[Federal Register Volume 60, Number 34 (Tuesday, February 21, 1995)]
[Rules and Regulations]
[Pages 9613-9616]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-2173]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 94-NM-27-AD; Amendment 39-9134; AD 95-02-15]
Airworthiness Directives; Boeing Model 747-100 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment supersedes an existing airworthiness directive
(AD), applicable to certain Boeing Model 747-100 series airplanes, that
currently requires repetitive inspections to detect cracking of the
wing front spar web above engine numbers 2 and 3, and repair, if
necessary. This amendment requires repetitive inspections to detect
cracks in the web and cracked or broken fasteners in an area beyond
that specified in the existing AD. This amendment also provides an
optional terminating action for the repetitive inspections. This
amendment is prompted by reports of broken fasteners and cracking of
the web common to the upper and lower chords in an area outside the
inspection zone specified in the existing AD. The actions specified by
this AD are intended to prevent fuel leakage onto an engine and a
resultant fire due to cracking or broken fasteners in the wing front
spar.
DATES: Effective March 23, 1995.
The incorporation by reference of Boeing Service Bulletin 747-
57A2266, dated June 6, 1991, as listed in the regulations, was approved
previously by the Director of the Federal Register as of May 4, 1992
(57 FR 10415, March 26, 1992).
The incorporation by reference of certain other publications, as
listed in the regulations, is approved by the Director of the Federal
Register as of March 23, 1995.
ADDRESSES: 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 Federal
Aviation Administration (FAA), Transport Airplane Directorate, Rules
Docket, 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: Tim Backman, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056; telephone (206) 227-2776; fax (206) 227-1181.
SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal
Aviation Regulations (14 CFR part 39) by superseding AD 92-07-11,
amendment 39-8207 (57 FR 10415, March 26, 1992), which is applicable to
certain Boeing Model 747-100 series airplanes, was published in the
Federal Register on August 23, 1994 (59 FR 43304). The action proposed
to require repetitive detailed visual and ultrasonic inspections to
detect cracks in an area beyond that specified in the existing AD;
repetitive ultrasonic inspections of the fasteners in the web-to-
chords, web-to-stiffeners, and web-to-rib posts to detect cracked or
broken fasteners between front spar stations (FSS) 570 and 684; and
oversizing the fastener holes, performing an eddy current inspection to
detect cracking of the fastener holes, and replacing cracked fasteners
with oversized fasteners, if necessary.
Discussion of Comments Received
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
One commenter supports the proposed rule.
Two commenters request that the initial inspection threshold
specified in paragraph (b) of the proposal be extended from 1,000 to
2,000 flight cycles (after the immediately preceding inspection) to be
consistent with the recommendations of Boeing Alert Service Bulletin
747-57A2266, Revision 3, dated March 31, 1994, which is referenced in
the proposal as the appropriate source of service information. The FAA
concurs. The FAA finds that such an extension of the inspection
threshold will not adversely affect safety. Therefore, the final rule
has been revised accordingly. In addition, the FAA has revised the
``grace period'' of 6 months (after the effective date of the AD), as
specified in proposed paragraph (b), to 9 months in order to correspond
with the recommendations of the service bulletin.
The Air Transport Association (ATA) of America, on behalf of one of
its members, requests that the FAA delay issuance of this AD until the
next revision of Boeing Service Bulletin 747-57A2266 is issued.
(Revision 3 of that service bulletin is referenced in the proposal as
the appropriate source of service information.) The commenter notes
that, in accomplishing the proposed inspection/modification, many of
the fastener holes required oversizing beyond the criteria described in
the referenced version of service bulletin. The commenter also states
that it has found several cracked rivets that had not been identified
using the ultrasonic inspection technique recommended in that service
bulletin. The commenter indicates that Boeing has advised that it is
considering issuance of a revision to the service bulletin to address
this concern.
The FAA does not concur with the commenter's request to delay
issuance of the final rule. Since the issuance of the proposal, Boeing
has issued Revision 4 of Boeing Service Bulletin 747-57A2266, dated
November 3, 1994. This revision is essentially the same as the previous
version, but specifies the locations of certain fasteners that must be
inspected using ultrasonic techniques. The locations of these fasteners
are in the web-to-chords, and in the top two and bottom two rows in the
web-to-stiffeners and web-to-rib posts of the wing front spar.
Paragraphs (b)(3) and (c)(3) of the final rule have been revised to
specify this.
Revision 4 of the service bulletin also updates certain information
concerning parts and materials, adds a reference to an ultrasonic
testing procedure in the Nondestructive Test Manual, provides an
additional inspection method for detecting cracks inside the fuel tank,
and includes an additional method of removing fasteners for inspection.
The final rule has been revised to cite the latest revision of the
service bulletin as [[Page 9614]] an additional source of service
information.
In addition, paragraphs (b)(1) and (c)(1) of the final rule have
been clarified to indicate that the detailed visual inspections of the
wing front spar chords, stiffeners, and rib posts between the fastener
heads are to be accomplished between FSS 570 to FSS 684, as specified
in Revisions 3 and 4 of the service bulletin.
The FAA points out that Revision 4 of the service bulletin does not
recommend increasing the oversize limits of the fastener holes, as
mentioned by the commenter. Boeing has advised the FAA that a review of
this issue is currently under way. Although this review is not yet
completed, preliminary results indicate that only certain holes may be
oversized beyond the limits specified in Revision 4 of the service
bulletin.
In addition, Boeing indicates that it has examined the cracked
rivets discussed by the commenter. Four of the six rivets submitted to
Boeing were not cracked. The other two rivets had small cracks that
were not detectable by the proposed ultrasonic inspection method.
Boeing indicates that the currently recommended ultrasonic inspection
method is not sensitive enough to detect small cracks in the rivets;
however, it is effective in detecting cracks that penetrate/propagate
more than halfway through the rivet, which does provide a safety
benefit. Boeing is currently working to refine the ultrasonic
inspection method to improve the detectability of small rivet cracks.
In light of the above, the FAA finds that to delay issuance of this
final rule would be inappropriate, since an unsafe condition exists and
the actions required by this AD must be accomplished to ensure
continued safety. Repair of fastener holes with cracks that cannot be
removed by oversizing the fastener holes must be accomplished in
accordance with a method approved by the FAA, as specified in paragraph
(d) of the final rule. The FAA may consider additional rulemaking once
the review discussed previously is completed.
Discussion of Other Changes Made to the Final Rule
The applicability statement contained in the proposal referenced
airplanes listed in Revision 3 of the service bulletin. Since Revision
4 of the service bulletin contains the same effectivity listing as that
specified in Revision 3, the FAA has revised the applicability
statement of the final rule to specify that this AD applies to
airplanes listed in Revision 4 of the service bulletin.
Paragraph (b)(1) of the final rule has been revised to clarify the
FAA's intent that the purpose of the detailed visual inspection is to
detect cracking.
As a result of recent communications with the ATA, the FAA has
learned that, in general, some operators may misunderstand the legal
effect of AD's on airplanes that are identified in the applicability
provision of the AD, but that have been altered or repaired in the area
addressed by the AD. The FAA points out that all airplanes identified
in the applicability provision of an AD are legally subject to the AD.
If an airplane has been altered or repaired in the affected area in
such a way as to affect compliance with the AD, the owner or operator
is required to obtain FAA approval for an alternative method of
compliance with the AD, in accordance with the paragraph of each AD
that provides for such approvals. A note has been added to this final
rule to clarify this requirement.
Additionally, the FAA has recently reviewed the figures it has used
over the past several years in calculating the economic impact of AD
activity. In order to account for various inflationary costs in the
airline industry, the FAA has determined that it is necessary to
increase the labor rate used in these calculations from $55 per work
hour to $60 per work hour. The economic impact information, below, has
been revised to reflect this increase in the specified hourly labor
rate.
In addition, Boeing has included in Revision 4 of the service
bulletin prices for kits necessary to accomplish the optional
terminating action. Accordingly, the economic impact information,
below, has been revised to reflect these costs, should an operator
elect to accomplish the optional terminating action.
After careful review of the available data, including the comments
noted above, the FAA has determined that air safety and the public
interest require the adoption of the rule with the changes previously
described. The FAA has determined that these changes will neither
increase the economic burden on any operator nor increase the scope of
the AD.
Economic Impact
There are approximately 190 Model 747-100 series airplanes of the
affected design in the worldwide fleet. The FAA estimates that 95
airplanes of U.S. registry will be affected by this AD.
The inspections that are required previously by AD 92-07-11, and
retained in this AD, take approximately 16 work hours per airplane to
accomplish, at an average labor rate of $60 per work hour. Based on
these figures, the total cost impact of that inspection requirement on
U.S. operators is estimated to be $91,200, or $960 per airplane, per
inspection cycle.
The FAA estimates that it will take approximately 54 work hours per
airplane to accomplish the required inspections of the expanded area
specified in this AD, and that the average labor rate is $60 per work
hour. Based on these figures, the future total cost impact of the
inspection requirement of the expanded area on U.S. operators is
estimated to be $307,800, or $3,240 per airplane.
Based on these figures, the total cost impact of this AD on U.S.
operators is estimated to be $399,000, or $4,200 per airplane.
The total cost impact figure discussed above is based on
assumptions that no operator has yet accomplished any of the
requirements of this AD action, and that no operator would accomplish
those actions in the future if this AD were not adopted.
Should an operator elect to accomplish the optional terminating
action (fastener replacement between FSS 570 and FSS 684) that is
provided by this AD action, it will take approximately 306 work hours
to accomplish it, at an average labor rate of $60 per work hour. The
cost of required parts will be approximately $15,478. Based on these
figures, the total cost impact of the optional terminating action will
be $33,838 per airplane.
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.
For the reasons discussed above, I certify that this action (1) is
not a ``significant regulatory action'' under Executive Order 12866;
(2) is not a ``significant rule'' under DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979); and (3) will not have a
significant economic impact, positive or negative, on a substantial
number of small entities under the criteria of the Regulatory
Flexibility Act. A final evaluation has been prepared for this action
and it is contained in the Rules Docket. A copy of it may be obtained
from the Rules [[Page 9615]] 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. App. 1354(a), 1421 and 1423; 49 U.S.C.
106(g); and 14 CFR 11.89.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by removing amendment 39-8207 (57 FR
10415, March 26, 1992), and by adding a new airworthiness directive
(AD), amendment 39-9134, to read as follows:
95-02-15 Boeing: Amendment 39-9134. Docket 94-NM-27-AD. Supersedes
AD 92-07-11, Amendment 39-8207.
Applicability: Model 747-100 series airplanes; as listed in
Boeing Service Bulletin 747-57A2266, Revision 4, dated November 3,
1994; 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 use the authority
provided in paragraph (f) to request approval from the FAA. This
approval may address either no action, if the current configuration
eliminates the unsafe condition; or different actions necessary to
address the unsafe condition described in this AD. Such a request
should include an assessment of the effect of the changed
configuration on the unsafe condition addressed by this AD. In no
case does the presence of any modification, alteration, or repair
remove any airplane from the applicability of this AD.
Compliance: Required as indicated, unless accomplished
previously.
To prevent fuel leakage onto an engine and a resultant fire,
accomplish the following:
Restatement of Actions Required by AD 92-07-11, Amendment 39-8207:
(a) For airplanes listed in Boeing Service Bulletin 747-57A2266,
dated June 6, 1991, on which the optional terminating action
(fastener replacement) specified in the original issue, dated June
6, 1991; Revision 1, dated May 21, 1992; or Revision 2, dated June
10, 1993; of the service bulletin has not been accomplished: Perform
a visual inspection and an ultrasonic inspection to detect cracks of
the wing front spar web between front spar station (FSS) 636 and FSS
675 in accordance with Boeing Service Bulletin 747-57A2266, dated
June 6, 1991; Revision 1, dated May 21, 1992; Revision 2, dated June
10, 1993; or Revision 3, dated March 31, 1994; or Revision 4, dated
November 3, 1994; at the time specified in paragraph (a)(1), (a)(2),
or (a)(3) of this AD, as applicable. Repeat these inspections
thereafter at intervals not to exceed 2,000 flight cycles until the
inspections required by paragraph (b) of this AD are accomplished.
(1) For airplanes that have accumulated more than 20,000 total
flight cycles as of May 4, 1992 (the effective date of AD 92-07-11,
amendment 39-8207): Inspect within 6 months after May 4, 1992.
(2) For airplanes that have accumulated between 15,000 and
20,000 total flight cycles as of May 4, 1992: Inspect within 15
months after May 4, 1992.
(3) For airplanes that have accumulated less than 15,000 total
flight cycles as of May 4, 1992: Inspect within 15 months after
accumulating 15,000 total flight cycles.
New Actions Required by This AD
(b) For airplanes on which the terminating action (fastener
replacement) specified in Boeing Service Bulletin 747-57A2266, dated
June 6, 1991; Revision 1, dated May 21, 1992; or Revision 2, dated
June 10, 1993; has not been accomplished: Prior to the accumulation
of 13,000 total flight cycles, or within 9 months after the
effective date of this AD, or within 2,000 flight cycles after the
immediately preceding inspection accomplished in accordance with
paragraph (a) of this AD, whichever occurs later, accomplish the
inspections specified in paragraphs (b)(1), (b)(2), and (b)(3) of
this AD in accordance with Boeing Service Bulletin 747-57A2266,
Revision 3, dated March 31, 1994; or Revision 4, dated November 3,
1994. Repeat these inspections thereafter at intervals not to exceed
2,000 flight cycles. Accomplishment of these inspections terminates
the inspections required by paragraph (a) of this AD. After the
effective date of this AD, the inspections required by this
paragraph shall be accomplished only in accordance with Revision 3
or 4 of the service bulletin.
(1) Perform a detailed visual inspection to detect cracking of
the wing front spar chords, stiffeners, and rib posts between the
fastener heads between FSS 570 and FSS 684; and
(2) Perform an ultrasonic inspection of the web under the upper
and lower chord footprints to detect cracking of the wing front spar
web between FSS 570 and FSS 684; and
(3) Perform an ultrasonic inspection of the fasteners in the
web-to-chords, and of the fasteners in the top two and bottom two
rows in the web-to-stiffeners and web-to-rib posts of the wing front
spar to detect cracked or broken fasteners between FSS 570 and FSS
684.
(c) For airplanes on which the terminating action (fastener
replacement) specified in Boeing Service Bulletin 747-57A2266, dated
June 6, 1991; Revision 1, dated May 21, 1992; or Revision 2, dated
June 10, 1993; has been accomplished: Within 18 months after
accomplishing the terminating action specified in the original
issue, Revision 1, or Revision 2 of the service bulletin, or within
9 months after the effective date of this AD, whichever occurs
later, accomplish the inspections specified in paragraphs (c)(1),
(c)(2), and (c)(3) of this AD in accordance with Boeing Service
Bulletin 747-57A2266, Revision 3, dated March 31, 1994; or Revision
4, dated November 3, 1994. Repeat these inspections thereafter at
intervals not to exceed 2,000 flight cycles. After the effective
date of this AD, the inspections required by this paragraph shall be
accomplished only in accordance with Revision 3 or 4 of the service
bulletin.
(1) Perform a detailed visual inspection of the wing front spar
chords, stiffeners, and rib posts between the fastener heads between
FSS 570 and FSS 684; and
(2) Perform an ultrasonic inspection of the web under the upper
and lower chord footprints to detect cracking of the wing front spar
web between FSS 570 and FSS 636 and between FSS 675 and FSS 684; and
(3) Perform an ultrasonic inspection of the fasteners in the
web-to-chords, and of the fasteners in the top two rows and bottom
two rows in the web-to-stiffeners and web-to-rib posts of the wing
front spar to detect cracked or broken fasteners between FSS 570 and
FSS 636 and between FSS 675 and 684.
(d) If any crack in the web or any cracked or broken fastener is
found during any inspection required by this AD, prior to further
flight, oversize the fastener hole, perform an eddy current
inspection to detect cracks in the fastener hole, and replace the
fastener with an oversized fastener, in accordance with Boeing
Service Bulletin 747-57A2266, Revision 3, dated March 31, 1994; or
Revision 4, dated November 3, 1994. Thereafter, continue to inspect
the remaining fasteners in accordance with paragraph (b) or (c) of
this AD, as applicable, until the terminating action specified in
paragraph (e) of this AD is accomplished. If any crack is found that
cannot be removed by oversizing the fastener hole, prior to further
flight, repair in accordance with a method approved by the Manager,
Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane
Directorate.
(e) Replacement of the fasteners in the web-to-chords and of the
fasteners in the web-to-stiffeners and web-to-rib posts, as
specified in Boeing Service Bulletin 747-57A2266, Revision 3, dated
March 31, 1994; or Revision 4, dated November 3, 1994; with
oversized fasteners on each wing spar in accordance with the service
bulletin constitutes terminating action for the repetitive
inspections required by paragraph (b) and (c) of this AD.
(f) 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.
Note 2: Information concerning the existence of approved
alternative methods of [[Page 9616]] compliance with this AD, if
any, may be obtained from the Seattle ACO.
(g) 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.
(h) Certain inspections shall be done in accordance with Boeing
Service Bulletin 747-57A2266, dated June 6, 1991, as indicated. The
incorporation by reference of this document 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 May 4, 1992 (57 FR 10415, March 26,
1992). Other inspections and replacement actions, as indicated,
shall be done in accordance with Boeing Service Bulletin 747-
57A2266, Revision 1, dated May 21, 1992; Boeing Service Bulletin
747-57A2266, Revision 2, dated June 10, 1993; Boeing Service
Bulletin 747-57A2266, Revision 3, dated March 31, 1994; and Boeing
Service Bulletin 747-57A2266, Revision 4, dated November 3, 1994.
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.
(i) This amendment becomes effective on March 23, 1995.
Issued in Renton, Washington, on January 24, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 95-2173 Filed 2-17-95; 8:45 am]
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