[Federal Register Volume 64, Number 161 (Friday, August 20, 1999)]
[Proposed Rules]
[Pages 45466-45468]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-21693]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-NM-282-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 inspections to detect
broken fasteners and cracking of the forward edge frame for main entry
door number 3, and repair, if necessary. This proposal is prompted by
reports of fatigue cracks at the inner chord and web of the body
station 1265 edge frame between stringers 23 and 27. The actions
specified by the proposed AD are intended to detect and correct such
cracking, which could result in rapid depressurization of the airplane.
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. 98-NM-282-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: Robert Breneman, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056; telephone (425) 227-2776; 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.
[[Page 45467]]
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 98-NM-282-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. 98-NM-282-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The FAA has received reports indicating that fatigue cracking has
been detected in the frame web and frame inner chord at stringer 26 at
body station 1265. In addition, one report indicates that, on one
airplane, the fuselage frame web and frame inner chord had severed
above stringer 24 near the top of a frame inner chord reinforcement
strap. This frame is the forward edge frame for main entry door number
3. Such fatigue cracking, if not detected and corrected in a timely
manner, could result in rapid depressurization of the airplane.
Explanation of Relevant Service Information
The FAA has reviewed and approved Boeing Alert Service Bulletin
747-53A2416, Revision 1, dated May 6, 1999, which describes procedures
for repetitive inspections to detect broken fasteners and cracking of
the forward edge frame for main entry door number 3, and repair, if
necessary. The inspection of the frames at the floor intercostal
includes a detailed visual inspection for broken fasteners, an open
hole high frequency eddy current (HFEC) inspection of certain fasteners
in the frame inner chord to detect cracking, and a surface HFEC
inspection of the frame web to detect cracking. For certain airplanes,
the service bulletin recommends a surface HFEC inspection and an open
hole HFEC inspection of the frames at the top of the inner chord
reinforcement strap to detect cracking. 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 AD
Operators should note that, although the alert service bulletin
specifies that the manufacturer may be contacted for repair data for
cracking conditions, this AD requires 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.
The alert service bulletin also indicates that a modification to
the frame and lateral intercostal can be made that will increase the
interval between frame inspections, and that the procedures for such a
modification will be included in a subsequent revision to the alert
service bulletin. Any modification incorporated to increase the
interval between inspections or as terminating action for the
inspections must be approved as an alternative method of compliance in
accordance with paragraph (d) of this AD.
Cost Impact
There are approximately 1,182 airplanes of the affected design in
the worldwide fleet. The FAA estimates that 251 airplanes of U.S.
registry would be affected by this proposed AD.
It would take approximately 1 work hour per airplane to accomplish
the proposed inspection of the frames at the floor intercostal, at an
average labor rate of $60 per work hour. Based on these figures, the
cost impact of this proposed inspection on U.S. operators is estimated
to be $15,060, or $60 per airplane, per inspection cycle.
The FAA estimates that the proposed inspection of the frames at the
top of the inner chord reinforcement strap would be required to be
accomplished on 103 U.S.-registered airplanes. It would take
approximately 1 work hour per airplane to accomplish the proposed
inspection, at an average labor rate of $60 per work hour. Based on
these figures, the cost impact of this proposed inspection on U.S.
operators is estimated to be $6,180, or $60 per airplane, per
inspection cycle.
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 98-NM-282-AD.
Applicability: Model 747 series airplanes, as listed in Boeing
Alert Service Bulletin 747-53A2416, Revision 1, dated May 6, 1999;
certificated in any category.
Note 1: This AD applies to airplanes that have been converted
from a passenger configuration to a special freighter configuration.
Note 2: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
[[Page 45468]]
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 cracking of the inner chord and web of the
body station 1265 edge frame between stringers 23 and 27, which
could result in rapid depressurization of the airplane, accomplish
the following:
Inspections
(a) Accomplish the flight safety inspections of the frames at
the floor intercostal to detect broken fasteners and cracking, in
accordance with Figure 5 of Boeing Alert Service Bulletin 747-
53A2416, Revision 1, dated May 6, 1999, at the applicable time
specified in paragraph (a)(1), (a)(2), or (a)(3) of this AD. Repeat
the inspection thereafter at intervals not to exceed 3,000 flight
cycles.
Note 3: Figure 5 of the alert service bulletin includes a
detailed visual inspection for broken fasteners, an open hole high
frequency eddy current (HFEC) inspection of certain fasteners in the
frame inner chord to detect cracking, and a surface HFEC inspection
of the frame web to detect cracking.
Note 4: 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 5: The alert service bulletin gives instructions to perform
an open hole inspection, but does not give instructions to oversize
the fastener hole after the inspection. This will keep sufficient
material to oversize the hole at a later date when the modification
work is accomplished.
(1) For airplanes that have accumulated fewer than 10,000 total
flight cycles as of the effective date of this AD: Inspect prior to
the accumulation of 10,000 total flight cycles, or within 1,000
flight cycles after the effective date of this AD, whichever occurs
later.
(2) For airplanes that have accumulated between 10,000 and
20,000 total flight cycles as of the effective date of this AD:
Inspect prior to the accumulation of 11,000 total flight cycles, or
within 750 flight cycles after the effective date of this AD,
whichever occurs later.
(3) For airplanes that have accumulated more than 20,000 total
flight cycles as of the effective date of this AD: Inspect prior to
the accumulation of 20,750 total flight cycles, or within 500 flight
cycles after the effective date of this AD, whichever occurs later.
(b) For Group 1 airplanes, as identified in Boeing Alert Service
Bulletin 747-53A2416, Revision 1, dated May 6, 1999, on which the
extended chord reinforcement strap modification specified in Boeing
Service Bulletin 747-53-2066, dated June 28, 1972, has not been
accomplished or on which the extended chord reinforcement strap
modification was accomplished after the accumulation of 10,000 total
flight cycles: Accomplish the surface HFEC inspection and the open
hole HFEC inspection, as applicable, of the frames at the top of the
inner chord reinforcement strap to detect cracking, in accordance
with Figure 6 of the alert service bulletin at the applicable time
specified in either paragraph (b)(1) or (b)(2) of this AD. Repeat
the inspection thereafter at intervals not to exceed 800 flight
cycles.
(1) For airplanes that have accumulated 20,000 total flight
cycles or fewer as of the effective date of this AD: Inspect prior
to the accumulation of 16,000 total flight cycles, or within 500
flight cycles after the effective date of this AD, whichever occurs
later.
(2) For airplanes that have accumulated more than 20,000 total
flight cycles as of the effective date of this AD: Inspect prior to
the accumulation of 20,500 total flight cycles, or within 250 flight
cycles after the effective date of this AD, whichever occurs later.
Repair
(c) If any broken fastener or cracking is detected during the
inspections required by paragraph (a) or (b) of this AD, 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 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 Manager's approval letter must specifically reference
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 6: 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. 99-21693 Filed 8-19-99; 8:45 am]
BILLING CODE 4910-13-P
