[Federal Register Volume 59, Number 136 (Monday, July 18, 1994)]
[Unknown Section]
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From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-17326]
[[Page Unknown]]
[Federal Register: July 18, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 94-NM-14-AD]
Airworthiness Directives; Boeing Model 707 and 720 Series
Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the supersedure of an existing
airworthiness directive (AD), applicable to certain Boeing Model 707
and 720 series airplanes, that currently requires repetitive visual and
dye penetrant inspections to detect cracks on the upper forward skin
panels of the wing center section, and repair, if necessary. That AD
also provided an optional terminating modification for the repetitive
inspections. This action would require visual and eddy current
inspections to detect cracks on the upper forward skin panels of the
wing center section, and repair, if necessary. This proposal is
prompted by reports that the currently required inspections are not
effective in detecting fatigue cracks in a timely manner. The actions
specified by the proposed AD are intended to prevent fatigue cracking
and subsequent failure of the upper forward skin panels of the wing
center section.
DATES: Comments must be received by October 5, 1994.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 94-NM-14-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: Phil Forde, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056; telephone (206) 227-2771; 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 94-NM-14-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. 94-NM-14-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The FAA issued AD 68-18-03, amendment 39-2056, applicable to
certain Boeing Model 707 and 720 series airplanes, to require
repetitive inspections to detect cracks on the upper forward skin
panels of the wing center section, and repair, if necessary. That AD
also provided an optional terminating modification for the repetitive
inspections. That action was prompted by several reports of fatigue
cracking and one report of skin blowout (failure of the wing skin
panel) on Model 720 series airplanes. Model 707 series airplanes were
included in the applicability of AD 68-18-03 because those airplanes
are similar in design to Model 720 series airplanes. The requirements
of that AD are intended to prevent fatigue cracking and subsequent
failure of the upper forward skin panels of the wing center section.
Since the issuance of AD 68-18-03, the FAA has received several
reports that the visual and dye penetrant inspection techniques
required by that AD have not been effective in detecting cracks in a
timely manner. The FAA, in conjunction with the airplane manufacturer
and the Boeing Model 707 Aging Fleet Structures Working Group (SWG),
conducted a structural review of those airplanes and determined that
inspections using visual and eddy current methods are necessary in
order to effectively detect cracks in a timely manner for airplanes on
which the optional terminating modification specified in AD 68-18-03
has not been accomplished.
Fatigue cracking in the upper forward skin panels of the wing
center section, if not detected and corrected in a timely manner, could
result in failure of the wing skin panels.
The FAA has reviewed and approved Boeing Service Bulletin 2590,
Revision 11, dated December 12, 1991, that describes procedures for
repetitive visual and eddy current inspections to detect cracks in
certain areas of the upper forward skin panels of the wing center
section, and repair, if necessary. This service bulletin is part of
Boeing Master Inspection Service Bulletins 3484 (for Model 707-100 and
-200 airplanes), 3485 (for Model 720 and 720B airplanes), and 3486 (for
Model 707-300, -300B, -300C, and -400 airplanes), all dated December
12, 1991. Boeing Service Bulletin 2590 references these master
inspection service bulletins as additional sources of service
information concerning accomplishment of the repetitive inspections.
The master inspection service bulletins describe an expanded inspection
area that includes a 4-inch wide strip centered on each chordwise bulb
angle stiffener installed in accordance with AD 68-18-03.
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 supersede AD 68-18-03 to require repetitive visual
and eddy current inspections to detect cracks in certain areas of the
upper forward skin panels of the wing center section, and repair, if
necessary. This AD also would provide an optional terminating action
for the repetitive inspections. The actions would be required to be
accomplished in accordance with Boeing Service Bulletin 2590, described
previously.
There are approximately 416 Model 707 and 720 series airplanes of
the affected design in the worldwide fleet. The FAA estimates that 82
airplanes of U.S. registry would be affected by this proposed AD, that
it would take approximately 32 work hours per airplane to accomplish
the proposed inspections, 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 $144,320, or $1,760
per airplane.
The total 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 that would be provided by this AD action, it would take
approximately 1,250 work hours to accomplish it, at an average labor
rate of $55 per work hour. The cost of required parts would be
approximately $45,000 per airplane. Based on these figures, the total
cost impact of the optional terminating action would be $113,750 per
airplane.
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. 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 removing amendment 39-2056, and by
adding a new airworthiness directive (AD), to read as follows:
Boeing: Docket 94-NM-14-AD. Supersedes AD 68-18-03, Amendment 39-
2056.
Applicability: All Model 707 and 720 series airplanes,
certificated in any category.
Compliance: Required as indicated, unless accomplished
previously.
To prevent fatigue cracking and subsequent failure of the upper
forward skin panels of the wing center section, accomplish the
following:
(a) For Model 707-100, -200, -300, -300B, -300C, and -400
airplanes on which no bulb angle stiffeners have been installed in
accordance with Boeing Service Bulletin 2590: Perform a visual
inspection and an eddy current inspection to detect cracks in the
areas of the upper forward skin of the wing center section specified
in paragraphs b. and f.(1) of Part I of the Accomplishment
Instructions of Boeing Service Bulletin 2590, Revision 8, dated June
2, 1972; Revision 9, dated March 14, 1975; Revision 10, dated
January 31, 1991; or Revision 11, dated December 12, 1991. Perform
the inspections at the time specified in paragraph (a)(1) or (a)(2)
of this AD, as applicable, in accordance with the procedures
specified in the service bulletin. Repeat these inspections
thereafter at intervals not to exceed 1,000 landings or 18 months,
whichever occurs first.
(1) For Model 707-300, -300B, -300C, and -400 airplanes: Inspect
at the later of the times specified in paragraphs (a)(1)(i) and
(a)(1)(ii) of this AD.
(i) Prior to the accumulation of 6,000 total landings; or
(ii) Within 500 landings or 18 months after the effective date
of this AD, whichever occurs first.
(2) For Model 707-100 and -200 airplanes: Inspect at the later
of the times specified in paragraphs (a)(2)(i) and (a)(2)(ii) of
this AD.
(i) Prior to the accumulation of 7,000 total landings; or
(ii) Within 500 landings or 18 months after the effective date
of this AD, whichever occurs first.
(b) For Model 720 and 720B airplanes on which no bulb angle
stiffeners have been installed in accordance with Boeing Service
Bulletin 2590: Perform a visual inspection and an eddy current
inspection to detect cracks in the area of the upper forward skin of
the wing center section specified in paragraph b. of Part I of the
Accomplishment Instructions of Boeing Service Bulletin 2590,
Revision 8, dated June 2, 1972; Revision 9, dated March 14, 1975;
Revision 10, dated January 31, 1991; or Revision 11, dated December
12, 1991. Perform the inspections at the later of the times
specified in paragraphs (b)(1) and (b)(2) of this AD, in accordance
with the procedures specified in the service bulletin. Repeat these
inspections thereafter at intervals not to exceed 1,000 landings or
18 months, whichever occurs first.
(1) Prior to the accumulation of 4,000 total landings; or
(2) Within 500 landings or 18 months after the effective date of
this AD, whichever occurs first.
(c) For Model 720 and 720B, and 707-100, -200, -300, -300B, -
300C, and -400 airplanes on which bulb angle stiffeners have been
installed, but on which the wing skin has not been replaced, in
accordance with Boeing Service Bulletin 2590: Accomplish the
inspections required by paragraph (c)(1), (c)(2), or (c)(3) of this
AD, as applicable, in accordance with Boeing Service Bulletin 2590,
Revision 11, dated December 12, 1991. Repeat these inspections
thereafter at intervals not to exceed 1,000 landings or 18 months,
whichever occurs first.
Note 1: Revision 11 of Boeing Service Bulletin 2590 is part of
Boeing Master Inspection Service Bulletins 3484 (for Model 707-100
and -200 airplanes), 3485 (for Model 720 and 720B airplanes), and
3486 (for Model 707-300, -300B, -300C, and -400 airplanes), all
dated December 12, 1991. Boeing Service Bulletin 2590 references
these master inspection service bulletins as additional sources of
service information concerning accomplishment of the inspections
required by paragraph (c) of this AD.
(1) For Model 720 and 720B airplanes: Perform a visual and an
eddy current inspection to detect cracks in the areas of the upper
forward skin of the wing center section specified in Boeing Master
Inspection Service Bulletin 3485, dated December 12, 1991, at the
later of the times specified in paragraphs (c)(1)(i) and (c)(1)(ii)
of this AD.
(i) Prior to the accumulation of 2,200 landings after
installation of the bulb angle stiffeners; or
(ii) Within 500 landings or 18 months after the effective date
of this AD, whichever occurs first.
(2) For Model 707-300, -300B, -300C, and -400 airplanes: Perform
a visual and an eddy current inspection to detect cracks in the
areas of the upper forward skin of the wing center section specified
in Boeing Master Inspection Service Bulletin 3486, dated December
12, 1991, at the later of the times specified in paragraphs
(c)(2)(i) and (c)(2)(ii) of this AD.
(i) Prior to the accumulation of 2,200 landings after
installation of the bulb angle stiffeners; or
(ii) Within 500 landings or 18 months after the effective date
of this AD, whichever occurs first.
(3) For Model 707-100 and -200 airplanes: Perform a visual and
an eddy current inspection to detect cracks in the areas of the
upper forward skin of the wing center section specified in Boeing
Master Inspection Service Bulletin 3484, dated December 12, 1991, at
the later of the times specified in paragraphs (c)(3)(i) and
(c)(3)(ii) of this AD.
(i) Prior to the accumulation of 2,200 landings after
installation of the bulb angle stiffeners; or
(ii) Within 500 landings or 18 months after the effective date
of this AD, whichever occurs first.
(d) If any crack is found during any of the inspections required
by paragraphs (a), (b), and (c) of this AD, prior to further flight,
repair in accordance with Part II of the Accomplishment Instructions
of Boeing Service Bulletin 2590, Revision 7, dated September 22,
1969; Revision 8, dated June 2, 1972; Revision 9, dated March 14,
1975; Revision 10, dated January 31, 1991; or Revision 11, dated
December 12, 1991.
(e) Accomplishment of the ``Reinforcing Stiffener Installation
and Skin Panel Replacement'' in accordance with Part III of the
Accomplishment Instructions of Boeing Service Bulletin 2590,
Revision 6, dated July 8, 1968; Revision 7, dated September 22,
1969; Revision 8, dated June 2, 1972; Revision 9, dated March 14,
1975; Revision 10, dated January 31, 1991; or Revision 11, dated
December 12, 1991; constitutes terminating action for the repetitive
inspections required by paragraphs (a), (b), and (c) of this AD.
(f) 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 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
(g) Special flight permits may be issued in accordance with
Sec. Sec. 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 12, 1994.
S.R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 94-17326 Filed 7-15-94; 8:45 am]
BILLING CODE 4910-13-U
