[Federal Register Volume 68, Number 19 (Wednesday, January 29, 2003)]
[Proposed Rules]
[Pages 4398-4401]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-1957]


 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
 
 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
 ========================================================================
 

  Federal Register / Vol. 68, No. 19 / Wednesday, January 29, 2003 / 
Proposed Rules  

[[Page 4398]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NM-232-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Series Airplanes 
Equipped with General Electric CF6-45 or CF6-50 Series Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to Boeing Model 747 series airplanes 
equipped with General Electric CF6-45 and CF6-50 series engines. This 
proposal would require an inspection to detect chafing of the fuel line 
or incorrect clearance between the fuel line and pneumatic duct 
insulation blanket; a fuel leak check and strut drain test; corrective 
action if necessary; replacement of the outboard strut fuel line 
coupling O-rings and retaining rings with new parts; replacement of the 
pneumatic duct boot with a new part; and, for certain airplanes, 
installation of a flame arrestor and drain line entry screens. This 
action is necessary to prevent leaking fuel line couplings, chafed fuel 
lines, restricted or clogged strut drain lines, migrating fluids or 
vapors toward ignition sources, and flashback of external flame into 
the strut; these conditions could result in an uncontained engine strut 
fire. This action is intended to address the identified unsafe 
condition.

DATES: Comments must be received by March 17, 2003.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket 2001-NM-232-AD, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056. Comments may be inspected at this location 
between 9 a.m. and 3 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-232-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: Dan Kinney, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone 
(425) 227-2666; 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:
    [sbull] 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.
    [sbull] For each issue, state what specific change to the proposed 
AD is being requested.
    [sbull] 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 2001-NM-232-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 2001-NM-232-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-
4056.

Discussion

    The FAA has received reports of fires inside and outside the 
outboard struts of Boeing Model 747 series airplanes equipped with 
General Electric CF6-45 and CF6-50 series engines. The fires were 
caused by leaking strut fuel line couplings, improperly installed fuel 
lines that chafed against a pneumatic duct insulation blanket, and 
clogged or restricted strut drain lines. Fuel leakage into the hot 
engine compartment and/or onto the hot engine case can ignite and 
result in a fire. In certain cases, external flame flashback through 
the strut drain holes has ignited fuel that had leaked and accumulated 
in the strut. These fires have occurred outside a designated ``fire 
zone'' where there is no means to detect, contain, or extinguish a 
fire. All known cases of engine strut fires have occurred on the ground 
during taxi-in after landing; such fires could result in airplane 
damage and an emergency evacuation. Leaking fuel line couplings, chafed 
fuel lines, restricted or clogged strut drain lines, fluids or vapors 
migrating to ignition sources, and flashback of external flame into the 
strut, if not corrected, could result in an uncontained engine strut 
fire.

[[Page 4399]]

Explanation of Relevant Service Information

    The FAA has reviewed and approved the service information listed in 
the following table:

------------------------------------------------------------------------
     Service information                  Procedures described
------------------------------------------------------------------------
Boeing Service Bulletin 747-   Inspection to detect chafing of the fuel
 36-2111, dated February 20,    line and measure the clearance between
 1992.                          the fuel line and the pneumatic duct
                                insulation blanket; and follow-on and
                                corrective actions (including rework of
                                the fuel line by blending nicks and
                                scratches, determining the maximum
                                thickness of the damaged area, and
                                performing a penetrant inspection to
                                detect cracking of the damaged area;
                                remeasuring the clearance between the
                                fuel line and the insulation blanket;
                                adjusting the duct and fuel line
                                positions; and performing repetitive
                                inspections for chafing).
Boeing Service Bulletin 747-   Replacement of the number 4 strut fuel
 28-2162, dated July 30, 1992.  tube with a new part if sufficient
                                clearance between the fuel line and the
                                insulation blanket cannot be achieved by
                                incorporation of Service Bulletin 747-36-
                                2111.
Boeing Service Bulletin 747-   Fuel pressure leak check of the fuel line
 28-2230, dated September 30,   in the strut area, a strut drain test
 1999.                          for the aft strut drain tubes to detect
                                blockage, and corrective action for any
                                discrepancy.
Boeing Service Letter 747-SL-  Repetitive replacement of the outboard
 28-052-B, dated August 30,     strut fuel line coupling O-rings and
 1998.                          retaining rings with new parts.
Boeing Service Bulletin 747-   Replacement of the pneumatic duct boot
 36-2118, dated January 28,     with a new part.
 1993.
Boeing Service Bulletin 747-   Installation of a flame arrestor in each
 54-2137, dated February 6,     aft condensate drain hole of the engine
 1992.                          struts.
Boeing Service Bulletin 747-   Installation of a drain line entry screen
 54-2122, Revision 4, dated     at each drain tube entry.
 August 29, 1991.
------------------------------------------------------------------------

    The FAA has reviewed Notice of Status Change 747-54-2122 NSC 2, 
dated May 14, 1992, which revises Boeing Service Bulletin 747-54-2122, 
Revision 4, and was issued to notify certain operators of part number 
changes. The FAA has also reviewed Information Notice 747-54-2122 IN 
03, dated August 19, 1999, which was issued to notify operators of 
errors in certain Figures in Boeing Service Bulletin 747-54-2122, 
Revision 4.
    Accomplishment of the actions specified in the service information 
is intended to adequately address the identified unsafe condition.
    Boeing Service Bulletins 747-28-2230 and 747-36-2122 recommend 
accomplishment of certain actions specified by other service bulletins; 
however, those additional actions are not included in this proposed AD 
because they are required by existing ADs or are not necessary to 
address the identified unsafe condition of this proposed AD. Those 
other service bulletins are described in the following table:

----------------------------------------------------------------------------------------------------------------
                                                       Which applies to
 The actions specified in Boeing                       Model 747 series
       Service Bulletin--          Are included in--  airplanes equipped     To require--           Within--
                                                            with--
----------------------------------------------------------------------------------------------------------------
747-28-2155, Revision 3, dated    Telegraphic         GE CF6 engines....  Clearing of the     72 hours after the
 September 28, 1984.               (emergency) AD 86-                      engine strut        effective date of
                                   01-51 R1,                               drains.             April 18, 1986.
                                   amendment 39-5269
                                   (51 FR 10820,
                                   March 31, 1986).
747-28-2160, dated July 23,       AD 95-02-07,        Certain GE or       Installation of a   18 months after
 1992, or Revision 1, dated        amendment 39-9126   Pratt & Whitney     seal on the wing    the effective
 December 16, 1993.                (60 FR 8292,        T9D series          front spar at       date of March 16,
                                   February 14,        engines.            each engine strut.  1995.
                                   1995).
747-54A2117, Revision 1, dated    AD 86-08-03,        Certain General     An inspection for   200/400 landings
 November 8, 1985.                 amendment 39-5289   Electric and        cracking in the     after the
                                   (51 FR 12836,       Pratt & Whitney     brace and           effective date of
                                   April 16, 1986).    engines.            application of      May 27, 1986.
                                                                           sealant in the
                                                                           strut lower aft
                                                                           bulkhead.
----------------------------------------------------------------------------------------------------------------

In addition, Boeing Service Bulletin 747-54-2122 recommends the prior 
or concurrent accomplishment of the actions specified in Boeing Service 
Bulletin 747-54-2083, which addresses hydraulic fluid leak problems; 
however, those actions would not be required by this proposed AD 
because there has been no evidence of a recent hydraulic fluid leak 
problem.

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 service information described previously, except as discussed 
below.

Differences Between Proposed AD and Relevant Service Information

    Although Boeing Service Bulletin 747-28-2230 recommends

[[Page 4400]]

accomplishing the leak check and drain inspection within 18 months 
(after the release of the service bulletin), we have determined that an 
interval of 18 months would not address the identified unsafe condition 
in a timely manner. In developing an appropriate compliance time for 
this proposed AD, we considered not only the manufacturer's 
recommendation, but the degree of urgency associated with addressing 
the subject unsafe condition, the average utilization of the affected 
fleet, and the time necessary to perform the actions. In light of all 
of these factors, we find a 12-month compliance time for completing the 
proposed actions to be warranted, in that it represents an appropriate 
interval of time allowable for affected airplanes to continue to 
operate without compromising safety.
    Boeing Service Bulletin 747-36-2111 specifies that, if the ultimate 
corrected clearance achieved between the fuel line and the pneumatic 
duct insulation blanket (for any strut position) is 0.50 inch or less, 
operators may repetitively inspect the area every 1,000 flight hours. 
However, this proposed AD would require replacement of the fuel tube on 
the number 4 engine strut position, as specified in Boeing Service 
Bulletin 747-28-2162, if clearance of at least 0.40 inch cannot be 
achieved during accomplishment of the actions specified in Boeing 
Service Bulletin 747-36-2111.
    Boeing Service Bulletin 747-54-2122 specifies that accomplishment 
of some of the actions that are specified in this proposed AD are to be 
done in accordance with either the Boeing 747 Airplane Maintenance 
Manual (AMM) or an ``operator's equivalent procedure.'' However, this 
proposed AD would require that the actions be accomplished in 
accordance with the procedures specified in the applicable subject of 
the Boeing 747 AMM. An ``operator's equivalent procedure'' may be used 
only if approved as an alternative method of compliance in accordance 
with paragraph (i) of this AD.
    In addition, Boeing Service Bulletin 747-36-2111 recommends that 
operators ``tell Boeing'' if the fuel line is chafed. Operators may 
report these findings to Boeing, but this proposed AD would not require 
a report.
    The applicability of this proposed AD is different from the 
effectivity of some of the cited service bulletins. The unsafe 
condition identified by this proposed AD is limited to the outboard 
struts on Model 747 series airplanes equipped with General Electric 
CF6-45 and CF6-50 series engines. However, the effectivity in Service 
Bulletins 747-54-2122, 747-36-2118, and 747-28-2162, and Service Letter 
747-SL-28-052-B is broader to encompass additional features common to 
other engine model structures not addressed by this proposed AD.

Cost Impact

    The following table provides the cost estimates to accomplish the 
proposed actions:

----------------------------------------------------------------------------------------------------------------
                                                                                            Number of
    Boeing service information for proposed        Work      Labor      Parts       Per-       U.S.       U.S.
                    actions                     hours per   rate per   cost per   airplane  airplanes    fleet
                                                 airplane     hour     airplane     cost     affected     cost
----------------------------------------------------------------------------------------------------------------
Service Bulletin 747-36-2111..................         10        $60         $0       $600         32    $19,200
Service Bulletin 747-28-2230..................          4         60          0        240         32      7,680
Service Letter 747-SL-28-052B.................          4         60          0        240         32      7,680
Service Bulletin 747-36-2118..................         10         60      1,269      1,869         32     59,808
Service Bulletin 747-54-2137..................         48         60      3,047      5,927         30    177,810
Service Bulletin 747-54-2122..................         56         60      2,590      5,950         30    178,500
----------------------------------------------------------------------------------------------------------------

    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.

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-232-AD.

    Applicability: Model 747 series airplanes equipped with General 
Electric CF6-45 or CF6-50 series engines, 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 (i) of 
this AD. The

[[Page 4401]]

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 prevent leaking fuel line couplings, chafed fuel lines, 
restricted or clogged strut drain lines, fluids or vapors migrating 
to ignition sources, and flashback of external flame into the strut, 
which could result in uncontained engine strut fire, accomplish the 
following:

Inspection for Chafing and Clearance

    Note 2: Paragraph (a) of this AD refers to certain portions of 
Boeing Service Bulletin 747-36-2111, dated February 20, 1992, for 
information regarding inspection and measurement actions. Further, 
paragraph (a) of this AD requires replacement of the fuel tube as 
corrective action for certain repair conditions; that action is not 
included in the service bulletin. Where this AD and Service Bulletin 
747-36-2111 differ, the AD prevails.

    (a) Within 1,000 flight hours after the effective date of this 
AD, perform a detailed inspection to detect chafing of the fuel line 
and measure the clearance between the fuel line and the insulation 
blanket on the pneumatic duct; in accordance with the Accomplishment 
Instructions of Boeing Service Bulletin 747-36-2111, dated February 
20, 1992. Before further flight, accomplish all applicable 
corrective actions (including reworking the fuel line, remeasuring 
the clearance between the fuel line and the insulation blanket, 
adjusting the pneumatic duct and fuel line positions, adjusting the 
insulation blanket installation, and inspecting and cleaning the 
strut and strut drain ports/screens); and, if applicable, repeat the 
fuel line inspection at the applicable time in the Accomplishment 
Instructions of the service bulletin. Do the corrective and follow-
on actions in accordance with Service Bulletin 747-36-2111. If, 
after corrective actions have been performed, a clearance of at 
least 0.40 inch on the number 4 strut cannot be achieved: Before 
further flight, replace the fuel tube with a new part in accordance 
with Boeing Service Bulletin 747-28-2162, dated July 30, 1992.

    Note 3: For the purposes of this AD, a detailed 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 the inspector. Inspection aids such as mirror, 
magnifying lenses, etc., may be used. Surface cleaning and elaborate 
access procedures may be required.''

Fuel Leak Check and Strut Drain Inspection

    (b) Within 12 months after the effective date of this AD, 
perform a fuel pressure leak check of the fuel line in the strut 
area, and perform a strut drain test for the aft strut drain tubes 
to detect blockage; in accordance with the Accomplishment 
Instructions of Boeing Service Bulletin 747-28-2230, dated September 
30, 1999. If any discrepancy is found, before further flight, 
perform applicable corrective actions (including performing the fuel 
pressure check procedure, clearing the strut drain tubes, and 
repairing seal leaks) in accordance with the service bulletin.

Replacement of O-Rings and Retaining Rings

    (c) At the earliest of the times specified by paragraphs (c)(1), 
(c)(2), and (c)(3) of this AD, replace the fuel line coupling O-
rings and retaining rings in the outboard strut positions with new 
Nitrile O-rings, part number MS29513-330, in accordance with Boeing 
Service Letter 747-SL-28-052-B, dated August 30, 1998. Replace the 
rings thereafter at the time specified by paragraph (d) of this AD.
    (1) Within 21,000 flight hours after the effective date of this 
AD.
    (2) Within 5 years after the effective date of this AD.
    (3) Before further flight after a coupling has been disassembled 
for any reason.

Repetitive Ring Replacement

    (d) Replace the rings as required by paragraph (c) of this AD at 
intervals not to exceed the earliest of the times specified by 
paragraphs (d)(1), (d)(2), and (d)(3) of this AD.
    (1) Every 21,000 flight hours.
    (2) Every 5 years.
    (3) Before further flight after a coupling has been disassembled 
for any reason.

Replacement of Pneumatic Duct Boot

    (e) At the earlier of the times specified in paragraphs (e)(1) 
and (e)(2) of this AD: Replace the pneumatic duct boot with a new 
part, in accordance with Boeing Service Bulletin 747-36-2118, dated 
January 28, 1993.
    (1) Within 12 months after the effective date of this AD; or
    (2) Before further flight following detection of any torn boot; 
or within 5 days following detection of any torn boot, provided 
there are no leaks, liquid fuel, or vapors in the affected strut 
compartment.

Installation of Flame Arrestor

    (f) For airplanes identified in Boeing Service Bulletin 747-54-
2137, dated February 6, 1992: Within 24 months after the effective 
date of this AD, install a flame arrestor in each aft condensate 
drain hole of the engine struts, in accordance with the 
Accomplishment Instructions of the service bulletin.

Installation of Drain Screen

    (g) For Group 2 and Group 4 airplanes listed in Boeing Service 
Bulletin 747-54-2122, Revision 4, dated August 29, 1991; as revised 
by Notice of Status Change 747-54-2122 NSC 2, dated May 14, 1992; 
and Information Notice 747-54-2122 IN 03, dated August 19, 1999: 
Within 24 months after the effective date of this AD, install a 
drain line entry screen at each drain tube entry at the outboard 
strut positions, in accordance with the Accomplishment Instructions 
of the service bulletin. Where the service bulletin specifies that 
certain actions may be accomplished in accordance with an operator's 
``equivalent procedure'': Those actions must be accomplished in 
accordance with the applicable Boeing 747 Airplane Maintenance 
Manual subject specified in the service bulletin.
    (h) Installation of drain screens before the effective date of 
this AD is also acceptable for compliance with the requirements of 
paragraph (g) of this AD if accomplished in accordance with Boeing 
Service Bulletin 747-54-2122, Revision 1, dated December 14, 1989; 
Revision 2, dated May 3, 1990; or Revision 3, dated October 4, 1990.

Alternative Methods of Compliance

    (i) 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 Aircraft Certification 
Office (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 Permits

    (j) 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 22, 2003.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 03-1957 Filed 1-28-03; 8:45 am]
BILLING CODE 4910-13-P