AD E7-10982

Recurring final rule

Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-300, 747-400, 747-400D, 747SR, and 747SP Series Airplanes

AD Number
E7-10982
Status
final_rule
Effective Date
Product Category
aircraft
Docket
Docket No. FAA-2007-27525
FR Citation
72 FR 31984

Applicability

TypeManufacturerModelDetails
aircraft Boeing 747-100 Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-300, 747-400, 747-400D, 747SR, and 747SP Series Airplanes

Unsafe Condition

Corrosion on the floor structure supports for the escape slides of the main deck entry doors could result in separation of the escape slide from the lower door sill during deployment. Incorrect installation of square and conical washers in the girt bar support fitting could result in failure of the escape slide when deployed.

AI-generated summary from the source AD text. Verify against the official source before acting.

Required Actions

Inspect for correct installation of square and conical washers in the girt bar support fitting for certain airplanes. Inspect to determine if the washers are installed for certain other airplanes. Perform related investigative and corrective action if necessary.

AI-generated summary from the source AD text. Verify against the official source before acting.

Compliance Time

Within the compliance times specified in the AD, unless the actions have already been done.

AI-generated summary from the source AD text. Verify against the official source before acting.

Affected Aircraft

Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-300, 747-400, 747-400D, 747SR, and 747SP series airplanes, certificated in any category, line numbers 1 through 868 inclusive.

AI-generated summary from the source AD text. Verify against the official source before acting.

Federal Register Abstract

The FAA is superseding an existing airworthiness directive (AD), which applies to certain Boeing Model 747 airplanes. That AD currently requires repetitive inspections to detect cracks and/or corrosion of the girt bar support fitting at certain main entry doors (MED), and repair or replacement of the support fitting. The existing AD also provides for various terminating actions for the repetitive inspections. This new AD requires the following additional actions: An inspection, for certain airplanes, for correct installation of square and conical washers in the girt bar support fitting; an inspection, for certain other airplanes, to determine if the washers are installed; and related investigative and corrective action if necessary. This AD results from a report that the square and conical washers may be installed incorrectly in the girt bar support fitting on airplanes on which the support fitting was repaired or replaced in accordance with the requirements of the existing AD. We are issuing this AD to detect and correct corrosion of the girt bar support fitting, which could result in separation of the escape slide from the lower door sill during deployment, and subsequently prevent proper operation of the escape slides at the main entry doors during an emergency. We are also issuing this AD to detect and correct incorrect installation of the square and conical washers in the girt bar support fitting, which could result in failure of the escape slide when deployed.

Document Text

Show stored source text (verify against official source)
[Federal Register Volume 72, Number 111 (Monday, June 11, 2007)]
[Rules and Regulations]
[Pages 31984-31988]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: E7-10982]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-27525; Directorate Identifier 2006-NM-159-AD; 
Amendment 39-15089; AD 2007-12-11]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-
100B SUD, 747-200B, 747-200C, 747-300, 747-400, 747-400D, 747SR, and 
747SP Series Airplanes

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

ACTION: Final rule.

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

SUMMARY: The FAA is superseding an existing airworthiness directive 
(AD), which applies to certain Boeing Model 747 airplanes. That AD 
currently requires repetitive inspections to detect cracks and/or 
corrosion of the girt bar support fitting at certain main entry doors 
(MED), and repair or replacement of the support fitting. The existing 
AD also provides for various terminating actions for the repetitive 
inspections. This new AD requires the following additional actions: An 
inspection, for certain airplanes, for correct installation of square 
and conical washers in the girt bar support fitting; an inspection, for 
certain other airplanes, to determine if the washers are installed; and 
related investigative and corrective action if necessary. This AD 
results from a report that the square and conical washers may be 
installed incorrectly in the girt bar support fitting on airplanes on 
which the support fitting was repaired or replaced in accordance with 
the requirements of the existing AD. We are issuing this AD to detect 
and correct corrosion of the girt bar support fitting, which could 
result in separation of the escape slide from the lower door sill 
during deployment, and subsequently prevent proper operation of the 
escape slides at the main entry doors during an emergency. We are also 
issuing this AD to detect and correct incorrect installation of the 
square and conical washers in the girt bar support fitting, which could 
result in failure of the escape slide when deployed.

DATES: This AD becomes effective July 16, 2007.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in the AD as of July 16, 
2007.
    On December 16, 1996 (61 FR 58318, November 14, 1996), the Director 
of the Federal Register approved the incorporation by reference of 
Boeing Service Bulletin 747-53A2378, Revision 1, dated March 10, 1994.

ADDRESSES: You may examine the AD docket on the Internet at <a href="http://dms.dot.gov">http://dms.dot.gov</a> or in person at the Docket Management Facility, U.S. 
Department of Transportation, 400 Seventh Street, SW., Nassif Building, 
Room PL-401, Washington, DC.
    Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for service information identified in this AD.

FOR FURTHER INFORMATION CONTACT: Patrick Gillespie, Aerospace Engineer, 
Cabin Safety and Environmental Systems Branch, ANM-150S, FAA, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98057-3356; telephone (425) 917-6429; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Examining the Docket

    You may examine the airworthiness directive (AD) docket on the 
Internet at <a href="http://dms.dot.gov">http://dms.dot.gov</a> or in person at the

[[Page 31985]]

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 street address stated in the ADDRESSES section.

Discussion

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 to include an AD that supersedes AD 96-23-05, amendment 39-
9810 (61 FR 58318, November 14, 1996). The existing AD applies to 
certain Boeing Model 747 airplanes. That NPRM was published in the 
Federal Register on March 15, 2007 (72 FR 12136). That NPRM proposed to 
continue to require repetitive inspections to detect cracks and/or 
corrosion of the girt bar support fitting at certain main entry doors 
(MED), and repair or replacement of the support fitting. The existing 
AD also provides for various terminating actions for the repetitive 
inspections. The NPRM also proposed to require the following additional 
actions: An inspection, for certain airplanes, for correct installation 
of square and conical washers in the girt bar support fitting; an 
inspection, for certain other airplanes, to determine if the washers 
are installed; and related investigative and corrective action if 
necessary.

Comments

    We provided the public the opportunity to participate in the 
development of this AD. We have considered the single comment that has 
been received on the NPRM. The commenter, Boeing, supports the NPRM.

Clarification of Alternative Method of Compliance (AMOC) Paragraph

    We have revised this action to clarify the appropriate procedure 
for notifying the principal inspector before using any approved AMOC on 
any airplane to which the AMOC applies.

Conclusion

    We have carefully reviewed the available data, including the 
comment that has been received, and determined that air safety and the 
public interest require adopting the AD with the change described 
previously. We have determined that this change will neither increase 
the economic burden on any operator nor increase the scope of the AD.

Costs of Compliance

    There are about 1,012 airplanes of the affected design in the 
worldwide fleet. The following table provides the estimated costs for 
U.S. operators to comply with this AD. The average labor rate per work 
hour is $80. The cost varies depending on the configuration of the 
airplane.

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                            Number of U.S.-
             Action                  Work hours       Cost per airplane  registered airplanes      Fleet cost
----------------------------------------------------------------------------------------------------------------
Inspection of MEDs (required by  Between 88 and 102  Between $7,040 and  169.................  Between
 AD 96-23-05).                                        $8,160, per                               $1,189,760 and
                                                      inspection cycle.                         $1,379,040, per
                                                                                                inspection
                                                                                                cycle.
Inspection for correct           6.................  $480..............  Up to 169...........  Up to $81,120.
 installation (new required
 action).
----------------------------------------------------------------------------------------------------------------

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 AD will not have federalism 
implications under Executive Order 13132. This AD will 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 this AD:
    (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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this 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, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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]

0
2. The Federal Aviation Administration (FAA) amends Sec.  39.13 by 
removing amendment 39-9810 (61 FR 58318, November 14, 1996) and by 
adding the following new airworthiness directive (AD):

2007-12-11 Boeing: Amendment 39-15089. Docket No. FAA-2007-27525; 
Directorate Identifier 2006-NM-159-AD.

Effective Date

    (a) This AD becomes effective July 16, 2007.

Affected ADs

    (b) This AD supersedes AD 96-23-05.

[[Page 31986]]

Applicability

    (c) This AD applies to Boeing Model 747-100, 747-100B, 747-100B 
SUD, 747-200B, 747-200C, 747-300, 747-400, 747-400D, 747SR, and 
747SP series airplanes, certificated in any category, line numbers 1 
through 868 inclusive.

Unsafe Condition

    (d) This AD results from reports that, during scheduled 
deployment tests of main entry door slides, corrosion was found on 
the floor structure supports for the escape slides of the main deck 
entry doors on these airplanes. This AD also results from a report 
that the square and conical washers may be installed incorrectly in 
the girt bar support fitting on airplanes on which the support 
fitting was repaired or replaced in accordance with the requirements 
of AD 96-23-05. We are issuing this AD to detect and correct 
corrosion of the girt bar support fitting, which could result in 
separation of the escape slide from the lower door sill during 
deployment, and subsequently prevent proper operation of the escape 
slides at the main entry doors during an emergency. We are also 
issuing this AD to detect and correct incorrect installation of the 
square and conical washers in the girt bar support fitting, which 
could result in failure of the escape slide when deployed.

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.

Restatement of Requirements of AD 96-23-05 With New Service Information

Doors Exempt From/Affected by This AD

    (f) The requirements of this AD are not applicable to doors 
where an escape slide or slide/raft is not installed or is not used 
for passenger egress (such as a deactivated door 3, at doors 4 and/
or 5 of an airplane being operated in the ``combi'' configuration, 
or any door not used for passenger egress in a ``convertible'' (an 
airplane configured for quick change from passenger to cargo)). The 
requirements of this AD are also not applicable to doors on 
airplanes converted to an all-cargo configuration. The requirements 
of this AD become applicable at the time when an escape slide or 
slide/raft is installed on such doors, or when such doors are 
activated and/or converted for passenger use. The requirements also 
become applicable at the time an airplane operating in an all-cargo 
configuration is converted to a passenger or passenger/cargo 
configuration.

Inspections and Corrective Actions for Airplanes Equipped With Main 
Entry Door (MED) 1

    (g) For airplanes equipped with MED 1: Prior to the accumulation 
of 16 years of service since date of manufacture of the airplane, or 
within 18 months after December 16, 1996 (the effective date of AD 
96-23-05), whichever occurs later, perform a detailed inspection to 
detect cracking and/or corrosion of the girt bar support fitting at 
the left and right MED 1, in accordance with Boeing Service Bulletin 
747-53A2378, Revision 1, dated March 10, 1994; or Boeing Service 
Bulletin 747-53A2378, Revision 3, dated August 11, 2005. After the 
effective date of this AD, only Revision 3 may be used.
    (h) If no cracking or corrosion is found during the inspection 
required by paragraph (g) of this AD, prior to further flight, 
accomplish either paragraph (h)(1) or (h)(2) of this AD, in 
accordance with the applicable instructions specified in Boeing 
Service Bulletin 747-53A2378, Revision 1, dated March 10, 1994; or 
Boeing Service Bulletin 747-53A2378, Revision 3, dated August 11, 
2005. After the effective date of this AD, only Revision 3 may be 
used.
    (1) Install a new fitting with new fasteners, and reinstall the 
threshold assembly with new corrosion-resistant fasteners, in 
accordance with the service bulletin. After these actions are 
accomplished, no further action is required by paragraph (h) of this 
AD; or
    (2) Reinstall the threshold assembly with corrosion-resistant 
fasteners, in accordance with the service bulletin. Thereafter, 
repeat the inspection required by paragraph (g) of this AD at 
intervals not to exceed 6 years.
    (i) If any cracking is found during the inspection required by 
paragraph (g) or (h)(2) of this AD, prior to further flight, install 
a new fitting with new fasteners, and reinstall the threshold 
assembly with new corrosion-resistant fasteners, in accordance with 
Boeing Service Bulletin 747-53A2378, Revision 1, dated March 10, 
1994; or Boeing Service Bulletin 747-53A2378, Revision 3, dated 
August 11, 2005. After the effective date of this AD, only Revision 
3 may be used. After these actions are accomplished, no further 
action is required by this paragraph.
    (j) If any corrosion is found during the inspection required by 
paragraph (g) or (h)(2) of this AD, prior to further flight, 
accomplish either paragraph (j)(1) or (j)(2) of this AD, in 
accordance with Boeing Service Bulletin 747-53A2378, Revision 1, 
dated March 10, 1994; or Boeing Service Bulletin 747-53A2378, 
Revision 3, dated August 11, 2005. After the effective date of this 
AD, only Revision 3 may be used.
    (1) Install a new fitting with new fasteners, and reinstall the 
threshold assembly with new corrosion-resistant fasteners in 
accordance with the service bulletin. After these actions are 
accomplished, no further action is required by this paragraph; or
    (2) Blend out corrosion in accordance with the service bulletin.
    (i) If blend out of corrosion is beyond 10 percent of original 
thickness or any crack is found during accomplishment of the blend 
out procedures, install a new fitting with new fasteners, and 
reinstall the threshold assembly with new corrosion-resistant 
fasteners, in accordance with the service bulletin. After these 
actions are accomplished, no further action is required by this 
paragraph.
    (ii) If blend out of corrosion does not exceed 10 percent of 
original material thickness, accomplish either paragraph 
(j)(2)(ii)(A) or (j)(2)(ii)(B) of this AD:
    (A) Install a new fitting with new fasteners, and reinstall 
threshold assembly with new corrosion-resistant fasteners, in 
accordance with the service bulletin. After these actions are 
accomplished, no further action is required by this paragraph; or
    (B) Install the repaired fitting with new fasteners and 
reinstall the threshold assembly with corrosion-resistant fasteners, 
in accordance with the service bulletin. Thereafter, repeat the 
inspection and applicable corrective actions required by paragraph 
(g) of this AD at intervals not to exceed 6 years.

Inspections and Corrective Actions for Airplanes Equipped With MED 
2, 4, and/or 5 (MED 2, 3, and/or 4 on Model 747SP Series Airplanes)

    (k) For airplanes equipped with MED 2, 4, and/or 5 (MED 2, 3, 
and/or 4 on Model 747SP series airplanes): Prior to the accumulation 
of 10 years of service since date of manufacture of the airplane, or 
within 18 months after December 16, 1996, whichever occurs later, 
perform a detailed inspection to detect cracking and/or corrosion of 
the girt bar support fitting at the left and right MED 2, 4, and 5 
(MED 2, 3, and 4 on Model 747SP series airplanes), in accordance 
with Boeing Service Bulletin 747-53A2378, Revision 1, dated March 
10, 1994; or Boeing Service Bulletin 747-53A2378, Revision 3, dated 
August 11, 2005. After the effective date of this AD, only Revision 
3 may be used.
    (l) If no cracking or corrosion is found during the inspection 
required by paragraph (k) of this AD, prior to further flight, 
accomplish either paragraph (l)(1) or (l)(2) of this AD, in 
accordance with the applicable instructions in Boeing Service 
Bulletin 747-53A2378, Revision 1, dated March 10, 1994; or Boeing 
Service Bulletin 747-53A2378, Revision 3, dated August 11, 2005. 
After the effective date of this AD, only Revision 3 may be used.
    (1) Remove the inspected fitting and reinstall it with a new 
coat of primer and new fasteners; and reinstall the threshold 
assembly with new corrosion-resistant fasteners; in accordance with 
the service bulletin. After these actions are accomplished, no 
further action is required by this paragraph; or
    (2) Reinstall the serrated plate assembly and the girt bar floor 
fitting with corrosion-resistant fasteners, in accordance with the 
service bulletin. Thereafter, repeat the inspection required by 
paragraph (k) of this AD at intervals not to exceed 6 years.
    (m) If any cracking is found during the inspection required by 
paragraph (k) or (l)(2) of this AD, prior to further flight, install 
a new fitting with new fasteners, and reinstall the threshold 
assembly with new corrosion-resistant fasteners, in accordance with 
Boeing Service Bulletin 747-53A2378, Revision 1, dated March 10, 
1994; or Boeing Service Bulletin 747-53A2378, Revision 3, dated 
August 11, 2005. After the effective date of this AD, only Revision 
3 may be used. After these actions are accomplished, no further 
action is required by this paragraph.
    (n) If any corrosion is found during the inspection required by 
paragraph (k) or (l)(2) of this AD, prior to further flight, 
accomplish either paragraph (n)(1) or (n)(2) of this AD, in 
accordance with Boeing Service Bulletin 747-53A2378, Revision 1, 
dated March 10, 1994; or Boeing Service Bulletin 747-

[[Page 31987]]

53A2378, Revision 3, dated August 11, 2005. After the effective date 
of this AD, only Revision 3 may be used.
    (1) Install a new fitting with new fasteners, and reinstall the 
threshold assembly with new corrosion-resistant fasteners, in 
accordance with the service bulletin. After these actions are 
accomplished, no further action is required by this paragraph; or
    (2) Blend out corrosion in accordance with the service bulletin.
    (i) If blend out of corrosion is beyond 10 percent of original 
thickness or any crack is found during accomplishment of the blend 
out procedures, install a new fitting with new fasteners, and 
reinstall the threshold assembly with new corrosion-resistant 
fasteners, in accordance with the service bulletin. After these 
actions are accomplished, no further action is required by this 
paragraph.
    (ii) If blend out of corrosion does not exceed 10 percent of 
original material thickness, install the repaired fitting with new 
fasteners, and reinstall the threshold assembly with new corrosion-
resistant fasteners, in accordance with the service bulletin. After 
these actions are accomplished, no further action is required by 
this paragraph.
    (o) For airplanes equipped with main entry door (MED) 3 (this 
paragraph does not apply to Model 747SP series airplanes): Prior to 
the accumulation of 16 years of service since date of manufacture of 
the airplane, or within 18 months after December 16, 1996, whichever 
occurs later, perform a detailed inspection to detect cracking and/
or corrosion of the girt bar support angles at the left and right 
MED 3, in accordance with Boeing Service Bulletin 747-53A2378, 
Revision 1, dated March 10, 1994; or Boeing Service Bulletin 747-
53A2378, Revision 3, dated August 11, 2005. After the effective date 
of this AD, only Revision 3 may be used.
    (p) If no cracking or corrosion is found during the inspection 
required by paragraph (o) of this AD, prior to further flight, 
accomplish either paragraph (p)(1) or (p)(2) of this AD in 
accordance with the applicable instructions in Boeing Service 
Bulletin 747-53A2378, Revision 1, dated March 10, 1994; or Boeing 
Service Bulletin 747-53A2378, Revision 3, dated August 11, 2005. 
After the effective date of this AD, only Revision 3 may be used.
    (1) Remove the inspected angle and reinstall it with a new coat 
of primer and new fasteners; and reinstall the threshold assembly 
with new corrosion-resistant fasteners; in accordance with the 
service bulletin. After these actions are accomplished, no further 
action is required by this paragraph; or
    (2) Reinstall the corner scuff plate and the threshold apron 
with corrosion-resistant fasteners, in accordance with the service 
bulletin. Thereafter, repeat the inspection required by paragraph 
(o) of this AD at intervals not to exceed 6 years.
    (q) If any crack common to the support angles is found during 
the inspection required by paragraph (o) or (p)(2) of this AD, prior 
to further flight, accomplish the actions specified in paragraph 
(q)(1) or (q)(2), as applicable, in accordance with Boeing Service 
Bulletin 747-53A2378, Revision 1, dated March 10, 1994; or Boeing 
Service Bulletin 747-53A2378, Revision 3, dated August 11, 2005. 
After the effective date of this AD, only Revision 3 may be used:
    (1) Install the new angles with new fasteners, and reinstall the 
threshold assembly with new corrosion-resistant fasteners. After 
these actions are accomplished, no further action is required by 
this paragraph of this AD; or
    (2) For any cracking found only in the corner casting as 
specified in the service bulletin, accomplish either paragraph 
(q)(2)(i) or (q)(2)(ii) prior to further flight:
    (i) Replace the corner casting in accordance with the service 
bulletin; or
    (ii) Repair the cracked part in accordance with a method 
approved by the Manager, Seattle Aircraft Certification Office 
(ACO), FAA, Transport Airplane Directorate. Refer to paragraph (w) 
of this AD for the appropriate procedure for seeking such an 
approval. (This option is provided in order to give operators time 
to obtain a replacement corner casing without grounding an 
airplane.) This repair is considered temporary action only; 
replacement of the corner casting eventually must be accomplished in 
accordance with a schedule prescribed by the Manager, Seattle ACO.
    (r) If any corrosion is found during the inspection required by 
paragraph (o) of this AD, prior to further flight, accomplish either 
paragraph (r)(1) or (r)(2) of this AD, in accordance with Boeing 
Service Bulletin 747-53A2378, Revision 1, dated March 10, 1994; or 
Boeing Service Bulletin 747-53A2378, Revision 3, dated August 11, 
2005. After the effective date of this AD, only Revision 3 may be 
used.
    (1) Install the new angles with new fasteners, and reinstall the 
threshold assembly with new corrosion-resistant fasteners, in 
accordance with the service bulletin. After these actions are 
accomplished, no further action is required by this paragraph; or
    (2) Blend out corrosion in accordance with the service bulletin.
    (i) If blend out of corrosion is beyond 10 percent of original 
thickness, or if any crack common to the support angles is found 
during accomplishment of the blend out procedures, install the new 
angles with new fasteners, and reinstall the threshold assembly with 
new corrosion-resistant fasteners, in accordance with the service 
bulletin. After these actions are accomplished, no further action is 
required by this paragraph.
    (ii) If blend out of corrosion does not exceed 10 percent of 
original material thickness, install the repaired angles with new 
fasteners, and reinstall the threshold assembly with new corrosion-
resistant fasteners, in accordance with the service bulletin. After 
these actions are accomplished, no further action is required by 
this paragraph.

Actions Accomplished According to Previous Issue of Service 
Bulletin

    (s) Installation of a girt bar support fitting in accordance 
with Boeing Service Bulletin 747-25A2831, dated August 29, 1991, 
before the effective date of this AD, is considered acceptable for 
compliance with the corresponding requirements of paragraphs (h), 
(i), (j), (l), (m), and (n) of this AD for each affected fitting 
location.

New Requirements of This AD

Inspections for the Washers and Related Investigative/Corrective 
Actions

    (t) For Groups 7, 8, and 9 airplanes identified in Boeing 
Service Bulletin 747-53A2378, Revision 3, dated August 11, 2005, on 
which the support fitting was replaced or repaired in accordance 
with Boeing Service Bulletin 747-53A2378, dated June 24, 1993; 
Revision 1, dated March 10, 1994; or Revision 2, dated July 24, 
2003; or Boeing Service Bulletin 747-25A2831, dated August 29, 1991: 
Within 18 months after the effective date of this AD, do a general 
visual inspection for correct installation of square and conical 
washers in the girt bar floor fittings, and, before further flight, 
do all applicable related investigative and corrective actions. Do 
all actions in accordance with Figure 18 and the applicable steps 
specified on page 52 in the Accomplishment Instructions of Boeing 
Service Bulletin 747-53A2378, Revision 3, dated August 11, 2005, 
except as provided by paragraph (v) of this AD.
    (u) For Groups 1 through 6 airplanes identified in Boeing 
Service Bulletin 747-53A2378, Revision 3, dated August 11, 2005, on 
which the support fitting was replaced or repaired in accordance 
with Boeing Service Bulletin 747-53A2378, dated June 24, 1993; 
Revision 1, dated March 10, 1994; or Revision 2, dated July 24, 
2003; or with Boeing Service Bulletin 747-25A2831, dated August 29, 
1991: Within 18 months after the effective date of this AD, do a 
general visual inspection to determine if square and conical washers 
are installed in the girt bar floor fittings, and before further 
flight, do all applicable related investigative and corrective 
actions. Do all actions in accordance with Figure 18 and the 
applicable steps specified on pages 52 and 53 in the Accomplishment 
Instructions of Boeing Service Bulletin 747-53A2378, Revision 3, 
dated August 11, 2005, except as provided by paragraph (v) of this 
AD.
    (v) If any damage is found during any inspection required by 
paragraphs (t) and (u) of this AD, and Boeing Service Bulletin 747-
53A2378, Revision 3, dated August 11, 2005, specifies contacting 
Boeing for appropriate action: Before further flight, do the repair 
using a method approved by the Manager, Seattle ACO, or in 
accordance with data meeting the certification basis of the airplane 
approved by an Authorized Representative for the Boeing Commercial 
Airplanes Delegation Option Authorization 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.

Alternative Methods of Compliance (AMOCs)

    (w)(1) The Manager, Seattle ACO, has the authority to approve 
AMOCs for this AD, if requested in accordance with the procedures 
found in 14 CFR 39.19.

[[Page 31988]]

    (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) AMOCs approved previously in accordance with AD 96-23-05, 
are approved as AMOCs for the corresponding provisions of this AD.

Material Incorporated by Reference

    (x) You must use Boeing Service Bulletin 747-53A2378, Revision 
1, dated March 10, 1994; or Boeing Service Bulletin 747-53A2378, 
Revision 3, dated August 11, 2005; as applicable, to perform the 
actions that are required by this AD, unless the AD specifies 
otherwise.
    (1) The Director of the Federal Register approved the 
incorporation by reference of Boeing Service Bulletin 747-53A2378, 
Revision 3, dated August 11, 2005, in accordance with 5 U.S.C. 
552(a) and 1 CFR part 51.
    (2) On December 16, 1996 (61 FR 58318, November 14, 1996), the 
Director of the Federal Register approved the incorporation by 
reference of Boeing Service Bulletin 747-53A2378, Revision 1, dated 
March 10, 1994.
    (3) Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for a copy of this service information. You 
may review copies at the FAA, Transport Airplane Directorate, 1601 
Lind Avenue, SW., Renton, Washington; or at the National Archives 
and Records Administration (NARA). For information on the 
availability of this material at NARA, call 202-741-6030, or go to: 
<a href="http://www.archives.gov/federal-register/cfr/ibr-locations.html">http://www.archives.gov/federal-register/cfr/ibr-locations.html</a>.

    Issued in Renton, Washington, on May 30, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E7-10982 Filed 6-8-07; 8:45 am]
BILLING CODE 4910-13-P

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