[Federal Register Volume 59, Number 96 (Thursday, May 19, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-11523]


[[Page Unknown]]

[Federal Register: May 19, 1994]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 93-NM-80-AD; Amendment 39-8913; AD 94-10-06]

 

Airworthiness Directives; Boeing Model 707/720 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 707/720 series airplanes, that 
requires certain structural inspections of older airplanes. This 
amendment is prompted by reports of incidents involving fatigue 
cracking and corrosion in transport category airplanes that are 
approaching or have exceeded their economic design service goal. The 
actions specified by this AD are intended to prevent degradation of the 
structural capabilities of the affected airplanes. This amendment 
relates to the recommendations of the Airworthiness Assurance Task 
Force assigned to review Model 707/720 series airplanes, which indicate 
that, to assure long term continued operational safety, various 
structural inspections should be accomplished.

DATES: Effective June 20, 1994.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of June 20, 1994.

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the Federal 
Aviation Administration (FAA), Transport Airplane Directorate, Rules 
Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of 
the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.

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: A proposal to amend part 39 of the Federal 
Aviation Regulations to include an airworthiness directive (AD) that is 
applicable to certain Boeing Model 707/720 series airplanes was 
published in the Federal Register on October 18, 1993 (58 FR 53678). 
That action proposed to require inspections of certain structural 
components on older airplanes for cracks, corrosion, and other 
discrepancies, and repair or correction of discrepancies, if necessary.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.
    One commenter supports the proposed rule.
    One commenter requests that the structural inspections and 
modifications referenced in section A.3 and section A.4 of appendix A 
of Boeing Document Number D6-54996, ``Aging Airplane Service Bulletin 
Structural Modification and Inspection Program--Model 707/720,'' 
Revision D, dated January 23, 1992, be combined and addressed as a 
single AD action, rather than in two separate actions, as proposed by 
the FAA in this notice. This commenter points out that the FAA 
previously issued AD 94-06-08, Amendment 39-8856 (59 FR 13446, March 
22, 1994), which requires the accomplishment of a certain structural 
modification of the wing front spar lower chord in accordance with 
section A.3 of appendix A of the Boeing Document. This commenter 
contends that by issuing a single AD to cover both sections of the 
Boeing Document, the FAA will contribute to reducing the cost and 
complexity of publishing and tracking multiple AD's, while maintaining 
the same level of safety.
    The FAA does not concur with this commenter's request, specifically 
because of the nature of the requirements of the rules. The 
requirements contained in AD 94-06-08 address a single structural 
modification applicable to Model 707 series airplanes listed in 
Appendix A.3 of the Boeing Document. The compliance time for 
accomplishing that modification is based on either the number of flight 
cycles on the airplane or a specific calendar time. The requirements of 
this AD, however, address structural inspections for both Model 707 and 
Model 720 series airplanes listed in section 4 and appendix A.4 of the 
Boeing Document. The compliance times for implementation of these 
various inspections vary, as do the repetitive inspection intervals. 
The FAA considers that combining the requirements for these dissimilar 
actions into one complex AD would create unnecessary confusion for 
affected operators. Therefore, the FAA finds it appropriate to issue 
one AD addressing the modification and another AD addressing 
``inspections only.'' This method of issuance will ease tracking of and 
facilitate compliance with the requirements of these two separate AD's.
    Since the issuance of the proposal, the FAA has reviewed and 
approved Revision E of Boeing Document Number D6-54996, ``Aging 
Airplane Service Bulletin Structural Modification and Inspection 
Program--Model 707/720,'' dated March 8, 1994. The inspections 
described in this revision are identical to those described in Revision 
D, which was referenced in the proposal as the appropriate source of 
service information. The only change effected by Revision E is that it 
excludes the inspections of the upper skin on the wing center section 
described in Boeing Service Bulletin 2590. The actions specified in 
Boeing Service Bulletin 2590 currently are the subject of AD 68-18-03, 
Amendment 39-2056. In light of this, the final rule has been revised to 
reference Revision E of the Boeing Document as the appropriate source 
of service information in order to eliminate these redundant inspection 
requirements. The applicability of the final rule has also been revised 
to reference those airplanes listed in Revision E of the Boeing 
Document in order to exclude those airplanes that are subject to the 
requirements of Boeing Service Bulletin 2590. Additionally, the 
economic impact information, below, has been revised to reflect the 
deletion of these inspections from the required number of work hours 
for accomplishment of the actions required by this final rule.
    Upon further review of the inspection actions required by this AD, 
the FAA has revised the final rule to extend the proposed 15-month 
compliance time to 18 months (for airplanes that have surpassed the 
specified compliance threshold in terms of accumulated flight cycles or 
time-in-service). The FAA has determined that increasing the compliance 
time by an additional three months will not adversely affect safety, 
and will allow the inspections to be performed during regularly 
scheduled maintenance at a main base where special equipment and 
trained maintenance personnel will be available if necessary. Moreover, 
this is the compliance time currently recommended by the manufacturer 
in the latest revision to the Boeing Document, which is referenced in 
the final rule.
    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.
    There are approximately 416 Model 707/720 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 82 
airplanes of U.S. registry will be affected by this AD, that it will 
take approximately 691 work hours per airplane to accomplish the 
required actions, and that the average labor rate is $55 per work hour. 
Based on these figures, the total cost impact of the AD on U.S. 
operators is estimated to be $3,116,410, or $38,005 per airplane.
    The total cost impact figure discussed above is based on 
assumptions that no operator has yet accomplished any of the 
requirements of this AD action, and that no operator would accomplish 
those actions in the future if this AD were not adopted.
    The FAA recognizes that the obligation to maintain aircraft in an 
airworthy condition is vital, but sometimes expensive. Because AD's 
require specific actions to address specific unsafe conditions, they 
appear to impose costs that would not otherwise be borne by operators. 
However, because of the general obligation of operators to maintain 
aircraft in an airworthy condition, this appearance is deceptive. 
Attributing those costs solely to the issuance of this AD is 
unrealistic because, in the interest of maintaining safe aircraft, most 
prudent operators would accomplish the required actions even if they 
were not required to do so by the AD.
    A full cost-benefit analysis has not been accomplished for this AD. 
As a matter of law, in order to be airworthy, an aircraft must conform 
to its type design and be in a condition for safe operation. The type 
design is approved only after the FAA makes a determination that it 
complies with all applicable airworthiness requirements. In adopting 
and maintaining those requirements, the FAA has already made the 
determination that they establish a level of safety that is cost-
beneficial. When the FAA, as in this AD, makes a finding of an unsafe 
condition, this means that this cost-beneficial level of safety is no 
longer being achieved and that the required actions are necessary to 
restore that level of safety. Because this level of safety has already 
been determined to be cost-beneficial, a full cost-benefit analysis for 
this AD would be redundant and unnecessary.
    The regulations adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules Docket at the location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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:

94-10-06 Boeing: Amendment 39-8913. Docket 93-NM-80-AD.

    Applicability: Model 707/720 series airplanes, as listed in 
section 4 and appendix A.4 of Boeing Document D6-54996, ``Aging 
Airplane Service Bulletin Structural Modification and Inspection 
Program-- Model 707/720,'' Revision E, dated March 8, 1994; 
certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent degradation of the structural capability of the 
airplane, accomplish the following:
    (a) Accomplish the inspections specified in Section 4 and 
Appendix A.4 of Boeing Document Number D6-54996, ``Aging Airplane 
Service Bulletin Structural Modification and Inspection Program--
Model 707/720,'' Revision E, dated March 8, 1994, in accordance with 
the schedule specified in paragraph (b) of this AD. Repeat these 
inspections thereafter at intervals not to exceed those specified in 
the Boeing Document for each inspection.
    (b) The maximum initial inspection time for the inspections 
required by paragraph (a) of this AD shall be the later of the times 
specified in either paragraph (b)(1) or (b)(2) of this AD:
    (1) The threshold for inspection time for the inspection 
specified in the Boeing Document, measured as an accumulated total 
of flight cycles or time-in-service, as appropriate; or
    (2) The ``phase-in'' period for the inspection specified in the 
Boeing Document, measured from a date 18 months after the effective 
date of this AD.

    Note 1: For the purposes of this AD, the ``phase-in period'' is 
defined as the allowable period to accomplish the initial inspection 
when the ``threshold'' specified in paragraph (b)(1) of this AD is 
imminent or has elapsed.

    (c) If any discrepant condition identified in the service 
bulletins (that are specified in the Boeing Document) is found as a 
result of the inspections required by this AD, prior to further 
flight, accomplish the corresponding corrective action specified in 
the service bulletins.
    (d) The terminating action for each inspection required by 
paragraph (a) of this AD consists of the accomplishment of the 
modification specified in the corresponding service bulletin.
    (e) 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.

    (f) 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.
    (g) The inspections and corrective actions shall be done in 
accordance with Boeing Document Number D6-54996, ``Aging Airplane 
Service Bulletin Structural Modification and Inspection Program--
Model 707/720,'' Revision E, dated March 8, 1994, which includes the 
following list of effective pages:

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               Page No.                   Revision level shown on page  
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List of active pages:                                                   
  Pages c.1 and c.2...................  E                               
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    (Note: The issue date of Revision E is indicated only on the 
title page; no other page of the document is dated.) This 
incorporation by reference was approved by the Director of the 
Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 
51. Copies may be obtained from Boeing Commercial Airplane Group, 
P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be 
inspected at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue, SW., Renton, Washington; or at the Office of the Federal 
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

    (h) This amendment becomes effective on June 20, 1994.

    Issued in Renton, Washington, on May 6, 1994.
S. R. Miller,
Acting Manager,
Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 94-11523 Filed 5-18-94; 8:45 am]
BILLING CODE 4910-13-U