[Federal Register Volume 62, Number 177 (Friday, September 12, 1997)]
[Rules and Regulations]
[Pages 47927-47929]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-24179]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-NM-180-AD; Amendment 39-10128; AD 97-19-08]
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 ultrasonic inspection of certain engine strut
diagonal brace lugs for cracks, and replacement, if necessary. This
amendment requires new repetitive inspections to detect discrepancies
of the diagonal brace lugs, and rework of the diagonal brace lug, if
necessary. In lieu of accomplishing the rework for certain cases, this
amendment provides for an option to defer the rework by accomplishing
repetitive inspections and resealing the bushing. This amendment also
provides for an optional terminating modification for repetitive
inspections. This amendment is prompted by additional reports of
fatigue cracking in the diagonal brace lug. The actions specified in
this 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.
DATES: Effective September 29, 1997.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of September 29, 1997.
Comments for inclusion in the Rules Docket must be received on or
before November 12, 1997.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 97-NM-180-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. Dow, Aerospace Engineer,
Airframe Branch, ANM-120S, Seattle Aircraft Certification Office, 1601
Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-
2771; fax (425) 227-1181.
SUPPLEMENTARY INFORMATION: On March 14, 1989, the FAA issued AD 89-07-
15, amendment 39-6167 (54 FR 11693, March 22, 1989), applicable to
certain Boeing Model 747 series airplanes, to require ultrasonic
inspection of certain engine strut diagonal brace lugs for cracks, and
replacement, if necessary. That action was prompted by reports of
cracked diagonal braces. The actions required by that AD are intended
to prevent overloading of the remaining strut attach points and
possible structural damage.
Actions Since Issuance of Previous Rule
Since the issuance of that AD, the FAA has received several reports
of six additional diagonal braces with cracks in one lug of the aft
clevis on Boeing Model 747 series airplanes. These incidents occurred
following accomplishment of the optional terminating action specified
in AD 89-07-15.
One diagonal brace, which had 3,386 flight cycles, had a crack from
the bore to the part edge in the aft lug. The second diagonal brace,
which had 5,206 flight cycles, had one lug in the aft clevis completely
fractured. The third diagonal brace, which had 13,964 flight cycles,
had a crack less than 0.10 inch in the aft lug bore. The fourth
diagonal brace, which had 1,275 flight cycles, had a crack from the
bore to the part edge in the aft lug. The fifth diagonal brace, which
had approximately 3,360 flight cycles, had a through thickness crack in
the lug. The sixth diagonal brace, which had approximately 8,350 flight
cycles, had a crack in the aft lug. The length of the cracks for the
fifth and sixth diagonal braces is not known. (The above mentioned
flight cycles refer to cycles following accomplishment of the rework.)
Investigation revealed that the apparent cause of these cracks was
attributed to fatigue, which may initiate at lug bore corrosion pits or
other lug surface anomalies. Fatigue cracking in the diagonal brace
lugs, if not detected and corrected in a timely manner, could result in
failure of the strut and consequent separation of the engine from the
airplane.
Discussion of Relevant Service Information
Subsequent to the finding of this new cracking, the manufacturer
issued, and
[[Page 47928]]
the FAA reviewed and approved, Boeing Alert Service Bulletin 747-
54A2126, Revision 5, dated June 26, 1997. The revised alert service
bulletin describes procedures for new repetitive detailed visual and
ultrasonic inspections to detect cracking, corrosion, and migrated or
rotated bushings of the diagonal brace lugs, and rework of the diagonal
brace lug or a follow-on ultrasonic inspection, if necessary. In lieu
of the rework for certain cases, the revised alert service bulletin
also describes procedures for resealing the bushing and follow-on
repetitive inspections. In addition, the revised alert service bulletin
provides procedures for modification of the strut/wing, which would
eliminate the need for repetitive inspections. The revised alert
service bulletin also expands the effectivity listing to include
additional airplanes that are subject to the addressed unsafe
condition.
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 89-07-15 to require new repetitive detailed visual and
ultrasonic inspections to detect cracking, corrosion, and migrated or
rotated bushings of the diagonal brace lugs, and rework of the diagonal
brace lugs, if necessary. In lieu of accomplishing the rework (prior to
further flight) for certain cases where no cracks or corrosion is
detected, this AD provides operators with an option to defer the rework
for a short period of time by accomplishing repetitive inspections and
resealing the bushing. This AD also provides procedures for
modification of the strut/wing, which would constitute terminating
action for the repetitive inspections requirements. In addition, this
AD expands the applicability of the existing AD to include additional
airplanes.
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 97-NM-180-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 39-6167 (54 FR
11693, March 22, 1989), and by adding a new airworthiness directive
(AD), amendment 39-10128, to read as follows:
97-19-08 Boeing: Amendment 39-10128. Docket 97-NM-180-AD.
Supersedes AD 89-07-15, Amendment 39-6167.
Applicability: Model 747 series airplanes having line positions
1 through 1046 inclusive; equipped with Pratt & Whitney Model JT9D
series engines, General Electric Model CF6-45 and -50 series
engines, or Rolls Royce Model RB211 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 (g)(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 cracking in the diagonal brace lug, which
could result in failure of the strut and consequent separation of
the engine from the airplane, accomplish the following:
(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 with and at the times specified
in Table 1 of Figure 1 of the alert service bulletin; except that
where the alert service bulletin states
[[Page 47929]]
that an inspection is to be performed within a specified number of
days after receipt of the alert service bulletin, the inspection
shall be accomplished within that number of days after the effective
date of this AD. Thereafter, repeat the inspections of the diagonal
brace lug as specified in paragraph (a)(1) or (a)(2) of this AD, as
applicable. After the effective date of this AD, only Revision 5 of
the alert service bulletin shall be used.
(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 alert 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 alert service bulletin, 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 the alert service; except that where the alert
service bulletin states that an inspection is to be performed within
a specified number of days after receipt of the alert service
bulletin, the inspection shall be accomplished within that number of
days after the effective date of this AD. Repeat the detailed visual
and ultrasonic inspections thereafter at intervals not to exceed
1,000 flight cycles. After the effective date of this AD, only
Revision 5 of the alert service bulletin shall be used.
(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; 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.
(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.
(1) If no other damage is detected during the inspection
required by paragraph (d) of this AD, prior to further flight,
reseal the bushings in accordance with the alert 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. Within 15 or 18 months (as applicable in the alert
service bulletin) since the initial migrated or rotated bushing was
detected, rework the diagonal brace lug in accordance with the alert
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 Aircraft Certification Office
(ACO), FAA, Transport Airplane Directorate.
(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 alert service bulletin, as applicable; except that
the repetitive detailed visual inspections are required within 9
months following accomplishment of the resealing.
(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. 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 alert
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 Aircraft Certification Office
(ACO), FAA, Transport Airplane Directorate.
(e) If any cracking or corrosion 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; 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 Aircraft Certification Office (ACO), FAA,
Transport Airplane Directorate.
(f) Accomplishment of the strut/wing modification in accordance
with Boeing Alert Service Bulletin 747-54A2126, Revision 5, dated
June 26,1997, constitutes terminating action for the repetitive
inspection requirements of this AD.
(g)(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 Aircraft Certification
Office (ACO), FAA, Transport Airplane Directorate. 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.
(g)(2) Alternative methods of compliance, approved previously in
accordance with AD 89-07-15, amendment 39-6167, and AD 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.
(h) Special flight permits may be issued in accordance with
sections 21.197 and 21.199 of the Federal Aviation Regulations (14
CFR 21.197 and 21.199) to operate the airplane to a location where
the requirements of this AD can be accomplished.
(i) The actions shall be done in accordance with Boeing Alert
Service Bulletin 747-54A2126, Revision 5, dated June 26, 1997. This
incorporation by reference was 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. 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.
(j) This amendment becomes effective on September 29, 1997.
Issued in Renton, Washington, on September 5, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 97-24179 Filed 9-11-97; 8:45 am]
BILLING CODE 4910-13-U
