Airworthiness Directives; McDonnell Douglas Model MD-11 Series Airplanes

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 MD-11 series airplanes, that currently requires deactivation of the forward and center cargo control units (CCU). That AD was prompted by a report of failure of a CCU, which produced overheating of the electrical pins inside the CCU; the subsequent release of hot gases and flames ignited an adjacent insulation blanket. This action would require, among other actions, a general visual inspection to verify that all six external connectors of suspect CCU's have a certain part number stamped on the connector bodies on all CCU assemblies, and follow-on actions, which would constitute terminating action for the deactiviation requirements. The actions specified by the proposed AD are intended to prevent overheating of the electrical pins inside the CCU's and subsequent release of hot gases and flames, which could result in smoke and fire in the cargo compartment.

DATES:

Comments must be received by September 11, 2000.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket

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:

Brett Portwood, 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) 627-5350; 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 2000-NM-38-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-38-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On April 12, 2000, the FAA issued AD 2000-08-03, amendment 39-11689 (65 FR 21134, April 20, 2000), applicable to certain McDonnell Douglas Model MD-11 series airplanes, to require deactivation of the forward and center cargo control units (CCU).

That action was prompted by a report of failure of a CCU, which produced overheating of the electrical pins inside the CCU; the subsequent release of hot gases and flames ignited an adjacent insulation blanket. The requirements of that AD are intended to prevent overheating of the electrical pins inside the CCU's and subsequent release of hot gases and flames, which could result in smoke and fire in the cargo compartment.

Actions Since Issuance of Previous Rule

In the preamble of AD 2000-08-03, the FAA indicated that the actions required by that AD were considered “interim action” and that further rulemaking was being considered to require modification of the CCU assembly, which would constitute terminating action for the requirements of AD 2000-08-03. The FAA now has determined that further rulemaking is indeed necessary, and this proposed AD follows from that determination.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Alert Service Bulletin MD11-25A253, dated March 10, 2000. The service bulletin describes procedures for a general visual inspection to verify that all six external connectors of the CCU's have a certain part number stamped on the connector bodies on all TRW Aeronautical Systems, Lucas Aerospace, CCU assemblies; and follow-on actions. The follow-on actions include: Returning any discrepant connector to the manufacturer; modifying the rear cover (40) of the CCU assembly [including aligning the center hole of the insulator with the center hole on the rear cover (40); ensuring that the top edge of the insulator is parallel to the top edge of the rear cover]; and reidentifying the CCU; as applicable. Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition.

Boeing Alert Service Bulletin MD11-25A253 references TRW Aeronautical Systems, Lucas Aerospace Alert Service Bulletin 462650-25-A01, dated March 10, 2000, as an additional source of service information to accomplish the inspection and follow-on actions described above.

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 2000-08-03 to continue to require deactivation of the forward and center CCU's, until accomplishment of the actions specified in Boeing Alert Service Bulletin MD11-25A253 described previously. The proposed AD also would require an inspection to determine the part number of the CCU's, and accomplishment of the actions specified in the Boeing service bulletin described previously, if necessary, except as discussed below.

Differences Between the Proposed AD and Relevant Service Bulletin

Although Boeing Alert Service Bulletin MD11-25A253 recommends accomplishing the general visual inspection within 15 days (from issue date of the service bulletin), the FAA has determined that an interval of 90 days would address the identified unsafe condition in a timely manner. Because operators have already accomplished the interim requirements (i.e., deactivation of the discrepant CCU's) of AD 2000-08-03 (which includes the requirements of AD 2000-05-01), the FAA finds that the safety risk of the affected airplanes has been reduced. Therefore, the FAA has determined that a 90-day compliance time for initiating the required inspection to be warranted, in that it represents an appropriate interval of time allowable for affected airplanes to continue to operate without compromising safety.

Boeing Alert Service Bulletin MD11-25A253 (which, as described previously, references TRW Aeronautical Systems, Lucas Aerospace Alert Service Bulletin 462650-25-A01 as an additional source of service information) recommends that certain discrepant CCU's be returned to the manufacturer; however, it does not describe any further procedures to correct the discrepancy. Therefore, this proposed AD requires replacement of the discrepant CCU with a CCU that has one of the following part numbers (P/N): 462650-21, 462650-22, or 462650-23.

Since the issuance of Boeing Alert Service Bulletin MD11-25A253, Lucas has incorporated a design change to the CCU's. Lucas incorporated this design change in CCU's having P/N 462650-21, 462650-22, and 462650-23. The FAA finds that these CCU's are not subject to the identified unsafe condition of this AD. Therefore, in addition to the procedures in the referenced service bulletin, this proposed AD would require a general visual inspection to determine the part number of the CCU's. Depending on the inspection results, the proposed AD would then require a general visual inspection to verify that all six external connectors of the suspect CCU have a certain part number stamped on the connector bodies on all CCU assemblies, as described in the referenced service bulletin, and follow-on actions.

Cost Impact

There are approximately 104 Model MD-11 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 20 airplanes of U.S. registry would be affected by this proposed AD.

The actions that are currently required by AD 2000-08-03 take approximately 1 work hour per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the currently required actions on U.S. operators is estimated to be $1,200, or $60 per airplane.

The new inspection that is proposed in this AD action would take approximately 1 work hour per airplane to accomplish, at an average labor rate of $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 $1,200, or $60 per airplane.

Should an operator be required to accomplish the new modification that is proposed in this AD action, it would take approximately 1 work hour per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts would be supplied by the manufacturer of the CCU at no cost to the operators. Based on these figures, the cost impact of the modification proposed by this AD on U.S. operators is estimated to be $60 per airplane.

Should an operator be required to accomplish the new replacement that is proposed in this AD action, it would take approximately 1 work hour per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts would be supplied by the manufacturer of the CCU at no cost to the operators. Based on these figures, the cost impact of the replacement proposed by this AD on U.S. operators is estimated to be $60 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 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.