[Federal Register Volume 71, Number 7 (Wednesday, January 11, 2006)]
[Proposed Rules]
[Pages 1718-1721]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-136]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-23441; Directorate Identifier 2005-NM-199-AD]
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: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede an existing airworthiness 
directive (AD) that applies to certain Boeing Model 747-100, 747-100B, 
747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP 
series airplanes. The existing AD currently 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 proposed AD would require repetitive replacement of the 
thrust links with new or overhauled thrust links, which ends the 
repetitive detailed and ultrasonic inspections. This proposed AD 
results from the finding of fractured and cracked forward lugs of the 
rear engine mount thrust link on the number one strut on two airplanes. 
We are proposing this AD to prevent 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: We must receive comments on this proposed AD by February 27, 
2006.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: 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 
proposed 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:

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 ``Docket No. 
FAA-2005-23441; Directorate Identifier 2005-NM-199-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 the DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or can 
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.

[[Page 1719]]

Discussion

    On September 6, 2005, we issued AD 2005-19-06, amendment 39-14271 
(70 FR 54474, September 15, 2005), for certain Boeing Model 747-100, 
747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, 
and 747SP series airplanes. (A correction to AD 2005-19-06 was 
published in the Federal Register on September 30, 2005 (70 FR 57124).) 
That 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. That AD resulted from the finding of a 
fractured forward lug of the rear engine mount thrust link on the 
number one strut. We issued that 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.

Actions Since Existing AD Was Issued

    In the preamble to AD 2005-19-06, we indicated that the actions 
required by that AD were considered ``interim action.'' We also 
indicated that we were considering further rulemaking action to require 
repetitive replacement of the thrust link with a new or overhauled 
thrust link. (The repetitive replacements are included as an optional 
terminating action in AD 2005-19-06.) However, the planned compliance 
time for that action was sufficiently long so that it was practicable 
to allow notice and opportunity for prior public comment. We have now 
determined that further rulemaking making action is indeed necessary, 
and this NPRM follows from that determination. We point out that this 
NPRM would require the repetitive replacements within a certain 
compliance time, regardless of any inspection results.

Comments

    We have considered the following comments to AD 2005-19-06.

Request To Use an Alternative Method of Compliance (AMOC)

    One commenter states that it can reduce the work required for 
replacing a thrust link by omitting the step for removing the engine to 
gain access to the thrust link. Part 2 of the accomplishment 
instructions of Boeing Alert Service Bulletin 747-71A2309, dated August 
18, 2005, specifies removal of the engine. The commenter states, 
however, that there is no load on the thrust link at static condition, 
so the engine does not need to be removed. Instead, only the engine 
exhaust sleeve needs to be removed to replace the thrust link. The 
commenter also states that, in Boeing message No. 1-385158991-9, dated 
September 16, 2005, the manufacturer agreed that removing the sleeve 
would be an appropriate alternative procedure for replacing the thrust 
link. On October 26, 2005, the commenter submitted this request for 
approval as an AMOC.
    We agree, since we have found the commenter's request for an AMOC 
to be acceptable. We have approved removing the side cowls, as an 
alternative to opening the side cowls as required by paragraph (g) of 
AD 2005-19-06. We have also approved removal of the turbine exhaust 
sleeve, as an alternative to removing the engine as required by 
paragraph (j) of AD 2005-19-06 (corresponding to paragraph (k) of this 
NPRM) provided that the engine is supported. We have included a 
provision in paragraph (l)(5) of this NPRM to account for the 
commenter's AMOC. Under the provisions of paragraph (l) of this NPRM, 
we may consider other requests for approval of an alternative method of 
compliance if sufficient data are submitted to substantiate that such a 
method would provide an acceptable level of safety.

Request To Clarify Inspection Requirements

    One commenter requests that we clarify the required actions of AD 
2005-19-06 for thrust links having part number (P/N) 65B90360-7. The 
commenter states that Boeing Alert Service Bulletin 747-71A2309 
requires repetitive replacement of those thrust links, but that the 
repetitive replacement is identified as an optional action in AD 2005-
19-06. The commenter would like to know if this means that there is no 
mandatory requirement for thrust links having P/N 65B90360-7.
    As discussed previously, repetitive replacement of the thrust links 
as required by AD 2005-19-06 is considered an optional action because 
the planned compliance time for that action was sufficiently long 
enough to allow the public time to comment. This NPRM, however, would 
require the repetitive replacement of thrust links having P/N 65B90360-
7 in agreement with the service bulletin. Also, we point out that AD 
2005-19-06 does require the repetitive replacement of P/N 65B90360-7. 
Although that action is conditional in AD 2005-19-06, depending on 
whether P/N 65B90360-7 was installed while accomplishing the corrective 
action as applicable or the optional terminating action, as specified 
in paragraphs (h)(1)(ii) and (j)(2) of AD 2005-19-06, respectively.

Clarification of 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.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to develop on other airplanes of the 
same type design. For this reason, we are proposing this AD, which 
would supersede AD 2005-19-06. This proposed AD would continue to 
require 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 proposed AD would also require 
repetitive replacement of the thrust links with new or overhauled 
thrust links, which would end the repetitive inspections.

Costs of Compliance

    There are about 274 airplanes of the affected design in the 
worldwide fleet. The following table provides the estimated costs, at 
an average labor rate of $65 per hour, for U.S. operators to comply 
with this proposed AD.

                                                 Estimated Costs
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                                                                                 Number of U.S.-
            Action                Work hours         Parts          Cost per       registered       Fleet cost
                                                                    airplane        airplanes
----------------------------------------------------------------------------------------------------------------
Inspection (required by AD     8 (2 per engine)  None.........  $520, per                   100  $52,000, per
 2005-19-06).                                                    inspection                       inspection
                                                                 cycle.                           cycle.

[[Page 1720]]

 
Replacement (new proposed      4 (1 per engine)  $41,424......  $41,684, per                100  $4,168,400, per
 action).                                                        replacement                      replacement
                                                                 cycle.                           cycle.
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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 
removing amendment 39-14271 (70 FR 54474, September 15, 2005), 
corrected at 70 FR 57124, September 30, 2005, and by adding the 
following new airworthiness directive (AD):

Boeing: Docket No. FAA-2005-23441; Directorate Identifier 2005-NM-
199-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by February 27, 
2006.

Affected ADs

    (b) This AD supersedes AD 2005-19-06.

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 fractured and cracked 
forward lugs of the rear engine mount thrust link on the number one 
strut on two airplanes. We are issuing this AD to prevent 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.

Restatement of Requirements of AD 2005-19-06

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 September 30, 2005 (the effective date of 
AD 2005-19-06), 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 repetitive replacement or overhaul of the thrust link 
required by paragraph (k) of this AD is accomplished. Accomplishing the 
repetitive replacement or overhaul of a thrust link as specified in 
paragraph (h) or (k) 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 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

[[Page 1721]]

applicable compliance time specified in paragraph (h)(1)(i) or 
(h)(1)(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.

Exception to Service Bulletin

    (i) Where the service bulletin specifies to contact Boeing for 
appropriate action, do the corrective action using a method approved in 
accordance with paragraph (m) of this AD.

Credit for Certain Corrective Actions

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

New Requirements of This AD

Terminating Action--Repetitive Replacement or Overhaul of All Thrust 
Links

    (k) At the applicable compliance times specified in Table 1 of this 
AD: Repetitively replace the thrust link of the rear engine mount of 
struts 1, 2, 3, and 4 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. During any replacement required by this 
paragraph, an existing thrust link may be replaced with a new or 
overhauled thrust link having P/N 65B90360-1, -4 or -7, provided that 
the applicable repetitive interval specified in Table 1 of this AD is 
complied with. If a fractured thrust link is found during any 
replacement or overhaul done in accordance with this paragraph: Before 
further flight, do the corrective actions specified in paragraph (h)(2) 
of this AD. Repetitive replacement of all thrust links having P/N 
65B90360-1 or -4 terminates the repetitive inspections required by 
paragraph (g) of this AD. Accomplishing the repetitive replacement or 
overhaul of a thrust link required by paragraph (h) of this AD 
constitutes compliance with the requirements of this paragraph for that 
thrust link only.

                       Table 1.--Compliance Times
------------------------------------------------------------------------
                              Initial replacement-- Repetitive interval--
    For thrust link P/N--
------------------------------------------------------------------------
65B90360-1 or -4............  Within 36 months      Thereafter at
                               after the effective   intervals not to
                               date of this AD.      exceed 6,000 flight
                                                     cycles.
65B90360-7..................  Within 12,000 flight  Thereafter at
                               cycles after the      intervals not to
                               new thrust link has   exceed 12,000
                               been installed.       flight cycles.
------------------------------------------------------------------------

Alternative Methods of Compliance (AMOCs)

    (l)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
Transport Airplane Directorate, 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.
    (4) The actions identified in paragraphs (g) and (k) 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.
    (5) AMOCs approved previously in accordance with AD 2005-19-06, 
amendment 39-14271, are approved as AMOCs for the corresponding 
provisions of this AD.

    Issued in Renton, Washington, on December 23, 2005.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E6-136 Filed 1-10-06; 8:45 am]
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