[Federal Register Volume 64, Number 161 (Friday, August 20, 1999)]
[Proposed Rules]
[Pages 45481-45483]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-21686]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 99-NM-88-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 747-100 and -200 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 747-100 and -
200 series airplanes. This proposal would require repetitive
inspections of the upper and lower chords of the wing front spar for
cracks, and corrective action, if necessary. For airplanes on which no
cracking is detected, this proposal would also provide optional
terminating action in lieu of repetitive inspections. This proposal is
prompted by reports of cracks in the upper chord of the wing front
spar. The actions specified by the proposed AD are intended to detect
and correct fatigue cracking of the upper and lower chords of the wing
front spar, which could result in reduced structural capability and
possible fuel leakage onto an engine and a resultant fire.
DATES: Comments must be received by October 4, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 99-NM-88-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-88-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-88-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The FAA has received reports of cracks in the upper chord of the
wing front spar at the fastener holes in the area of the number 2 and
number 3 strut outboard upper link fitting. The cracks are believed to
initiate by fatigue on the forward surface of the chord and propagate
into the thickness of the part. The lower chord of the wing front spar
is similar in design to the upper chord; therefore, the lower chord may
be subject to the same unsafe condition. This condition, if not
corrected, could result in reduced structural capability and possible
fuel leakage onto an engine and resultant fire.
Explanation of Relevant Service Information
The FAA has reviewed and approved Boeing Service Bulletin 747-57-
2305, Revision 1, dated January 21, 1999, which describes procedures
for repetitive ultrasonic inspections of the upper and lower chords of
the wing front spar for cracks, and corrective action, if necessary.
The corrective action involves accomplishment of a terminating action
that includes a high frequency eddy current inspection of the upper and
lower chords of the spar, repair of cracks, and installation of
oversized fasteners. For airplanes on which cracking is not detected,
accomplishment of the terminating action is optional, and eliminates
the need for the repetitive inspections.
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, except as discussed below.
This proposed AD also would provide optional terminating action for the
repetitive inspections for airplanes on which no cracking is detected.
Operators should note that the FAA has determined that the
repetitive inspections proposed by this AD can be
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allowed to continue in lieu of accomplishment of a terminating action.
In making this determination, the FAA considers that, in this case,
long-term continued operational safety will be adequately assured by
accomplishing the repetitive inspections to detect fatigue cracking of
the upper and lower chords of the wing front spar before it represents
a hazard to the airplane.
Differences Between the Proposed Rule and Service Bulletin
Boeing Service Bulletin 747-57-2305, Revision 1, specifies
accomplishment of the actions that would be required by paragraphs (a)
and (b) of this AD in accordance with either the Boeing-specified
manuals or ``operator's equivalent procedure.'' However, this proposed
AD would require that the ultrasonic inspection and high frequency eddy
current inspection actions required by those paragraphs be accomplished
in accordance with the procedures specified in the Boeing 747 NDT
Manual D6-7170. ``Operator's equivalent procedures'' may be used for
Boeing-specified manuals with the exception of the Boeing 747 NDT
Manual D6-7170. ``Operator's equivalent procedures'' to the Boeing 747
NDT Manual D6-7170 may be used only if approved as an alternative
method of compliance in accordance with paragraph (c) of this AD.
Operators should note that, although the 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. For a repair method to be approved by the Manager,
Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane
Directorate, as specified by paragraph (a)(3) of this proposed AD, the
Manager's approval letter must specifically reference this AD.
Cost Impact
There are approximately 332 airplanes of the affected design in the
worldwide fleet. The FAA estimates that 137 airplanes of U.S. registry
would be affected by this proposed AD, that it would take approximately
2 work hours per airplane to accomplish the proposed inspection, and
that the average labor rate is $60 per work hour. Based on these
figures, the cost impact of the proposed AD on U.S. operators is
estimated to be $16,440, or $120 per airplane, per inspection cycle.
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 elect to accomplish the optional terminating
action rather than continue the repetitive inspections, it would take
approximately 37 work hours per airplane to accomplish the
modification, at an average labor rate of $60 per work hour. Required
parts would cost approximately $5,000 per airplane. Based on these
figures, the cost impact of this optional terminating action is
estimated to be $7,220 per airplane.
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-88-AD.
Applicability: Model 747-100 and -200 series airplanes, listed
in Boeing Service Bulletin 747-57-2305, Revision 1, dated January
21, 1999, 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 (d) 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 upper and lower
chords of the wing front spar, which could result in reduced
structural capability and possible fuel leakage onto an engine and a
resultant fire, accomplish the following:
Inspections and Corrective Action
(a) Prior to the accumulation of 12,000 total flight cycles, or
within 24 months after the effective date of this AD, whichever
occurs later, accomplish an ultrasonic inspection for cracking of
the upper and lower chord of the wing front spar, in accordance with
Boeing Service Bulletin 747-57-2305, Revision 1, dated January 21,
1999.
(1) If no cracking is found, repeat this inspection thereafter
at intervals not to exceed 6,000 flight cycles, until the
requirements of paragraph (c) of this AD have been accomplished.
(2) If any cracking is found, prior to further flight,
accomplish ``Part 2--Terminating Action'' of the Accomplishment
Instructions of the service bulletin, except as provided by
paragraph (b) of this AD. Accomplishment of this action constitutes
terminating action for the requirements of this AD.
(b) During accomplishment of the terminating action required by
paragraph (a)(2) of this AD, if any crack is found in the upper
chord that is outside the limits specified in Boeing Service
Bulletin 747-57-2305, Revision 1, dated January 21, 1999; or if any
crack is found in the lower chord; prior to further flight, repair
in accordance with a method approved by the Manager, Seattle
Aircraft Certification Office (ACO), FAA, Transport Airplane
Directorate; or in
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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. For a repair method to be approved by the Manager, Seattle
ACO, as required by this AD, the Manager's approval letter must
specifically reference this AD.
Optional Terminating Action
(c) Accomplishment of ``Part 2--Terminating Action'' of the
Accomplishment Instructions of Boeing Service Bulletin 747-57-2305,
Revision 1, dated January 21, 1999, constitutes terminating action
for the requirements of this AD.
Alternative Methods of Compliance
(d) 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 2: 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
(e) Special flight permits may be issued in accordance with
Secs. 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 August 16, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-21686 Filed 8-19-99; 8:45 am]
BILLING CODE 4910-13-P
