Airworthiness Directives; McDonnell Douglas Model MD-90-30 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Supplemental notice of proposed rulemaking; reopening of comment period.

SUMMARY:

This document revises an earlier proposed airworthiness directive (AD), applicable to certain McDonnell Douglas Model MD-90-30 series airplanes, that would have required replacement of certain ground block screws with new screws; and retermination of the circuit ground wires of the electrical power control unit (EPCU) to separate grounding points. That proposal was prompted by reports of complete loss of the primary electrical power on an airplane during flight. This new action revises the proposed rule by expanding the applicability of the proposed AD to include additional airplanes. The actions specified by this new proposed AD are intended to prevent a loose electrical ground block of the circuit ground wires of the EPCU, which could result in complete loss of the primary electrical power of an airplane during flight.

DATES:

Comments must be received by July 7, 2000.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-329-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. Comments may also be sent via the Internet using the following address: 9-anm-nprmcomment@faa.gov. Comments sent via the Internet must contain “Docket No. 99-NM-329-AD” in the subject line and need not be submitted in triplicate.

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:

George Mabuni, Aerospace Engineer, Systems and Equipment Branch, ANM-130L, FAA, Transport Airplane Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137; telephone (562) 627-5341; 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.

Submit comments using the following format:

• Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
• For each issue, state what specific change to the proposed AD is being requested.
• Include justification (e.g., reasons or data) for each request.

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-329-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-329-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to add an airworthiness directive (AD), applicable to certain McDonnell Douglas Model MD-90-30 series airplanes, was published as a notice of proposed rulemaking (NPRM) in the Federal Register on December 7, 1999 (64 FR 68302). That NPRM would have required replacement of certain ground block screws with new screws; and retermination of the circuit ground wires of the electrical power control unit (EPCU) to separate grounding points. That NPRM was prompted by reports of complete loss of the primary electrical power on an airplane during flight. That condition, if not corrected, could result in a loose electrical ground block of the circuit ground wires of the EPCU, which could result in complete loss of the primary electrical power of an airplane during flight.

Comments

Due consideration has been given to the comment received in response to the NPRM:

One commenter requests that the FAA revise paragraph (b) of the NPRM to reference McDonnell Douglas Service Bulletin MD90-24-062, dated February 3, 2000, as the appropriate source of service information for accomplishing the proposed retermination rather than a method approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. The commenter states that referencing the service bulletin will eliminate the requirement for the ACO to approve an alternative method of compliance (AMOC), and that the proposed retermination could be accomplished easily in accordance with the service bulletin.

The FAA concurs with the commenter. Since issuance of the NPRM, the FAA has reviewed and approved McDonnell Douglas Service Bulletin MD90-24-062, dated February 3, 2000. The service bulletin describes procedures for relocating the ground wires of the EPCU system and installing a new ground stud bracket. Accomplishment of this modification will minimize the possibility of electrical power loss of an airplane during flight. Therefore, the FAA has revised paragraph (b) of the supplemental NPRM to reference the subject service bulletin as the appropriate source of service information for accomplishing the proposed retermination. In addition, the FAA has revised the work hour estimate of the final rule for accomplishing the retermination to conicide with the estimates in the subject service bulletin.

Explanation of Changes to the Applicability of the NPRM

The applicability statement of the NPRM referenced McDonnell Douglas Alert Service Bulletin MD90-24A060, Revision 01, dated September 2, 1999, as the appropriate source of service information for determining the affected airplanes. However, the FAA has revised the applicability statement of the supplemental NPRM to also reference McDonnell Douglas Service Bulletin MD90-24-062, dated February 3, 2000. McDonnell Douglas Service Bulletin MD90-24-062 (described above) includes additional airplanes that are subject to the identified unsafe condition of this AD. As a result of this change, the FAA also has revised the applicability of paragraphs (a) and (b) accordingly.

Conclusion

Since these changes expands the scope of the originally proposed rule, the FAA has determined that it is necessary to reopen the comment period to provide additional opportunity for public comment.

Cost Impact

There are approximately 104 Model MD-90-30 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 21 airplanes of U.S. registry would be affected by this proposed AD.

It would take approximately 1 work hour per airplane to accomplish the proposed replacement, at an average labor rate of $60 per work hour. Required parts would be procured from the operator's stock. Based on these figures, the cost impact of the replacement proposed by this AD on U.S. operators is estimated to be $1,260, or $60 per airplane.

It would take approximately 1 work hour per airplane to accomplish the proposed retermination of the circuit ground wires of the EPCU, at an average labor rate of $60 per work hour. The manufacturer has committed previously to its customers that it will bear the cost of replacement parts. As a result, the cost of those parts is not attributable to this proposed AD. Based on these figures, the cost impact of the retermination proposed by this AD on U.S. operators is estimated to be $1,260, or $60 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 a substantial direct effect 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, it is determined that this proposal would not have federalism implications under Executive Order 13132.

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.