[Federal Register Volume 70, Number 178 (Thursday, September 15, 2005)]
[Rules and Regulations]
[Pages 54474-54477]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-18212]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-22413; Directorate Identifier 2005-NM-167-AD; 
Amendment 39-14271; AD 2005-19-06]
RIN 2120-AA64


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

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

ACTION: Final rule; request for comments.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-
200C, 747-200F, 747-300, 747SR, and 747SP series airplanes. This AD 
requires repetitive detailed and ultrasonic inspections of the thrust 
links of the rear engine mounts for any crack or fracture and 
corrective actions if necessary. This AD results from the finding of a 
fractured forward lug of the rear engine mount thrust link on the 
number one strut. We are issuing this AD to detect and correct cracked 
or fractured thrust links that could lead to the loss of the load path 
for the rear engine mount bulkhead and damage to other primary engine 
mount structure, which could result in the in-flight separation of the 
engine from the airplane and consequent loss of control of the 
airplane.

DATES: This AD becomes effective September 30, 2005.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in the AD as of September 30, 
2005.
    We must receive comments on this AD by November 14, 2005.

ADDRESSES: Use one of the following addresses to submit comments on 
this 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 service information identified in this AD.

FOR FURTHER INFORMATION CONTACT: Ivan Li, Aerospace Engineer, Airframe 
Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind 
Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6437; 
fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Discussion

    We have received a report indicating that one operator found a 
fractured forward lug of the rear engine mount thrust link on the 
number one strut. The fractured thrust link was found on a Model 747-
200B series airplane equipped with Pratt & Whitney JT9D-7Q engines. The 
fractured thrust link had accumulated 91,173 total flight hours (and 
27,931 total flight cycles). The fracture occurred about 65,000 flight 
hours (and 14,000 flight cycles) after the thrust link had been 
overhauled to replace a worn spherical bearing. The same operator also 
reported finding a cracked thrust link on the number one strut of a 
Model 747-200B series airplane equipped with Pratt & Whitney JT9D-7Q 
engines. That cracked thrust link had accumulated about 66,000 total 
flight hours (and about 19,000 total flight cycles) and about 55,700 
flight hours (and about 11,100 flight cycles) since it was last 
overhauled. Metallurgical analysis by the airplane manufacturer 
indicates that cracking of the high-strength steel thrust links 
resulted from fatigue. In both of the reported incidents, cracking 
could have occurred before the overhaul. Continued airplane operation 
with a cracked or fractured thrust link could lead to the loss of the 
load path for the rear engine mount bulkhead and damage to other 
primary engine mount structure. This condition, if not detected and 
corrected, could result in the in-flight separation of the engine from 
the airplane and consequent loss of control of the airplane.
    The rear engine mount thrust links on the Model 747-200B series 
airplanes equipped with Pratt & Whitney JT9D-7Q engines are similar to 
those on the affected Model 747-100, 747-100B, 747-100B SUD, 747-200C, 
747-200F, 747-300, 747SR, and 747SP series airplanes, equipped with 
Pratt & Whitney JT9D-3 and -7 series engines, except JT9D-70 engines. 
Therefore, all of these models may be subject to the same unsafe 
condition.

Other Related Rulemaking

    On July 19, 2001, we issued AD 2001-15-15, amendment 39-12349 (66 
FR 39425, dated July 31, 2001), applicable to certain Boeing Model 747 
airplanes powered by Pratt & Whitney JT9D-7 series engines. That AD 
requires detailed visual inspections of the lugs on the bulkhead 
fitting of the rear engine mounts, and corrective action if necessary. 
That AD also requires ultrasonic inspections and, for certain 
airplanes, rework of the bulkhead fitting of the rear engine mounts. 
Reworking the lugs on the bulkhead fitting of the rear engine mounts 
(in accordance with ``Part 5--Rework'' of the Accomplishment 
Instructions of Boeing Service Bulletin 747-54A2200, Revision 1, dated 
February 15, 2001) as specified in paragraphs (b)(2), (e), and (f) of 
AD 2001-15-15 is acceptable for compliance with ``Part 3--Rear Engine 
Mount Bulkhead Inspection and Lug Overhaul and Upper Fitting Overhaul 
and Bolt Replacement'' of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 747-71A2309, dated August 18, 2005 (which is 
referenced as the appropriate source of service information for doing 
the actions required by this AD).
    On March 24, 2004, we issued AD 2004-07-22, amendment 39-13566 (69 
FR 18250, April 7, 2004), applicable to all Boeing Model 747 airplanes. 
(A correction to AD 2004-07-22 was published in the Federal Register on 
May 3, 2004 (69 FR 24063).) That AD requires that the FAA-approved 
maintenance inspection program be revised to include inspections that 
will give no less than the required damage tolerance rating for each 
structural significant item (SSI), and repair of cracked structure. 
Accomplishing the inspections and repetitive overhaul or replacement 
specified in paragraphs (g) and (j) of this AD are approved as an 
alternative method of compliance to paragraphs (c) and (d) of AD 2004-
07-22 for the inspections of SSI S-2, for the thrust links only, of the 
Boeing Supplemental Structural Inspection Document D6-35022, Revision 
G, dated December 2000.

[[Page 54475]]

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 747-71A2309, dated 
August 18, 2005. The service bulletin describes procedures for doing 
detailed and ultrasonic inspections of the thrust link lugs of the rear 
engine mount of struts 1, 2, 3, and 4 for any crack or fracture and 
other specified and corrective actions as applicable.
    If a thrust link is not cracked or fractured, the service bulletin 
specifies repeating the detailed and ultrasonic inspections and doing 
other specified actions. The other specified actions are to 
repetitively replace the thrust link with a new or overhauled thrust 
link, which ends the repetitive inspections of the thrust link lugs.
    If a thrust link is cracked, the corrective action is to 
repetitively replace the cracked thrust link with a new or overhauled 
thrust link. If the thrust link is fractured, the corrective actions 
include the following:
    <bullet> Repetitively replacing the fractured thrust link with a 
new or overhauled thrust link (Part 2 of the Accomplishment 
Instructions of the service bulletin).
    <bullet> Inspecting the upper fitting assembly of the rear engine 
mount for cracks and material deformation and repairing if necessary; 
doing a detailed inspection of the bulkhead assembly of the rear engine 
mount for cracks, fracture, and material deformation and contacting the 
manufacturer for additional instructions if necessary; overhauling the 
lugs of the rear engine mount bulkhead and upper fitting assembly and 
contacting the manufacturer for additional instructions if necessary; 
and replacing the bolts that attach the upper fitting to the rear 
engine mount bulkhead with new bolts (Part 3 of the Accomplishment 
Instructions of the service bulletin).
    <bullet> Doing the inspection of the engine nacelle for damage, as 
specified in Chapter 05-51-06 of the Boeing 747-100/-200/-300 Airplane 
Maintenance Manual, and contacting the manufacturer for additional 
instructions if necessary (Part 4 of the Accomplishment Instructions of 
the service bulletin).
    <bullet> Doing a detailed inspection of the forward engine mount 
for material deformation and contacting the manufacturer for additional 
instructions if necessary (Part 5 of the Accomplishment Instructions of 
the service bulletin).

FAA's Determination and Requirements of This AD

    The unsafe condition described previously is likely to exist or 
develop on other airplanes of the same type design. For this reason, we 
are issuing this AD to detect and correct cracked or fractured thrust 
links of the rear engine mount that could lead to the loss of the load 
path for the rear engine mount bulkhead and damage to other primary 
engine mount structure, which could result in the in-flight separation 
of the engine from the airplane and consequent loss of control of the 
airplane. This AD requires repetitive detailed and ultrasonic 
inspections of the thrust link lugs of the rear engine mount of struts 
1, 2, 3, and 4 for any crack or fracture and corrective actions as 
applicable in accordance with the service information described above, 
except as discussed under ``Differences Between the AD and Service 
Bulletin.''

Differences Between the AD and Service Bulletin

    The service bulletin specifies to contact the manufacturer for 
instructions on how to repair certain conditions, but this AD requires 
repairing those conditions in one of the following ways:
    <bullet> Using a method that we approve; or
    <bullet> 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 service bulletin specifies doing corrective actions if a 
fractured thrust link is found during any required inspections, but 
does not specify what action to take if one is found during any 
replacement or overhaul of the thrust link. This AD requires 
accomplishing those same corrective actions before further flight, 
whether the fractured thrust link is found during an inspection, 
replacement, or overhaul. (Those corrective actions are defined in the 
``Relevant Service Information'' section of this AD.) This difference 
has been coordinated with the manufacturer.
    Although the service bulletin recommends repetitively replacing the 
thrust links of the rear engine mounts with new or overhauled thrust 
links at an initial threshold of within 36 months after issuance of the 
service bulletin, this AD is not mandating those replacements in this 
rulemaking action. Instead, we have included those replacements as an 
optional terminating action in this AD.

Interim Action

    This is considered to be interim action. The FAA is currently 
considering requiring the repetitive replacement or overhaul of the 
thrust links of the rear engine mounts, which will constitute 
terminating action for the repetitive inspections required by this AD 
action. However, the planned compliance time for the other specified 
actions is sufficiently long so that notice and opportunity for prior 
public comment will be practicable.

FAA's Determination of the Effective Date

    Since an unsafe condition exists that requires the immediate 
adoption of this AD, we have found that notice and opportunity for 
public comment before issuing this AD are impracticable, and that good 
cause exists to make this AD effective in less than 30 days.

Comments Invited

    This AD is a final rule that involves requirements that affect 
flight safety and was not preceded by notice and an opportunity for 
public comment; however, we invite you to submit any relevant written 
data, views, or arguments regarding this AD. Send your comments to an 
address listed in the ADDRESSES section. Include ``Docket No. FAA-2005-
22413; Directorate Identifier 2005-NM-167-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the AD that might 
suggest a need to modify it.
    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 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 the 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 Dockets

    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

[[Page 54476]]

the AD docket shortly after the Docket Management System receives them.

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 the 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 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 
adding the following new airworthiness directive (AD):

2005-19-06 Boeing: Amendment 39-14271. Docket No. FAA-2005-22413; 
Directorate Identifier 2005-NM-167-AD.

Effective Date

    (a) This AD becomes effective September 30, 2005.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 747-100, 747-100B, 747-100B 
SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series 
airplanes, certificated in any category; equipped with Pratt & 
Whitney JT9D-3 and -7 series engines, except JT9D-70 engines; as 
identified in Boeing Alert Service Bulletin 747-71A2309, dated 
August 18, 2005.

Unsafe Condition

    (d) This AD results from the finding of a fractured forward lug 
of the rear engine mount thrust link on the number one strut. We are 
issuing this AD to detect and correct cracked or fractured thrust 
links that could lead to the loss of the load path for the rear 
engine mount bulkhead and damage to other primary engine mount 
structure, which could result in the in-flight separation of the 
engine from the airplane and consequent 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.

Service Bulletin References

    (f) The term ``service bulletin,'' as used in this AD, means the 
Accomplishment Instructions of Boeing Alert Service Bulletin 747-
71A2309, dated August 18, 2005.

Repetitive Inspections of Thrust Links

    (g) Within 90 days after the effective date of this AD, do a 
detailed inspection and ultrasonic inspection of thrust link lugs 
having part number (P/N) 65B90360-1 or -4 of the rear engine mount 
of struts 1, 2, 3, and 4 for any crack or fracture, in accordance 
with Part 1 of the service bulletin. If the thrust link is not found 
cracked or fractured: Repeat the inspections thereafter at intervals 
not to exceed 1,200 flight cycles or 18 months, whichever is first, 
until the optional repetitive replacement or overhaul of the thrust 
link as specified in paragraph (j) of this AD is accomplished. 
Accomplishing the repetitive replacement or overhaul of a thrust 
link specified in paragraph (h) or (j) of this AD terminates the 
repetitive inspections for that thrust link only.

Corrective Actions

    (h) If a cracked thrust link is found during any inspection 
required by paragraph (g) of this AD or during any replacement or 
overhaul done in accordance with the service bulletin: Before 
further flight, do the actions specified in paragraph (h)(1) of this 
AD. If a fractured thrust link is found during any inspection 
required by paragraph (g) of this AD or during any replacement or 
overhaul done in accordance with the service bulletin: Before 
further flight, do the actions specified in paragraphs (h)(1) and 
(h)(2) of this AD.
    (1) Replace the cracked thrust link with a new or overhauled 
thrust link in accordance with Part 2 of the service bulletin; 
except as provided by paragraph (i) of this AD. Repeat the 
replacement at the applicable compliance time specified in paragraph 
(h)(1)(i) or (h)(2)(ii) of this AD.
    (i) For replacement with a thrust link assembly having P/N 
65B90360-1 or -4: Thereafter at intervals not to exceed 6,000 flight 
cycles.
    (ii) For replacement with a thrust link assembly having P/N 
65B90360-7: Thereafter at intervals not to exceed 12,000 flight 
cycles.
    (2) Do the corrective actions in accordance with Parts 3, 4, and 
5 of the service bulletin; except as provided by paragraph (i) of 
this AD.
    (i) Where the service bulletin specifies to contact Boeing for 
appropriate action, do the corrective action using a method approved 
in accordance with paragraph (l) of this AD.

Optional Repetitive Replacement or Overhaul of a Thrust Link

    (j) For a thrust link that is not found cracked or fractured 
during the inspections required by paragraph (g) of this AD: 
Repetitive replacement of the thrust link with a new or overhauled 
thrust link at the applicable compliance time specified in paragraph 
(j)(1) or (j)(2) of this AD, in accordance with Part 2 of the 
service bulletin, terminates the repetitive inspections required by 
paragraph (g) of this AD for that thrust link only. If a cracked or 
fractured thrust link is found during any replacement or overhaul 
done in accordance with the service bulletin: Before further flight, 
do the applicable corrective actions specified in paragraph (h) of 
this AD at the applicable compliance time specified in that 
paragraph.
    (1) For a thrust link assembly having P/N 65B90360-1 or -4: 
Within 36 months after the effective date of this AD. Thereafter at 
intervals not to exceed 6,000 flight cycles.
    (2) For a thrust link assembly having P/N 65B90360-7: Within 
12,000 flight cycles after the new or overhauled thrust link has 
been installed. Thereafter at intervals not to exceed 12,000 flight 
cycles.

Credit for Certain Corrective Actions

    (k) Reworking the lugs on the bulkhead fitting of the rear 
engine mount as specified in paragraphs (b)(2), (e), and (f) of AD 
2001-15-15, amendment 39-12349, is acceptable for compliance with 
accomplishing the corrective action specified in ``Part 3--Rear 
Engine Mount Bulkhead Inspection and Lug

[[Page 54477]]

Overhaul and Upper Fitting Overhaul and Bolt Replacement'' of the 
service bulletin.

Alternative Methods of Compliance (AMOCs)

    (l)(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) 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.
    (3) The actions identified in paragraphs (g) and (j) of this AD 
are approved as an AMOC to paragraphs (c) and (d) of AD 2004-07-22, 
amendment 39-13566, for the inspections of structural significant 
item S-2, for the thrust links only, of Boeing Supplemental 
Structural Inspection Document D6-35022, Revision G, dated December 
2000. All provisions of AD 2004-07-22 that are not specifically 
referenced in this paragraph, including the initial inspection 
threshold required by paragraph (d) of AD 2004-07-22, remain fully 
applicable and must be complied with.

Material Incorporated by Reference

    (m) You must use Boeing Alert Service Bulletin 747-71A2309, 
dated August 18, 2005, to perform the actions that are required by 
this AD, unless the AD specifies otherwise. The Director of the 
Federal Register approved the incorporation by reference of this 
document in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. 
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 Docket Management Facility, U.S. Department 
of Transportation, 400 Seventh Street SW., room PL-401, Nassif 
Building, Washington, DC; on the Internet at http://dms.dot.gov; or 
at the National Archives and Records Administration (NARA). For 
information on the availability of this material at the NARA, call 
(202) 741-6030, or go to http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

    Issued in Renton, Washington, on September 6, 2005.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-18212 Filed 9-14-05; 8:45 am]
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