Airworthiness Directives; McDonnell Douglas Model DC-8 Series Airplanes

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-217-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-217-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received reports of stress corrosion cracking in the forward tang of the lower cap of the wing front spar of McDonnell Douglas Model DC-8 series airplanes. Investigation revealed that some front spar lower caps were manufactured from 7079-T6 material, which is susceptible to stress corrosion cracking. This condition, if not corrected, could result in reduced structural integrity of the wing.

Other Relevant Rulemaking

AD 90-16-05, amendment 39-6614 (55 FR 31818, August 6, 1990) requires certain inspections and structural modifications. McDonnell Douglas Service Bulletin DC8-57-030, Revision 3, dated December 10, 1970, was mandated as part of the service action requirements program required by AD 90-16-05. Revision 3 of the service bulletin describes procedures for a one-time visual inspection for cracks in the forward tang of the lower cap of the front spar, and modification, if cracking is detected.

Explanation of Relevant Service Information

The FAA has reviewed and approved McDonnell Douglas Service Bulletin DC8-57-030, Revision 04, dated August 17, 1995; and Revision 05, dated April 28, 1998. Revisions 04 and 05 of the service bulletin describe procedures for a one-time eddy current conductivity test to determine the material type of the forward tang of the lower cap of the wing front spar, and modification of the front spar, if necessary. The modification involves replacement of lower cap of the wing front spar with a new lower cap. Revision 04 of the service bulletin recommends that airplanes previously modified in accordance with Revision 3 of the service bulletin be reworked if the lower cap was made of 7079-T6 material. (Revision 04 of the service bulletin was approved as an alternative method of compliance to AD 90-16-05.) Revision 05 of the service bulletin adds 52 additional airplanes to the list of effective airplane serial numbers. Accomplishment of the actions specified in the service bulletins 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.

Cost Impact

There are approximately 294 airplanes of the affected design in the worldwide fleet. The FAA estimates that 251 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 3 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 $45,180, or $180 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 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

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:

McDonnell Douglas: Docket 99-NM-217-AD.

Applicability: Model DC-8 series airplanes, as listed in McDonnell Douglas Service Bulletin DC8-57-30, Revision 05, dated April 28, 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 (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 prevent stress corrosion cracking of the lower cap of the wing front spar, which if not corrected, could result in reduced structural integrity of the wing, accomplish the following: (a) Within 48 months after the effective date of this AD, perform a one-time eddy current conductivity test to determine the material type of the forward tang of the lower cap of the front spar in the center section of the wing, in accordance with McDonnell Douglas Service Bulletin DC8-57-30, Revision 05, dated April 28, 1998, or Revision 04, dated August 17, 1995. (1) If 7079-T6 aluminum is not found, no further action is required by this AD. (2) If any 7079-T6 aluminum is found, within 48 months after the effective date of this AD, modify the forward tang of the lower cap of the front spar, in accordance with the service bulletin. (b) Accomplishment of the eddy current conductivity test, and modification, if necessary, specified in paragraph (a) of this AD constitutes terminating action for the repetitive inspection requirements of paragraph (a) of AD 90-16-05, amendment 39-6614, as it applies to the inspections of the forward tang of the lower cap of the front spar specified in McDonnell Douglas Service Bulletin DC8-57-30, Revision 3, dated December 10, 1970.

Alternative Methods of Compliance

(c) An alternative method of compliance that provides an acceptable level of safety may be used if approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA, Transport 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, Los Angeles ACO.

Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO.

Special Flight Permits

(d) Special flight permits may be issued in accordance with Secs. 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 October 21, 1999. D.L. Riggin, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 99-28077 Filed 10-26-99; 8:45 am] BILLING CODE 4910-13-U