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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 2000-NM-50-AD] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Notice of proposed rulemaking (NPRM). 

# SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model DC-10-10, -15, -30, -30F (KC-10A military), and -40 series airplanes. This proposal would require performing repetitive ultrasonic inspections of the attaching bolts on the inboard and outboard support on the inboard and outboard flap assembly to detect failed bolts, or verifying the torque of the attaching bolts on the inboard support on the outboard flap; and follow-on actions. This proposal also would require replacing all bolts with bolts made from Inconel, which would constitute terminating action for the repetitive inspection requirements. This proposal is prompted by a report of an in-flight loss of the inboard flap assembly on an airplane during approach for landing. The actions specified by the proposed AD are intended to prevent in-flight loss of inboard and outboard flap assemblies due to failure of H-11 attaching bolts, which could result in reduced controllability of the airplane. 

# DATES:

Comments must be received by June 26, 2000. 

# ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-50-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 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:

Ron Atmur, Aerospace Engineer, Airframe Branch, ANM-120L, FAA, Transport Airplane Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137; telephone (562) 627-5224; 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 2000-NM-50-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. 2000-NM-50-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. 

## Discussion 

The FAA has received a report of an in-flight loss of the left inboard flap assembly on a McDonnell Douglas Model DC-10 series airplane during approach for landing. Investigation revealed that bolts made from H-11 steel, which attach the outboard hinge to the lower surface of the flap, had failed. Analysis of the bolts determined the cause of failure to be stress corrosion. The FAA has received no damage or failure reports about the outboard flaps. However, the inboard and outboard hinges are attached to the lower surface of the flap using similar type design and the same material as the installation of the inboard flap outboard hinge. Failure of H-11 attaching bolts could result in an in-flight loss of inboard and outboard flap assemblies, and consequent reduced controllability of the airplane. 

## Explanation of Relevant Service Information 

                    The FAA has reviewed and approved McDonnell Douglas Alert Service Bulletin DC10-57A143, dated December                           ( print page 30022)                        20, 1999. The service bulletin describes procedures for performing an ultrasonic inspection of the attaching bolts on the inboard and outboard support on the inboard and outboard flap assembly to detect failed bolts, or verifying the torque of the attaching bolts on the inboard support on the outboard flap, and follow-on actions. The follow-on actions include replacing any failed bolt and associated parts, if necessary; performing repetitive ultrasonic inspection of the subject area, if necessary; temporarily installing a new Inconel bolt without a new PLI washer; and replacing the PLI washer with a new washer; if necessary. The service bulletin also describes procedures for replacing all bolts with bolts made from Inconel, which would eliminate the need for the repetitive inspections.                 

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 require accomplishment of the actions specified in the service bulletin described previously. 

## Cost Impact 

There are approximately 412 airplanes of the affected design in the worldwide fleet. The FAA estimates that 244 airplanes of U.S. registry would be affected by this proposed AD. 

It would take between 2 and 8 work hours per airplane to accomplish the proposed inspection/torque verification, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the inspection/torque verification proposed by this AD on U.S. operators is estimated to be between $29,280 and $117,120, or between $120 and $480 per airplane, per inspection cycle. 

It would take approximately 288 work hours per airplane to accomplish the proposed bolt replacement, at an average labor rate of $60 per work hour. Required parts would cost approximately $2,987 per airplane. Based on these figures, the cost impact of the replacement proposed by this AD on U.S. operators is estimated to be $4,945,148, or $20,267 per airplane. 

The cost impact figures discussed above are 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. 

§ 39.13 

2. Section 39.13 is amended by adding the following new airworthiness directive:

**McDonnell Douglas:**                                 Docket 2000-NM-50-AD.                             

*Applicability:*                                Model DC-10-10, -15, -30, -30F (KC-10A military), and -40 series airplanes, as listed in McDonnell Douglas Alert Service Bulletin DC10-57A143, dated December 20, 1999; 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 (d) 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 in-flight loss of inboard and outboard flap assemblies due to failure of H-11 attaching bolts, which could result in reduced controllability of the airplane, accomplish the following: 

## Inspection and Corrective Actions 

(a) Within 2 months after the effective date of this AD, perform an ultrasonic inspection of the attaching bolts on the inboard and outboard support on the inboard and outboard flap assembly to detect failed bolts, or verify the torque of the attaching bolts on the inboard support on the outboard flap, in accordance with McDonnell Douglas Alert Service Bulletin DC10-57A143, dated December 20, 1999. 

(1) If no failed bolt is found, repeat the ultrasonic inspection thereafter at intervals not to exceed 6 months. 

(2) If any failed bolt is found, prior to further flight, replace the bolt and associated parts with a new Inconel bolt and new associated parts in accordance with the service bulletin, except as provided by paragraphs (a)(2)(i) and (a)(2)(ii) of this AD. Accomplishment of the replacement constitutes terminating action for the repetitive inspection requirements of paragraph (a)(1) of this AD for that bolt. 

(i) If an Inconel bolt is not available for accomplishment of the replacement, replacement with a new H-11 steel bolt is acceptable provided that operators repeat the ultrasonic inspection thereafter at intervals not to exceed 6 months until the requirements of paragraph (b) of this AD are accomplished. 

(ii) If a PLI washer is not available for accomplishment of the Inconel replacement, a new Inconel bolt can be temporarily installed without a new PLI washer provided that the bolt is torqued to the applicable value specified in the service bulletin. Within 6,000 flight hours after an Inconel bolt is torqued, replace the PLI washer with a new washer in accordance with the service bulletin. 

## Bolt Replacement 

(b) Within 2 years after accomplishing the initial inspection required by paragraph (a) of this AD, accomplish the action specified in paragraph (a)(2) of this AD for all H-11 bolts. Accomplishment of the replacement of all H-11 bolts with Inconcel bolts constitutes terminating action for the requirements of this AD. 

## Spares 

                                (c) As of 2 years after the effective date of this AD, no person shall install, on any                                       ( print page 30023)                                    airplane, an H-11 steel bolt, part number 71658-8-44, 71658-7-44, 71658-7-54, 71658-7-56, 71658-7-29, 71658-9-31, 71658-9-34, 71658-9-38, 71658-9-41, 71658-10-41, 71658-7-26, 71658-7-27, or 71658-8-29, on the inboard or outboard flap assembly.                             

## Alternative Methods of Compliance 

(d) 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 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 

(e) 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 4, 2000. 

Vi L. Lipski,

 Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. 

[FR Doc. 00-11724 Filed 5-9-00; 8:45 am] 

BILLING CODE 4910-13-U