Airworthiness Directives; McDonnell Douglas Model MD-11 and MD-11F 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 and MD-11F series airplanes, that currently requires opening the circuit breaker of the pneumatic sense line heater tape, installing an inoperative ring, and coiling and stowing the electrical wire to the circuit breaker of the pneumatic sense line heater tape. That AD also provides for an optional inspection, which, if accomplished, constitutes terminating action for deactivation of the pneumatic sense line heater tape. This proposal is prompted by the FAA's determination that the one-time optional terminating inspection in the existing AD does not adequately detect chafing, electrical arcing, or inadequate clearance of the subject area. The actions specified by the proposed AD are intended to detect and correct such inadequate clearance, which could result in a hole in the fuel feed pipe caused by electrical arcing, and consequent fuel leakage and possible ignition of the fuel vapors. This action would require repetitive inspections of the subject area and corrective actions, if necessary, and would provide for an optional terminating modification(s) for the repetitive inspection requirements.

DATES:

Comments must be received by August 28, 2000.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-243-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 be submitted via fax to (425) 227-1232. Comments may also be sent via the Internet using the following address: 9-anm-nprmcomment@faa.gov. Comments sent via fax or the Internet must contain “Docket No. 99-NM-243-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

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 the FAA, Transport Airplane Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California.

FOR FURTHER INFORMATION CONTACT:

Stephen Kolb, Senior Aerospace Engineer, Propulsion Branch, ANM-140L, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712; telephone (562) 627-5244; 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-243-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-243-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On April 16, 1998, the FAA issued AD 98-08-11, amendment 39-10491 (63 FR 20066, April 23, 1998), applicable to certain McDonnell Douglas Model MD-11 and MD-11F series airplanes, to require opening the circuit breaker of the pneumatic sense line heater tape, installing an inoperative ring, and coiling and stowing the electrical wire to the circuit breaker of the pneumatic sense line heater tape. That AD also provides for an optional inspection, which, if accomplished, constitutes terminating action for deactivation of the pneumatic sense line heater tape. That action was prompted by a report indicating that, while an airplane was on the ground, fuel was found leaking from the fuel feed pipe of the number 2 engine due to inadequate clearance between the fuel feed pipe and the pneumatic sense line heater tape. The requirements of that AD are intended to detect and correct such inadequate clearance, which could result in a hole in the fuel feed pipe caused by electrical arcing, and consequent fuel leakage and possible ignition of the fuel vapors.

Actions Since Issuance of Previous Rule

Since the issuance of AD 98-08-11, the FAA has determined that the optional one-time inspection provided by that AD does not ensure adequate clearance between the heater tape of the pneumatic sense lines and fuel feed pipe of the number 2 engine, which could result in a hole in the fuel feed pipe caused by electrical arcing, and consequent fuel leakage and possible ignition of the fuel vapors. Because the pneumatic sense lines can move and cause the heater tape to contact the fuel feed pipe of the number 2 engine, the FAA finds that repetitive detailed visual inspections of the subject area are necessary in order to address the identified unsafe condition of this AD.

Explanation of Relevant Service Information

The FAA has reviewed and approved McDonnell Douglas Alert Service Bulletin MD11-36A030, Revision 03, dated December 14, 1999. The alert service bulletin describes procedures for opening the circuit breaker of the pneumatic sense line heater tape, installing an inoperative ring, and coiling and stowing the electrical wire to the circuit breaker of the pneumatic sense line heater tape. Accomplishment of the above actions deactivates the pneumatic sense line heater tape. The alert service bulletin also describes procedures for repetitive detailed visual inspections to detect chafing, electrical arcing, or inadequate clearance of the heater tape of the pneumatic sense lines and fuel feed pipe of the number 2 engine; and corrective actions, if necessary. The corrective actions involve repositioning the pneumatic sense lines, rewrapping the insulation on the pneumatic sense lines, and repairing or replacing damaged parts with new parts. Accomplishment of the repetitive inspections eliminates the need for deactivation of the pneumatic sense line heater tape.

The FAA also has reviewed and approved the following optional service bulletins. Accomplishment of the applicable actions specified in these service bulletins eliminates the need for the repetitive inspections described above.

• McDonnell Douglas Service Bulletin MD11-36-018 R01, Revision 1, dated July 18, 1995, describes, for certain airplanes, procedures for modification of the high stage pilot valve located in the aft accessory compartment (including purging the sense lines and revising wiring of the high stage pilot valve).
• McDonnell Douglas Service Bulletin MD11-36-026, dated September 30, 1996, describes, for certain airplanes, procedures for disconnecting and splicing together the heater tape wires of the pneumatic sense lines for the high stage and fan air valves from the terminal strips in the lower vertical stabilizer.
• McDonnell Douglas Service Bulletin MD11-36-025 R01, Revision 01, dated July 31, 1997, describes, for certain airplanes, modification and reidentification of the pilot pressure regulator valve located in the aft accessory compartment (including purging the sense lines and revising the wiring of the pilot pressure regulator valve).
• McDonnell Douglas Service Bulletin MD11-36-028, dated December 7, 1998, describes, for certain airplanes, procedures for disconnecting the heater tape wires from their respective terminal strips and splicing the wire ends together.

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 98-08-11 to require accomplishment of the actions specified in McDonnell Douglas Alert Service Bulletin MD11-36A030, Revision 03, dated December 14, 1999, described previously. The proposed AD also would provide for an optional terminating modification for the repetitive inspection requirements. The proposed AD also would require that operators report results of inspection findings to the FAA.

The FAA is not proposing to mandate the modification specified in paragraph (d)(1), (d)(2), (d)(3), or (d)(4) of this AD for several reasons:

1. Accessing the pneumatic sense lines and fuel feed pipe of the number 2 engine for inspection is easily accomplished.

2. The chafing, electrical arcing, or inadequate clearance of the subject area is easily detectable.

3. The repetitive detailed visual inspections will minimize the probability of a hole in the fuel feed pipe being caused by electrical arcing, which may result in fuel leakage and possible ignition of the fuel vapor.

Differences Between the Proposed AD and Relevant Service Information

Operators should note that, although McDonnell Douglas Alert Service Bulletin MD11-26A030 recommends accomplishing the repetitive detailed visual inspections at intervals not to exceed 5,000 flight hours, the FAA has determined that an interval of 5,000 flight hours or 18 months, whichever occurs later, would address the identified unsafe condition in a timely manner. 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 high utilization of some operator's affected fleet, and the time necessary to perform the inspection (one hour). In light of all of these factors, the FAA finds an interval of 5,000 flight hours or 18 months, whichever occurs later, for the repetitive detailed visual inspections to be warranted, in that it represents an appropriate interval of time allowable for affected airplanes to continue to operate without compromising safety.

In addition to the procedures described above, McDonnell Douglas Service Bulletin MD11-36-018 R01, Revision 1, describes procedures for modification of the high stage pilot valve of the left and right wings, and McDonnell Douglas Service Bulletin MD11-36-025 R01, Revision 01, describes procedures for modification and reidentification of the pilot pressure regulator valve of the left and right wings. Accomplishment of these modifications is not necessary to comply with certain optional actions provided by this AD. These particular modifications do not address the identified unsafe condition of this AD.

Cost Impact

There are approximately 174 Model MD-11 and MD-11F series airplanes of the affected design in the worldwide fleet. The FAA estimates that 67 airplanes of U.S. registry would be affected by this proposed AD.

The modification that is currently required by AD 98-08-11, and retained in this proposed AD, takes 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 $4,020, 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 new inspection proposed by this AD on U.S. operators is estimated to be $4,020, or $60 per airplane, per inspection cycle.

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.

Should an operator elect to accomplish the optional terminating action that would be provided by paragraph (d)(1) of this proposed AD, it would take approximately 4 work hours to accomplish it, at an average labor rate of $60 per work hour. The cost of required parts would be approximately $4,500 per airplane. Based on these figures, the cost impact of this optional terminating action would be $4,740 per airplane.

Should an operator elect to accomplish the optional terminating action that would be provided by paragraph (d)(2) of this proposed AD, it would take approximately 1 work hour to accomplish it, at an average labor rate of $60 per work hour. The cost of required parts would be approximately $50 per airplane. Based on these figures, the cost impact of this optional terminating action would be $110 per airplane.

Should an operator elect to accomplish the optional terminating action that would be provided by paragraph (d)(3) of this proposed AD, it would take approximately 2 work hours to accomplish it, at an average labor rate of $60 per work hour. The cost of required parts would be approximately $2,500 per airplane. Based on these figures, the cost impact of this optional terminating action would be $2,620 per airplane.

Should an operator elect to accomplish the optional terminating action that would be provided by paragraph (d)(4) of this proposed AD, it would take approximately 4 work hours to accomplish it, at an average labor rate of $60 per work hour. The cost of required parts would be approximately $50 per airplane. Based on these figures, the cost impact of this optional terminating action would be $290 per airplane.

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.