[Federal Register Volume 59, Number 49 (Monday, March 14, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-5853]
[[Page Unknown]]
[Federal Register: March 14, 1994]
VOL. 59, NO. 49
Monday, March 14, 1994
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 93-NM-204-AD]
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
in the upper row of fasteners in the lower lobe of the fuselage skin
lap joints, and repair, if necessary. This proposal is prompted by
reports of incidents involving fatigue cracking and corrosion in
transport category airplanes that are approaching or have exceeded
their design life goal. The actions specified by the proposed AD are
intended to prevent separation of the fuselage skin and rapid loss of
pressure in the airplane. This proposal also relates to the
recommendations of the Airworthiness Assurance Task Force assigned to
review Model 747 series airplanes, which indicate that, to assure long
term continued operational safety, various structural inspections
should be accomplished.
DATES: Comments must be received by May 9, 1994.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 93-NM-204-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056. Comments may be inspected at this
location between 9 a.m. and 3 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: Steven C. Fox , Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056; telephone (206) 227-2777; fax (206) 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 93-NM-204-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-103, Attention: Rules
Docket No. 93-NM-204-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
In April 1988, a transport category airplane managed to land after
cracks in rivet holes in the upper fuselage linked together, causing
structural failure and uncontrolled decompression. An 18-foot section
ripped from the fuselage. This accident focused greater attention on
the problem of aging aircraft.
In June 1988, the FAA sponsored a conference on aging airplane
issues, which was attended by representatives of the aviation industry
from around the world. It became obvious that, because of the
tremendous increase in air travel, the relatively slow pace of new
airplane production, and the apparent economic feasibility of operating
older technology airplanes rather than retiring them, increased
attention needed to be focused on this aging fleet and maintaining its
continued operational safety.
The Air Transport Association (ATA) of America and the Aerospace
Industries Association (AIA) of America committed to identifying and
implementing procedures to ensure continuing structural airworthiness
of aging transport category airplanes. An Airworthiness Assurance Task
Force, with representatives from the aircraft operators, manufacturers,
regulatory authorities, and other aviation representatives, was
established in August 1988. The objective of the Task Force was to
sponsor ``Working Groups'' to:
1. Select service bulletins, applicable to each airplane model in
the transport fleet, to be recommended for mandatory modification of
aging airplanes,
2. Develop corrosion directed inspections and prevention programs,
3. Review the adequacy of each operator's structural maintenance
program,
4. Review and update the Supplemental Structural Inspection
Documents (SSID), and
5. Assess repair quality.
The Working Group assigned to review the Boeing Model 747 series
airplanes completed its work on Item 2 in July 1989 and developed a
baseline program for controlling corrosion problems that may jeopardize
the continued airworthiness of the Boeing Model 747 fleet. This program
is contained in Boeing Document Number D6-36022, ``Aging Airplane
Corrosion Prevention and Control Program--Model 747,'' dated July 1989.
The FAA issued AD 90-25-05, Amendment 39-6790 (55 FR 49268, November
27, 1990), which requires implementation of a corrosion prevention and
control program.
The Working Group completed a portion of its work on Item 1, above.
The Working Group's proposal is contained in Boeing Document Number D6-
35999, ``Aging Airplane Service Bulletin Structural Modification
Program--Model 747.'' The FAA issued AD 90-06-06, Amendment 39-6490 (55
FR 8374, March 7, 1990), which requires the installation of the
structural modifications identified in the Boeing Document, and AD 92-
27-04, Amendment 39-8437 (58 FR 8693, February 17, 1993), which
requires structural inspections of older airplanes.
Additional structural inspections are required by AD 86-09-07 R1,
Amendment 39-5580 (52 FR 7564, March 12, 1987), which references Boeing
Alert Service Bulletin 747-53A2267, dated March 28, 1986, and Revision
1, dated September 25, 1986.
The action being proposed herein follows from the ongoing
activities of the Working Group relative to Item 1. The Working Group
has identified certain service difficulties that warrant mandatory
inspections following mandatory modification of these airplanes. The
Working Group considers that these service difficulties can be
controlled safely by repetitively inspecting following modification of
these airplanes, and that, because of the safety implications, the
inspections should be mandatory to assure that all operators perform
them. Typically, the addressed unsafe conditions have occurred
infrequently on older airplanes, and the Working Group has a very high
degree of confidence in the ability of an inspection program to detect
the damage before it impairs safety.
The Working Group has reviewed Boeing Service Bulletin 747-53A2267,
and has recommended it to the FAA for mandatory inspection following
modification to ensure the successful long-term operation of Model 747
series airplanes. The procedures contained in this service bulletin
address reports of corrosion and cracking in the body skin of the lap
joints under the wing-to-body fairing on Model 747 series airplanes
that had accumulated between 21,500 flight hours and 33,000 flight
hours. Operators have also reported finding corrosion and cracks at the
lower body lap joints forward and aft of the wing-to-body fairing on
airplanes that had accumulated more than 9,000 flight hours.
Additionally, operators have reported finding fatigue cracking in the
body frames adjacent to the lap joints on airplanes that had
accumulated more than 10,000 flight cycles. Continued operation of
these airplanes with corroded lap joints and cracked or broken adjacent
frames could cause the skin to separate, which could lead to rapid loss
of pressure in the airplane.
The FAA has concurred with the Working Group's recommendations and
has determined that AD action is warranted to mandate the inspections
to assure the continued airworthiness of the Model 747 fleet.
The FAA has reviewed and approved Revision 3 of Boeing Service
Bulletin 747-53A2267, dated March 26, 1992, that describes procedures
for external high frequency eddy current (HFEC) inspections to detect
cracking in the upper row of fasteners in the lower lobe of the
fuselage skin lap joints. Certain inspections to detect cracking of the
lower lobe lap joints described in this service bulletin are required
by AD 86-09-07 R1, which references the original issue of this service
bulletin, dated March 8, 1986, and Revision 1, dated September 25,
1986. The ``full'' modification (including the ``permanent'' repair)
and the ``optional'' modification of the lower lobe lap joints
described in this service bulletin are required by AD 90-06-06, which
also references both the original issue of this service bulletin and
Revision 1. The inspections to detect corrosion described in this
service bulletin are required by AD 90-25-05, Amendment 39-6790 (55 FR
49268, November 27, 1990).
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 repetitive external high frequency eddy
current inspections to detect cracking in the upper row of fasteners in
modified lap joints, and repair, if necessary. The inspections would be
required to be accomplished in accordance with the service bulletin
described previously.
The requirements of this proposed AD are not intended to duplicate,
rescind, or supersede the requirements of AD 86-09-07 R1, AD 90-06-06,
or AD 90-25-05. The FAA's intent is to require the external HFEC
inspections, described above, of older airplanes following the
mandatory modifications required by AD 90-06-06, in addition to those
inspections required by AD 86-09-07 R1 and AD 90-25-05.
There are approximately 200 Model 747 series airplanes of the
affected design in the worldwide fleet. The FAA estimates that 118
airplanes of U.S. registry would be affected by this proposed AD, that
it would take approximately 124 work hours per airplane to accomplish
the proposed actions, and that the average labor rate is $55 per work
hour. Based on these figures, the total cost impact of the proposed AD
on U.S. operators is estimated to be $804,760, or $6,820 per airplane.
This total cost figure assumes that no operator has yet accomplished
the proposed requirements of this AD action.
The FAA recognizes that the proposed inspections would require a
large number of work hours to accomplish. However, the compliance times
specified in paragraph (a) of this proposed AD should allow ample time
for the inspections to be accomplished coincidentally with scheduled
major airplane inspection and maintenance activities, thereby
minimizing the costs associated with special airplane scheduling.
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 14
CFR part 39 of the Federal Aviation Regulations as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.
106(g); and 14 CFR 11.89.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
Boeing: Docket 93-NM-204-AD.
Applicability: Model 747 series airplanes having line positions
1 through 200 inclusive; certificated in any category.
Compliance: Required as indicated, unless accomplished
previously.
To prevent separation of fuselage skin and rapid loss of
pressure in the airplane, accomplish the following: (a) Perform an
external high frequency eddy current inspection to detect cracks in
the upper row of fasteners in the modified lap joints in accordance
with Boeing Service Bulletin 747-53A2267, Revision 3, dated March
26, 1992, at the time specified in paragraph (a)(1) or (a)(2) or
(a)(3) of this AD, as applicable.
(1) For airplanes on which the full modification required by AD
90-06-06, Amendment 39-6490, has been accomplished in accordance
with Revision 2 of Boeing Service Bulletin 747-53A2267, dated March
29, 1990, or Revision 3, dated March 26, 1992: Prior to the
accumulation of 10,000 flight cycles after accomplishment of the
full modification.
(2) For airplanes on which the full modification required by AD
90-06-06, Amendment 39-6490, has been accomplished in accordance
with Boeing Service Bulletin 747-53A2267, dated March 8, 1986, or
Revision 1, dated September 25, 1986: Prior to the accumulation of
7,000 flight cycles after accomplishment of the full modification.
(3) For airplanes on which the optional modification has been
accomplished in accordance with Boeing Service Bulletin 747-53A2267,
dated March 28, 1986; or Revision 1, dated September 25, 1986; or
Revision 2, dated March 29, 1990; or Revision 3, dated March 26,
1992: Prior to the accumulation of 7,000 flight cycles after
accomplishment of the optional modification.
(b) If no cracking is detected, repeat these inspections
thereafter at intervals not to exceed 3,000 flight cycles.
(c) If any cracking is detected, prior to further flight, repair
in accordance with the Section 53-30-03 of the 747 Structural Repair
Manual, and repeat these inspections thereafter at intervals not to
exceed 3,000 flight cycles.
(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 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: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
(e) Special flight permits may be issued in accordance with
Federal Aviation Regulations (FAR) 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 8, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 94-5853 Filed 3-11-94; 8:45 am]
BILLING CODE 4910-13-U
