[Federal Register Volume 60, Number 25 (Tuesday, February 7, 1995)]
[Proposed Rules]
[Pages 7143-7146]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-2932]



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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: Supplemental notice of proposed rulemaking; reopening of 
comment period.

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SUMMARY: This document revises an earlier proposed airworthiness 
directive (AD), applicable to certain Boeing Model 707 and 720 series 
airplanes, that would have superseded an existing AD to require 
repetitive inspections to detect cracks in certain areas of the upper 
forward skin panels of the wing center section, and repair, if 
necessary. That AD also would have provided an optional terminating 
modification for the repetitive inspections. That proposal was prompted 
by reports that the inspections required by the existing AD are not 
effective in detecting fatigue cracks in a timely manner. This action 
revises the proposed rule by reducing certain compliance times and by 
revising the applicability statement of the AD. The actions specified 
by this 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 March 6, 1995.

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, [[Page 7144]] 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-121S, 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

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to add an airworthiness directive (AD), applicable to 
certain Boeing Model 707 and 720 series airplanes, was published as a 
notice of proposed rulemaking (NPRM) in the Federal Register on July 
18, 1994 (59 FR 36376). That NPRM would have superseded an existing AD 
to require repetitive inspections to detect cracks in certain areas of 
the upper forward skin panels of the wing center section, and repair, 
if necessary. That AD also would have provided an optional terminating 
modification for the repetitive inspections. That NPRM was prompted by 
reports that the inspections required by the existing AD are not 
effective in detecting fatigue cracks in a timely manner. That 
condition, if not corrected, could result in failure of the upper 
forward skin panels of the wing center section.
    One commenter to the NPRM submitted a request that the proposal be 
revised to eliminate duplicate or conflicting requirements with AD 85-
12-01 (50 FR 26690, June 28, 1985) for unmodified airplanes (those 
having no bulb angle or thicker skin). That AD requires accomplishment 
of inspections specified in Supplemental Structural Inspection Document 
(SSID) D6-44860 for Model 707/720 series airplanes. The FAA concurs 
partially. The SSID provides procedures for accomplishment of dye 
penetrant or eddy current inspections to detect cracks on the upper 
forward skin panels of the wing center section. However, the FAA has 
determined that the dye penetrant inspection techniques contained in 
the SSID for the affected airplanes have not been effective in 
detecting cracks in a timely manner. Boeing has advised the FAA that it 
plans to remove those inspections from the next revision of the SSID; 
subsequently, the FAA may consider further rulemaking to revise AD 85-
12-01 accordingly. For this reason, the FAA finds that inspections 
using eddy current techniques, as proposed in this supplemental NPRM, 
are necessary to detect cracks effectively in a timely manner for those 
airplanes having no bulb angle or thicker skin.
    Further, upon reevaluation of certain inspection thresholds and 
repetitive intervals, the FAA finds that the compliance times specified 
in paragraphs (a), (a)(2)(i), and (b) of the proposal are less 
conservative than those recommended in the SSID. In light of this 
consideration, the FAA finds that, for unmodified airplanes, the 
compliance times specified in this proposal must be revised to make 
them more consistent with the more conservative times recommended in 
the SSID. Therefore, the proposed repetitive interval of 1,000 landings 
or 18 months, whichever occurs first, specified in paragraphs (a) and 
(b) of the original NPRM, has been revised to 450 landings in this 
supplemental NPRM. In addition, the proposed inspection threshold of 
7,000 total landings, specified in paragraph (a)(2)(i) of the original 
NPRM, has been revised to 6,400 total landings in this supplemental 
NPRM. The FAA has determined that accomplishment of the required 
actions at these revised compliance times will provide an acceptable 
level of safety.
    The commenter also submitted a request that the applicability 
statement of the proposal be revised to specify airplanes listed in 
Boeing Service Bulletin 2590, Revision 11, dated December 12, 1991. 
Certain Model 707 series airplanes were modified during production and, 
therefore, need not be inspected in accordance with the requirements of 
the proposed AD; the service bulletin listing excludes those airplanes. 
The FAA concurs, and has revised the proposal accordingly.
    The FAA also has revised the proposed repetitive inspection 
interval, specified in paragraph (c) of the original NPRM, to remove 
the reference to an optional 18-month repetitive inspection interval 
and to require that these inspections be performed only at intervals 
not to exceed 1,000 landings. This revised interval corresponds with 
the recommendation of the Structures Working Group for Model 707/720 
series airplanes, and the FAA has determined that it will ensure that 
cracking is detected in a timely manner.
    Since these changes expand the scope of the originally proposed 
rule, the FAA has determined that it is necessary to reopen the comment 
period to provide additional opportunity for public comment.
    As a result of recent communications with the Air Transport 
Association (ATA) of America, the FAA has learned that, in general, 
some operators may misunderstand the legal effect of AD's on airplanes 
that are identified in the applicability provision of the AD, but that 
have been altered or repaired in the area addressed by the AD. The FAA 
points out that all airplanes identified in the applicability provision 
of an AD are legally subject to the AD. If an airplane has been altered 
or repaired in the affected area in such a way as to affect compliance 
with the AD, the owner or operator is required to obtain FAA approval 
for an alternative method of compliance with the AD, in accordance with 
the paragraph of each AD that provides for such approvals. A note has 
been included in this notice to clarify this requirement.
    The FAA has recently reviewed the figures it has used over the past 
several years in calculating the economic [[Page 7145]] impact of AD 
activity. In order to account for various inflationary costs in the 
airline industry, the FAA has determined that it is necessary to 
increase the labor rate used in these calculations from $55 per work 
hour to $60 per work hour. The economic impact information, below, has 
been revised to reflect this increase in the specified hourly labor 
rate.
    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 actions, and that the average labor rate is $60 per work 
hour. Based on these figures, the total cost impact of the proposed AD 
on U.S. operators is estimated to be $157,440, or $1,920 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 $60 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 $120,000 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 the following new airworthiness directive:

Boeing: Docket 94-NM-14-AD. Supersedes AD 68-18-03, Amendment 39-
2056.

    Applicability: Model 707 and 720 series airplanes; as listed in 
Boeing Service Bulletin 2590, Revision 11, dated December 12, 1991; 
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 use the authority 
provided in paragraph (f) to request approval from the FAA. This 
approval may address either no action, if the current configuration 
eliminates the unsafe condition; or different actions necessary to 
address the unsafe condition described in this AD. Such a request 
should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any airplane from the applicability of this AD.

    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 series 
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 450 landings.
    (1) For Model 707-300, -300B, -300C, and -400 series 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 series 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 6,400 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 series 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 450 landings.
    (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 series 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.

    Note 2: Revision 11 of Boeing Service Bulletin 2590 is part of 
Boeing Master Inspection Service Bulletins 3484 (for Model 707-100 
and -200 series airplanes), 3485 (for Model 720 and 720B series 
airplanes), and 3486 (for Model 707-300, -300B, -300C, and -400 
series 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.

     [[Page 7146]] (1) For Model 720 and 720B series 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 series 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 series 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 inspection required by 
paragraph (a), (b), or (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 
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 3: 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 
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 February 1, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-2932 Filed 2-6-95; 8:45 am]
BILLING CODE 4910-13-U