[Federal Register Volume 67, Number 6 (Wednesday, January 9, 2002)]
[Proposed Rules]
[Pages 1167-1169]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-457]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NM-40-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Series Airplanes 
Powered by General Electric (GE) CF6-45/50, Pratt & Whitney (P&W) JT9D-
70, or JT9D-7 Series Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain Boeing Model 747 series 
airplanes powered by GE CF6-45/50, P&W JT9D-70, or JT9D-7 series 
engines. This proposal would require repetitive inspections to find 
cracks and broken fasteners of the inboard and outboard nacelle struts 
of the rear engine mount bulkhead, and repair, if necessary. For 
certain airplanes, this proposal provides for an optional terminating 
modification for the inspections of the outboard nacelle struts. This 
action is necessary to find and fix cracks and broken fasteners of the 
inboard and outboard nacelle struts, which could result in possible 
loss of the bulkhead load path and consequent separation of the engine 
from the airplane. This action is intended to address the identified 
unsafe condition.

DATES: Comments must be received by February 25, 2002.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2001-NM-40-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2001-NM-40-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 for Windows or 
ASCII text.
    The service information referenced in the proposed rule may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Tamara Anderson, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2771; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications shall identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this action may be changed in 
light of the comments received.
    Submit comments using the following format:
     Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
     For each issue, state what specific change to the proposed 
AD is being requested.
     Include justification (e.g., reasons or data) for each 
request.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2001-NM-40-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules 
Docket No. 2001-NM-40-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports indicating that fatigue cracking of 
the inboard and outboard nacelle struts of the rear engine mount 
bulkhead was found on certain Boeing Model 747 series airplanes powered 
by General Electric CF6-45/50 and Pratt & Whitney (P&W) JT9D-3, -7, and 
-70 series engines. Cracking found on airplanes powered by P&W JT9D-3 
and -7 series engines was located in the frame webs at the inner 
angles, extending in a radial direction. Cracking also was found in the 
inner flange radius and web. Cracking found on airplanes powered by GE 
CF6-45/50 and P&W JT9D-70 series engines was located in the frame 
flange common to the strut skin. Such cracking, if not found and fixed, 
could result in possible loss of the bulkhead load path and consequent 
separation of the engine from the airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
747-54A2202, dated December 21, 2000, which describes procedures for 
repetitive detailed visual and high frequency eddy current (HFEC) 
inspections to find cracks and broken fasteners of the inboard and 
outboard nacelle struts of the rear engine mount bulkhead, and repair, 
if necessary. For certain airplanes with web doublers installed per the 
Boeing service bulletins listed below, an HFEC inspection is to be done 
in the stop-drilled holes or around the fasteners, if installed. The 
service bulletin specifies contacting Boeing for repair instructions if 
discrepancies (cracks, broken fasteners) are found.
    The FAA also has reviewed and approved Boeing Service Bulletins 
747-54-2033, Revision 2, dated July 29, 1977, and 747-54-2065, Revision 
6, dated May 29, 1997. These service bulletins describe procedures for 
a detailed visual inspection for cracks and broken fasteners, and 
modification of

[[Page 1168]]

the outboard nacelle struts of the rear engine mount bulkhead. These 
service bulletins are referenced in Boeing Alert Service Bulletin 747-
54A2202.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would require accomplishment of the actions specified in 
the alert service bulletin described previously, except as discussed 
below.

Differences Between Alert Service Bulletin and This Proposed AD

    The alert service bulletin specifies that the manufacturer must be 
contacted for repair of certain conditions, but this proposal would 
require the repair of those conditions to be accomplished per a method 
approved by the FAA, or per data meeting the type certification basis 
of the airplane approved by a Boeing Company Designated Engineering 
Representative who has been authorized by the FAA to make such 
findings.

Interim Action

    This is considered to be interim action. At this time, the FAA is 
considering a separate rulemaking action to mandate accomplishment of 
the optional terminating modification for certain outboard struts, and 
the manufacturer has advised that it currently is developing a 
terminating modification for the inboard struts and the remaining 
outboard struts.

Cost Impact

    There are approximately 456 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 165 airplanes of U.S. registry 
would be affected by this proposed AD.
    It would take approximately 4 work hours per airplane to accomplish 
the proposed detailed visual inspection, at an average labor rate of 
$60 per work hour. Based on these figures, the cost impact of the 
proposed inspection on U.S. operators is estimated to be $39,600, or 
$240 per airplane, per inspection cycle.
    It would take approximately 32 work hours per airplane to 
accomplish the proposed high frequency eddy current inspection, at an 
average labor rate of $60 per work hour. Based on these figures, the 
cost impact of the proposed high frequency eddy current inspection on 
U.S. operators is estimated to be $316,800, or $1,920 per airplane, per 
inspection cycle.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the proposed requirements 
of this AD action, and that no operator would accomplish those actions 
in the future if this proposed AD were not adopted. The cost impact 
figures discussed in AD rulemaking actions represent only the time 
necessary to perform the specific actions actually required by the AD. 
These figures typically do not include incidental costs, such as the 
time required to gain access and close up, planning time, or time 
necessitated by other administrative actions.
    Should an operator elect to accomplish the optional terminating 
modification that would be provided by this AD action, it would take 
approximately 368 work hours to accomplish, at an average labor rate of 
$60 per work hour. The cost of required parts would be approximately 
$20,000 per airplane. Based on these figures, the cost impact of the 
optional terminating action is estimated to be $42,080 per airplane.

Regulatory Impact

    The regulations proposed herein 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. Therefore, it 
is determined that this proposal would not have federalism implications 
under Executive Order 13132.
    For the reasons discussed above, I certify that this 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) if promulgated, 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. A copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
part 39 of the Federal Aviation Regulations (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. Section 39.13 is amended by adding the following new 
airworthiness directive:

Boeing: Docket 2001-NM-40-AD.

    Applicability: Model 747 series airplanes, as listed in Boeing 
Alert Service Bulletin 747-54A2202, dated December 21, 2000, 
certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (g) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To find and fix cracks and broken fasteners of the inboard and 
outboard nacelle struts of the rear engine mount bulkhead, which 
could result in possible loss of the bulkhead load path and 
consequent separation of the engine from the airplane, accomplish 
the following:

Detailed Visual Inspections

    (a) Do a detailed visual inspection to find cracks and broken 
fasteners of the inboard and outboard nacelle struts of the rear 
engine mount bulkhead at the time specified in paragraph (a)(1) or 
(a)(2) of this AD, as applicable. Do the inspection per Part 1 of 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
747-54A2202, dated December 21, 2000. Repeat the inspection at least 
every 350 flight cycles until paragraph (b) of this AD has been 
done.
    (1) For airplanes on which the inspections specified in Boeing 
Service Bulletin 747-54-2065, Revision 6, dated May 29, 1997, HAVE 
NOT been done: Within 120 days after the effective date of this AD.
    (2) For airplanes on which the inspections specified in Boeing 
Service Bulletin 747-54-2065, Revision 6, dated May 29, 1997, HAVE 
been done: Within 1,600 flight hours after doing the last inspection 
with no crack finding, or within 600 flight hours after doing the 
last inspection with a crack finding.

    Note 2: For the purposes of this AD, a detailed visual 
inspection is defined as: ``An intensive visual examination of a 
specific structural area, system, installation, or assembly to 
detect damage, failure, or irregularity. Available lighting is 
normally supplemented with a direct source of good lighting at 
intensity deemed appropriate by

[[Page 1169]]

the inspector. Inspection aids such as mirror, magnifying lenses, 
etc., may be used. Surface cleaning and elaborate access procedures 
may be required.''

Detailed Visual/High Frequency Eddy Current Inspections

    (b) Within 1,200 flight cycles or 18 months after the effective 
date of this AD, whichever is first: Do detailed visual and high 
frequency eddy current (HFEC) inspections to find cracks and broken 
fasteners of the inboard and outboard nacelle struts of the rear 
engine mount bulkhead per Part 1 and Part 2 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 747-54A2202, dated 
December 21, 2000, as applicable. Doing the inspections required by 
this paragraph terminates the inspections required by paragraph (a) 
of this AD.
    (1) For airplanes on which the modification of the inboard 
struts specified in Boeing Service Bulletin 747-54-2065, Revision 6, 
dated May 29, 1997, HAS NOT been done: Repeat the applicable 
inspection at least every 1,200 flight cycles or 18 months, 
whichever is first.
    (2) For Groups 3 and 4 airplanes on which the modification of 
the inboard struts specified in Boeing Service Bulletin 747-54-2065, 
Revision 6, dated May 29, 1997, HAS been done: Repeat the applicable 
inspection at least every 1,200 flight cycles.
    (c) For Groups 1 and 5 airplanes, as listed in Boeing Alert 
Service Bulletin 747-54A2202, dated December 21, 2000, with web 
doublers and angle chords installed to repair cracking, as specified 
in Boeing Service Bulletin 747-54-2065, Revision 6, dated May 29, 
1997; or Boeing Service Bulletin 747-54-2033, Revision 2, dated July 
29, 1977: Within 1,200 flight cycles or 18 months after the 
effective date of this AD, whichever is first, do an HFEC inspection 
of the stop-drilled holes per Figure 1, Flag Notes 1 and 2, of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 747-
54A2202, dated December 21, 2000. Repeat the inspection at least 
every 600 flight cycles.

    Note 3: Accomplishment of the actions specified in paragraphs 
(b)(1), (b)(2), and (c) of this AD before the effective date of this 
AD, per Boeing Service Bulletin 747-54-2033, dated September 13, 
1974; or Revision 1, dated November 14, 1975; or Boeing Service 
Bulletin 747-54-2065, dated October 30, 1981; Revision 1, dated 
December 19, 1983; Revision 2, dated October 23, 1984; Revision 3, 
dated March 14, 1986; or Revision 5, dated November 2, 1989; is 
considered acceptable for compliance with the applicable actions 
specified in this AD.

Repair

    (d) Except as provided by paragraph (e) of this AD: Before 
further flight, repair any discrepancy (crack or broken fastener) 
found during any inspection required by this AD, per a method 
approved by the Manager, Seattle Aircraft Certification Office 
(ACO), FAA; or per data meeting the type certification basis of the 
airplane approved by a Boeing Company Designated Engineering 
Representative (DER) who has been authorized by the Manager, Seattle 
ACO, to make such findings. For a repair method to be approved by 
the Manager, Seattle ACO, as required by this paragraph, the 
approval letter must specifically reference this AD.
    (e) Web cracks in the existing bulkhead frames repaired with the 
web doublers and angle chords are acceptable, provided they are stop 
drilled and are within the limits specified in Figure 1, Flag Notes 
1 and 2, of the Accomplishment Instructions of Boeing Alert Service 
Bulletin 747-54A2202, dated December 21, 2000.

Optional Terminating Modification

    (f) For Groups 3, 4, and 5 airplanes, as listed in Boeing Alert 
Service Bulletin 747-54A2202, dated December 21, 2000: 
Accomplishment of the modification of the outboard nacelle struts, 
as specified in Boeing Service Bulletin 747-54-2065, Revision 6, 
dated May 29, 1997, terminates the repetitive inspections required 
by paragraphs (a) and (b) of this AD for the outboard nacelle struts 
only.

    Note 4: Accomplishment of the modification of the outboard 
nacelle struts before the effective date of this AD per Boeing 
Service Bulletin 747-54-2065, dated October 30, 1981; Revision 1, 
dated December 19, 1983; Revision 2, dated October 23, 1984; 
Revision 3, dated March 14, 1986; or Revision 5, dated November 2, 
1989; is considered acceptable for compliance with paragraph (e) of 
this AD.

Alternative Methods of Compliance

    (g) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Seattle ACO, FAA. Operators shall 
submit their requests through an appropriate FAA Principal 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Seattle ACO.

    Note 5: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Special Flight Permit

    (h) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.

    Issued in Renton, Washington, on January 2, 2002.
Lirio Liu Nelson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 02-457 Filed 1-8-02; 8:45 am]
BILLING CODE 4910-13-P