[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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