Also, the FAA has revised paragraph (b) of this final rule to apply to:

Allow Use of Later Revisions of OHM

One commenter requests that the FAA revise paragraph (d) of the proposed rule to specify overhaul of the actuator attach fittings for the flaps in accordance with Boeing OHM 575255, Temporary Revision 577, dated June 1, 1999, or Temporary Revision 579, dated May 14, 2000; and Boeing OHM 575235, Temporary Revision 578, dated June 10, 1999, Temporary Revision 5710, dated May 8, 2000, or Full Revision 57 10, dated July 1, 2000. The commenter also requests that the FAA refer to Boeing OHM 575235, Temporary Revision 5710, or Full Revision 57 10, in Note 4 of the proposed rule. The commenter states that these later revisions of the OHM chapters describe the same actions as those revisions referred to in the proposed rule but provide additional repair information.

Similarly, a second commenter requests that the FAA revise paragraph (d) of the proposed rule to specify overhaul of the actuator attach fittings in accordance with Boeing OHM 575255, Temporary Revision 577, dated June 1, 1999, or later, and Boeing OHM 575235, Temporary Revision 578, dated June 10, 1999, or later. The commenter states that this would allow use of the latest revision of the OHM when overhauling the fittings.

The FAA partially concurs with the commenters' requests. The FAA has reviewed the specific revisions referenced by the first commenter and finds them acceptable. The FAA has also reviewed Boeing OHM 5752 55, Full Revision 579, dated July 1, 2000, and finds it acceptable. However, rather than revising paragraph (d) to cite all of these revisions, the FAA finds that paragraph (d) of this AD may be revised to refer to the accomplishment instructions of Boeing Service Bulletin 74757A2310, Revision 1, dated November 23, 1999, or Revision 2, dated February 22, 2001, as acceptable sources of service information for the accomplishment of the overhaul required by that paragraph. The FAA finds that this change will clarify the requirements of paragraph (d) of this AD, and make it easier for operators to comply with that paragraph. The FAA has revised paragraph (d) accordingly. In addition, for the actuator attach fittings on the inboard flaps, the FAA has revised Note 4 of this AD to refer to specific OHM revisions referenced by the first commenter and reviewed and accepted by the FAA. Allow Approval of Repairs By Designated Engineer Representative (DER)

One commenter requests that the FAA revise the ``Alternative Methods of Compliance'' paragraphparagraph (f) in the proposed rule to allow repairs of corrosion or cracking that is outside the limits specified in the OHM in accordance with a method approved by a Boeing DER, in lieu of requiring replacement of the actuator attach fittings before further flight. The commenter states that this allowance is necessary to prevent unnecessary delays or grounding of airplanes if operators find conditions outside the rework limits in the OHM.

The FAA partially concurs with the commenter's request. The FAA does not concur with the commenter's request to revise the ``Alternative Methods of Compliance'' paragraph to allow the Boeing DER to approve repairs. However, the FAA finds that a new paragraph may be added to provide for repair of actuator attach fittings, in lieu of replacement. Therefore, the FAA has added paragraph (f) to this final rule (and reordered subsequent paragraphs accordingly), to allow for repair of the actuator attach fittings on the inboard and outboard flaps in accordance with a method approved by the FAA or data approved by a Boeing Company DER who has been authorized to make such findings. Revise Cost Impact Estimate

One commenter requests that the FAA revise the estimate of the cost impact in the proposed rule. The commenter states that the estimate of 5 work hours
[[Page 34528]]
per airplane for overhaul of the actuator attach fittings is extremely low. The commenter notes that the procedures for each actuator attach fitting include cleaning, removing sleeves, machining, performing non destructive tests, and manufacturing and installing new sleeves. The commenter also submits estimates from several vendors as well as their own estimate of 192 work hours per airplane.

The FAA partially concurs with the commenter's request. The FAA does not concur that the commenter's estimate of 192 work hours is appropriate for use in this AD. The cost impact information in AD actions includes only the ``direct'' costs of the specific actions required by the 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.

However, the FAA does concur that the estimated number of work hours can be adjusted somewhat. The estimate of 5 work hours included only the time necessary specifically for the overhaul, based on the data included in the manufacturer's service bulletin. The FAA finds it appropriate to include the estimate of work hours needed for removal, inspection, and reinstallation, as well as overhaul, of the subject parts. Based on the data provided in the airplane manufacturer's service bulletin, the FAA estimates the number of work hours for these actions to be 37 work hours per airplane. Similarly, the FAA finds that the cost estimate for replacement of the actuators should include time for the inspection that is included in the procedures for the replacement. Thus, the number of work hours for the replacement has been increased from 2 to 4 work hours per airplane. The FAA has revised the cost impact estimate in this final rule accordingly.
Reduce Compliance Time for Actions on Attach Fittings on Outboard Flap

One commenter, an operator, requests that the FAA reduce the proposed initial compliance time for actions on the actuator attach fittings on the outboard flap that have been overhauled per OHM 5752 55. The commenter requests a compliance time of 6 years or 6,000 flight cycles, whichever occurs first, after the attach fitting was overhauled, for the accomplishment of paragraph (c), (d), or (e) of this AD. The commenter states that the earlier of 6 years or 6,000 flight cycles is its ``hard time'' interval between overhauls.

The FAA does not concur. The compliance time of 8 years or 8,000 flight cycles, whichever occurs first, is based on when cracking of actuator attach fittings has been found, and the manufacturer's recommendation in the service bulletin. However, an operator may choose to accomplish the actions in this AD prior to the 8yearor8,000 flightcycle threshold. No change to the final rule is necessary in this regard.

Conclusion

After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

Cost Impact

There are approximately 1,111 Model 747 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 237 airplanes of U.S. registry will be affected by this AD.

It will take approximately 2 work hours per airplane to accomplish the required inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of this inspection on U.S. operators is estimated to be $28,440, or $120 per airplane, per inspection cycle.

The overhaul of actuator attach fittings, which is offered as one alternative for compliance with this AD action, will take approximately 37 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of this overhaul is estimated to be $2,220 per airplane, per overhaul cycle.

In lieu of the overhaul, this AD provides for a replacement of actuator attach fittings, which would take approximately 4 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will cost approximately $6,623 (for the four attach fittings on the outboard flaps) and $7,566 (for the four attach fittings on the inboard flaps). Based on these figures, the cost impact of this replacement is estimated to be $14,429, per airplane, per replacement cycle.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the 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.

Should an operator elect to accomplish the optional replacement with improved attach fittings, which terminates the requirements of this AD, it would take approximately 16 work hours to accomplish, at an average labor rate of $60 per work hour. The cost of required parts would be approximately $15,322 per airplane. Based on these figures, the cost impact of the optional terminating action would be $16,282 per airplane.

Regulatory Impact

The regulations adopted herein will 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 final rule does not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this action (1) is not a ``significant regulatory action'' under Executive Order 12866; (2) is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows: [[Page 34529]]

PART 39AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new airworthiness directive:

20011312 Boeing: Amendment 3912292. Docket 99NM313AD.

Applicability: Model 747 series airplanes, as listed in Boeing Service Bulletin 74757A2310, Revision 2, dated February 22, 2001; certificated in any category.

Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the
requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (g) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To detect and correct cracking on the actuator attach fittings of the trailing edge flaps, which could result in abnormal operation or retraction of a trailing edge flap, and consequent reduced controllability of the airplane, accomplish the following:
Actuator Attach Fittings That Have Not Been Overhauled or Replaced (a) For actuator attach fittings on the outboard flaps that have NOT been overhauled in accordance with revisions of Boeing 747 Overhaul Manual (OHM) 575255 dated prior to June 1, 1999, or replaced with a new fitting, prior to the effective date of this AD; and for actuator attach fittings on the inboard flap actuators that have NOT been overhauled in accordance with revisions of OHM 5752 35, dated prior to June 1, 1999, or replaced with a new fitting, prior to the effective date of this AD: Accomplish the actions in paragraph (c), (d), or (e) of this AD at the later of the times specified in paragraphs (a)(1) and (a)(2) of this AD.
(1) Prior to the accumulation of 8 years since date of manufacture or 8,000 total flight cycles, whichever occurs first. (2) Within 6 months after the effective date of this AD. Actuator Attach Fittings That Have Been Overhauled or Replaced (b) For actuator attach fittings on the outboard flaps that HAVE been overhauled in accordance with revisions of OHM 575255 dated prior to June 1, 1999, or replaced with a new fitting, prior to the effective date of this AD; and for actuator attach fittings on the inboard flap actuators that HAVE been overhauled in accordance with revisions of OHM 575235 dated prior to June 1, 1999, or replaced with a new fitting, prior to the effective date of this AD: Accomplish the actions in paragraph (c), (d), or (e) of this AD at the later of the times specified in paragraphs (b)(1) and (b)(2) of this AD.
(1) Within 8 years or 8,000 total flight cycles after the attach fitting was overhauled or replaced, whichever occurs first. (2) Within 6 months after the effective date of this AD. Inspections and Corrective Action
(c) Perform a detailed visual inspection to detect corrosion around the lower bearing journal on the actuator attach fittings on the inboard and outboard flaps, and perform an ultrasonic inspection to detect cracks around the lower bearing journal of the actuator attach fittings on the outboard flaps, in accordance with Boeing Service Bulletin 74757A2310, Revision 1, dated November 23, 1999; or Revision 2, dated February 22, 2001.

Note 2: For the purposes of this AD, a detailed visual inspection is defined as: ``An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.''

Note 3: Inspections and replacements accomplished in accordance with Boeing Alert Service Bulletin 74757A2310, dated June 17, 1999, are acceptable for compliance with the requirements of paragraph (c) of this AD.
(1) If no corrosion or cracks are detected, repeat the inspections required by paragraph (c) of this AD at intervals not to exceed 18 months. Within 5 years after the initial inspections required by paragraph (c) of this AD, accomplish the actions specified in paragraph (d) or (e) of this AD.
(2) If any corrosion is detected, prior to further flight, remove the corrosion by accomplishing the actions of either paragraph (c)(2)(i) or (c)(2)(ii) of this AD.
(i) If corrosion is within the limits of the Boeing 747 OHM: Prior to further flight, accomplish the actions specified in paragraph (d) or (e) of this AD.
(ii) If corrosion is not within the limits of the Boeing 747

FOR FURTHER INFORMATION CONTACT Tamara L. Anderson, Aerospace Engineer, Airframe Branch, ANM120S, FAA, Seattle Aircraft
Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055 4056; telephone (425) 2272771; fax (425) 2271181.