary. Because inspections specified by this proposed AD may overlap with certain inspections presently mandated by AD 95-20-04 R1, the FAA is considering further rulemaking action that would remove those inspections from the requirements of AD 95-20-04 R1.
Cost Impact
There are approximately 236 airplanes of the affected design in the worldwide fleet. The FAA estimates that 118 airplanes of U.S. registry would be affected by this proposed AD.
The inspection that is currently required by AD 95-12-24 takes approximately 16 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 inspection on U.S. operators is estimated to be $113,280, or $960 per airplane.
The new inspections of the bulkhead web that are proposed in this AD action would take approximately 16 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 inspections of the bulkhead web proposed by this AD on U.S. operators is estimated to be $113,280, or $960 per airplane, per inspection cycle.
The new inspections of the bulkhead cap that are proposed in this AD action would take approximately 40 work hours per airplane to accomplish, at an
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average labor rate of $60 per work hour. Based on these figures, the cost impact of the inspections of the bulkhead cap proposed by this AD on U.S. operators is estimated to be $283,200, or $2,400 per airplane, per inspection cycle.
Should an operator be required to accomplish the repair of cracking in the bulkhead web, it would take between 8 to 32 work hours per airplane (8 work hours for each cracked area) to accomplish the repair, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of any necessary repair of the bulkhead web is estimated to be between $480 to $1,920 per airplane.
Should an operator be required to accomplish the repair of cracking in the bulkhead cap, it would take approximately 200 work hours per airplane to accomplish the repair, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of any necessary repair of the bulkhead cap is estimated to be $12,000 per airplane.
The cost impact figures discussed above are 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.
Should an operator elect to accomplish the optional modification of the bulkhead web that would be provided by this AD action, it would take approximately 48 work hours to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the optional modification of the bulkhead web would be $2,880 per airplane.
Should an operator elect to accomplish the optional modification of the bulkhead cap that would be provided by this AD action, it would take approximately 200 work hours to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the optional modification of the bulkhead cap would be $12,000 per airplane.
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 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
-
The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
-
Section 39.13 is amended by removing amendment 39-9277 (60 FR 31624, June 16, 1995), and by adding a new airworthiness directive (AD), to read as follows:
Lockheed: Docket 97-NM-315-AD. Supersedes AD 95-12-24, amendment 39- 9277.
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 (i) 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 bulkhead web and cap, which could result in reduced structural integrity of the fuselage, accomplish the following:
Restatement of the Requirements of AD 95-12-24, Amendment 39-9277
(a) Prior to the accumulation of 18,000 total landings, or within 30 days after July 3, 1995 (the effective date of AD 95-12- 24, amendment 39-9277), whichever occurs later, perform a visual inspection to detect cracking of the bulkhead at fuselage station (FS) 1363 in the area of the stiffeners at left and right butt line (BL) 42.5; in accordance with the procedures specified in paragraphs 2.A. and 2.B. of Part I of the Accomplishment Instructions of Lockheed L-1011 Service Bulletin 093-53-268, dated April 15, 1993; or in accordance with the procedures specified in paragraphs 2.A. and 2.B. of Part II of the Accomplishment Instructions of Lockheed L-1011 Service Bulletin 093-53-268, Revision 1, dated July 2, 1996.
Note 2: This AD does not require that the eddy current inspection referenced in paragraph 2.B. of Part I of the Accomplishment Instructions of Lockheed L-1011 Service Bulletin 093- 53-268, dated April 15, 1993; and referenced in paragraph 2.B. of Part II of the Accomplishment Instructions of Lockheed L-1011 Service Bulletin 093-53-268, Revision 1, dated July 2, 1996; be accomplished as a requirement of paragraph (a) of this AD.
(b) Except as provided by paragraph (d) of this AD, if any cracking of the bulkhead is detected below waterline (WL) 117 during any inspection performed in accordance with paragraph (a) of this AD: Prior to further flight, perform the inspections required by paragraphs (b)(1), (b)(2), and (b)(3) of this AD, in accordance with Lockheed Document LCC-7622-373, dated May 9, 1995. Prior to further flight, repair any cracking of the bulkhead cap found during these inspections, in accordance with Lockheed Document LCC-7622-374, dated May 9, 1995.
(1) Perform a bolt hole eddy current inspection to detect cracking of the eight fastener holes at the intersection of the vertical stiffener at BL 42.5 and the bulkhead cap vertical flange; and
(2) Perform a bolt hole eddy current inspection to detect cracking at eight fastener locations in the bulkhead cap lower flange that connect the lower fuselage skin panel to the frame at the BL 42.5 vertical stiffener; and
(3) Perform a visual inspection to detect stress corrosion cracking of the accessible portions of the fillet radius of the bulkhead cap.
(c) Except as provided by paragraph (d) of this AD, if any cracking of the bulkhead is detected at or above WL 117 during any inspection performed in accordance with paragraph (a) of this AD: Prior to further flight, repair the bulkhead cracking in accordance with the procedures specified in Part II of the Accomplishment Instructions of Lockheed L-1011 Service Bulletin 093-53-268, dated April 15, 1993; or in accordance with the procedures specified in Part III of the Accomplishment Instructions of Lockheed L-1011 Service Bulletin 093-53-268, Revision 1, dated July 2, 1996.
(d) Continued flight with cracking of the bulkhead is permitted, provided that the
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conditions specified in paragraph 1.C. of the Planning Information of Lockheed L-1011 Service Bulletin 093-53-268, dated April 15, 1993; or Revision 1, dated July 2, 1996; are met. For flight with cracking, both the visual and eddy current inspections specified in paragraphs 2.B. and 2.C. of Part I of the Accomplishment Instructions of Lockheed L-1011 Service Bulletin 093-53-268, dated April 15, 1993; or specified in paragraphs 2.B. and 2.C. of Part II of the Accomplishment Instructions of Lockheed L-1011 Service Bulletin 093-53-268, Revision 1, dated July 2, 1996; must be accomplished prior to returning the aircraft to service. These visual and eddy current inspections must be repeated within 900 landings. Prior to the accumulation of 1,800 total landings, these inspections must be terminated by the installation of the repair specified in Part II of the Accomplishment Instructions of Lockheed L-1011 Service Bulletin 093-53-268, dated April 15, 1993; or by installation of the repair specified in Part III of the Accomplishment Instructions of Lockheed L-1011 Service Bulletin 093- 53-268, Revision 1, dated July 2, 1996.
New Requirements of This of AD
(e) Prior to the accumulation of 18,000 total landings, or within 6 months after the effective date of the AD, whichever occurs later, perform a visual and eddy current surface scan inspection for cracking of the bulkhead web at FS 1363, in accordance with Lockheed L-1011 Service Bulletin 093-53-268, Revision 1, dated July 2, 1996.
(1) If no cracking of the bulkhead web is detected, except as provided by paragraph (f) of this AD, repeat the visual and eddy current surface scan inspections thereafter at intervals not to exceed 2,000 landings.
(2) If cracking of the bulkhead web is detected, and that cracking is within the limits specified in Part I of the Accomplishment Instructions of the service bulletin: Accomplish the requirements of either paragraph (e)(2)(i) or (e)(2)(ii) of this AD, in accordance with the service bulletin. Except as provided by paragraph (f) of this AD, repeat the inspections thereafter at intervals not to exceed 2,000 landings after repair of the cracking.
(i) Prior to further flight, repair the cracking. Or
(ii) Repeat the inspections specified in Part I of the Accomplishment Instructions of the service bulletin at intervals not to exceed 900 landings, and repair the cracking within 1,800 landings after the cracking was detected.
(3) If cracking of the bulkhead web is detected, and that cracking is outside the limits specified in Part I of the Accomplishment Instructions of the service bulletin: Prior to further flight, repair in accordance with Part III of the Accomplishment Instructions of the service bulletin. Except as provided by paragraph (f) of this AD, repeat the inspections thereafter at intervals not to exceed 2,000 landings.
(f) For airplanes on which modification of the bulkhead web is accomplished in accordance with Part IV of the Accomplishment Instructions of Lockheed L-1011 Service Bulletin 093-53-268, Revision 1, dated July 2, 1996: Repeat the inspections specified in paragraph (e) of this AD within 18,000 landings after accomplishment of the modification, in accordance with the service bulletin.
(g) Prior to the accumulation of 18,000 total landings, or within 6 months after the effective date of this AD, whichever occurs later, perform visual, bolt hole eddy current, eddy current surface scan, and X-ray inspections for cracking of the bulkhead cap at FS 1363, in accordance with Lockheed L-1011 Service Bulletin 093- 53-272, dated November 12, 1996.
(1) If no cracking of the bulkhead cap is detected, except as provided by paragraph (h) of this AD, repeat the inspections thereafter at intervals not to exceed 2,000 landings, in accordance with the service bulletin.
(2) If any cracking of the bulkhead cap is detected, accomplish the requirements of either paragraph (g)(2)(i) or (g)(2)(ii) of this AD, in accordance with the service bulletin.
(i) Prior to further flight, repair in accordance with Part I of the Accomplishment Instructions of the service bulletin. Thereafter, repeat the inspections at intervals not to exceed 2,000 landings. Or
(ii) Prior to further flight, replace the bulkhead cap, in accordance with Part II of the Accomplishment Instructions of the service bulletin. Following such replacement, repeat the inspection within 18,000 landings, in accordance with the service bulletin.
(h) For airplanes on which replacement of the bulkhead cap is accomplished in accordance with Part II of the Accomplishment Instructions of Lockheed L-1011 Service Bulletin 093-53-272, dated November 12, 1996: Repeat the inspections specified in paragraph (g) of this AD within 18,000 landings after accomplishment of the replacement, in accordance with the service bulletin.
(i) 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.
(j) 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 4, 1998. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 98-24406Filed9-10-98; 8:45 am]
BILLING CODE 4910-13-P
