[Federal Register Volume 63, Number 59 (Friday, March 27, 1998)]
[Proposed Rules]
[Pages 14863-14865]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-8133]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-NM-309-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 repetitive detailed visual
inspections to detect corrosion on the rear spar web of the wing center
section and adjacent bulkhead fittings at body station 1241; and
corrective action, if necessary. This proposal is prompted by reports
of corrosion found on the rear spar web and bulkhead fitting. The
actions specified by the proposed AD are intended to detect and correct
such corrosion, which could cause cracking of the rear spar web, and
result in a fuel leak and consequent fire/explosion in the wheel well
of the main landing gear.
DATES: Comments must be received by May 11, 1998.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 97-NM-309-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: Bob Breneman, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office,
1601 Lind Avenue, SW., Renton, Washington; telephone (425) 227-2776;
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 97-NM-309-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. 97-NM-309-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The FAA has received reports of corrosion found on Boeing Model 747
series airplanes. The corrosion was found on the rear spar web and the
bulkhead fitting of body station 1241; corrosion thicknesses ranged
from 0.030 to 0.250 inch. Investigation revealed that moisture trapped
between the rear
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spar web and the bulkhead fitting resulted in the corrosion. Such
corrosion, if not detected and corrected in a timely manner, could
cause cracking of the rear spar web, and result in a fuel leak and
consequent fire/explosion in the wheel well of the main landing gear.
Explanation of Relevant Service Information
The FAA has reviewed and approved Boeing Service Bulletin 747-57-
2263, Revision 1, dated December 21, 1995, which describes procedures
for repetitive detailed visual inspections to detect corrosion of the
rear spar web of the wing center section and adjacent bulkhead fittings
at body station 1241; and corrective action, if necessary.
Accomplishment of the actions specified in the 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 service bulletin described previously, except as discussed in the
following section.
Differences Between Proposed Rule and Service Bulletin
Operators should note that, while the service bulletin specifies
that the application of corrosion inhibitor following an inspection
eliminates the necessity for further inspections, this proposed AD
would require that the inspection be repeated at regular intervals. The
FAA has determined that repetitive inspections and corrective action
are necessary in order to detect and correct corrosion in a timely
manner and to adequately address the identified unsafe condition.
Additionally, operators should note that, although the service
bulletin specifies that the manufacturer may be contacted for
disposition of certain repair conditions, this proposal would require
that the repair of those conditions be accomplished in accordance with
a method approved by the FAA.
Cost Impact
There are approximately 816 airplanes of the affected design in the
worldwide fleet. The FAA estimates that 236 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 actions, 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
$28,320, 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.
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 97-NM-309-AD.
Applicability: Model 747 series airplanes, line positions 1
through 816 inclusive, 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 (b) 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 corrosion and consequent cracking of the
rear spar web of the wing center section and adjacent bulkhead
fittings at body station 1241, which could result in a fuel leak and
subsequent fire/explosion in the wheel well of the main landing
gear, accomplish the following:
(a) Within 18 months after the effective date of this AD,
perform a detailed visual inspection to detect corrosion of the rear
spar web of the wing center section and adjacent bulkhead fittings
at body station 1241, in accordance with Boeing Service Bulletin
747-57-2263, Revision 1, dated December 21, 1995. Thereafter, repeat
the inspection at intervals not to exceed 2 years.
(1) If no corrosion is detected during the inspection: Prior to
further flight, apply corrosion inhibitor in accordance with the
service bulletin.
(2) If any corrosion is detected during the inspection, and the
corrosion is within the limits specified by the service bulletin:
Prior to further flight, accomplish the actions specified in
paragraphs (a)(2)(i), (a)(2)(ii), and (a)(2)(iii).
(i) Remove the corrosion in accordance with the service
bulletin. And
(ii) Perform a high frequency eddy current inspection to detect
cracking in the area of removed corrosion in accordance with the
service bulletin. If any crack is detected, prior to further flight,
repair it in accordance with a method approved by the Manager,
Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane
Directorate. And
(iii) Apply corrosion inhibitor in accordance with the service
bulletin.
(3) If any corrosion is detected during the inspection, and the
corrosion exceeds the limits specified by the service bulletin:
Prior to further flight, repair the corroded area in accordance with
a method approved by the Manager, Seattle ACO.
(b) 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
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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.
(c) 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 March 23, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 98-8133 Filed 3-25-98; 8:45 am]
BILLING CODE 4910-13-U
