[Federal Register Volume 65, Number 155 (Thursday, August 10, 2000)]
[Proposed Rules]
[Pages 48941-48943]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-20247]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-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 all Boeing Model 707 and 720 
series airplanes. This proposal would require repetitive inspections of 
certain stringers and around certain fastener holes of the lower skin 
of the wings to detect fatigue cracking, and repair, if necessary. This 
action is necessary to detect and correct such cracking and consequent 
damage to adjacent structure, which could result in reduced structural 
integrity of the airplane. This action is intended to address the 
identified unsafe condition.

DATES: Comments must be received by September 25, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-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: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 99-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: James Rehrl, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2783; 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 notice may be changed in 
light of the comments received.
    Submit comments using the following format:
     Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
     For each issue, state what specific change to the proposed 
AD is being requested.
     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 notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 99-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. 99-NM-378-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    In 1981, the FAA issued AD 81-11-06 R1, amendment 39-4178 (46 FR 
38900), which is applicable to all Boeing Model 707 and 720 series 
airplanes. That AD was prompted by reports of cracking in the wing 
lower skin and stringers 5 and 7, and requires certain inspections of 
the lower skin of the wing and adjacent stringers to detect cracking. 
Such cracking could result in reduced structural integrity of the 
airplane. For Model 720 series airplanes, the AD requires low frequency 
eddy current (LFEC) inspections of the wing lower surface to detect 
cracks. For Model 707 series airplanes, the AD requires high frequency 
eddy current (HFEC) and optional LFEC inspections of the wing lower 
surface to detect cracks.

Actions Since Issuance of Previous Rule

    Since the issuance of that AD, the FAA has received a report 
indicating

[[Page 48942]]

that the area where cracking was originally detected has expanded to 
numerous stringers, resulting in complete fracture of stringers 5 and 7 
between wing station (WS) 470 and WS 733. In addition, there have been 
severed stringers at certain weep hole locations. In light of this 
fact, the manufacturer issued Boeing Alert Service Bulletin A3395, 
Revision 4, dated October 28, 1999. The FAA has reviewed and approved 
Revision 4 to the service bulletin, which expands the procedures 
specified in Revision 3, dated July 17, 1981, by adding an HFEC 
inspection to examine the area between WS 470 and WS 733 to detect 
cracking, and expands the current inspection area of stringers 5 and 7 
to include the rib chord attachment. Accomplishment of the HFEC 
inspections specified in the service bulletin eliminates the need for 
the optional LFEC inspections, as stated above, for Model 707 series 
airplanes. In addition, the service bulletin describes procedures for 
inspecting the area around all fastener weep holes to detect cracking. 
The service bulletin also describes procedures for internal inspections 
if any cracking is detected. Accomplishment of the actions specified in 
the service bulletin is intended to adequately address the 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.

Difference Between Service Bulletin and Proposed AD

    Operators should note that, although the service bulletin specifies 
that the manufacturer may be contacted for disposition of certain 
repair conditions, this proposed AD would require the repair of those 
conditions to be accomplished in accordance with a method approved by 
the FAA, or in accordance with data meeting the type certification 
basis of the airplane approved by a Boeing Company Designated 
Engineering Representative who has been authorized by the FAA to make 
such findings.

Cost Impact

    There are approximately 49 Model 707 and 720 series airplanes of 
the affected design in the worldwide fleet. The FAA estimates that 2 
airplanes of U.S. registry would be affected by this proposed AD, that 
it would take approximately 56 work hours per airplane to accomplish 
the proposed inspections, and that the average labor rate is $60 per 
work hour. Based on these figures, the cost impact of the proposed AD 
on U.S. operators is estimated to be $3,360, or $6,720 per airplane, 
per inspection cycle.
    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 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 99-NM-378-AD.

    Applicability: All Model 707 and 720 series airplanes, 
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 (e) 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 detect fatigue cracking of certain stringers, and around 
certain fastener holes of the lower skin of the wings, which could 
result in damage to adjacent structure and consequent reduced 
structural integrity of the airplane, accomplish the following:

Initial and Repetitive Inspections

    (a) For Model 720 series airplanes: Within 500 flight cycles 
after the effective date of this AD, perform an initial high 
frequency eddy current (HFEC) inspection to detect cracking, in 
accordance with Figure 1 of Boeing Alert Service Bulletin A3395, 
Revision 4, dated October 28, 1999.
    (b) For Model 707 series airplanes having fewer than 15,000 
total flight cycles as of the effective date of this AD: Prior to 
the accumulation of 15,000 total flight cycles, or within 150 flight 
cycles after the effective date of this AD, whichever occurs later, 
perform an initial HFEC inspection in accordance with Figure 2; 
steps 1, 2, and 3; of Boeing Alert Service Bulletin A3395, Revision 
4, dated October 28, 1999. Repeat the inspection thereafter at 
intervals not to exceed 1,300 flight cycles. Accomplishment of the 
repetitive HFEC inspections terminates the low frequency eddy 
current inspections specified in AD 81-11-06 R1, amendment 39-4178.
    (c) For Model 707 series airplanes having 15,000 total flight 
cycles or more as of the effective date of this AD: Within 150 
flight cycles after the effective date of this AD, perform an 
initial HFEC inspection in accordance with Figure 2; steps 4, 5, and 
6; of Boeing Alert Service Bulletin A3395, Revision 4, dated October 
28, 1999, and accomplish the requirements in paragraphs (c)(1) and 
(c)(2) of this AD.

[[Page 48943]]

    (1) Repeat the inspection thereafter at intervals not to exceed 
150 flight cycles until accomplishment of the inspections required 
by paragraph (c)(2) of this AD.
    (2) Within 400 flight cycles after accomplishment of the initial 
inspection required by paragraph (c) of this AD, accomplish the HFEC 
inspections required by paragraph (b) of this AD. Accomplishment of 
these inspections terminates the repetitive inspections required by 
paragraph (c)(1) of this AD.

    Note 2: The actions required by AD 81-11-06 R1, amendment 39-
4178 [with the exception of the LFEC inspections, as specified in 
paragraph (b) of this AD] remain in effect.

Inspect and Repair

    (d) If any cracking is detected during any inspection required 
by this AD, prior to further flight, perform an internal inspection 
in accordance with the Work Instructions specified in Boeing Alert 
Service Bulletin A3395, Revision 4, dated October 28, 1999; and, 
prior to further flight, repair in accordance with a method approved 
by the Manager, Seattle Aircraft Certification Office (ACO), FAA, 
Transport Airplane Directorate; or in accordance with data meeting 
the type certification basis of the airplane approved by a Boeing 
Company Designated Engineering Representative who has been 
authorized by the Manager, Seattle ACO, to make such findings. For a 
repair method to be approved by the Manager, Seattle ACO, as 
required by this paragraph, the Manager's approval letter must 
specifically reference this AD.

Alternative Methods of Compliance

    (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 ACO. 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 Permit

    (f) 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 August 3, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-20247 Filed 8-9-00; 8:45 am]
BILLING CODE 4910-13-U