Airworthiness Directives; Boeing Model 757-200 and −300 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 all Boeing Model 757-200 series airplanes, that would have required repetitive clearing of the drain passage at the aft end of the main landing gear (MLG) truck beam to ensure moisture and contaminants within the truck beam can properly drain. That proposal was prompted by reports of fracture of MLG truck beams. This new action revises the proposed rule by expanding the applicability and, for certain airplanes, adding a new inspection and follow-on actions. The actions specified by this new proposed AD are intended to prevent stress corrosion cracking, leading to fracture of a MLG truck beam during ground operations, which could result in either reduced controllability of the airplane or a fire.

DATES:

Comments must be received by October 13, 2000.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-124-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-124-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 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:

Dennis Stremick, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2776; 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.

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-124-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-124-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 all Boeing Model 757-200 series airplanes, was published as a notice of proposed rulemaking (NPRM) in the Federal Register on September 15, 1999 (64 FR 50016). That NPRM would have required repetitive clearing of the drain passage at the aft end of the main landing gear (MLG) truck beam to ensure moisture and contaminants within the truck beam can properly drain. That NPRM was prompted by reports of fracture of MLG truck beams. That condition, if not corrected, could result in either reduced controllability of the airplane or a fire.

Actions Since Issuance of Previous Proposal

Since the issuance of that NPRM, the FAA has reviewed and approved Boeing Alert Service Bulletins 757-32A0135 (for Model 757-200 series airplanes), and 757-32A0138 (for Model 757-300 series airplanes), both dated June 8, 2000. The service bulletins describe procedures for repetitive clearing of the drain passage at the aft end of the truck beam of the MLG to ensure moisture and contaminants within the truck beam can properly drain. For certain airplanes, Service Bulletin 757-32A0135 also specifies an internal inspection of the truck beam protective finish (plating and primer) to detect discrepancies, and either overhaul or replacement of the truck beam if the primer is flaked, cracked, or missing, or if corrosion is present. The service bulletin references Chapter 32-11-56 of the Boeing 757 Component Maintenance Manual for overhaul of the truck beam, and Chapter 32-11-17 of the Boeing 757 Airplane Maintenance Manual for replacement of the truck beam.

Additionally, a note has been added to the supplemental NPRM to give credit to operators that may have previously accomplished the clearing procedure in accordance with Boeing Service Letter 757-SL-32-060, dated March 31, 1999, which was referenced as the appropriate source of service information in the NPRM.

Conclusion

Since this change 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.

Differences Between Proposed Rule and Alert Service Bulletins

Operators should note that, although the alert service bulletins recommend repeating the clearing procedure at planned maintenance intervals (such as “C” checks), after accomplishment of the initial action, the FAA has determined that repeating the procedure at every “C” check thereafter would not 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 average utilization of the affected fleet, and the time necessary to perform the inspection (less than one hour). In light of all of these factors, the FAA finds a compliance time of 4 years since the last overhaul of the MLG or since the date of manufacture of the MLG (for MLG that has not been overhauled), or within 90 days after the effective date of this AD, whichever occurs latest, for initiating the initial actions to be warranted. For the repetitive clearing procedures, the FAA finds an interval of 6 months, if the drain was previously found to be clogged, or 18 months, if the drain was previously found to be unclogged, to be warranted. The FAA finds that these intervals are warranted in that they represent appropriate intervals of time allowable for affected airplanes to continue to operate without compromising safety.

Cost Impact

There are approximately 874 airplanes of the affected design in the worldwide fleet. The FAA estimates that 350 Model 757-200 series airplanes of U.S. registry would be affected by this AD.

It would take approximately 1 work hour per airplane to accomplish the proposed inspection, at that the average labor rate of $60 per work hour. Based on these figures, the cost impact of the proposed inspection on U.S. operators is estimated to be $21,000, or $60 per airplane, per inspection cycle.

For Group 1 airplanes, as listed in Boeing Alert Service Bulletin 757-32A0135: It would take approximately 28 work hours per airplane to accomplish the proposed internal inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the proposed inspection is estimated to be $1,680 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. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Currently, there are no 757-300 series airplanes on the U.S. Register. However, should an affected airplane be imported and placed on the U.S. Register in the future, it would require approximately 1 work hour to accomplish the proposed inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of this inspection would be $60 per airplane, per inspection cycle.

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.