[Federal Register: September 15, 2005 (Volume 70, Number 178)]
[Rules and Regulations]
[Page 54474-54477]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr15se05-4]
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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.
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: Docket Management Facility; U.S. Department of
Transportation, 400 Seventh Street SW., Nassif Building, room PL-401,
Washington, DC 20590.
Fax: (202) 493-2251.
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:
Repetitively replacing the fractured thrust link with a
new or overhauled thrust link (Part 2 of the Accomplishment
Instructions of the service bulletin).
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).
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).
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:
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 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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