[Federal Register Volume 59, Number 136 (Monday, July 18, 1994)]
[Unknown Section]
[Page 0]
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