Airworthiness Directives; McDonnell Douglas Model DC-10-10, -15, -30, -30F (KC-10A Military), and -40 Series Airplanes

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 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.