[Federal Register Volume 72, Number 53 (Tuesday, March 20, 2007)]
[Proposed Rules]
[Pages 13048-13051]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-5013]


========================================================================
Proposed Rules
                                                Federal Register
________________________________________________________________________

This section of the FEDERAL REGISTER contains notices to the public of 
the proposed issuance of rules and regulations. The purpose of these 
notices is to give interested persons an opportunity to participate in 
the rule making prior to the adoption of the final rules.

========================================================================


Federal Register / Vol. 72, No. 53 / Tuesday, March 20, 2007 / 
Proposed Rules

[[Page 13048]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-27619; Directorate Identifier 2005-NM-164-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 777 Airplanes

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

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain Boeing Model 777 airplanes. This proposed AD would require 
repetitive measurements of the freeplay of certain joints of the 
trailing edge flap supports; repetitive lubrication of the support 
joints; and related investigative and corrective actions if necessary. 
The proposed AD also provides for modifying certain components of the 
trailing edge flap supports, which would extend the intervals for the 
repetitive measurements, and revising the maintenance practices of the 
maintenance planning data document. This proposed AD results from 
reports of excessive wear of the pins, bushings, and bearings, and 
corrosion at the joints of the outboard trailing edge flap supports. We 
are proposing this AD to prevent wear and corrosion at the flap support 
joints, which could result in loss of the trailing edge flap and 
possible loss of control of the airplane.

DATES: We must receive comments on this proposed AD by May 4, 2007.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
    <bullet> DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
    <bullet> Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
    <bullet> Mail: Docket Management Facility, U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, room PL-401, 
Washington, DC 20590.
    <bullet> Fax: (202) 493-2251.
    <bullet> Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., 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: Gary Oltman, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 
917-6443; 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-
27619; Directorate Identifier 2005-NM-164-AD'' at the 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 Management Facility office 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The Docket Management Facility office (telephone (800) 647-
5227) is located on the plaza level of the Nassif 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 reports of excessive wear of the pins, bushings, 
and bearings, and corrosion at certain support joints on Boeing Model 
777 airplanes. An operator investigating an unrelated issue during 
heavy maintenance first discovered these discrepancies. In addition, 
some flap support joints were completely dry due to blocked grease 
paths, and many pins were seized in the fittings. Inadequate 
lubrication and the use of clay-based lubricants can accelerate pin 
wear. The pins are made of titanium and coated with D-gun coating for 
wear resistance. The wear characteristics of titanium pins are unknown, 
so if the wear progresses through the D-gun coating, the pins could 
eventually crack and then fracture. Moreover, undetected wear of the 
joint bushings results in freeplay-induced dynamic loading of the pin 
that is in excess of design loads. Wear and corrosion at the flap 
support joints, if not corrected, could result in loss of the trailing 
edge flap and possible loss of control of the airplane.

Relevant Service Information

    We have reviewed Boeing Service Bulletin 777-27A0066, Revision 1, 
dated May 18, 2006. The service bulletin describes procedures for 
repetitive measurements of the freeplay of support joints A, B, C, and 
D of the trailing edge flap supports, numbers 1 through 3 inclusive and 
6 through 8 inclusive; and of joint B of the trailing edge flap 
supports, numbers 4 and 5. The service bulletin also describes 
procedures for disassembling any joint that exceeds the freeplay limits 
specified in the service bulletin, and doing the related investigative 
and corrective actions in the ``support teardown inspection.'' The 
related

[[Page 13049]]

investigative and corrective actions are doing a detailed inspection of 
the joint for worn pins, bearings, and bushings, and for blocked 
lubrication paths; doing a dye penetrant inspection for cracks of pins 
with an acceptable surface finish; and replacing worn or cracked parts 
and unblocking the lubrication path if necessary.
    As an option to the support teardown inspection, for certain 
airplanes, the service bulletin describes procedures for a ``temporary 
return to service'' inspection. The temporary return to service 
inspection is similar to the support teardown inspection, except 
inspection for wear of the bearings and bushings may be accomplished 
without removing the flap from the airplane by insuring that joint 
freeplay is limited to temporarily acceptable levels when combined with 
frequent repetitive freeplay inspections. Doing the temporary return to 
service inspection extends the compliance time before the service 
bulletin specifies the support teardown inspection should be done. The 
service bulletin notes that certain pins identified during the support 
teardown inspection or temporary return to service inspection are 
acceptable for continued, time-limited use if the wear is within 
certain limits specified in the service bulletin.
    The service bulletin also describes procedures for repetitive 
lubrications of certain joints of the trailing edge flap supports, 
using Boeing Material Standard (BMS) 3-33 grease. The service bulletin 
specifies that part of this lubrication is verifying that grease 
emerges from the interface common to the pin outer diameter. If grease 
does not emerge, the service bulletin describes procedures for doing 
the following related investigative and corrective actions:
    <bullet> Removing the pin and doing the detailed and dye penetrant 
inspection procedures described in the support teardown inspection, and 
replacing excessively worn or cracked parts if necessary;
    <bullet> Inspecting for a blocked lubrication path, and clearing it 
if necessary; and
    <bullet> Doing a detailed inspection for wear of the interfacing 
bearings and bushings and replacing them if necessary.
    The service bulletin also refers to Boeing Alert Service Bulletin 
777-27A0071, Revision 1, dated October 16, 2006 (described below), 
which eliminates the need for the repetitive measurements and 
lubrications of certain trailing edge flap supports after accomplishing 
the specified actions.
    We have also reviewed Boeing Alert Service Bulletin 777-27A0071, 
Revision 1, dated October 16, 2006. The service bulletin describes 
procedures for modifying certain components of the trailing edge flap 
supports. The modification includes replacing the pins, ball sets, and 
bushings on the joints of the trailing edge flap at support numbers 1 
through 8 inclusive, with new, improved components; doing a detailed 
inspection of the components that interface with the flap support pins 
for discrepancies (corrosion, damage, or excessive wear); doing a 
general visual inspection of those components for any blocked 
lubrication paths; and doing corrective actions if necessary. If any 
discrepancies are found, the corrective actions include replacing the 
components and clearing any blocked lubrication paths. The service 
bulletin also describes procedures for revising the maintenance 
practices of the Boeing 777 Maintenance Planning Data (MPD) Document to 
update certain lubrication and inspection intervals. Accomplishing 
these actions extends the intervals for the repetitive measurement of 
certain trailing edge flap supports specified in Boeing Service 
Bulletin 777-27A0066, Revision 1.

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 the Service Bulletins.''

Differences Between the Proposed AD and the Service Bulletins

    Note (b) in Table 1 of Paragraph 1.E. ``Compliance'' of Boeing 
Service Bulletin 777-27A0066, Revision 1, recommends repeating the 
freeplay measurement every 6,000 flight cycles if the joints can be 
proven to have been lubricated with only BMS 3-33 grease every 1,000 
flight cycles or every 240 days, whichever occurs first, after the 
airplane delivery or the last support teardown inspection. However, 
this proposed AD would require repeating the freeplay measurement under 
those conditions at intervals not to exceed 6,000 flight cycles, as 
specified in the service bulletin, but would add a compliance time of 
120 months (whichever occurs first).
    Note (c) in Table 1 of Paragraph 1.E. ``Compliance'' of Boeing 
Service Bulletin 777-27A0066, Revision 1, specifies that freeplay 
levels greater than 0.020 inch are not recommended later than 30 months 
after release of the service bulletin. This proposed AD would require 
the initial measurement of the freeplay, for airplanes that have 
accumulated 6,000 total flight cycles or more on or before the 
effective date of this AD or on which a teardown inspection has not 
been accomplished before the effective date of this AD; at the earlier 
of the following compliance times.
    <bullet> Prior to the accumulation of 10,000 total flight cycles, 
or within 9 months after the effective date of this AD, whichever 
occurs later.
    <bullet> Within 30 months after the effective date of this AD.
    Boeing Alert Service Bulletin 777-27A0071 specifies revising the 
maintenance practices for performing periodic inspections and 
maintenance of the support joints of the trailing edge flap for the 
maintenance inspection program of the Boeing 777 MPD Document by doing 
the actions specified in Part 7 of the Accomplishment Instructions of 
the service bulletin. However, this proposed AD would mandate only the 
maintenance actions specified in paragraphs 1 and 3 of Part 7 of the 
service bulletin. Parts 3, 4, and 6 of the service bulletin include 
optional actions for certain structure in order to increase the 
interval of the repetitive freeplay measurement.
    These differences have been coordinated with Boeing.

Costs of Compliance

    There are about 546 airplanes of the affected design in the 
worldwide fleet. The following table provides the estimated costs for 
U.S. operators to comply with this proposed AD.

[[Page 13050]]



                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                           Average                                  Number of
                                   Work     labor      Parts                          U.S.-
             Action               hours    rate per     cost    Cost per airplane  registered      Fleet cost
                                             hour                                   airplanes
----------------------------------------------------------------------------------------------------------------
Freeplay measurement, per cycle       28        $80         $0  $2,240, per cycle         145  $324,800, per
                                                                                                cycle.
Lubrication, per cycle.........        2         80          0  $160, per cycle..         145  $23,200 per
                                                                                                cycle.
Modification for flap support        135         80     58,521  $69,321..........         145  $10,051,545.
 No. 3 and 6.
----------------------------------------------------------------------------------------------------------------

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-2007-27619; Directorate Identifier 2005-NM-
164-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by May 4, 
2007.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 777-200, -200LR, -300, and -
300ER series airplanes, certificated in any category; as identified 
in Boeing Service Bulletin 777-27A0066, Revision 1, dated May 18, 
2006.

Unsafe Condition

    (d) This AD results from reports of excessive wear of the pins, 
bushings, and bearings, and corrosion at the joints of the outboard 
trailing edge flap supports. We are issuing this AD to prevent wear 
and corrosion at the flap support joints, which could result in loss 
of the trailing edge flap and possible loss of control 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.

Initial Freeplay Measurement

    (f) At the applicable time in paragraph (f)(1) or (f)(2) of this 
AD: Measure the freeplay of support joints A, B, C, and D of the 
trailing edge flap supports, numbers 1 through 3 inclusive and 6 
through 8 inclusive, and of joint B of the trailing edge flap 
supports, numbers 4 and 5; in accordance with the Accomplishment 
Instructions of Boeing Service Bulletin 777-27A0066, Revision 1, 
dated May 18, 2006.
    (1) For airplanes that have accumulated 6,000 total flight 
cycles or more on or before the effective date of this AD or on 
which a teardown inspection has not been accomplished before the 
effective date of this AD: At the earlier of the times in paragraph 
(f)(1)(i) or (f)(1)(ii) of this AD.
    (i) Prior to the accumulation of 10,000 total flight cycles, or 
within 9 months after the effective date of this AD, whichever 
occurs later.
    (ii) Within 30 months after the effective date of this AD.
    (2) For airplanes that have accumulated fewer than 6,000 total 
flight cycles on or before the effective date of this AD: At the 
later of the times in paragraph (f)(2)(i) or (f)(2)(ii) of this AD.
    (i) Prior to the accumulation of 6,000 total flight cycles, or 
within 120 months after the date of issuance of the original 
standard airworthiness certificate or the date of issuance of the 
original export certificate of airworthiness, whichever occurs 
first.
    (ii) Within 30 months after the effective date of this AD.

Repetitive Intervals if the Freeplay Measurement Is Less Than 0.020 
Inch

    (g) If, during any freeplay measurement required by paragraph 
(f), (g), or (h) of this AD, the freeplay measurement is less than 
0.020 inch: Repeat the freeplay measurement required by paragraph 
(f) of this AD at the applicable interval in paragraph (g)(1) or 
(g)(2) of this AD. Accomplishing the actions specified in paragraph 
(j) or (k) of this AD, as applicable, extends the intervals for the 
repetitive measurements for the associated flap support only.
    (1) At intervals not to exceed 1,000 flight cycles.
    (2) At intervals not to exceed 6,000 flight cycles or 120 
months, whichever occurs first, if a review of airplane maintenance 
records can conclusively determine that the joints have been 
lubricated with only BMS 3-33 grease at the earlier of intervals not 
to exceed 1,000 flight cycles or 240 days since the last support 
teardown inspection, or since the date of issuance of the original 
standard airworthiness certificate or the date of issuance of the 
original export certificate of airworthiness.

[[Page 13051]]

Related Investigative and Corrective Actions, and Repetitive Intervals 
if the Freeplay Measurement Is 0.020 Inch or Greater

    (h) If, during any freeplay measurement required by paragraph 
(f), (g), or (h) of this AD, the freeplay measurement is 0.020 inch 
or greater: Do the applicable action in paragraph (h)(1), (h)(2), or 
(h)(3) of this AD. Accomplishing the actions specified in paragraph 
(j) or (k) of this AD, as applicable, extends the intervals for 
repetitive measurements for the associated flap support only. Do all 
actions in accordance with the Accomplishment Instructions of Boeing 
Service Bulletin 777-27A0066, Revision 1, dated May 18, 2006, and 
note (e) of Table 1 in paragraph 1.E., ``Compliance.''
    (1) For airplanes that have accumulated 6,000 total flight 
cycles or more as of the effective date of this AD, and for which 
the freeplay measurement is 0.020 inch to 0.100 inch inclusive: 
Repeat the freeplay measurement required by paragraph (f) of this AD 
thereafter at intervals not to exceed 500 flight cycles until the 
support teardown inspection in paragraph (h)(1)(i) or (h)(1)(ii) of 
this AD is done.
    (i) Within 12 months after the first freeplay measurement of 
0.020 inch to 0.100 inch inclusive, do the applicable related 
investigative and corrective actions specified in the service 
bulletin as the ``Support Teardown Inspection,'' and repeat the 
freeplay measurement required by paragraph (f) of this AD thereafter 
at intervals not to exceed 6,000 flight cycles or 120 months, 
whichever occurs first.
    (ii) Before further flight after the first freeplay measurement 
of 0.020 inch to 0.100 inch inclusive, do the applicable related 
investigative and corrective actions specified in the service 
bulletin as the ``Temporary Return to Service Inspection'' and, 
within 24 months after the first freeplay measurement of 0.020 inch 
to 0.100 inch inclusive, do the applicable related investigative and 
corrective actions specified in the service bulletin as the 
``Support Teardown Inspection.'' Repeat the freeplay measurement 
required by paragraph (f) of this AD thereafter at intervals not to 
exceed 6,000 flight cycles, or 120 months, whichever occurs first.
    (2) For airplanes that have accumulated 6,000 total flight 
cycles or more as of the effective date of this AD, and the freeplay 
measurement is greater than 0.100 inch: Do the action in paragraph 
(h)(2)(i) or (h)(2)(ii) of this AD.
    (i) Before further flight after the first freeplay measurement 
of greater than 0.100 inch, do the applicable related investigative 
and corrective actions specified in the service bulletin as the 
``Support Teardown Inspection.'' Repeat the freeplay measurement 
required by paragraph (f) of this AD thereafter at intervals not to 
exceed 6,000 flight cycles or 120 months, whichever occurs first.
    (ii) Before further flight after the first freeplay measurement 
of greater than 0.100 inch, do applicable related investigative and 
corrective actions in the ``Temporary Return to Service 
Inspection,'' and within 6 months after the first freeplay 
measurement of greater than 0.100 inch, do the applicable related 
investigative and corrective actions in the ``Support Teardown 
Inspection.'' Repeat the freeplay measurement required by paragraph 
(f) of this AD thereafter at intervals not to exceed 6,000 flight 
cycles or 120 months, whichever occurs first.
    (3) For airplanes that have accumulated fewer than 6,000 total 
flight cycles as of the effective date of this AD: Before further 
flight after the first freeplay measurement of 0.020 inch or 
greater, do the related investigative and corrective actions 
specified in the service bulletin as the ``Support Teardown 
Inspection.'' Repeat the freeplay measurement required by paragraph 
(f) of this AD thereafter at intervals not to exceed 6,000 flight 
cycles or 120 months, whichever occurs first.

Repetitive Lubrications

    (i) Within 12 months after the effective date of this AD: 
Lubricate the joints of the trailing edge flap supports using BMS 3-
33 grease. Repeat the lubrication thereafter at intervals not to 
exceed 1,000 flight cycles, or 240 days, whichever occurs first. Do 
all actions in accordance with the Accomplishment Instructions, and 
note (d) of Table 1 in paragraph 1.E., ``Compliance'' of Boeing 
Service Bulletin 777-27A0066, Revision 1, dated May 18, 2006.

Modification/Repetitive Freeplay Measurements

    (j) Before the accumulation of 23,000 total flight cycles or 
within 24 months after the effective date of this AD, whichever is 
later: Replace the pins, ball sets, and bushings on the joints of 
the trailing edge flap at support numbers 3 and 6 with new, improved 
components by doing all the applicable actions, including all 
applicable corrective actions, in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin 777-27A0071, Revision 
1, dated October 16, 2006. Before further flight after doing the 
actions, do a detailed inspection of the components that interface 
with the flap support pins for discrepancies (corrosion, damage, or 
excessive wear), and a general visual inspection for any blocked 
lubrication paths; and do all applicable corrective actions. Repeat 
the freeplay measurements for the associated flap support at 
intervals not to exceed 16,000 flight cycles in accordance with the 
Accomplishment Instructions of Boeing Alert Service Bulletin 777-
27A0071, Revision 1, dated October 16, 2006. Accomplishing the 
actions in this paragraph constitutes terminating action for the 
actions specified in paragraphs (f), (g), (h), and (i) of this AD, 
for the associated trailing edge flap support only.

Optional Modification

    (k) Accomplishing the actions specified in paragraph (j) of this 
AD at support numbers 1, 2, 4, 5, 7, and 8, extends the intervals 
for the repetitive measurements required by paragraph (g) of this AD 
for the associated flap support only.

Revise Maintenance Planning Data (MPD) Document

    (l) Within 12 months after the effective date of this AD: Revise 
the maintenance practices for performing periodic inspections and 
maintenance of the support joints of the trailing edge flap for the 
maintenance inspection program of the Boeing 777 MPD Document by 
doing the actions specified in paragraphs 1 and 3 only of Part 7 of 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
777-27A0071, Revision 1, dated October 16, 2006.

Actions Accomplished Previously

    (m) Actions done before the effective date of this AD in 
accordance with Boeing Alert Service Bulletin 777-27A0066, dated 
July 28, 2005, are acceptable for compliance with paragraphs (f), 
(g), (h), and (i) of this AD, as applicable. Actions done before the 
effective date of this AD in accordance with Boeing Alert Service 
Bulletin 777-27A0071, dated March 30, 2006, are acceptable for 
compliance with paragraphs (j), (k), and (l) of this AD, as 
applicable.

Alternative Methods of Compliance (AMOCs)

    (n)(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) Before using any AMOC approved in accordance with Sec.  
39.19 on any airplane to which the AMOC applies, notify the 
appropriate principal inspector in the FAA Flight Standards 
Certificate Holding District Office.
    (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.

    Issued in Renton, Washington, on March 9, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E7-5013 Filed 3-19-07; 8:45 am]
BILLING CODE 4910-13-P