[Federal Register Volume 65, Number 147 (Monday, July 31, 2000)]
[Proposed Rules]
[Pages 46672-46674]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-19267]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-134-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 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 certain Boeing Model 747 series 
airplanes. This proposal would require inspections to detect cracking 
of the front spar web of the wing, and corrective action, if necessary. 
This action is necessary to detect and correct fatigue cracking of the 
front spar web, which could result in fuel leaking onto an engine and a 
consequent fire. This action is intended to address the identified 
unsafe condition.

DATES: Comments must be received by September 14, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-134-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: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2000-NM-134-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must

[[Page 46673]]

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: Tamara 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.
    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 2000-NM-134-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. 2000-NM-134-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received a report indicating that an operator found a 
24-inch-long crack in the front spar web of the right wing of a Boeing 
Model 747 series airplane. Metallurgical analysis of the cracked web 
section indicated that three cracks initiated from a hole common to a 
rib post located on the front spar at front spar station inboard (FSSI) 
656. The initiation and propagation of the cracking have been 
attributed to fatigue. This condition, if not corrected, could result 
in fuel leaking onto an engine and a consequent fire.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
747-57A2311, dated January 27, 2000, which describes procedures for 
various repetitive external inspections to detect cracking of the front 
spar web of the wing. The inspections include:
     A detailed visual inspection to detect cracking of the 
front spar web between the seal rib at FSSI 628 and the rib post at 
FSSI 684;
     An ultrasonic inspection to detect cracking of the web 
behind the front spar stiffeners and for horizontal cracks in the web 
under the upper and lower chords between FSSI 628 and FSSI 684; and
     A high frequency eddy current (HFEC) inspection to detect 
vertical cracks in the web near the vertical flanges of the upper and 
lower chords.
    The alert service bulletin also describes procedures for an 
optional web inspection that can be performed in lieu of the external 
web inspections. The optional inspection necessitates less access than 
the external inspection when the fuel tanks are already being accessed 
for other reasons, and is intended to provide an alternative method of 
inspection. The optional method includes:
     Detailed visual inspections from inside the fuel tank to 
detect cracks of the aft side of the web, and from outside the fuel 
tank to detect cracks between the upper and lower chords at the wing 
station (WS) 642 rib post;
     Ultrasonic inspections from outside the fuel tank to 
detect horizontal cracks in the web between the rib post and the upper 
and lower chords at the WS 642 rib post, and to detect cracks in the 
web behind the front spar stiffener at FSSI 628; and,
     An HFEC inspection to detect vertical cracks in the web 
near the vertical flanges of the upper and lower chords at the WS 642 
rib post.
    Accomplishment of the actions specified in the alert service 
bulletin is intended to adequately address the identified unsafe 
condition.

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 alert service bulletin described previously, except as discussed 
below.

Differences Between Alert Service Bulletin and This Proposed AD

    Operators should note that, although the alert service bulletin 
specifies that the manufacturer may be contacted for disposition of 
certain repair conditions, this proposed AD would require the repair of 
those conditions to be accomplished in accordance with a method 
approved by the FAA, or in accordance with data meeting the type 
certification basis of the airplane approved by a Boeing Company 
Designated Engineering Representative who has been authorized by the 
FAA to make such findings.

Cost Impact

    There are approximately 478 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 97 airplanes of U.S. registry 
would be affected by this proposed AD.
    The external inspections that are one option for compliance with 
this proposed AD would take approximately 48 work hours per airplane 
(not including access and close-up), at an average labor rate of $60 
per work hour. Based on these figures, the cost impact of the proposed 
external inspections on U.S. operators is estimated to be $2,880 per 
airplane, per inspection cycle.
    In lieu of accomplishment of the external inspections, this 
proposed AD would provide for an optional web inspection that would 
take approximately 50 work hours per airplane, at an average labor rate 
of $60 per work hour. Based on these figures, the cost impact of the 
proposed optional web inspection on U.S. operators is estimated to be 
$3,000 per airplane, per inspection cycle.

[[Page 46674]]

    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 proposed 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.

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.


Sec. 39.13  [Amended]

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

Boeing: Docket 2000-NM-134-AD.

    Applicability: Model 747 series airplanes, as listed in Boeing 
Alert Service Bulletin 747-57A2311, dated January 27, 2000; 
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 (c) 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 fatigue cracking of the front spar web of 
the wing, which could result in fuel leaking onto an engine and a 
consequent fire, accomplish the following:

Repetitive Inspections

    (a) At the later of the times specified in paragraphs (a)(1) and 
(a)(2) of this AD, perform the Part 1 external web inspection--
including detailed visual, ultrasonic, and high frequency eddy 
current (HFEC) inspections--to detect cracking of the front spar web 
of the wing, in accordance with Boeing Alert Service Bulletin 747-
57A2311, dated January 27, 2000. In lieu of the Part 1 external web 
inspection, accomplishment of the Part 2 optional web inspection to 
detect cracking--which also includes detailed visual, ultrasonic, 
and HFEC inspections--in accordance with Boeing Alert Service 
Bulletin 747-57A2311, dated January 27, 2000, is acceptable for 
compliance with this paragraph. Repeat the inspections thereafter at 
intervals not to exceed 2,000 flight cycles.

    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.''

    (1) Prior to the accumulation of 13,000 total flight cycles or 
30,000 total flight hours, whichever occurs first.
    (2) Within 18 months after the effective date of this AD.

Repair

    (b) If any cracking is detected during any inspection required 
by paragraph (a) of this AD, prior to further flight, repair in 
accordance with a method approved by the Manager, Seattle Aircraft 
Certification Office (ACO), FAA; or in accordance with data meeting 
the type certification basis of the airplane approved by a Boeing 
Company Designated Engineering Representative who has been 
authorized by the Manager, Seattle ACO, to make such findings. For a 
repair method to be approved by the Manager, Seattle ACO, as 
required by this paragraph, the approval letter must specifically 
reference this AD.

Alternative Methods of Compliance

    (c) 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 ACO. 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 3: 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

    (d) 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 July 25, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-19267 Filed 7-28-00; 8:45 am]
BILLING CODE 4910-13-U