[Federal Register Volume 72, Number 145 (Monday, July 30, 2007)]
[Proposed Rules]
[Pages 41462-41465]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-14638]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-28811; Directorate Identifier 2006-NM-246-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 707 Airplanes and Model 
720 and 720B Series Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for all Boeing Model 707 airplanes and Model 720 and 720B series 
airplanes. This proposed AD would require identifying the material used 
in the elevator hinge support fittings of the horizontal stabilizer 
trailing edge, doing repetitive detailed inspections for cracking of 
the fittings and corrective actions if necessary, and doing an eventual 
terminating action. This proposed AD results from a report that stress 
corrosion cracking of the elevator hinge support fittings has been 
discovered on several Model 707 airplanes. We are proposing this AD to 
prevent cracking of the elevator hinge support fittings, which could 
reduce the elevator support stiffness and lead to in-flight airframe 
vibration, consequent damage to the elevator and horizontal stabilizer, 
and reduced controllability of the airplane.

DATES: We must receive comments on this proposed AD by September 13, 
2007.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
     DOT Docket Web site: Go to  http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Fax: (202) 493-2251.
     Hand Delivery: Room W12-140 on the ground floor of the 
West Building, 1200 New Jersey Avenue, SE., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for the service information identified in this 
proposed AD.

FOR FURTHER INFORMATION CONTACT: Duong Tran, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 
917-6452; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite you to submit any relevant written data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed in the ADDRESSES section. Include the docket number ``FAA-2007-
28811; Directorate Identifier 2006-NM-246-AD'' at the

[[Page 41463]]

beginning of your comments. We specifically invite comments on the 
overall regulatory, economic, environmental, and energy aspects of the 
proposed AD. We will consider all comments received by the closing date 
and may amend the proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this proposed AD. Using the search function of 
that Web site, anyone can find and read the comments in any of our 
dockets, including the name of the individual who sent the comment (or 
signed the comment on behalf of an association, business, labor union, 
etc.). You may review DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or you 
may visit http://dms.dot.gov.

Examining the Docket

    You may examine the AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Operations office between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays. The 
Docket Operations office (telephone (800) 647-5527) is located on the 
ground floor of the West Building at the DOT street address stated in 
the ADDRESSES section. Comments will be available in the AD docket 
shortly after the Docket Management System receives them.

Discussion

    We have received a report indicating that stress corrosion cracking 
of the elevator hinge support fittings (made of 7079-T6 material) of 
the horizontal stabilizer trailing edge has been discovered on several 
Model 707 airplanes. In some cases, multiple fittings on one stabilizer 
were found to be cracked; excessive cracking at multiple rib locations 
will reduce the elevator support stiffness. This condition, if not 
corrected, could lead to in-flight airframe vibration, consequent 
damage to the elevator and horizontal stabilizer, and reduced 
controllability of the airplane.

Relevant Service Information

    We have reviewed Boeing 707 Alert Service Bulletin A3518, dated 
October 9, 2006. The alert service bulletin describes procedures for:
     Repetitively verifying whether or not the elevator hinge 
support fittings of the horizontal stabilizer trailing edge are made of 
7079-T6 or 7075-T6 material;
     Modifying certain rib web segments by fabricating and 
installing nutplates to create access to the web area for inspection;
     Doing initial and repetitive inspections for cracking of 
hinge support fittings made of 7079-T6 or 7075-T6 material, and 
corrective actions if necessary; and
     Eventually replacing all affected hinge support fittings 
with new, improved fittings made of 7075-T7351 material.

Corrective actions include repairing or replacing any cracked fitting 
with a new or serviceable fitting made of 7079-T6 or 7075-T6 material, 
or with a new, improved fitting. Replacing any affected fitting with a 
new, improved fitting made of 7075-T7351 material eliminates the need 
for the repetitive inspections for that fitting. Accomplishing the 
actions specified in the service information is intended to adequately 
address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to exist or develop on other airplanes 
of this same type design. For this reason, we are proposing this AD, 
which would require accomplishing the actions specified in the service 
information described previously, except as discussed under 
``Differences Between the Proposed AD and Service Bulletin.''

Differences Between the Proposed AD and Service Bulletin

    The alert service bulletin specifies to contact Boeing for 
instructions on how to repair certain conditions, but this proposed AD 
would require repairing those conditions in one of the following ways:
     Using a method that we approve; or
     Using data that meet the certification basis of the 
airplane, and that have been approved by an Authorized Representative 
for the Boeing Commercial Airplanes Delegation Option Authorization 
Organization whom we have authorized to make those findings.
    The alert service bulletin does not specify a number of work hours 
for modifying the rib web segments. However, we have confirmed with 
Boeing that this action should take about 6 work hours and have 
estimated the costs to accomplish this proposed AD accordingly.
    The alert service bulletin specifies to repeat the verification of 
the hinge material at intervals not to exceed 180 days after the date 
on the alert service bulletin or before further flight after the 
replacement of any hinge support fitting, whichever occurs first. We 
have confirmed with Boeing that repetitive verification at intervals 
not to exceed 180 days is not necessary. Therefore, this proposed AD 
would only require repeat verification of the hinge material before 
further flight after the replacement of any hinge support fitting.

Costs of Compliance

    There are about 185 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 52 airplanes of 
U.S. registry. The following table provides the estimated costs for 
U.S. operators to comply with this proposed AD, at an average labor 
rate of $80 per work hour.

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
             Action                   Work hours             Parts         Cost per airplane      Fleet cost
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Material verification...........  1.................  No parts needed...  $80...............  $4,160.
Detailed inspections............  24, per inspection  No parts needed...  $1,920............  $47,840, per
                                   cycle.                                                      inspection cycle.
Modification (fabrication and     6.................  Operator supplied.  $480..............  $24,960.
 installation of nutplates).
Terminating action..............  132...............  $53,078 \1\ or      $63,638 \1\ or      Up to $5,112,120.
                                                       $87,750 \2\.        $98,310 \2\.
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\1\ For Group 1 airplanes.
\2\ For Group 2 airplanes.


[[Page 41464]]

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, Section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD 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.
    For the reasons discussed above, I certify that the 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. 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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD and placed it in the AD docket. See the 
ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 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. The Federal Aviation Administration (FAA) amends Sec.  39.13 by 
adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2007-28811; Directorate Identifier 2006-NM-
246-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by September 
13, 2007.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to all Model 707-100 long body, -200, -100B 
long body, and -100B short body series airplanes; Model 707-300, -
300B, -300C, and -400 series airplanes; and Model 720 and 720B 
series airplanes; certificated in any category.

Unsafe Condition

    (d) This AD results from a report that stress corrosion cracking 
of the elevator hinge support fittings of the horizontal stabilizer 
trailing edge has been discovered on several Model 707 airplanes. We 
are issuing this AD to prevent cracking of the elevator hinge 
support fittings, which could reduce the elevator support stiffness 
and lead to in-flight airframe vibration, consequent damage to the 
elevator and horizontal stabilizer, and reduced controllability of 
the airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Service Bulletin Reference

    (f) The term ``service bulletin,'' as used in this AD, means the 
Accomplishment Instructions of Boeing 707 Alert Service Bulletin 
A3518, dated October 9, 2006.

Material Identification

    (g) Within 180 days after the effective date of this AD or 
before further flight after any horizontal stabilizer is replaced: 
Verify the type of material used in the elevator hinge support 
fittings of the horizontal stabilizer trailing edge, in accordance 
with Part 1 of the Accomplishment Instructions of the service 
bulletin, then do the requirements of paragraph (g)(1) or (g)(2) of 
this AD, as applicable. Repeat the verification before further 
flight after the replacement of any hinge support fitting.
    (1) For any hinge support fitting made of 7075-T7351 material: 
No further action is required by paragraph (h) or (i) of this AD.
    (2) For any hinge support fitting made of 7079-T6 or 7075-T6 
material: Do the actions required by paragraph (h) of this AD.

Repetitive Inspections, One-Time Modification, and Corrective Actions

    (h) Before further flight after doing paragraph (g) of this AD, 
do a detailed inspection for cracking of the hinge support fittings 
and modify certain segments of the rib webs, in accordance with Part 
2 of the Accomplishment Instructions of the service bulletin. For 
any hinge support fitting found to be cracked or damaged, before 
further flight, do the actions of paragraph (h)(1) or (h)(2) of this 
AD; in accordance with Part 3 of the Accomplishment Instructions of 
the service bulletin. Do all actions in accordance with the 
Accomplishment Instructions of the service bulletin; except where 
the service bulletin specifies to contact the manufacturer for 
repair procedures, this AD requires repair using a method approved 
in accordance with the procedures specified in paragraph (k) of this 
AD.
    (1) Replace the fitting with a serviceable fitting made of 7079-
T6 or 7075-T6 material. Repeat the detailed inspection thereafter at 
intervals not to exceed 180 days, until the terminating action of 
paragraph (i) of this AD has been done.
    (2) Replace the fitting with a new, improved fitting made of 
7075-T7351 material.

Terminating Action

    (i) For all airplanes: Within 48 months after the effective date 
of this AD, replace all hinge support fittings made of 7079-T6 or 
7075-T6 material with new, improved fittings made of 7075-T7351 
material, in accordance with Part 4 of the Accomplishment 
Instructions of the service bulletin. Doing this action terminates 
all requirements of paragraphs (g) and (h) of this AD.

Parts Installation

    (j) As of the effective date of this AD, no person may install, 
on any airplane, a new or serviceable hinge support fitting made of 
7079-T6 or 7075-T6 material, unless the requirements of paragraph 
(h)(1) of this AD are accomplished.

Alternative Methods of Compliance (AMOCs)

    (k)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.
    (2) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Before using any approved AMOC on any airplane to which the AMOC 
applies, notify your appropriate principal inspector (PI) in the FAA 
Flight Standards District Office (FSDO), or lacking a PI, your local 
FSDO.
    (3) An AMOC that provides an acceptable level of safety may be 
used for any repair required by this AD, if it is approved by an 
Authorized Representative for the Boeing Commercial Airplanes 
Delegation Option Authorization Organization who has been authorized 
by the Manager, Seattle ACO, to make those findings. For a repair 
method to be approved, the repair must meet the certification basis 
of the airplane and the approval must specifically refer to this AD.


[[Page 41465]]


    Issued in Renton, Washington, on July 18, 2007.
Stephen P. Boyd,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E7-14638 Filed 7-27-07; 8:45 am]
BILLING CODE 4910-13-P