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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 99-NM-60-AD] 
          - RIN 2120-AA64 

# 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 certain McDonnell Douglas Model DC-8 series -10 through -50, -61, -61F, -71, -71F airplanes, that currently requires a visual or eddy current inspection(s) of the left and right wing front spar lower caps to detect cracks migrating from attachment holes; and repair, if necessary. That AD also provided for an optional terminating modification of the front spar lower cap. This proposal is prompted by a report that additional cracking was found in the front spar lower cap of a wing. This action would require accomplishment of the previously optional terminating action. The proposed AD also would expand the applicability of the existing AD to include additional airplanes and to increase the interval for the repetitive eddy current inspections. The actions specified by the proposed AD are intended to prevent reduced structural integrity of the left or right wing due to metal fatigue failure of the front spar lower cap. 

# DATES:

Comments must be received by June 26, 2000. 

      ( print page 30029)    

# ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-60-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 Boeing Commercial Aircraft Group, Long Beach Division, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Technical Publications Business Administration, Dept. C1-L51 (2-60). This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Transport Airplane Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California. 

# FOR FURTHER INFORMATION CONTACT:

Greg DiLibero, Aerospace Engineer, Airframe Branch, ANM-120L, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712; telephone (562) 627-5231; fax (562) 627-5210. 

# 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-60-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-60-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. 

## Discussion 

On September 26, 1986, the FAA issued AD 86-20-06, amendment 39-5434 (51 FR 35502, October 6, 1986), applicable to certain McDonnell Douglas Model DC-8-10 through -50 inclusive, -61, -61F, -71, -71F series airplanes, to require repetitive visual or eddy current inspections to detect cracks of the left and right wing front spar lower caps between stations Xfs=515.00 and Xfs=526.760; and repair, if necessary. That AD also provides for an optional terminating modification for the repetitive inspection requirements. That action was prompted by reports of fatigue cracking on the spar caps of two airplanes. The requirements of that AD are intended to prevent reduced structural integrity of the left or right wing due to metal fatigue failure of the front spar lower cap. 

## Actions Since Issuance of Previous Rule 

Since the issuance of AD 86-20-06, the FAA has received a report of two instances in which cracking was found in the front spar lower cap of a wing on affected airplanes that have accumulated between 46,093 and 48,942 flight hours. The cracking originated at an attachment hole in the forward leg and progressed to a point partially through the vertical and aft leg of the spar cap. The cause of such cracking has been attributed to material fatigue. The FAA has determined that accomplishment of the visual inspection(s) required by AD 86-20-06 does not adequately ensure timely detection of fatigue cracks in the subject area. 

## Explanation of Relevant Service Information 

Subsequent to the finding of this new cracking, the manufacturer issued, and the FAA reviewed and approved McDonnell Douglas Service Bulletin DC8-57-090, Revision 05, dated June 16, 1997. The eddy current inspection and modification procedures are identical to those described in McDonnell Douglas DC-8 Service Bulletin 57-90, dated October 3, 1983 (which was referenced as the appropriate source of service information in AD 86-20-06). The only changes effected by Revision 05 of the service bulletin are to remove the inadequate visual inspection procedures; to add additional airplanes to the effectivity listing; and to add an inspection following accomplishment of the preventative modification. 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 86-20-06 to continue to require an eddy current inspection(s) to detect cracks of the lower front spar caps of the wings at the attachment holes of the leading edge assembly between stations Xfs=515.000 and Xfs=526.760, and corrective actions, if necessary. The proposed AD would require accomplishment of the previously optional terminating action and a follow-on inspection. The proposed AD also would expand the applicability of the existing AD to include additional airplanes that are subject to the identified unsafe condition of this AD and to increase the interval for the repetitive eddy current inspections. 

## Differences Between the Proposed Rule and the Service Bulletin 

Operators should note that, although the service bulletin recommends that the repetitive eddy current inspections be accomplished at intervals not to exceed 3,600 flight hours or 1 year, whichever occurs first, the proposed AD would require those inspection at intervals not to exceed 3,600 flight hours or 3 years, whichever occurs first. The FAA consulted with the manufacturer and has determined through a damage tolerance assessment that the subject fatigue cracking is dependant only on flight hours. However, because some affected airplanes have very low utilization rates, the FAA has determined that extending the calendar year repetitive inspection interval from 1 year to 3 years will ensure that the inspection is accomplished within an acceptable time frame. Therefore, the proposed rule would require that the eddy current inspection interval be 3,600 flight hours or 3 years, whichever occurs first. 

                    Although the service bulletin recommends accomplishing the eddy                           ( print page 30030)                        current inspection within 3,200 flight hours after the issue date of the service bulletin on airplanes that have accumulated 30,000 total flight hours, the proposed AD requires, for certain airplanes, that the inspection be accomplished within 3,200 flight hours or 2 years after the effective date of this AD, whichever occurs first. In developing an appropriate compliance time for this AD, the FAA considered not only the manufacturer's recommendation, but the degree of urgency associated with addressing the subject unsafe condition, the average utilization of the affected fleet, and the time necessary to perform the inspection (two hours). In addition, the FAA has determined that all affected airplanes have accumulated 30,000 or more total flight cycles. In light of all of these factors, the FAA finds a compliance time of within 3,200 flight hours or 2 years after the effective date of this AD, whichever occurs first, for initiating the proposed actions to be warranted, in that it represents an appropriate interval of time allowable for affected airplanes to continue to operate without compromising safety.                 

## Cost Impact 

There are approximately 294 Model DC-8 series 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. 

It would take approximately 2 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 inspection proposed by this AD on U.S. operators is estimated to be $30,120, or $120 per airplane, per inspection cycle. 

It would take approximately between 12 and 14 work hours per airplane to accomplish the proposed modification, and that the average labor rate is $60 per work hour. Required parts would cost approximately between $303 and $1,202 per airplane. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be between $256,773, or $512,542, or between $1,023, or $2,042 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. 

## 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. 

§ 39.13 

2. Section 39.13 is amended by removing amendment 39-5434 (51 FR 35502, October 6, 1986), and by adding a new airworthiness directive (AD), to read as follows: 

**McDonnell Douglas:**                                 Docket 99-NM-60-AD. Supersedes AD 86-20-06, Amendment 39-5434.                            

*Applicability:*                                 Model DC-8 series airplanes, as listed in McDonnell Douglas Service Bulletin DC8-57-090, Revision 05, dated June 16, 1997; 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 (h)(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 prevent reduced structural integrity of the left or right wing due to metal fatigue failure of the front spar lower cap, accomplish the following: 

# Note 2:

This AD will affect the inspections, corrective actions, and reports required by AD 93-01-15, amendment 39-8469 (58 FR 5576, January 22, 1993), for Principal Structural Elements (PSE) 57.08.021 and 57.08.022 of the DC-8 Supplemental Inspection Document (SID).

# Note 3:

Where there are differences between this AD and the referenced service bulletin, the AD prevails.

## Eddy Current Inspection 

(a) For Model DC-8-10 through DC-8-50, inclusive, DC-8-61, -61F, -71, and -71F series airplanes, equipped with left or right wing front spar lower cap, part number (P/N) 5597838-1 or -2; not modified in accordance with McDonnell Douglas DC-8 Service Bulletin 57-90, dated October 3, 1983: Perform an eddy current inspection to detect cracks of the lower front spar caps of the wings at the attachment holes of the leading edge assembly between stations Xfs=515.000 and Xfs=526.760, in accordance with McDonnell Douglas Service Bulletin DC8-57-090, Revision 05, dated June 16, 1997; at the time specified in either paragraph (a)(1), (a)(2), or (a)(3) of this AD, as applicable. 

# Note 4:

Eddy current inspections accomplished prior to the effective date of this AD in accordance McDonnell Douglas DC-8 Service Bulletin 57-90, Revision 1, dated June 16, 1988; Revision 2, dated March 1, 1991; Revision 3, dated March 25, 1992; or Revision 4, dated March 3, 1995; are considered acceptable for compliance with the requirements of paragraph (a) of this AD.

(1) For airplanes on which the immediately preceding inspection was conducted using eddy current techniques in accordance with AD 86-20-06 prior to the effective date of this AD: Inspect within 3,600 flight hours or 3 years after accomplishment of the last eddy current inspection, whichever occurs first. 

(2) For airplanes on which the immediately preceding inspection was conducted visually in accordance with AD 86-20-06 prior to the effective date of this AD: Inspect within 3,200 flight hours or 2 years after accomplishment of the last visual inspection, whichever occurs first. 

                                (3) For airplanes on which a visual or eddy current inspection or the modification required by AD 86-20-06 has not been accomplished: Inspect prior to the accumulation of 30,000 total flight hours, or within 200 flight hours after the effective date of this AD.                                       ( print page 30031)    

(b) For airplanes other than those identified in paragraph (a) of this AD: Within 3,200 flight hours or 2 years after the effective date of this AD, whichever occurs first, perform the eddy current inspection specified in paragraph (a) of this AD. 

## Repetitive Inspections 

(c) If no crack is detected during any inspection required by this AD, repeat the eddy current inspection thereafter at intervals not to exceed 3,600 flight hours or 3 years, whichever occurs first. 

## Repair 

(d) If any crack is detected during any inspection required this AD, prior to further flight, accomplish the action specified in either paragraph (d)(1) or (d)(2) of this AD, as applicable. 

(1) For cracks within the limits specified in Conditions 2 through 6, inclusive, Table 1 of paragraph 3.B.4 of the Accomplishment Instructions of McDonnell Douglas Service Bulletin DC8-57-090, Revision 05, dated June 16, 1997: Modify the lower front spar cap in accordance with McDonnell Douglas Service Bulletin DC8-57-090, Revision 05, dated June 16, 1997. Accomplishment of the modification constitutes compliance with the requirements paragraphs (c) and (e) of this AD. 

(2) For cracks that exceed the limits specified in Conditions 2 through 6, inclusive, Table 1 of paragraph 3.B.4 of the Accomplishment Instructions of McDonnell Douglas Service Bulletin DC8-57-090, Revision 05, dated June 16, 1997: Repair in accordance with a method approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. 

## Preventative Modification 

(e) Within 100,000 flight hours after the effective date of this AD, modify the lower front spar cap in accordance with paragraph 3.B.2.B of the Accomplishment Instructions of McDonnell Douglas Service Bulletin DC8-57-090, Revision 05, dated June 16, 1997. Accomplishment of the modification constitutes compliance with the requirements paragraphs (a), (b), and (c) of this AD. 

# Note 5:

Modification of the lower front spar cap accomplished prior to the effective date of this AD in accordance with McDonnell Douglas DC-8 Service Bulletin 57-90, Revision 1, dated June 16, 1988; Revision 2, dated March 1, 1991; Revision 3, dated March 25, 1992; or Revision 4, dated March 3, 1995; is considered acceptable for compliance with the requirements of paragraph (d) of this AD.

(f) Accomplishment of the modification required by paragraph B. of AD 90-16-05, amendment 39-6614 (55 FR 31818, August 6, 1990) [which references “DC-8 Aging Aircraft Service Action Requirements Document” (SARD), McDonnell Douglas Report MDC K1579, Revision A, dated March 1, 1990, as the appropriate source of service information for accomplishing the modification] constitutes compliance with paragraphs (a), (b), (c), and (e) of this AD. 

## Follow-On Inspection 

(g) Prior to the accumulation of 32,900 total flight hours following accomplishment of the modification required by either paragraph (d)(1) or (e) of this AD, or 2 years after the effective date of this AD, whichever occurs later, perform an inspection to detect cracks in the area specified in paragraph (a) of this AD, and corrective actions, if necessary, in accordance with a method approved by the Manager, Los Angeles ACO. 

## Alternative Methods of Compliance 

(h)(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, Los Angeles ACO. 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 6:

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

(2) Alternative methods of compliance, approved previously in accordance with AD 86-20-06, amendment 39-5434, are approved as alternative methods of compliance with this AD. 

## Special Flight Permits 

(i) 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 May 3, 2000. 

Vi L. Lipski, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

[FR Doc. 00-11721 Filed 5-9-00; 8:45 am] 

BILLING CODE 4910-13-U