Airworthiness Directives; Boeing Model 747-100, −200, −300, −400, and 747SR 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 747 series airplanes, that would have required a one-time inspection to determine whether H-11 steel bolts are installed as attach and support bolts at the trailing edge flap transmissions, and replacement of any H-11 steel bolt with an Inconel bolt. That proposal was prompted by reports of fracturing or cracking of H-11 steel bolts at the flap transmissions. This new action revises the proposed rule by expanding the applicability to include additional airplanes. The actions specified by this new proposed AD are intended to prevent loss of a flap transmission, which could reduce lateral controllability of the airplane.

DATES:

Comments must be received by July 5, 2000.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-206-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:

Barbara Mudrovich, 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) 227-2983; 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 99-NM-206-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-206-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 747 series airplanes, was published as a notice of proposed rulemaking (NPRM) in the Federal Register on December 28, 1999 (64 FR 72582). That NPRM would have required a one-time inspection to determine whether H-11 steel bolts are installed as attach and support bolts at the trailing edge flap transmissions, and replacement of any H-11 steel bolt with an Inconel bolt. That NPRM was prompted by reports of fracturing or cracking of H-11 steel bolts at the flap transmissions. That condition, if not corrected, could result in loss of a flap transmission, which could reduce lateral controllability of the airplane.

Comments

Due consideration has been given to the comments received in response to the NPRM. Certain comments have resulted in changes to the NPRM.

Request To Expand Applicability

One commenter, an operator, requests that the FAA expand the applicability of the proposed rule to include all Model 747 series airplanes. The commenter points out that, though only Model 747 series airplanes having line numbers 1 through 871 inclusive were delivered with the affected bolts, the affected bolts may have been installed as spares on Model 747 series airplanes after line number 871. The commenter states that it found the subject bolts installed on airplanes in its fleet that are not included in the applicability of the proposed rule. The FAA concurs with the commenter's request and has revised the applicability statement of this supplemental NPRM to include all Model 747-100, -100B, -100B SUD, -200B, -200C, -200F, -300, -400, -400D, -400F, and 747SR series airplanes.

Request To Revise “Cost Impact” Section

Several commenters request that the FAA revise the cost impact information provided in the preamble of the NPRM. One commenter states that the cost information in the NPRM is not consistent with the service bulletin, and requests that the cost impact information be revised to reflect the estimates in the service bulletin. Another commenter states that it does not understand the estimate of 6 work hours per airplane and estimates a total of 24 work hours will be necessary to accomplish both the inspection and replacement described in the NPRM. The same commenter further states, “The NPRM cost estimate does not include replacement costs nor does it even include the access costs required for the inspection. This is not industry-accepted practice.”

The FAA partially concurs with the commenters' request. The cost impact information in AD rulemaking actions describes only the “direct” costs of the specific actions required by this AD. The FAA recognizes that, in accomplishing the requirements of any AD, operators may incur “incidental” costs in addition to the “direct” costs. The cost analysis in AD rulemaking actions, however, typically does not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions. Because incidental costs may vary significantly from operator to operator, they are almost impossible to calculate.

The estimate of 6 work hours in the NPRM is based on the figures in the service bulletin of 0.25 work hour for inspection and 0.50 work hour for replacement of bolts, for a total of 0.75 hour per transmission, and 6.0 work hours per airplane. However, based on the comments received, the FAA finds that clarification of the breakdown of the costs associated with the proposed AD is necessary. Therefore, the FAA has revised the cost impact information in this supplemental NPRM to separate the cost estimates for inspection and bolt replacement (if necessary). In addition, the estimated parts cost has been included.

Request To Revise Language in “Discussion” Section

One commenter, the manufacturer, requests that the FAA revise certain language in the “Discussion” section of the NPRM. The subject sentence reads, “Broken bolts could lead to loss of a flap transmission, which could result in flap asymmetry, flap skew, or collateral system damage.” The commenter requests that the sentence be revised to read, “* * * flap skew, and/or collateral system damage.” The commenter states, “* * * in addition to the flap skew or asymmetry, a reduction in flight control system capability is also possible due to potential adjacent systems damage (e.g., hydraulic lines, cables, wiring, etc.).”

The FAA concurs with the intent of the commenter's request. However, the “Discussion” section is not restated in this supplemental NPRM; therefore, no change is necessary in this regard.

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 1,240 airplanes of the affected design in the worldwide fleet. The FAA estimates that 281 airplanes of U.S. registry would be affected by this proposed AD.

It would take approximately 2 work hours per airplane to accomplish the proposed inspection, 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 $33,720, or $120 per airplane.

The cost impact figure discussed above is 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.

Should an operator be required to accomplish the bolt replacement, it will take approximately 4 work hours per airplane (0.5 hours per transmission) to accomplish, at an average labor rate of $60 per work hour. Required parts will cost approximately $5,049 per airplane. Based on these figures, the cost impact of the replacement is estimated to be $5,289 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.