[Federal Register Volume 66, Number 108 (Tuesday, June 5, 2001)]
[Proposed Rules]
[Pages 30105-30107]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-14045]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-378-AD]
RIN 2120-AA64


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 adoption of a new airworthiness 
directive (AD) that is applicable to certain Boeing Model 707 and 720 
series airplanes. This proposal would require a preventive modification 
of the front spar fitting on the outboard engine nacelle. This action 
is necessary to prevent fatigue cracking of the front spar fitting on 
the outboard engine nacelle, which could reduce the structural 
integrity of the nacelle, and result in separation of the engine from 
the airplane. This action is intended to address the identified unsafe 
condition.

DATES: Comments must be received by July 20, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-378-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. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
<a href="/cdn-cgi/l/email-protection#1c25317d727131726c6e717f7371717972685c7a7d7d327b736a"><span class="__cf_email__" data-cfemail="cdf4e0aca3a0e0a3bdbfa0aea2a0a0a8a3b98dabacace3aaa2bb">[email protected]</span></a>. Comments sent via fax or the Internet must 
contain ``Docket No. 2000-NM-378-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 for Windows or 
ASCII text.
    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: Duong Tran, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2773; fax (425) 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 action may be changed in 
light of the comments received.
    Submit comments using the following format:
    <bullet> Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a

[[Page 30106]]

request to change the service bulletin reference as two separate 
issues.
    <bullet> For each issue, state what specific change to the proposed 
AD is being requested.
    <bullet> Include justification (e.g., reasons or data) for each 
request.
    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 action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2000-NM-378-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-114, Attention: Rules 
Docket No. 2000-NM-378-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports that fatigue cracks have been found in 
the front spar fitting on the outboard engine nacelle on certain Boeing 
Model 707 and 720 series airplanes. The cracks originated at the 
rearmost of the seven fasteners which attach the front spar fitting to 
the front spar chord. Such cracking, if not corrected, could reduce the 
structural integrity of the nacelle, and result in separation of the 
engine from the airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 1541, 
Revision 3, dated February 15, 1967, which describes procedures for, 
among other actions, installation of a preventive modification of the 
front spar fitting on the outboard engine nacelle. The modification 
involves replacement of the front spar fitting with a new, improved 
(stronger) fitting and modification of the front spar chord to 
distribute stress loads over the entire front spar fitting. 
Accomplishment of the actions specified in the service bulletin is 
intended to adequately address the identified unsafe condition.

Explanation of Requirements of Proposed Rule

    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 accomplishment of the actions specified in 
the service bulletin described previously, except as discussed below.

Differences Between Proposed Rule and Service Bulletin

    This proposed rule differs from the service bulletin in the 
compliance time for the proposed modification. For certain airplanes, 
the service bulletin recommends accomplishment of the modification of 
the front spar fitting, but does not specify a compliance time; for 
other airplanes, the service bulletin specifies that the modification 
is optional and may be installed on an attrition basis. This proposed 
AD would require installation of the modification prior to the 
accumulation of 20,000 total flight cycles, or within 24 months after 
the effective date of this AD, whichever occurs later. In developing an 
appropriate compliance time for this AD, the FAA considered not only 
the manufacturer's recommendation, but the degree of urgency associated 
with addressing the subject unsafe condition, the average utilization 
of the affected fleet, and the time necessary to perform the actions. 
In light of all of these factors, the FAA finds that the proposed 
compliance time for completing the required actions represents an 
appropriate interval of time allowable for affected airplanes to 
continue to operate without compromising safety.
    The proposed rule also differs from the service bulletin in that it 
would not require the repetitive inspections to detect cracking of the 
front spar fitting, which are described in the service bulletin. The 
decision to mandate the preventive modification of the front spar 
fitting is based on the FAA's determination that long-term continued 
operational safety will be better assured by design changes to remove 
the source of the problem, rather than by repetitive inspections. Long-
term inspections may not provide the degree of safety assurance 
necessary for the transport airplane fleet. This, coupled with a better 
understanding of the human factors associated with numerous continual 
inspections, has led the FAA to consider placing less emphasis on 
inspections and more emphasis on design improvements. The proposed 
modification requirement is consistent with these findings.
    Operators should note that Section 3., Part II, ``l,'' of the 
service bulletin refers to an incorrect part number for the new, 
improved front spar fitting. That item reads, ``Install applicable new 
fitting 65-13347-4* * *''; the FAA has determined that the correct part 
number for the new, improved fitting in this case is 65-13347-5. Figure 
1 of the service bulletin references the correct part number.

Cost Impact

    There are approximately 13 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 3 airplanes of U.S. registry 
would be affected by this proposed AD, that it would take approximately 
64 work hours per airplane to accomplish the proposed modification, and 
that the average labor rate is $60 per work hour. Required parts would 
cost approximately $1,300 per airplane. Based on these figures, the 
cost impact of the proposed AD on U.S. operators is estimated to be 
$15,420, or $5,140 per airplane.
    The 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 proposed AD were not adopted. The cost impact 
figures discussed in AD rulemaking actions represent only the time 
necessary to perform the specific actions actually required by the AD. 
These figures typically do not include incidental costs, such as the 
time required to gain access and close up, planning time, or time 
necessitated by other administrative actions.

Regulatory Impact

    The regulations proposed herein would not have a substantial direct 
effect 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, it 
is determined that this proposal would not have federalism implications 
under Executive Order 13132.
    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

[[Page 30107]]

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. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

Boeing: Docket 2000-NM-378-AD.

    Applicability: Model 707 and 720 series airplanes, listed in 
Boeing Service Bulletin 1541, Revision 3, dated February 15, 1967; 
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 request approval for an 
alternative method of compliance in accordance with paragraph (c) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent fatigue cracking of the front spar fitting on the 
outboard engine nacelle, which could reduce the structural integrity 
of the nacelle, and result in separation of the engine from the 
airplane, accomplish the following:

Preventive Modification

    (a) Prior to the accumulation of 20,000 total flight cycles, or 
within 24 months after the effective date of this AD, whichever 
occurs later, install the preventive modification of the front spar 
fitting on the outboard engine nacelle. Do the modification 
(including replacement of the front spar fitting with a new, 
improved (stronger) fitting, and modification of the front spar 
chord to distribute stress loads over the entire front spar fitting) 
according to Boeing Service Bulletin 1541, Revision 3, dated 
February 15, 1967.

    Note 2: Modification of the front spar fitting on the outboard 
engine nacelle (including replacement of the front spar fitting with 
a new, improved (stronger) fitting, and modification of the front 
spar chord to distribute stress loads over the entire front spar 
fitting) accomplished prior to the effective date of this AD 
according to Boeing Service Bulletin 1541, dated July 1, 1962; 
Revision 1, dated January 29, 1963; Revision 2, dated February 11, 
1964; or Supplement 1541(R-2)A, dated April 2, 1964; is acceptable 
for compliance with the requirements of paragraph (a) of this AD.

Spares

    (b) As of the effective date of this AD, no person shall install 
a front spar fitting, part number 65-2532 or 65-2532-5, on the 
outboard engine nacelle on any airplane.

Alternative Methods of Compliance

    (c) 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. 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.

Special Flight Permits

    (d) 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.

    Issued in Renton, Washington, on May 30, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-14045 Filed 6-4-01; 8:45 am]
BILLING CODE 4910-13-U


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