[Federal Register Volume 65, Number 79 (Monday, April 24, 2000)]
[Proposed Rules]
[Pages 21675-21677]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-10162]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-313-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-100, -200, -300, -400, 
and 747SR Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to all Boeing Model 747-100, -200, -
300, -400, and 747SR series airplanes. This proposal would require 
repetitive inspections to detect cracks and corrosion around the lower 
bearing of the actuator attach fittings of the inboard and outboard 
flaps. This proposal also would require repetitive overhauls for 
certain attach fittings or repetitive replacement of the attach 
fittings with new attach fittings, as applicable, which would 
constitute terminating action for certain repetitive actions. This 
proposal is prompted by reports of cracks on the lower bearing journal 
of the inboard actuator attach fittings of the outboard trailing edge 
flaps due to stress corrosion. The actions specified by the proposed AD 
are intended 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.

DATES: Comments must be received by June 8, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-313-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: Tamara L. Anderson, Aerospace 
Engineer, Airframe Branch, ANM-120S, FAA, Transport Airplane 
Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, 
SW., Renton, Washington 98055-4056; telephone (425) 227-2771; 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-313-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-313-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports of stress corrosion cracks on the 
lower

[[Page 21676]]

bearing journal of the number 2 and 7 inboard attach fittings of the 
outboard trailing edge flaps on Boeing Model 747-200 and -300 series 
airplanes. Each flap assembly has two attach fittings, one on each 
ballscrew which is attached to the flap transmission. Such cracking, if 
not detected and corrected, could result in abnormal operation or 
retraction of a trailing edge flap, and consequent reduced 
controllability of the airplane.
    The subject actuator attach fittings on the inboard and outboard 
flaps on Boeing Model 747-100, -400, and 747SR series airplanes are 
identical to that of the affected Boeing Model 747-200 and -300 series 
airplanes. Therefore, all of these airplanes may be subject to the same 
unsafe condition.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 747-
57A2310, Revision 1, dated November 23, 1999. This service bulletin 
describes procedures for repetitive ultrasonic and detailed visual 
inspections (as applicable) to detect cracks and corrosion around the 
lower bearing of the actuator attach fittings of the inboard and 
outboard flaps. This service bulletin also describes procedures for 
repetitive overhauls for the attach fittings on the outboard flaps or 
repetitive replacement of the attach fittings with new attach fittings, 
as applicable, which would eliminate the need for certain repetitive 
actions. In addition, the service bulletin describes procedures for 
accomplishing a terminating action for the inboard flap attach 
fittings.

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 require accomplishment of the actions specified in 
the service bulletin described previously.

Interim Action

    This is considered to be interim action. The manufacturer has 
advised that it currently is developing a modification that will 
positively address the unsafe condition addressed by this AD. Once this 
modification is developed, approved, and available, the FAA may 
consider additional rulemaking.

Cost Impact

    There are approximately 1,008 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 206 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(s), at an average labor rate of $60 per work 
hour. Based on these figures, the cost impact of the inspection(s) 
proposed by this AD on U.S. operators is estimated to be $24,720, or 
$120 per airplane, per inspection cycle.
    Should an operator be required to accomplish the proposed overhaul, 
it would take approximately 5 work hours per airplane to accomplish at 
an average labor rate of $60 per work hour. Based on these figures, the 
cost impact of the overhaul proposed by this AD on U.S. operators is 
estimated to be $61,800, or $300 per airplane, per overhaul cycle.
    Should an operator be required to accomplish the proposed 
replacement, it would take approximately 2 work hours per airplane to 
accomplish at an average labor rate of $60 per work hour. Required 
parts would cost approximately $6,623 (for each of the 4 attach 
fittings on the outboard flaps) and $7,566 (for each 4 attach fittings 
on the inboard flaps) per airplane. Based on these figures, the cost 
impact of the replacement proposed by this AD on U.S. operators is 
estimated to be $26,972 (outboard flaps) and $30,744 (inboard flaps) 
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.

Regulatory Impact

    The regulations proposed herein would not have substantial direct 
effects 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, in 
accordance with Executive Order 12612, it is determined that this 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    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.


Sec. 39.13  [Amended]

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

Boeing: Docket 99-NM-313-AD.

    Applicability: All Model 747-100, -200, -300, -400, and 747SR 
series airplanes; 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 (f) 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:

Attach Fittings That Have Not Been Overhauled or Replaced

    (a) For attach fittings on the outboard flaps that have not been 
overhauled in accordance with Boeing 747 OHM 57-52-55, dated June 1, 
1997, or replaced with a new fitting; and for attach fittings on the 
inboard actuators that have not been replaced with a new fitting: 
Accomplish the actions of paragraph (c) of this AD at the later of 
the times specified in paragraphs (a)(1) and (a)(2) of this AD.

[[Page 21677]]

    (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.

Attach Fittings That Have Been Overhauled or Replaced

    (b) For attach fittings on the outboard flaps that have been 
overhauled in accordance with Boeing 747 OHM 57-52-55, dated June 1, 
1997, prior to the effective date of this AD, or replaced with a new 
fitting; and for attach fittings on the inboard actuators that have 
been replaced with a new fitting: Accomplish the actions of 
paragraph (c) 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 attach 
fittings of the outboard flaps, in accordance with Boeing Service 
Bulletin 747-57A2310, Revision 1, dated November 23, 1999.

    Note 2: For the purposes of this AD, a detailed 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 
mirrors, 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 747-57A2310, 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 Overhaul 
Manual, 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 
Overhaul Manual, prior to further flight, accomplish the actions 
specified in paragraph (e) of this AD.
    (3) If any crack is detected, prior to further flight, 
accomplish the actions specified in paragraph (e) of this AD.

Overhaul

    (d) Overhaul the actuator attach fittings on the outboard flaps 
in accordance with Boeing OHM 57-52-55, Temporary Revision 57-7, 
dated June 1, 1999. Repeat the overhaul of actuators on the outboard 
flaps as specified in Part 2 of the Work Instructions of the service 
bulletin thereafter at intervals not to exceed 8 years or 8,000 
flight cycles, whichever occurs first. Accomplishment of the 
overhaul of the attach fittings on the outboard flaps constitutes 
terminating action for the repetitive inspection requirements of 
paragraph (c)(1) of this AD. Overhaul the attach fittings on the 
inboard flaps in accordance with Boeing OHM 57-52-35, Temporary 
Revision 57-8, dated June 10, 1999. Accomplishment of the overhaul 
of the actuators on the inboard flaps constitutes terminating action 
for the requirements of this AD for the inboard flap attach 
fittings.

Replacement

    (e) Replace the attach fittings on the inboard and outboard flap 
actuators with new attach fittings in accordance with Boeing Service 
Bulletin 747-57A2310, Revision 1, dated November 23, 1999. 
Accomplishment of the replacement constitutes terminating action for 
the repetitive inspection and overhaul requirements of paragraphs 
(c)(1), (c)(2), and (c)(3) of this AD. Within 8 years or 8,000 
flight cycles following accomplishment of the replacement, whichever 
occurs first, repeat the replacement or accomplish the overhaul 
specified in paragraph (d) of this AD.

    Note 4: Replacement of the attach fitting on the inboard flaps 
with fittings that have been overhauled in accordance with Boeing 
OHM 57-52-35, Temporary Revision 57-8, dated June 10, 1999, 
constitutes terminating action for the requirements of this AD for 
the inboard flap attach fittings.

Alternative Methods of Compliance

    (f) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Seattle Aircraft Certification 
Office (ACO), FAA, Transport Airplane Directorate. Operators shall 
submit their requests through an appropriate FAA Principal 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Seattle ACO.

    Note 5: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Special Flight Permits

    (g) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.

    Issued in Renton, Washington, on April 18, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-10162 Filed 4-21-00; 8:45 am]
BILLING CODE 4910-13-U