AD 95-21-16

This amendment adopts a new airworthiness directive (AD), applicable to all Lockheed Model L-1011-385 series airplanes, that requires an inspection to detect evidence of sealant around the lug bushing flanges of certain actuator attach pin assemblies of the main landing gear (MLG), and replacement of the pin assembly with a serviceable unit if no sealant is present. This amendment is prompted by reports of cracks emanating from corrosion pits of the lug bores on the actuator attach pin assemblies of two MLG's. The actions specified by this AD are intended to prevent failure of the actuator attach pins as a result of corrosion and subsequent cracking of the lug bores. Such failure could result in the MLG failing to extend completely or rapidly free-falling during extension and causing additional damage to the landing gear.

Final Rule

95-21-16 LOCKHEED AERONAUTICAL SYSTEMS COMPANY: Amendment 39-9403. Docket 95-NM-30-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 use the authority provided in paragraph (c) of this AD to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition; or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any airplane from the applicability of this AD.

Compliance: Required as indicated, unless accomplished previously.

To prevent failure of the actuator attach pins as a result of corrosion and subsequent cracking of the lug bores, which could result in the main landing gear (MLG) failing to extend completely or rapidly free-falling during extension and causing additional damage to the landing gear, accomplish the following:

(a) Within 90 days after the effective date of this AD, perform a one-time inspection to detect evidence of sealant around the lug bushing flanges of the actuator attach pin assembly, part number 1642699-101, of the MLG, in accordance with Lockheed Service Bulletin 093-32- 256, dated November 11, 1994.

(1) If the inspection reveals that sealant is present, no further action is required by this AD.

(2) If the inspection reveals that no evidence of sealant is present, within 6 months after accomplishing the inspection, replace the actuator attach pin assembly with a serviceable unit in accordance with Lockheed Service Bulletin 093-32-256, dated November 11, 1994.

(b) As of the effective date of this AD, no actuator attach pin assembly, part number 1642699-101, shall be installed on the MLG of any airplane unless that assembly has been inspected in accordance with the requirements of paragraph (a) of this AD and evidence of sealant has been found; or unless that assembly has been reworked and reidentified with the letter "A" etched at the end of the serial number, in accordance with Lockheed Service Bulletin 093-32-256, dated November 11, 1994.

(c) 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 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 inspection and replacement shall be done in accordance with Lockheed Service Bulletin 093-32-256, dated November 11, 1994. 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, 1601Lind 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 November 17, 1995.

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 April 27, 1995 (60 FR 20659). That action proposed to require a one-time inspection to detect evidence of sealant around the lug bushing flanges of certain actuator attach pin assemblies of the MLG and, if no sealant is present, replacement of the pin assembly.

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

One commenter supports the proposed rule.

The Air Transport Association (ATA) of America, on behalf of one of its members, requests that the FAA extend the compliance time for replacement of discrepant actuator attach pin assemblies from 6 months to at least 12 months to coincide with scheduled maintenance activities. The commenter indicates that replacement parts may not be procurable within the proposed compliance time. The commenter adds that it conducts a visual inspection of the affected area every 40 flight hours due to previous pin failures.

The FAA does not concur with the commenter's request. The FAA has confirmed that a sufficient quantity of new parts are available to support the initiation of a replacement program. Additionally, the service bulletin cited in the AD contains an option that provides for rework of discrepant pin assemblies for reuse. The FAA is unaware of a visual inspection procedure that would detect incipient pin failure. However, the FAA would consider a request for use of such a procedure as an interim measure, or for an adjustment of the compliance time, in accordance with the provisions of paragraph (c) of this AD, provided that adequate justification is presented to support such a request.

The commenter also contends that this AD action is not warranted. The commenter indicates that it has not incurred any damage to the landing gear or aircraft of its fleet resulting from pin failures. The FAA infers from these remarks that the commenter requests the proposal be withdrawn. The FAA does not concur with the commenter's position that this AD is not warranted. Investigation of several reports of cracked lugs found on the actuator attach pin assemblies of the main landing gears installed on Model L-1011-385 series airplanes has revealed that the lugs cracked due to corrosion beneath the bushing surface on the lug bores. This corrosion may have been caused by the intrusion of moisture between the lug surface and the bushing flange. Such corrosion and cracking presents an unsafe condition in these airplanes, since it could eventually lead to failure of the attach pins. Failure of the pins could result in the main landing gear failing to extend completely, or rapidly free-falling during extension and causing additional damage to the landing gear. The FAA has determined that this unsafe condition could exist or eventually develop on Model L-1011-385 series airplanes since the actuator attach pin assemblies are similar, if not identical, on all models of this series. The FAA also has determined that an inspection of the affected area, and correction of discrepancies, must be mandated in order to ensure that the safety of this fleet is not degraded. The appropriate vehicle for mandating such action to correct an unsafe condition is the airworthiness directive.

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 as proposed.

There are approximately 236 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 1 work hour per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $7,020, or $60 per airplane.

The total 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.

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 USC 106(g), 40101, 40113, 44701.

39.13 - [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: