[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
