Airworthiness Directives; Boeing Model 737, 757, and 767 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 Boeing Model 737, 757, and 767 series airplanes, that would have required repetitive inspections of certain motor operated hydraulic shutoff valves to detect malfunctioning; and replacement with new valves, if necessary. That proposal also would have required eventual replacement of certain existing valves with new valves, which would have constituted terminating action for the repetitive inspections. That proposal was prompted by reports that the motor switch contacts on certain hydraulic shutoff valves were misaligned, causing subsequent malfunction of those valves. This new action revises the proposed rule by extending a certain compliance time and revising certain actions. The actions specified by this new proposed AD are intended to prevent failure of the motor operated hydraulic shutoff valves, which could result in leakage of hydraulic fluid to the engine fire zone, reduced ability to retract the landing gear, loss of backup electrical power or other combinations of failures; and consequent reduced controllability of the airplane.

DATES:

Comments must be received by July 17, 2000.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 98-NM-298-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.

The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

Kenneth W. Frey, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2673; fax (425) 227-1181.

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 98-NM-298-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. 98-NM-298-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 Boeing Model 737, 757, and 767 series airplanes, was published as a notice of proposed rulemaking (NPRM) in the Federal Register on October 27, 1999 (64 FR 57808). That NPRM would have required repetitive inspections of certain motor operated hydraulic shutoff valves to detect malfunctioning; and replacement with new valves, if necessary. That NPRM also would have required eventual replacement of certain existing valves with new valves, which would have constituted terminating action for the repetitive inspections. That NPRM was prompted by reports that the motor switch contacts on certain hydraulic shutoff valves were misaligned, causing subsequent malfunction of those valves. That condition, if not corrected, could result in failure of the motor operated hydraulic shutoff valves, subsequent leakage of hydraulic fluid to the engine fire zone, reduced ability to retract the landing gear, loss of backup electrical power or other combinations of failures; and consequent reduced controllability of the airplane.

Comments Received to Previous Proposal

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

Request To Revise Inspection Category Described in the Proposed Rule

Several commenters request that the phrase “general visual inspection” be changed to “operational check.” One commenter states that it defines a general visual inspection as a static inspection, and the inspections described in the alert service bulletins are dynamic inspections and require verification that certain criteria are met during operation of the valves. Another commenter states that the term “visual inspection” is misleading, as the valve failures can be identified only by the operational checks identified in the alert service bulletins; additionally, two commenters state that the bulletins do not describe a general visual inspection and, in fact, contain instructions for detailed operational checks. Yet another commenter suggests the instructions for a general visual inspection be expanded in order to clarify what needs to be inspected.

The FAA concurs with the commenters' requests to change the phrase “general visual inspection” to “operational check.” The alert service bulletins describe instructions for detailed operational checks of the motor operated shutoff valves; however, there is no general visual inspection specified in the bulletins. Therefore, paragraph (a) of the supplemental NPRM (SNPRM) has been revised to specify accomplishment of an operational check in lieu of a general visual inspection. In addition, ‘NOTE 2’ of the NRPM, which describes a general visual inspection, has been removed.

Request for Extension of Compliance Time

Several commenters request that the FAA extend the proposed compliance time for the replacement of the valves as specified in paragraph (b) of the proposed rule. One commenter states that fleet safety would not be adversely impacted if the compliance time for the proposed terminating action were extended to a proposed four years. The commenter's reasons for this statement are the calculated mean time between valve failures, in combination with an unlikely event that creates the need for only one of the valves to operate; and the operational checks accomplished in the interim. The commenter has been working with the valve supplier and the airlines to create a fleet retrofit program and notes that it does not consider it possible to complete the retrofit of the affected airplanes in less than four years. Another commenter requests a minimum of six years to complete the replacement of all the valves due to the large number of valves involved. Another commenter states that there is concern that the parts suppliers will not be able to supply sufficient “seed” units at a turn around time adequate to support a two-year retrofit program. Another commenter contends that the data should be analyzed prior to mandating a valve replacement period and requests that the two-year mandatory replacement be deleted from the proposal. The commenter remarks that the present six-month repetitive operational check interval will provide an acceptable level of safety until such time as the valves can be retrofitted. Another commenter requests that relief be given to allow for installation (replacement) of the valves past the effective date of the proposed AD, as long as all units on the airplane are inspected at six-month intervals and replaced prior to the proposed compliance time. Yet another commenter states that two years is a short compliance time, considering that a very large number of airplanes (over 2,000) with five or more Circle Seal control valves installed that need to be retrofitted. The commenter doubts that this is a realistic proposal and would like to have an extension of the compliance date, in addition to split compliance times for the valves used in sensitive and non-sensitive applications, which would reduce the number of valves that need to be replaced urgently. The last commenter states that the manufacturer is scheduled to release new service bulletins that detail the replacement of the valves used in sensitive and non-sensitive applications.

The FAA concurs partially with the commenters' requests/suggestions. Following careful consideration of all the comments, the FAA agrees to an extension of the compliance time for replacement of the valves to three years, due to the large number of valves involved, and in order to allow operators to obtain the necessary parts based on supplier ability to produce the parts within that timeframe. However, the FAA has determined that three years is the maximum amount of time allowable for this extension so that it will not adversely affect fleet safety, in that data received from the manufacturer shows that a longer extension could result in the risk of failure of a defective valve through normal operation of opening and closing repeatedly. Due to this risk, the six-month repetitive operational check interval, to ensure the valve is operating and the valve motor has not burned up due to repetitive operation, will provide an acceptable level of safety until such time as the valves can be retrofitted. Therefore, paragraph (b) of the SNPRM has been revised accordingly.

Request To Delete or Revise Paragraph (b)(2) of the Proposed Rule

Several commenters request that paragraph (b)(2) of the proposal be either deleted or revised. One commenter states that based on past performance, there is a high probability that installation of the fourth generation Circle Seal valves will not adequately address the identified unsafe condition. The commenter requests that the option to replace the existing valves with new Circle Seal valves, as specified in paragraph (b)(2) of the proposed AD, be deleted. Another commenter states that paragraph (b)(2) should apply only to those valves identified in the alert service bulletins referenced in the proposal. The commenter notes that the words in this paragraph could apply to a valve installed in another location on the airplane where failures do not have a negative impact on safety. Another commenter requests that the requirement to replace the valves be postponed until the problems being experienced with the valves are completely resolved. Yet another commenter would like to have the option of replacing a defective valve with either a Whittaker or a Circle Seal valve, independent of the part number used.

The FAA concurs partially with the commenters' requests. The FAA has reviewed information provided by the manufacturer regarding the failure rate of the valves. Based on this information, the FAA has determined that the valves are not an adequate replacement, in addition to difficulty in the installation and operational testing of the valves, resulting in failure of numerous valves; therefore, paragraph (a)(1) of the SNPRM has been revised to remove all references to replacement with Circle Seal valves, and paragraph (b)(2) of the NPRM has been deleted. However, the replacement of the existing valves with Whittaker valves required by paragraph (b)(1) of the NPRM will remain in the AD, and has been moved to paragraph (b) of the SNPRM.

Conclusion

Since these changes expand 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 3,029 Boeing Model 737 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 1,234 airplanes of U.S. registry would be affected by this proposed AD, and that it would take approximately 2 work hours per airplane to accomplish the proposed operational check, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $148,080, or $120 per airplane, per operational check.

There are approximately 802 Boeing Model 757 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 558 airplanes of U.S. registry would be affected by this proposed AD, and that it would take approximately 3 work hours per airplane to accomplish the proposed operational check, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $100,440, or $180 per airplane, per operational check.

There are approximately 701 Boeing Model 767 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 280 airplanes of U.S. registry would be affected by this proposed AD, and that it would take approximately 4 work hours per airplane to accomplish the proposed operational check, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $67,200, or $240 per airplane, per operational check.

For all airplanes, it would take approximately 5 work hours per valve to accomplish the proposed replacement, at an average labor rate of $60 per work hour. Required parts and hydraulic fluid would cost approximately $4,316 per airplane. Based on these figures, the cost impact of the valve replacements proposed by this AD on U.S. operators is estimated to be $4,616 per airplane, per valve replacement. This proposed AD would require eventual replacement of approximately 5,000 valves.

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.