[Federal Register Volume 63, Number 251 (Thursday, December 31, 1998)]
[Rules and Regulations]
[Pages 72143-72148]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-34676]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-327-AD; Amendment 39-10976; AD 99-01-10]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to certain Boeing Model 747 series airplanes, that 
currently requires repetitive inspections to detect discrepancies of 
the diagonal brace lugs of the engine strut, and rework of the diagonal 
brace lugs, if necessary. That AD also provides an option to defer the 
rework for certain cases by accomplishing repetitive inspections and 
resealing the bushing. That AD also provides for an optional 
terminating modification for the repetitive inspections. This amendment 
adds a requirement to repetitively inspect a new area of the diagonal 
brace of the engine strut. For certain airplanes, this amendment also 
adds new repetitive inspections of the subject area and requires that 
certain previously required repetitive inspections be accomplished at 
reduced intervals. This amendment is prompted by reports of fatigue or 
stress corrosion cracking in new areas of the diagonal brace. The 
actions specified in this AD are intended to prevent such fatigue or 
stress corrosion cracking, which could result in failure of the strut 
and consequent separation of the engine from the airplane.

DATES: Effective January 15, 1999.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of January 15, 1999.
    The incorporation by reference of Boeing Alert Service Bulletin 
747-54A2126, Revision 5, dated June 26, 1997, as listed in the 
regulations, was approved previously by the Director of the Federal 
Register as of September 29, 1997 (62 FR 47927, September 12, 1997).
    Comments for inclusion in the Rules Docket must be received on or 
before March 1, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-327-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056.
    The service information referenced in this AD 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; or at 
the Office of the Federal Register, 800 North Capitol Street, NW., 
suite 700, Washington, DC.

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

SUPPLEMENTARY INFORMATION: On September 5, 1997, the FAA issued AD 97-
19-08, amendment 39-10128 (62 FR 47927, September 12, 1997), applicable 
to certain Boeing Model 747 series airplanes, to require repetitive 
detailed visual and ultrasonic inspections to detect cracking, 
corrosion, and migrated or rotated bushings of the diagonal brace lugs 
of the engine strut, and rework of the diagonal brace lugs, if 
necessary. In lieu of accomplishing the rework prior to further flight 
in certain cases where no cracking or corrosion is detected, that AD 
provides an option to defer the rework for a short period of time by 
resealing the bushing and accomplishing repetitive inspections. That AD 
also provides for an optional modification of the strut/wing, which 
would constitute terminating action for the repetitive inspection 
requirements. That action was prompted by reports of fatigue cracking 
in the diagonal brace lug. The actions required by that AD are intended 
to prevent such fatigue cracking, which could result in failure of the 
strut and consequent separation of the engine from the airplane.

[[Page 72144]]

Actions Since Issuance of Previous Rule

    Since the issuance of that AD, the FAA has received several reports 
indicating that additional cracking of the diagonal brace lugs has been 
detected on the affected airplanes. On several airplanes, cracks were 
found in the area of the lug common to the long axis of the diagonal 
brace. An ultrasonic inspection of that area was not required by AD 97-
19-08. Therefore, cracking in the area of the lug common to the long 
axis of the diagonal brace may have gone undetected. Cracking was also 
detected in the root radius of the aft clevis of the diagonal brace. 
That area was not subject to inspections in accordance with AD 97-19-
08.
    On other airplanes, during repetitive inspections performed in 
accordance with AD 97-19-08, cracking of the diagonal brace lugs was 
detected during inspections performed earlier than the scheduled 
repetitive interval. Those airplanes had accumulated between 213 and 
267 flight cycles since the previous inspection of the diagonal brace 
lugs.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 747-
54A2126, Revision 6, dated August 28, 1997. That service bulletin is 
substantially similar to Boeing Alert Service Bulletin 747-54A2126, 
Revision 5, dated June 26, 1997 (which was referenced as the 
appropriate source of service information in AD 97-19-08). However, 
Boeing Service Bulletin 747-54A2126, Revision 6, clarifies the 
inspection method and intervals for the forward and aft diagonal brace 
lugs, and updates the effectivity listing of the service bulletin to 
reflect changes in airplane operators but adds no new airplanes.
    The FAA also has reviewed and approved Boeing Alert Service 
Bulletin 747-54A2126, Revision 7, dated November 20, 1998. Revision 7 
of the alert service bulletin was issued subsequent to the findings of 
new cracking, and describes procedures for a repetitive ultrasonic 
inspection that are substantially similar to those described in 
Revision 5 of the alert service bulletin and in Boeing Service Bulletin 
747-54A2126, Revision 6. Revision 7 also describes procedures for 
rework of the diagonal brace lug; and an option to defer the rework, in 
cases where no cracking or corrosion is found, by resealing the bushing 
or applying a corrosion-inhibiting compound, and performing repetitive 
inspections. Those procedures are substantially similar to the 
procedures described in Revision 5 of the alert service bulletin and in 
Boeing Service Bulletin 747-54A2126, Revision 6. However, Revision 7 
also describes procedures for a detailed visual inspection, for all 
airplanes, to detect cracks, corrosion, or other damage of the diagonal 
brace lug, as well as of the root radius of the clevis of the inboard 
and outboard diagonal braces. Revision 7 also describes procedures for 
repetitive high frequency eddy current inspections, for certain 
airplanes, to detect cracking or corrosion of the diagonal brace lugs. 
Revision 7 also specifies, for certain airplanes, revised repetitive 
inspection intervals.

Other Relevant Rulemaking

    The FAA previously has issued AD 95-10-16, amendment 39-9233 (60 FR 
27008, May 22, 1995), applicable to Boeing Model 747 series airplanes 
equipped with Pratt & Whitney Model JT9D series engines (excluding 
Model JT9D-70 engines); AD 95-13-05, amendment 39-9285 (60 FR 33333, 
June 28, 1995), applicable to Boeing Model 747 series airplanes 
equipped with Rolls Royce Model RB211 series engines; and AD 95-13-07, 
amendment 39-9287 (60 FR 33336, June 28, 1995), applicable to Boeing 
Model 747 series airplanes equipped with General Electric Model CF6-45 
or -50 series engines, or Pratt & Whitney Model JT9D-70 series engines. 
Those AD's require accomplishment of certain modifications of the 
nacelle strut/wing structure, which constitutes terminating action for 
the repetitive inspection requirements of this AD.

Explanation of Requirements of Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of this same type design, this AD 
supersedes AD 97-19-08 to continue to require repetitive inspections to 
detect discrepancies of the diagonal brace lugs of the engine strut, 
and rework of the diagonal brace lugs, if necessary. This AD also 
continues to provide an option to defer the rework by accomplishing 
repetitive inspections and resealing the bushing. This AD also 
continues to provide for an optional terminating action for the 
repetitive inspection requirements.
    This AD adds new repetitive inspections to detect discrepancies of 
the root radius of the clevis of the diagonal brace of the engine 
strut. For certain airplanes, this AD also adds new repetitive 
inspections to detect discrepancies of the diagonal brace lugs of the 
engine strut and requires that certain previously required repetitive 
inspections be accomplished at reduced intervals. The actions are 
required to be accomplished in accordance with the service bulletin or 
alert service bulletin described previously, except as discussed below.

Explanation of Addition to Compliance Options

    AD 97-19-08 provides an option--in cases where a migrated or 
rotated bushing, but no cracking or corrosion, is detected--to defer 
the rework of the diagonal brace lugs by accomplishing repetitive 
inspections and resealing the bushing. However, Boeing Alert Service 
Bulletin 747-54A2126, Revision 5, specified that the rework could be 
deferred by accomplishing repetitive inspections and either resealing 
the bushing or applying a corrosion-inhibiting compound (and repeating 
the application of such compound at intervals not to exceed 9 months). 
The FAA finds that the option for application of a corrosion-inhibiting 
compound was inadvertently omitted from paragraph (d)(1) of AD 97-19-
08. Therefore, paragraph (d)(1) of this AD, which restates the 
requirements of paragraph (d)(1) of AD 97-19-08, has been amended to 
read, ``* * * reseal the bushings or apply corrosion-inhibiting 
compound * * *.'' Related to this change, paragraph (d)(1) also 
specifies, ``If corrosion-inhibiting compound is applied, repeat the 
application at intervals not to exceed 9 months * * *.''

Differences Between the Alert Service Bulletin and This AD

    Operators should note that Boeing Alert Service Bulletin 747-
54A2126, Revision 7, specifies that the initial inspection threshold 
may be increased for diagonal braces that have been reworked in 
accordance with Boeing Service Bulletin 747-54-2126, dated June 16, 
1988; Revision 1, dated August 25, 1988; Revision 2, dated April 27, 
1989; Revision 3, dated October 19, 1989; or Revision 4, dated January 
31, 1991. This AD, however, does not provide for such an increase in 
initial inspection thresholds for diagonal braces that have been 
reworked.
    The FAA has determined that the compliance times for the initial 
inspection as specified in Tables 1 and II of Figure 1 of the alert 
service bulletin represent an appropriate interval of time allowable, 
such that the inspections do not pose an undue burden upon operators, 
and an acceptable level of safety of the transport airplane fleet can 
be maintained. In making this determination, the FAA has considered the 
manufacturer's recommendations as well as the safety implications of 
discrepancies of the diagonal brace lugs of the engine strut. However, 
under the

[[Page 72145]]

provisions of paragraph (l)(1) of this AD, the FAA may approve requests 
for adjustment of the initial inspection threshold for diagonal braces 
that have been reworked in accordance with Boeing Service Bulletin 747-
54-2126, original issue, Revision 1, Revision 2, Revision 3, or 
Revision 4.
    Operators also should note that, although the service bulletins 
specify that the manufacturer may be contacted for disposition of 
certain repair conditions, this AD requires the repair of those 
conditions to be accomplished in accordance with a method approved by 
the FAA, or in accordance with 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.
    Operators also should note that Boeing Alert Service Bulletin 747-
54A2126, Revision 5, dated June 26, 1997, and Revision 7, dated 
November 20, 1998; and Boeing Service Bulletin 747-54A2126, Revision 6; 
specify that certain corrective actions may be accomplished in 
accordance with ``an operator's equivalent procedure.'' However, this 
AD requires that all inspection and rework procedures be accomplished 
in accordance with the procedures specified in the service bulletin. An 
``operator's equivalent procedure'' for inspecting or reworking the 
diagonal brace may be used only if approved as an alternative method of 
compliance in accordance with paragraph (l)(1) of this AD.

Determination of Rule's Effective Date

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 98-NM-327-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    The regulations adopted herein will not have substantial direct 
effects 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, in 
accordance with Executive Order 12612, it is determined that this final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, may be obtained from the Rules Docket at the 
location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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 removing amendment 39-10128 (62 FR 
47927, September 12, 1997), and by adding a new airworthiness directive 
(AD), amendment 39-10976, to read as follows:

99-01-10  Boeing: Amendment 39-10976. Docket 98-NM-327-AD. 
Supersedes AD 97-19-08, Amendment 39-10128.

    Applicability: Model 747 series airplanes having line positions 
1 through 1046 inclusive; certificated in any category; equipped 
with Pratt & Whitney Model JT9D series engines, General Electric 
Model CF6-45 and -50 series engines, or Rolls Royce Model RB211 
series engines; excluding those airplanes on which modifications of 
the strut/wing structure have been accomplished in accordance with 
one of the following AD's:
 AD 95-10-16, amendment 39-9233, or
 AD 95-13-05, amendment 39-9285, or
 AD 95-13-07, amendment 39-9287.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise 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 (l)(1) 
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 prevent fatigue and stress corrosion cracking in the diagonal 
brace, which could result in failure of the strut and consequent 
separation of the engine from the airplane, accomplish the 
following:

Restatement of Requirements of AD 97-19-08

    (a) For airplanes identified as Groups 1, 2, 3, and 4 in Boeing 
Alert Service Bulletin 747-54A2126, Revision 5, dated June 26, 1997: 
Perform a detailed visual and ultrasonic inspection to detect 
cracking, corrosion, and migrated or rotated bushings of the 
diagonal brace lugs, in accordance

[[Page 72146]]

with and at the times specified in Table 1 of Figure 1 of Boeing 
Alert Service Bulletin 747-54A2126, Revision 5, dated June 26, 1997, 
or Boeing Service Bulletin 747-54A2126, Revision 6, dated August 28, 
1997; except that where the service bulletin states that an 
inspection is to be performed within a specified number of days 
after receipt of the service bulletin, the inspection shall be 
accomplished within that number of days after September 29, 1997 
(the effective date of AD 97-19-08, amendment 39-10128). Thereafter, 
repeat the inspections of the diagonal brace lug as specified in 
paragraph (a)(1) or (a)(2) of this AD, as applicable, until the 
inspections required by paragraph (e) have been accomplished.
    (1) For the aft diagonal brace lug: Repeat the detailed visual 
and ultrasonic inspections thereafter at intervals not to exceed 
those specified in paragraph (d) or (e) in Table 1 of Figure 1 of 
the service bulletin, as applicable.
    (2) For the forward diagonal brace lug: Repeat the detailed 
visual and ultrasonic inspections thereafter at intervals not to 
exceed 600 landings. These inspections on the forward diagonal brace 
lug must be accomplished in accordance with 747 Non-Destructive Test 
(NDT) Manual D6-7170, Part 4, Subject 54-40-05.

    Note 2: Where there are differences between the AD and the 
referenced service bulletins, the AD prevails.

    (b) For airplanes identified as Groups 3, 4, and 5 in Boeing 
Alert Service Bulletin 747-54A2126, Revision 5, dated June 26, 1997: 
Perform a detailed visual and ultrasonic inspection to detect 
cracking, corrosion, or migrated or rotated bushings of the diagonal 
brace lugs, in accordance with and at the times specified in Table 
II of Figure 1 of Boeing Alert Service Bulletin 747-54A2126, 
Revision 5, dated June 26, 1997, or Boeing Service Bulletin 747-
54A2126, Revision 6, dated August 28, 1997; except that, where the 
service bulletin states that an inspection is to be performed within 
a specified number of days after receipt of the service bulletin, 
the inspection shall be accomplished within that number of days 
after September 29, 1997. Repeat the detailed visual and ultrasonic 
inspections thereafter at intervals not to exceed 1,000 flight 
cycles, until the inspections required by paragraph (f) have been 
accomplished.
    (c) If any migrated or rotated bushing is detected during any of 
the inspections required by paragraph (a) or (b) of this AD, prior 
to further flight, rework the diagonal brace lug, in accordance with 
Boeing Alert Service Bulletin 747-54A2126, Revision 5, dated June 
26, 1997, or Boeing Service Bulletin 747-54A2126, Revision 6, dated 
August 28, 1997; except as provided in paragraph (d) of this AD. 
Thereafter, repeat the detailed visual and ultrasonic inspections 
required by paragraph (a) of this AD prior to the accumulation of 
5,000 landings, and/or repeat the detailed visual and ultrasonic 
inspections required by paragraph (b) of this AD prior to the 
accumulation of 9,000 landings. If the lug bore diameter is not 
within the rework limits, prior to further flight, replace the 
diagonal brace or repair it, in accordance with a method approved by 
the Manager, Seattle Aircraft Certification Office (ACO), FAA, 
Transport Airplane Directorate; or in accordance with 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.
    (d) In lieu of accomplishing the requirements of paragraph (c) 
of this AD, perform an ultrasonic inspection to detect cracking or 
corrosion of the diagonal brace lug, in accordance with Boeing Alert 
Service Bulletin 747-54A2126, Revision 5, dated June 26, 1997, or 
Boeing Service Bulletin 747-54A2126, Revision 6, dated August 28, 
1997.
    (1) If no other damage is detected during the inspection 
required by paragraph (d) of this AD, prior to further flight, 
reseal the bushings or apply corrosion-inhibiting compound in 
accordance with the service bulletin; and thereafter, repeat the 
inspections of the diagonal brace lug as specified in paragraph 
(d)(1)(i) or (d)(1)(ii) of this AD, as applicable. If corrosion-
inhibiting compound is applied, repeat the application at intervals 
not to exceed 9 months, in accordance with the service bulletin. 
Within 15 or 18 months (as applicable in the service bulletin) since 
the initial detection of the migrated or rotated bushing, rework the 
diagonal brace lug in accordance with the service bulletin; and 
thereafter, repeat the detailed visual and ultrasonic inspections 
required by paragraph (a) of this AD prior to the accumulation of 
5,000 landings and/or repeat the detailed visual and ultrasonic 
inspections required by paragraph (b) of this AD prior to the 
accumulation of 9,000 landings. If the lug bore diameter is not 
within the rework limits, prior to further flight, replace the 
diagonal brace or repair it, in accordance with a method approved by 
the Manager, Seattle ACO, or in accordance with data meeting the 
type certification basis of the airplane approved by a Boeing 
Company DER who has been authorized by the Manager, Seattle ACO, to 
make such findings.
    (i) For the aft diagonal brace lug: Repeat the detailed visual 
and ultrasonic inspections required by paragraphs (a) and (b) of 
this AD thereafter at intervals not to exceed those specified in 
paragraph (d) or (e) in Table 1 and paragraph (d) of Table II of 
Figure 1 of the service bulletin, as applicable; except that the 
repetitive detailed visual inspections are required within 9 months 
following accomplishment of the resealing or application of 
corrosion-inhibiting compound.
    (ii) For the forward diagonal brace lug: Repeat the detailed 
visual and ultrasonic inspections required by paragraphs (a) and (b) 
of this AD thereafter at the repetitive intervals specified in those 
paragraphs, as applicable; except that the repetitive detailed 
visual inspections are required within 9 months following 
accomplishment of the resealing or application of corrosion-
inhibiting compound. These inspections on the forward diagonal brace 
lug must be accomplished in accordance with 747 NDT Manual D6-7170, 
Part 4, Subject 54-40-05.
    (2) If any cracking or corrosion is detected during the 
inspection required by paragraph (d) of this AD, prior to further 
flight, rework the diagonal brace lug in accordance with the service 
bulletin; and thereafter, repeat the detailed visual and ultrasonic 
inspections required by paragraph (a) of this AD prior to the 
accumulation of 5,000 landings, and/or repeat the detailed visual 
and ultrasonic inspections required by paragraph (b) of this AD 
prior to the accumulation of 9,000 landings. If the lug bore 
diameter is not within the rework limits, prior to further flight, 
replace the diagonal brace or repair it, in accordance with a method 
approved by the Manager, Seattle ACO, or in accordance with data 
meeting the type certification basis of the airplane approved by a 
Boeing Company DER who has been authorized by the Manager, Seattle 
ACO, to make such findings.

New Requirements of This AD

    (e) For airplanes identified as Groups 1, 2, 3, and 4 in Boeing 
Alert Service Bulletin 747-54A2126, Revision 7, dated November 20, 
1998: Perform detailed visual, high frequency eddy current (HFEC), 
and ultrasonic inspections, as applicable, to detect cracking, 
corrosion, and migrated or rotated bushings of the diagonal brace 
lugs or of the root radius of the clevis of the diagonal brace, in 
accordance with Table 1 of Figure 1 of Revision 7 of the alert 
service bulletin, at the time specified in paragraph (e)(1) or 
(e)(2) of this AD, whichever occurs later. Repeat the inspections 
thereafter at the times specified in Table 1 of Figure 1 of Revision 
7 of the alert service bulletin. Accomplishment of the applicable 
inspections constitutes terminating action for the repetitive 
inspection requirements of paragraphs (a)(1) and (a)(2) of this AD. 
For airplanes on which any migrated or rotated bushing was detected 
during any inspection required by paragraph (a) of this AD, but on 
which the rework required by paragraph (c) of this AD has not been 
accomplished, accomplishment of the inspections required by 
paragraph (e) of this AD constitutes terminating action only for the 
repetitive inspection requirements of paragraph (d)(1) of this AD. 
However, rework of the diagonal brace lug in accordance with 
paragraph (d)(1) of this AD is still required within 15 or 18 months 
after the initial detection of the migrated or rotated bushing; 
repetitive detailed visual inspections are required within 9 months 
after accomplishment of the resealing or application of corrosion-
inhibiting compound; and, if corrosion-inhibiting compound was 
applied in lieu of resealing the bushings in accordance with 
paragraph (d)(1) of this AD, reapplication of the corrosion-
inhibiting compound is required at intervals not to exceed 9 months.
    (1) Inspect prior to the accumulation of 5,000 total flight 
cycles; or within 5,000 flight cycles after rework of the diagonal 
brace lugs in accordance with Boeing Alert Service Bulletin 747-
54A2126, Revision 5, dated June 26, 1997, or Revision 7, or Boeing 
Service Bulletin 747-54A2126, Revision 6, dated August 28, 1997. Or
    (2) Inspect within 150 flight cycles or 60 days after the 
effective date of this AD, whichever occurs first.
    (f) For airplanes identified as Groups 3, 4, and 5 in Boeing 
Alert Service Bulletin 747-

[[Page 72147]]

54A2126, Revision 7, dated November 20, 1998: Perform detailed 
visual, HFEC, and ultrasonic inspections; as applicable; to detect 
cracking, corrosion, and migrated or rotated bushings of the 
diagonal brace lugs or of the root radius of the clevis of the 
diagonal brace; in accordance with Table II of Figure 1 of Revision 
7 of the alert service bulletin; at the time specified in paragraph 
(f)(1) or (f)(2) of this AD, whichever occurs later. Repeat the 
inspections thereafter at intervals not to exceed 1,000 flight 
cycles. Accomplishment of the applicable inspections constitutes 
terminating action for the repetitive inspection requirements of 
paragraph (b) of this AD. For airplanes on which any migrated or 
rotated bushing was detected during any inspection required by 
paragraph (b) of this AD, but on which the rework required by 
paragraph (c) of this AD has not been accomplished, accomplishment 
of the inspections required by paragraph (f) of this AD constitutes 
terminating action only for the repetitive inspection requirements 
of paragraph (d)(1) of this AD. However, rework of the diagonal 
brace lug in accordance with paragraph (d)(1) of this AD is still 
required within 15 or 18 months, as applicable, after the initial 
detection of the migrated or rotated bushing; repetitive detailed 
visual inspections are required within 9 months after accomplishment 
of the resealing or application of corrosion-inhibiting compound; 
and, if corrosion-inhibiting compound was applied in lieu of 
resealing the bushings in accordance with paragraph (d)(1) of this 
AD, reapplication of the corrosion-inhibiting compound is required 
at intervals not to exceed 9 months.
    (1) Inspect prior to the accumulation of 9,000 total flight 
cycles; or within 9,000 flight cycles after rework of the diagonal 
brace lug in accordance with Boeing Alert Service Bulletin 747-
54A2126, Revision 5, dated June 26, 1997, or Revision 7, or Boeing 
Service Bulletin 747-54A2126, Revision 6, dated August 28, 1997. Or
    (2) Inspect within 60 days after the effective date of this AD.
    (g) If any migrated or rotated bushing is detected during any of 
the inspections required by paragraph (e) or (f) of this AD, prior 
to further flight, rework the diagonal brace lug, in accordance with 
Boeing Alert Service Bulletin 747-54A2126, Revision 5, dated June 
26, 1997, or Revision 7, dated November 20, 1998; or Boeing Service 
Bulletin 747-54A2126, Revision 6, dated August 28, 1997; except as 
provided in paragraph (h) of this AD. Thereafter, repeat the 
detailed visual, HFEC, and ultrasonic inspections required by 
paragraph (e) of this AD within 5,000 flight cycles, and repeat the 
detailed visual, HFEC, and ultrasonic inspections required by 
paragraph (f) of this AD within 9,000 flight cycles, as applicable. 
If the lug bore diameter is not within the rework limits, or if any 
cracking of the root radius of the clevis is detected, prior to 
further flight, replace the diagonal brace with a new diagonal brace 
or repair it, in accordance with a method approved by the Manager, 
Seattle ACO, or in accordance with data meeting the type 
certification basis of the airplane approved by a Boeing Company DER 
who has been authorized by the Manager, Seattle ACO, to make such 
findings.
    (h) In lieu of accomplishing the requirements of paragraph (g) 
of this AD, perform ultrasonic and HFEC inspections to detect 
cracking or corrosion of the diagonal brace lug, in accordance with 
Boeing Alert Service Bulletin 747-54A2126, Revision 7, dated 
November 20, 1998.
    (1) If no cracking or corrosion is detected during the 
inspections required by paragraph (h) of this AD, prior to further 
flight, reseal the bushings or apply corrosion-inhibiting compound 
in accordance with the alert service bulletin, and accomplish the 
actions specified in paragraphs (h)(1)(i) and (h)(1)(ii) of this AD 
at the times specified in those paragraphs. If corrosion-inhibiting 
compound is applied, repeat the application at intervals not to 
exceed 9 months, in accordance with the alert service bulletin, 
until the actions required by paragraph (h)(1)(ii) of this AD have 
been accomplished.
    (i) Thereafter, repeat the detailed visual, HFEC, and ultrasonic 
inspections required by paragraphs (e) and (f) of this AD, as 
applicable, at intervals not to exceed those specified in Table 1 
and Table II of Figure 1 of the alert service bulletin, as 
applicable; except that the detailed visual inspection is required 
within 9 months after the resealing of the bushing or the 
application of corrosion-inhibiting compound. Accomplishment of such 
repetitive inspections terminates the repetitive inspection 
requirement of paragraph (d) of this AD.
    (ii) Within 15 or 18 months (as applicable in accordance with 
the alert service bulletin) since the initial detection of the 
migrated or rotated bushing required by paragraph (e) or (f) of this 
AD, rework the diagonal brace lug in accordance with Boeing Alert 
Service Bulletin 747-54A2126, Revision 5, dated June 26, 1997, or 
Revision 7, dated November 20, 1998; or Boeing Service Bulletin 747-
54A2126, Revision 6, dated August 28, 1997. Thereafter, repeat the 
detailed visual, HFEC, and ultrasonic inspections required by 
paragraph (e) of this AD within 5,000 flight cycles and repeat the 
detailed visual, HFEC, and ultrasonic inspections required by 
paragraph (f) of this AD within 9,000 landings, as applicable. If 
the lug bore diameter is not within the rework limits, or if any 
cracking of the root radius of the clevis is detected, prior to 
further flight, replace the diagonal brace with a new diagonal brace 
or repair it, in accordance with a method approved by the Manager, 
Seattle ACO; or in accordance with data meeting the type 
certification basis of the airplane approved by a Boeing Company DER 
who has been authorized by the Manager, Seattle ACO, to make such 
findings.
    (2) If any cracking or corrosion is detected during the 
inspection required by paragraph (h) of this AD, prior to further 
flight, rework the diagonal brace lug in accordance with Boeing 
Alert Service Bulletin 747-54A2126, Revision 5, dated June 26, 1997, 
or Revision 7, dated November 20, 1998; or Boeing Service Bulletin 
747-54A2126, Revision 6, dated August 28, 1997. Thereafter, repeat 
the detailed visual, HFEC, and ultrasonic inspections required by 
paragraph (e) of this AD within 5,000 landings and repeat the 
detailed visual, HFEC, and ultrasonic inspections required by 
paragraph (f) of this AD within 9,000 landings, as applicable. If 
the lug bore diameter is not within the rework limits, or if any 
cracking of the root radius of the clevis is detected, prior to 
further flight, replace the diagonal brace with a new diagonal brace 
or repair it, in accordance with a method approved by the Manager, 
Seattle ACO, or in accordance with data meeting the type 
certification basis of the airplane approved by a Boeing Company DER 
who has been authorized by the Manager, Seattle ACO, to make such 
findings.
    (i) If any cracking or corrosion is detected during any of the 
inspections required by paragraph (a), (b), (e), or (f) of this AD, 
prior to further flight, rework the diagonal brace lug in accordance 
with Boeing Alert Service Bulletin 747-54A2126, Revision 5, dated 
June 26, 1997, or Revision 7, dated November 20, 1998; or Boeing 
Service Bulletin 747-54A2126, Revision 6, dated August 28, 1997. 
Thereafter, repeat the detailed visual, HFEC, and ultrasonic 
inspections required by paragraph (e) of this AD within 5,000 
landings and/or repeat the detailed visual, HFEC, and ultrasonic 
inspections required by paragraph (f) of this AD within 9,000 
landings, as applicable. If the lug bore diameter is not within the 
rework limits, or if any cracking of the root radius of the clevis 
is detected, prior to further flight, replace the diagonal brace or 
repair it, in accordance with a method approved by the Manager, 
Seattle ACO, or in accordance with data meeting the type 
certification basis of the airplane approved by a Boeing Company DER 
who has been authorized by the Manager, Seattle ACO, to make such 
findings.
    (j) Accomplishment of a strut/wing modification in accordance 
with AD 95-10-16, amendment 39-9233; AD 95-13-05, amendment 39-9285; 
or AD 95-13-07, amendment 39-9287; as applicable; constitutes 
terminating action for the repetitive inspection requirements of 
this AD.
    (k) If Boeing Alert Service Bulletin 747-54A2126, Revision 5, 
dated June 26, 1997, or Revision 7, dated November 20, 1998; or 
Boeing Service Bulletin 747-54A2126, Revision 6, dated August 28, 
1997; specifies that corrective actions may be accomplished in 
accordance with an operator's ``equivalent procedure'': The 
inspection and rework must be accomplished in accordance with the 
procedures or the chapter of the Boeing manuals specified in the 
service bulletin.
    (l)(1) 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. 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.
    (2) Alternative methods of compliance, approved previously in 
accordance with AD 97-19-08, amendment 39-10128, are approved as 
alternative methods of compliance with this AD.
    (3) Alternative methods of compliance, approved previously in 
accordance with AD

[[Page 72148]]

95-10-16, amendment 39-9233, are not considered to be approved as 
alternative methods of compliance with this AD.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (m) 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.
    (n) Except as provided by paragraphs (a)(2), (c), (d)(1), 
(d)(1)(ii), (d)(2), (g), (h)(1)(ii), (h)(2), (h)(2)(i), and (k) of 
this AD, the inspections, rework, and reseal shall be done in 
accordance with Boeing Alert Service Bulletin 747-54A2126, Revision 
5, dated June 26, 1997; Boeing Service Bulletin 747-54A2126, 
Revision 6, dated August 28, 1997; or Boeing Alert Service Bulletin 
747-54A2126, Revision 7, dated November 20, 1998.
    (1) The incorporation by reference of Boeing Alert Service 
Bulletin 747-54A2126, Revision 5, dated June 26, 1997, was approved 
previously by the Director of the Federal Register in accordance 
with 5 U.S.C. 552(a) and 1 CFR part 51, as of September 29, 1997 (62 
FR 47927, September 12, 1997).
    (2) The incorporation by reference of Boeing Service Bulletin 
747-54A2126, Revision 6, dated August 28, 1997; and Boeing Alert 
Service Bulletin 747-54A2126, Revision 7, dated November 20, 1998; 
is approved by the Director of the Federal Register in accordance 
with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from 
Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 
98124-2207.
    (3) Copies may be inspected at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the 
Office of the Federal Register, 800 North Capitol Street, NW., suite 
700, Washington, DC.
    (o) This amendment becomes effective on January 15, 1999.

    Issued in Renton, Washington, on December 23, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-34676 Filed 12-30-98; 8:45 am]
BILLING CODE 4910-13-U