[Federal Register Volume 60, Number 98 (Monday, May 22, 1995)]
[Rules and Regulations]
[Pages 27008-27016]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-11968]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-NM-187-AD; Amendment 39-9233; AD 95-10-16]


Airworthiness Directives; Boeing Model 747 Series Airplanes 
Equipped with Pratt & Whitney Model JT9D Series Engines (Excluding 
Model JT9D-70 Engines)

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 747 series airplanes, that requires 
modification of the nacelle strut and wing structure, inspections and 
checks to detect discrepancies, and correction of discrepancies. This 
amendment is prompted by the development of a modification of the strut 
and wing structure that improves the damage tolerance capability and 
durability of the strut-to-wing attachments, and reduces reliance on 
inspections of those attachments. The actions specified by this AD are 
intended to prevent failure of the strut and subsequent loss of the 
engine.

DATES: Effective June 21, 1995.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of June 21, 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) to include an airworthiness 
directive (AD) that is applicable to certain Boeing Model 747 series 
airplanes was published in the Federal Register on December 21, 1994 
(59 FR 65733). That action proposed to require modification of the 
nacelle strut and wing structure, inspections and checks to detect 
discrepancies in the adjacent structure, and correction of 
discrepancies.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Revision of Descriptive Language

    One commenter notes that the description of the unsafe condition 
that appeared in the Discussion section of the preamble to the notice 
refers to ``the structural fail-safe capability of the strut-to-wing 
attachment.'' The commenter states that this description is inaccurate, 
since it implies that the strut-to-wing attachment is inadequate. The 
commenter suggests that a more accurate description would be ``damage 
tolerance capability of the strut-to-wing attachment.'' The FAA 
acknowledges that the commenter's wording is more accurate. The 
pertinent wording this preamble to the final rule has been revised to 
reflect this change. Furthermore, the FAA considers the new structure 
of the strut as meeting the damage tolerance requirements of amendment 
45 of section 25.571, ``Damage--tolerance and fatigue evaluation of 
structure'' of the Federal Aviation Regulations (14 CFR 25.571, 
amendment 45), which provides an even higher level of safety than 
simply fail-safe requirements.
    One commenter provides further information to describe the purpose 
of the proposed modification of the nacelle strut and wing structure. 
This commenter suggests that the rule should specify that the 
modification not only significantly improves the load-carrying and 
durability of the strut-to-wing attachments, but ``reduces the reliance 
on non-routine inspections,'' as well. The FAA concurs with this 
suggestion and has revised the Summary section of the preamble to this 
final rule to include wording relevant to this aspect. -
    One commenter provides clarification of the description in the 
Explanation of Service Information section of the preamble to the 
proposal. That section of the preamble described the various 
terminating actions specified in the service bulletins listed in 
paragraph I.C., Table 2, Prior or Concurrent Service 
[[Page 27009]] Bulletins,'' on page 13 of Boeing Alert Service Bulletin 
747-54A2159, dated November 3, 1994 (which was referenced in the notice 
as the appropriate source of service information). The commenter notes 
that it is replacement of the ``diagonal brace strut lower spar 
fitting'' which is specified as a terminating action in that listing. 
The notice, however, incompletely described that particular terminating 
action as the replacement of ``the diagonal brace strut and wing and 
attachment fittings.'' The FAA acknowledges that the commenter provides 
a more complete description of that terminating action. However, since 
the Explanation of Service Information section is not restated in this 
rule, no change to the final rule is necessary.

Clarification of Note 1 -

    One commenter requests that Note 1 of the proposal be clarified 
since it is too vague to determine exactly when FAA approval of 
alternative methods of compliance (AMOC) is necessary. The FAA concurs. 
Although every effort is made to keep the language simple and clear, it 
is apparent that some additional explanation is necessary to clarify 
the intent of Note 1. Performance of the requirements of this final 
rule is ``affected'' if an operator is unable to perform those 
requirements in the manner described in this AD. For example, if an AD 
requires a visual inspection in accordance with a certain service 
bulletin, and the operator cannot perform that inspection because of 
the placement of a repair doubler over the structure to be inspected, 
then ``performance of the AD is affected.'' -
    In addition, performance of the requirements is ``affected'' if it 
is physically possible to perform the requirements, but the results 
achieved are different from those specified in the AD. For example, if 
the AD requires a non-destructive test (NDT) inspection in accordance 
with a certain service bulletin, and the operator is able to move the 
NDT probe over the specified area in the specified manner, but the 
results are either meaningless or inaccurate because of a repair 
doubler placed over that area, then ``performance of the AD is 
affected.'' -
    While Note 1 itself is not capable of addressing every possible 
situation, ``affected'' is normally an easy standard to apply: either 
it is possible to perform the requirements as specified in the AD and 
achieve the specified results, or it is not possible. Therefore, if the 
requirements of this AD cannot be performed, then operators must submit 
a request for an approval of an AMOC from the FAA, in accordance with 
the provision of paragraph (d) of this final rule. -
    Accomplishment of any modification requirement of an AD, such as 
the modification of the nacelle strut and wing structure required by 
this final rule, does not ``affect performance of the AD;'' it is 
performance of the AD. Every AD includes a provision, with which 
operators are familiar, that states, ``Compliance required as 
indicated, unless accomplished previously .'' If an operator performs 
such a requirement before the AD is issued, the FAA is confident that 
the operator will recognize that it has already complied with the AD 
and no further action (including obtaining approval of an AMOC) is 
required. This is consistent with current law and practice, which Note 
1 is not intended to change.

Compliance Time for Modification -

    One commenter requests that the compliance times of proposed 
paragraph (a), which requires modification of the nacelle strut and 
wing structure, be extended by 4 months. The commenter notes that a 4-
month extension of the compliance times would coincide with the times 
recommended in the referenced Boeing Alert Service Bulletin 747-54A2159 
for that modification. Furthermore, the commenter states that the 
referenced alert service bulletin contains numerous errors, and a 4-
month extension would allow the manufacturer sufficient time to publish 
a revision to that alert service bulletin to correct those errors. -
    The FAA does not concur with the commenter's request. In developing 
an appropriate compliance time for this action, the FAA considered not 
only the degree of urgency associated with addressing the subject 
unsafe condition, but the manufacturer's recommendation as to an 
appropriate compliance time, the availability of required parts, and 
the practical aspect of installing the required modification within a 
maximum interval of time allowable for all affected airplanes to 
continue to operate without compromising safety. Further, the FAA took 
into account the 3-year and 5-year compliance times recommended by the 
manufacturer, as well as the number of days required for the rulemaking 
process; in consideration of these factors, the FAA finds that 32 
months and 56 months after the effective date of this final rule will 
fall approximately at the same time for compliance as recommended by 
the manufacturer. Furthermore, the FAA does not consider that delaying 
this action until after the release of the manufacturer's planned 
revision to the alert service bulletin is warranted, since the changes 
in the revised alert service bulletin are mostly minor and clarifying 
in nature and do not affect the procedures to accomplish the 
modification of the nacelle strut and wing structure.
    However, under the provisions of paragraph (d) of the final rule, 
any operator may submit requests for adjustments to the compliance time 
along with data demonstrating that such requests will not compromise 
safety. In evaluating such requests for adjustments to the compliance 
time, the FAA will closely examine the operator's explanation of why an 
extension is needed. The FAA will also consider the operator's good 
faith attempt at complying within the compliance times contained in 
this final rule, which can be demonstrated by accomplishing the 
modification on a significant percentage of the airplanes in the 
operator's fleet prior to submitting a request for adjustments to the 
compliance times. The FAA will take into consideration the number of 
airplanes in the operator's fleet on which the modification has been 
accomplished and the number of unmodified airplanes remaining in the 
operator's fleet. Additionally, the operator may be asked to submit a 
schedule for accomplishing the modification on the airplanes remaining 
in its fleet.

Calculation of Age of Affected Airplanes -

    Several commenters request that the age of the airplanes be 
measured as of the date of issuance of Boeing Alert Service Bulletin 
747-54A2159, rather than as of the effective date of the AD, as 
proposed in paragraphs (a)(1) and (a)(2). Some of these commenters 
state that this change would coincide with the thresholds recommended 
in that alert service bulletin. One of these commenters notes that this 
change would move three of the airplanes in its fleet from the 
applicability provisions of paragraph (a)(2) (which would allow it 32 
months) to paragraph (a)(1) (which would allow it the maximum amount of 
time of 56 months) to accomplish the modification of the nacelle strut 
and wing structure. -
    The FAA concurs. As discussed above, the FAA's intent was to align 
the compliance times as closely as possible with those recommended by 
the manufacturer in the referenced alert service bulletin. Therefore, 
paragraphs (a)(1) and (a)(2) of the final rule have been revised to 
specify that the age of the airplane is to be measured as of November 
3, 1994, which is the date of issuance of the alert service bulletin. 
[[Page 27010]] 

Service Bulletins Listed in Note 2 -

    Several commenters request that Note 2, which follows proposed 
paragraph (a)(2)(i), be revised either to exclude or to add service 
bulletins to the list of bulletins that describe modifications that 
must be accomplished in order to gain the maximum time allowable (56 
months) in which to accomplish the modification of the nacelle strut 
and wing structure. One of these commenters requests that the list be 
revised to exclude all Boeing service bulletins, with the exception of 
the following two: -
    1. Boeing Alert Service Bulletin 747-54A2155, dated September 23, 
1993, which specifies inspection of the midspar fittings; and -
    2. Boeing Alert Service Bulletin 747-54A2152, Revision 2, dated 
September 16, 1993, which specifies installation of (third generation 
fuse pins) upper link diagonal brace and midspar fuse pins [required by 
AD 93-17-07, amendment 39-8678 (58 FR 45827, August 31, 1993)]. -
    This commenter states that, if the other service bulletins are 
excluded from the list, safety would not be compromised since various 
repetitive inspections already are required by numerous other AD's that 
are intended to ensure the structural integrity of the strut-to-wing 
attachments and the fail-safe capability of the strut structure. -
    The FAA does not concur. As stated in the preamble to the proposal, 
one of the purposes of this rulemaking action is to reduce reliance on 
inspections of the strut-to-wing attachments. The FAA has determined 
that long term continued operational safety will be better assured by 
actual modification of the airframe to remove the source of the 
problem, rather than by repetitive inspections. Long term inspections 
may not be providing the degree of safety assurance necessary for the 
transport airplane fleet. This, coupled with a better understanding of 
the human factors associated with numerous repetitive inspections, has 
led the FAA to consider placing less emphasis on special procedures and 
more emphasis on design improvements. The modification requirement of 
this final rule is in consonance with these considerations.

Modification of Engine Mounts -

    Two commenters request that the list of service bulletins be 
revised to exclude Boeing Alert Service Bulletin 747-71A2269, Revision 
1, dated July 7, 1994, which describes procedures for modification of 
the engine mounts. These commenters state that modification of the 
engine mounts is an entirely separate subject that is not related to 
the unsafe condition addressed by the proposed rule. One of these 
commenters believes that modification of the engine mounts is addressed 
more appropriately in AD 94-10-05. -
    The FAA does not concur. The FAA finds that the unsafe conditions 
addressed in both AD 94-10-05 [amendment 39-8912 (59 FR 25288, May 16, 
1994)] and this AD are closely related. AD 94-10-05 requires 
replacement of the existing nut with a new castellated nut, and 
references Boeing Alert Service Bulletin 747-71A2269 as the appropriate 
source of service information. That AD addresses migration of the bolts 
out of the engine lug joint, which may lead to loss of the engine from 
the strut. Therefore, the FAA has determined that accomplishing the 
requirements of AD 94-10-05, prior to accomplishing the requirements of 
this final rule, reduces reliance on repetitive inspections, and 
decreases the likelihood of the engine separating from the airplane.

Replacement of Diagonal Braces -

    Certain commenters request that the list of service bulletins be 
revised to exclude Boeing Service Bulletin 747-54-2123, which describes 
procedures for replacement of the diagonal braces. One of these 
commenters notes that it has found no significant discrepancies on any 
of the airplanes in its fleet while performing the inspections of this 
area that are required by AD 90-20-20. Therefore, this commenter 
contends that replacement of the diagonal braces prior to 
accomplishment of the proposed modification of nacelle strut and wing 
structure is unnecessary if the brace lugs have been modified in 
accordance with Boeing Service Bulletin 747-54-2126 and the diagonal 
braces have been inspected in accordance with Boeing Service Bulletin 
747-54-2123. -
    Further, these commenters contend that temporarily replacing the 
diagonal braces is cost-prohibitive: one of these commenters estimates 
the cost at $50,000 per airplane, while the other commenter estimates 
the cost at $60,000 per airplane. These commenters also point out that 
these costs are unreasonable, especially in light of the fact that the 
diagonal braces must be replaced once more as part of the proposed 
modification of the nacelle strut and wing structure. -
    Additionally, one of these commenters suggests that there is 
potential for a parts availability problem if all operators choose to 
replace these diagonal braces. Consequently, these commenters request 
the removal of Boeing Service Bulletin 747-54-2123 from the list of 
service bulletins.
    The FAA does not concur. In addressing these particular comments, 
the FAA points out that there are three types of diagonal braces 
currently available:
    1. ``Type 1 Braces'' have been addressed previously by two AD's:

--AD 89-07-15, amendment 39-6167 (54 FR 11693, March 22, 1989), 
references Boeing Service Bulletin 747-54-2126. That AD requires the 
lugs of Type 1 Braces to ultrasonically inspected every 1,000 flight 
cycles. That AD was prompted by reports of cracking in the lugs that 
had initiated at corrosion pits in the lug bores and was propagated by 
fatigue. Terminating action for those inspections consists of removing 
bushings, oversizing of the hole to eliminate corrosion, and installing 
high interference fit bushings. There have been reports of 11 cracked 
braces found during the inspections required by this AD.
--AD 90-20-20, amendment 39-6725 (55 FR 37859, September 14, 1990), 
references Boeing Service Bulletin 747-54-2123. That AD requires Type 1 
Braces to be either visually inspected every 1,000 flight cycles, or 
ultrasonically inspected every 3,000 flight cycles; any cracked brace 
is required to be replaced with either a serviceable Type 1 Brace or a 
``Type 2 Brace'' (see below). That AD was prompted by the finding of a 
completely separated brace in service. Separation was attributed to 
circumferential cracks initiating from a tool mark in the brace's inner 
surface. (There also has been one additional report of a crack found, 
but separation did not occur.) Terminating action for these inspections 
consists of replacing Type 1 Braces with ``Type 2 Braces.''

    2. ``Type 2 Braces'' are not susceptible to the cracking conditions 
of the brace's inner surface (as was found on the Type 1 Braces) 
because of their revised internal and external surface finish. 
Additionally, during production, the lugs associated with these Type 2 
Braces were modified in accordance with the terminating action 
specified in AD 89-07-15; with this modification, the ultrasonic 
inspections required by that AD are not necessary on this type of 
brace.
    3. ``Type 3 Braces'' are those that are required to be installed as 
part of the full strut modification program on which this AD is based. 
These braces are optimal because they have increased 
[[Page 27011]] strength and are not susceptible to the type of cracking 
found in Type 1 Braces.
    The FAA points out that this final rule provides operators 32 
months in which to accomplish the full strut modification if Type 1 
Braces are currently installed. Likewise, this final rule provides 
operators 56 months in which to accomplish the full strut modification 
if Type 2 Braces are currently installed, or if Type 2 Braces are 
installed within 32 months (and the additional modifications specified 
in the service bulletins listed in Note 2 are accomplished, as well).
    Optimally, the FAA would prefer that all affected airplanes be 
modified within 32 months. However, when developing the compliance time 
for this AD, the FAA recognized the high costs (down time) that would 
be imposed on operators when accomplishing the full strut modification 
program. In so doing, the FAA looked for ways to lessen that economic 
burden, while still ensuring that a higher level of safety would exist 
than that currently provided. Based on analyses following relevant 
accidents involving failure of the strut-to-wing attachment and 
subsequent separation of the engine from the airplane during flight, 
the FAA determined that the Type 1 Brace, with its extensive history of 
service difficulties, is not adequate for long term assurance of 
safety. Even with repetitive inspections, these Type 1 Braces have 
inadequate damage tolerance. In light of this and the catastrophic 
consequences of fatigue cracking and/or corrosion in the strut-to-wing 
attachments, the FAA has determined that Type 1 Braces must be removed 
from the fleet sooner than the other braces that have a better service 
record.
    As for the costs of replacement of the braces, the FAA finds that 
the figures quoted by the commenters need clarification. The 
manufacturer has provided the following figures relative to costs:

--Installation of Type 2 Braces requires from 88 to 116 work hours per 
airplane, at an average labor rate of $60 per work hour. The cost of 
each brace is, at most, $13,282 (in 1990 dollars) per brace; there are 
4 braces on each airplane. Using these figures, the cost to install 
four Type 2 Braces on an airplane would be, at most, $53,128 in parts 
and $6,960 in labor charges.
--Parts and labor costs for the installation of Type 3 Braces, as part 
of the full strut modification kit, will be absorbed by the 
manufacturer.

    Regardless of these costs, the FAA has determined that the safety 
benefit justifiably outweighs the economic cost of replacing diagonal 
braces. Further, the replacement of the Type 1 Brace with a Type 2 
Brace is required only if the operator wants the longer compliance time 
of 56 months for accomplishing the full strut modification. This 
extended compliance time lessens the economic impact on operators in 
terms of the costs of special scheduling and down time. The FAA notes 
that certain operators have already accomplished the full strut 
modification; these operators have found it to be more cost effective 
to do so, since they incur no charges for parts. A full discussion of 
the cost impact of this rule on U.S. operators is discussed later in 
this preamble.
    As for the availability of parts, the manufacturer has advised that 
there would be a problem with parts availability only if many of the 
affected operators elected to install the Type 2 Braces as an interim 
measure. However, as a matter of fact, both the manufacturer and the 
FAA expect that many operators will not elect to do this, but will opt 
to install the full strut modification, which includes the Type 3 
Brace. The manufacturer has indicated that there are ample numbers of 
the full strut modification kits available.

Rework of Midspar Fitting Lugs

    One commenter requests that the list of service bulletins be 
revised to add Boeing Service Bulletin 747-54-2100 as an alternative to 
Boeing Alert Service Bulletin 747-54A2152 (original or Revision 1). The 
commenter believes that procedures for rework of the midspar fitting 
lugs, which is described Service Bulletin 747-54-2100, is equivalent to 
that specified in Service Bulletin 747-54A2152.
    The FAA does not concur, since it does not find that the two 
procedures described in the referenced service bulletins are 
equivalent. For example, the rework procedure described in Boeing 
Service Bulletin 747-54-2100 does not include an ``insurance'' cut that 
is included in the rework procedure described in Boeing Alert Service 
Bulletin 747-54A2152 (original issue and Revision 1). Further, Revision 
2 of Boeing Alert Service Bulletin 747-54A2152 has refined the 
procedure even further: this revision [which is referenced in 
paragraphs (a)(2)(iii) and (a)(2)(iv) of the final rule] describes a 
magnetic particle inspection to detect cracking of the midspar fitting 
lugs. Consequently, the FAA finds the procedures described in Revision 
2 of Boeing Alert Service Bulletin 747-54A2152 to be significantly 
better in detecting and removing undetected cracks than those described 
in the earlier versions of that alert service bulletin or in Boeing 
Service Bulletin 747-54-2100.

Clarification of Requirements for Modified Airplanes

    One commenter requests that the requirements of proposed paragraph 
(a)(2)(i) be clarified. The commenter notes that Boeing Service 
Bulletin 747-54-2062, Revision 5, which is referenced in the list of 
modifications under Note 2 of the proposal, must be accomplished to 
obtain the maximum amount of time allowable (56 months) in which to 
accomplish the proposed modification of the nacelle strut and wing 
structure. (These modifications are described in the service bulletins 
listed in paragraph I.D., ``Compliance,'' on page 17 of Boeing Alert 
Service Bulletin 747-54A2159, dated November 3, 1994.) However, the 
commenter notes that Revision 7 of that service bulletin, which is 
referenced in the list of terminating actions for the proposed rule, 
must be accomplished prior to or concurrently with the proposed 
modification of the nacelle strut and wing structure. (These 
terminating actions are described in the service bulletins listed in 
paragraph I.C., Table 2, ``Prior or Concurrent Service Bulletins,'' on 
page 13 of Boeing Alert Service Bulletin 747-54A2159, dated November 3, 
1994.)
    The FAA concurs that clarification is warranted. Although Note 2 
following paragraph (a)(2)(i) clearly states that subsequent revisions 
of the service bulletins ``are acceptable and preferred for 
accomplishment of the modifications,'' a footnote has been added to the 
final rule following that list to point out specifically that 
additional actions described in a subsequent revision of that service 
bulletin are required to be accomplished prior to or concurrently with 
the modification of the nacelle strut and wing structure, required by 
paragraph (a) of the final rule.

Shortening the Compliance Times of Other Related AD's
    One commenter considers it inappropriate to use the proposed rule 
to shorten the 4,000-landing compliance time of AD 87-04-13 R1, 
amendment 39-5546 (52 FR 3421, February 4, 1987). That AD requires 
repetitive ultrasonic inspections of the fastener holes of the midspar 
fittings. The commenter states that, if the 1,000-landing compliance 
time specified in proposed paragraphs (a)(2)(ii)(B) and (a)(2)(iv)(B) 
is appropriate to accomplish the requirements of the proposal, then it 
[[Page 27012]] should also be appropriate for accomplishing the 
inspection requirements of AD 87-04-13 R1.
    -Similarly, the commenter states that it is equally inappropriate 
to use the proposal to shorten the 5,000-landing compliance time of AD 
93-17-07. That AD requires repetitive ultrasonic inspections of the 
inboard midspar fitting lugs and references Boeing Alert Service 
Bulletin 747-54A2152 (original issue or Revision 1) as the appropriate 
source of service information. The commenter states that if the 2,500-
landing compliance time specified in proposed paragraphs (a)(2)(iii)(B) 
and (a)(2)(iv)(C) is appropriate to accomplish the requirements of the 
proposal, then it should also be appropriate for accomplishing the 
requirements of AD 93-17-07. The commenter believes that the 
appropriate means to effect a change to the compliance times of AD 87-
04-13 R1 and AD 93-17-07 should be by revising those AD's.
    -The FAA concurs with the commenter's observations.
    -As for AD 87-04-13 R1, the FAA will consider re-examining its 
compliance time to determine if a revision to it is appropriate. 
However, any revision to that AD would be proposed as a separate 
rulemaking action. Further, in re-examining the compliance times of 
proposed paragraphs (a)(2)(ii)(B), (a)(2)(iii)(B), (a)(2)(iv)(B), and 
(a)(2)(iv)(C), the FAA finds that operators may not be afforded the 
opportunity to obtain the maximum amount of time allowable to 
accomplish the modification of the nacelle strut and wing structure if 
the ``shortened'' compliance times of AD 87-04-13 R1 (from 4,000 
landings to 1,000 landings) and AD 93-17-07 (from 5,000 landings or 5 
years to 2,500 landings or 3 years) have already been exceeded. 
Therefore, the FAA has revised those paragraphs of the final rule to 
include a ``grace period.''
    -As for AD 93-17-07, Note 4 of this final rule explains that the 
compliance time of 2,500 landings or 3 years since rework of the lugs, 
whichever occurs earlier, coincides with the compliance time 
recommended in Revision 2 of Boeing Alert Service Bulletin 747-54A2152, 
dated September 15, 1993, which the FAA has approved as an alternative 
method of compliance for accomplishment of the requirements of AD 93-
17-07. However, the FAA will consider re-examining the compliance time 
of AD 93-17-07 to determine if further rulemaking is warranted. In the 
interim, the compliance time of paragraphs (a)(2)(iii)(B) and 
(a)(2)(iv)(C) of this final rule will remain unchanged. Any revision to 
the compliance time of AD 93-17-07, if deemed necessary, must be 
proposed in a separate rulemaking action.

Inspection Interval for the Inboard Midspar Fitting Lugs

    One commenter requests that proposed paragraph (a)(2)(iii)(B) be 
revised to require the reduced 2,500-cycle compliance time only for the 
ultrasonic inspection of the inboard midspar fitting lugs. This change 
would make this requirement consistent with that of AD 93-17-07, 
amendment 39-8678 (58 FR 45827, August 31, 1993). This commenter also 
notes that outboard struts do not have spring beams.
    -The FAA concurs. Further, the FAA finds that this change is also 
applicable to paragraph (a)(2)(iv)(C) of the final rule. Therefore, 
paragraphs (a)(2)(iii)(B) and (a)(2)(iv)(C) of the final rule have been 
revised accordingly.

Correction of Typographical Error in Note 6

    Three commenters request that a typographical error that appeared 
in Note 6 [which follows proposed paragraph (a)(2)(v)] be corrected. 
The commenters note that the Table in Note 6 erroneously referred to 
Boeing Alert Service Bulletin 747-54A2159. The correct reference should 
have been Boeing Alert Service Bulletin 747-54A2152, as it correctly 
appeared in paragraphs (a)(2)(iii) and (a)(2)(iv) of the proposal. The 
FAA concurs and has made the correction accordingly. Additionally, the 
FAA has reformatted the Table in Note 6 for purposes of clarification: 
the column headed ``Revision Level'' has been removed, and the revision 
level of the service bulletin has been inserted adjacent to the service 
bulletin number itself.

Requirements Redundant to Part 121

    -One commenter requests that proposed paragraph (b) be deleted 
since the proposed inspection and repair of components (referenced in 
Notes 8, 9, and 10 of the Accomplishment Instructions on page 150 of 
Boeing Alert Service Bulletin 747-54A2159, dated November 3, 1994) are 
redundant to the requirements of part 121 of the Federal Aviation 
Regulations (14 CFR 121). Furthermore, the commenter believes that the 
proposed torque check of the fasteners of the diagonal brace fittings 
(referenced in Note 11 of the alert service bulletin) should be 
incorporated as part of the Accomplishment Instructions of the Boeing 
Alert Service Bulletin 747-54A2159, rather than as merely a Note in the 
Accomplishment Instructions.
    The FAA does not concur with the commenter that the requirements of 
paragraph (b) should be deleted from the final rule. According to 
section 39.1 of the Federal Aviation Regulations (14 CFR 39.1), the 
issuance of an AD is based on the finding that an unsafe condition 
exists or is likely to develop in aircraft of a particular type design. 
Further, it is within the FAA's authority to issue an AD to require 
actions to address unsafe conditions that are not otherwise being 
addressed (or addressed adequately) by normal maintenance procedures. 
The FAA points out that fatigue cracking and corrosion in the strut-to-
wing attachments have resulted in several incidents and catastrophic 
accidents. Although 14 CFR 121 addresses damage found on components 
during other maintenance activities, the FAA has determined that the 
catastrophic consequences of the unsafe condition are such that 
reiterating the necessity of performing inspections and repairs when 
any damage or corrosion is found while performing the modification of 
the nacelle strut and wing structure is warranted and necessary. The AD 
is the appropriate vehicle for mandating such actions.

AD's Terminated by This Final Rule

    One commenter notes that the AD's listed in proposed paragraph (c) 
as those that are terminated once the actions of the proposal are 
accomplished, differs from those listed in Table 1 of Boeing Alert 
Service Bulletin 747-54A2159.
    The FAA concurs that a difference does exist. However, several of 
the AD's included in the listing contained in the Boeing alert service 
bulletin have been superseded by new AD's. The FAA points out that, 
when an AD is superseded, it is deleted from the system, and as such, 
no longer exists, since it has been replaced with a ``new'' AD that has 
a new (different) AD number and amendment number. The FAA considers 
that referencing nonexistent AD's would serve no meaningful purpose, 
and may result in some confusion for affected operators. Consequently, 
no change to paragraph (c) of the final rule is necessary.

Clarification of Cost Estimate Information

    Two commenters request that the cost estimate be revised to include 
the cost of out-of-service time for each aircraft during the time that 
the modification is accomplished, and the additional fuel costs that 
would be incurred due to the additional weight added to each aircraft 
by the modification hardware.
    The FAA does not concur that a revision is necessary. The 
appropriate [[Page 27013]] number of hours required to accomplish the 
required actions, specified as between 7,700 and 8,892 work hours in 
the economic impact information, below, was developed with data 
provided by the manufacturer. This number represents the time required 
to gain access, remove parts, inspect, modify, install, and close up. 
The cost analysis in AD rulemaking actions typically does not include 
out-of-service time for each aircraft or additional fuel costs, as was 
suggested by the commenter. These costs would be impossible to 
calculate accurately due the differences in out-of-service time for 
each operator. Furthermore, the increase in fuel costs due to the 
weight added by the modification, would vary greatly from operator to 
operator, depending upon airplane utilization.
    The Air Transport Association of America (ATA) requests that the 
FAA include costs ``beyond just parts and labor costs'' when 
calculating the estimated costs to accomplish the proposed actions. The 
ATA points out that the FAA should consider such costs to avoid 
requiring actions that the ATA considers inconsequential.
    The FAA does not concur. Contrary to the ATA's assertion, in 
establishing the requirements of all AD's, the FAA does consider cost 
impact to operators beyond the estimates of parts and labor costs 
contained in AD preambles. For example, where safety considerations 
allow, the FAA attempts to impose compliance times that generally 
coincide with operators' maintenance schedules. However, because 
operators' schedules vary substantially, the FAA is unable to 
accommodate every operator's optimal scheduling in each AD. Each AD 
does allow individual operators to obtain approval for extensions of 
compliance times, based on a showing that the extension will not affect 
safety adversely. Therefore, the FAA does not consider it appropriate 
to attribute to the AD, the costs associated with the type of special 
scheduling that might otherwise be required.
    Furthermore, because the FAA generally attempts to impose 
compliance times that coincide with operators' scheduled maintenance, 
the FAA considers it inappropriate to attribute the costs associated 
with aircraft ``downtime'' to the cost of the AD, because, normally, 
compliance with the AD will not necessitate any additional downtime 
beyond that of a regularly scheduled maintenance hold. Even if, in some 
cases, additional downtime is necessary for some airplanes, the FAA 
does not possess sufficient information to evaluate the number of 
airplanes that may be so affected or the amount of additional downtime 
that may be required. Therefore, attempting to estimate such costs 
would be futile.
    The FAA points out that this AD is an excellent example of the fact 
that costs to operators are fully considered beginning at the earliest 
possible stages of AD development. In this case, the service bulletin 
that is referenced in this final rule was developed by Boeing only 
after extensive and detailed consultations with large numbers of 
operators of Model 747's. The compliance times and various optional 
means of compliance presented in this AD are based on those 
consultations, and were developed in order to minimize the economic 
impacts on operators to the extent possible consistent with the service 
bulletin's and this AD's safety objectives. Therefore, the costs that 
the ATA asserts were not considered by the FAA have, in fact, been a 
major consideration throughout this AD process; the fact that the FAA 
has not attempted to quantify speculative costs does not diminish the 
extent of this consideration.

Conclusion

    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.

Cost Impact

    There are approximately 600 Model 747 series airplanes equipped 
with Pratt & Whitney Model JT9D series engines (excluding Model JT9D-70 
engines) of the affected design in the worldwide fleet. The FAA 
estimates that 146 airplanes of U.S. registry will be affected by this 
AD.
    The full strut modification required by this AD may take as many as 
7,700 to 8,892 work hours to accomplish, depending upon the 
configuration of the airplane. The manufacturer will incur the cost of 
labor, on a pro-rated basis, with 20 years being the expected life of 
these airplanes. The total cost impact of this AD on U.S. operators is 
based on the median age for the fleet of Model 747 series airplanes 
equipped with Pratt & Whitney Model JT9D series engines, which is 
estimated to be 15 years. The average labor rate is estimated to be $60 
per work hour. Required parts will be supplied by the manufacturer at 
no cost to the operator. Based on these figures, the cost impact of 
this proposal on U.S. operators is estimated to be between $50,589,000 
($346,500 per airplane) and $58,420,440 ($400,140 per airplane).
    This cost impact figure does not reflect the cost of the 
terminating actions described in the service bulletins listed in 
paragraph I.C., Table 2, ``Prior or Concurrent Service Bulletins,'' on 
page 13 of Boeing Alert Service Bulletin 747-54A2159, dated November 3, 
1994, that are required to be accomplished prior to or concurrently 
with the modification of the nacelle strut and wing structure. Since 
some operators may have accomplished certain modifications on some or 
all of the airplanes in its fleet, while other operators may not have 
accomplished any of the modifications on any of the airplanes in its 
fleet, the FAA is unable to provide a reasonable estimate of the cost 
of accomplishing the terminating actions described in the service 
bulletins listed in Table 2 of the Boeing alert service bulletin.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the proposed requirements of 
this AD action, and that no operator would accomplish those actions in 
the future if this AD were not adopted. However, the FAA is aware that 
some operators have already installed the strut modification that is 
required by this AD; therefore, the future economic cost impact of this 
rule on U.S. operators is reduced by that amount.
    The FAA recognizes that the obligation to maintain aircraft in an 
airworthy condition is vital, but sometimes expensive. Because AD's 
require specific actions to address specific unsafe conditions, they 
appear to impose costs that would not otherwise be borne by operators. 
However, because of the general obligation of operators to maintain 
aircraft in an airworthy condition, this appearance is deceptive. 
Attributing those costs solely to the issuance of this AD is 
unrealistic because, in the interest of maintaining safe aircraft, 
prudent operators would accomplish the required actions even if they 
were not required to do so by the AD.
    A full cost-benefit analysis has not been accomplished for this AD. 
As a matter of law, in order to be airworthy, an aircraft must conform 
to its type design and be in a condition for safe operation. The type 
design is approved only after the FAA makes a determination that it 
complies with all applicable airworthiness requirements. In adopting 
and maintaining those requirements, the FAA has already made the 
determination that they establish a level of safety that is cost- 
[[Page 27014]] beneficial. When the FAA, as in this proposed AD, makes 
a finding of an unsafe condition, this means that the original cost-
beneficial level of safety is no longer being achieved and that the 
required actions are necessary to restore that level of safety. Because 
this level of safety has already been determined to be cost-beneficial, 
a full cost-benefit analysis for this AD would be redundant and 
unnecessary.

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 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 adding the following new 
airworthiness directive:

95-10-16  Boeing: Amendment 39-9233. Docket 94-NM-187-AD.

    Applicability: Model 747 series airplanes having line positions 
001 through 814 inclusive, equipped with Pratt & Whitney Model JT9D 
series engines (excluding Model JT9D-70 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 use the authority 
provided in paragraph (d) 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 failure of the strut and subsequent loss of the 
engine, accomplish the following:
    (a) Accomplish the modification of the nacelle strut and wing 
structure in accordance with Boeing Alert Service Bulletin 747-
54A2159, dated November 3, 1994, at the time specified in either 
paragraph (a)(1) or (a)(2) of this AD, as applicable. All of the 
terminating actions described in the service bulletins listed in 
paragraph I.C., Table 2, ``Prior or Concurrent Service Bulletins,'' 
on page 13 of Boeing Alert Service Bulletin 747-54A2159, dated 
November 3, 1994, must be accomplished in accordance with those 
service bulletins prior to or concurrently with the accomplishment 
of the modification of the nacelle strut and wing structure required 
by this paragraph.
    (1) For airplanes that are younger than 15 years as of November 
3, 1994, within 56 months after the effective date of this AD, 
accomplish the modification.
    (2) For airplanes that are 15 years or older as of November 3, 
1994, accomplish the modification, and other required actions, at 
the time specified in paragraph (a)(2)(i), (a)(2)(ii), (a)(2)(iii), 
(a)(2)(iv), or (a)(2)(v) of this AD, as applicable.
    (i) For airplanes on which all of the modifications described in 
the service bulletins referenced by paragraph I.D., ``Compliance,'' 
on page 17 of Boeing Alert Service Bulletin 747-54A2159, dated 
November 3, 1994, have been accomplished: Within 56 months after the 
effective date of this AD, accomplish the modification of the 
nacelle strut and wing structure and perform the inspections of the 
adjacent structure that has not been replaced by the modification.

    Note 2: Paragraph I.D., ``Compliance,'' on page 17 of Boeing 
Alert Service Bulletin 747-54A2159, dated November 3, 1994, 
references the following Boeing service bulletins. Subsequent 
revisions of the following service bulletins are acceptable and 
preferred for accomplishment of the modifications described therein:

------------------------------------------------------------------------
Service bulletin   Revision                                             
       No.           level                       Date                   
------------------------------------------------------------------------
747-54-2027.....  1.........  February 23, 1973.                        
747-54-2030.....  Initial     February 23, 1973.                        
                   release.                                             
*747-54-2062....  5.........  June 1, 1984.                             
747-54A2069.....  6.........  October 22, 1982.                         
747-54-2118.....  Initial     July 25, 1986.                            
                   release.                                             
747-54-2123.....  1.........  March 1, 1990.                            
747-54A2151.....  Initial     October 6, 1992.                          
                   release.                                             
747-54A2152.....  2.........  September 16, 1993.                       
747-54A2155.....  Initial     September 23, 1993.                       
                   release.                                             
747-57A2235.....  Initial     June 27, 1986.                            
                   release.                                             
747-71A2269.....  1.........  July 7, 1994.                             
------------------------------------------------------------------------
*AD 79-17-07, amendment 39-3533, requires inspection of the strut-to-   
  diagonal brace fittings, which may be terminated by replacing the     
  aluminum fittings with steel fittings in accordance with Revision 1   
  (or subsequent revisions) of Boeing Service Bulletin 747-54-2062.     
  Revision 7 of this service bulletin (referenced in paragraph I.C.,    
  Table 2, ``Prior or Concurrent Service Bulletins,'' on page 13 of     
  Boeing Alert Service Bulletin 747-54A2159, dated November 3, 1994)    
  specifies the replacement of aluminum fittings with steel fittings and
  sealing the gap between the steel fitting and the closure web.        

    (ii) For airplanes on which all of the modifications described 
in the service bulletins referenced by paragraph I.D., 
``Compliance,'' on page 17 of Boeing Alert Service Bulletin 747-
54A2159, dated November 3, 1994, have been accomplished, excluding 
the modification described in Boeing Service Bulletin 747-54-2118, 
dated July 25, 1986:
    (A) Within 56 months after the effective date of this AD, 
accomplish the modification of the nacelle strut and wing structure 
and perform the inspections of the adjacent structure that has not 
been replaced by the modification.
    (B) Repeat the ultrasonic inspections to detect cracking of the 
aft-most two fastener holes in both strut midspar fittings on the 
inboard and outboard nacelle struts, as required by AD 87-04-13 R1, 
amendment 39-5546, within 4,000 landings following the immediately 
preceding inspection performed in accordance with AD 87-04-13 R1 or 
within 1,000 landings after the effective date of this AD, whichever 
occurs earlier, in accordance with Boeing Service Bulletin 747-54-
2118, dated July 25, 1986, until the modification of the nacelle 
strut and wing structure is accomplished in accordance with Boeing 
Alert Service Bulletin 747-54A2159, dated November 3, 1994. Repeat 
this [[Page 27015]] inspection thereafter at intervals not to exceed 
1,000 landings.

    Note 3: These inspections of the fastener holes are required by 
AD 87-04-13 R1, amendment 39-5546, at 4,000-landing intervals. 
Accomplishment of the inspections of the fastener holes, as required 
by this paragraph at 1,000-landing intervals, constitutes compliance 
with paragraph A. of AD 87-04-13 R1.

    (iii) For airplanes on which all of the modifications described 
in the service bulletins referenced by paragraph I.D., 
``Compliance,'' on page 17 of Boeing Alert Service Bulletin 747-
54A2159, dated November 3, 1994, have been accomplished; except that 
rework of the midspar fitting lugs was accomplished in accordance 
with Boeing Alert Service Bulletin 747-54A2152, dated December 23, 
1992, or Revision 1, dated July 15, 1993, instead of Revision 2, 
dated September 16, 1993:
    (A) Within 56 months after the effective date of this AD, 
accomplish the modification of the nacelle strut and wing structure 
and perform the inspections of the adjacent structure that has not 
been replaced by the modification.
    (B) Prior to the accumulation of 3 years since rework of the 
inboard lugs, or within 6 months after the effective date of this 
AD, whichever occurs later, perform an ultrasonic inspection to 
detect cracking of the midspar fitting lugs of the inboard struts, 
in accordance with Boeing Alert Service Bulletin 747-54A2152, 
Revision 2, dated September 16, 1993. Repeat this inspection 
thereafter as required by AD 93-17-07.

    Note 4: This ultrasonic inspection is required by AD 93-17-07, 
amendment 39-8678, to be performed prior to the accumulation of 
5,000 landings or 5 years since accomplishment of the rework of the 
lugs, whichever occurs earlier, in accordance with Boeing Alert 
Service Bulletin 747-54A2152, dated December 23, 1992, or Revision 
1, dated July 15, 1993. Repetitive inspections are required by that 
AD at intervals not to exceed 500 landings for inboard struts and 
1,000 landings for outboard struts. Since the issuance of that AD, 
the FAA has approved Revision 2 of Boeing Alert Service Bulletin 
747-54A2152, dated September 16, 1993, as an alternative method of 
compliance for accomplishment of these ultrasonic inspections and 
rework of the lugs. Revision 2 of the alert service bulletin 
recommends that inboard lugs that have been reworked in accordance 
with the original issue or Revision 1 of the alert service bulletin 
be inspected prior to the accumulation of 2,500 landings or 3 years 
since accomplishment of the rework of the lugs, whichever occurs 
earlier. Therefore, accomplishment of ultrasonic inspections prior 
to the accumulation of 2,500 landings or 3 years since 
accomplishment of rework of the lugs, whichever occurs earlier, and 
thereafter as required by AD 93-17-07, constitutes compliance with 
paragraph (e)(2)(i)(A) of AD 93-17-07 for the inboard lugs.

    (iv) For airplanes on which all of the modifications described 
in the service bulletins referenced by paragraph I.D., 
``Compliance,'' on page 17 of Boeing Alert Service Bulletin 747-
54A2152, dated November 3, 1994, have been accomplished; except that 
rework of the midspar fitting lugs was accomplished in accordance 
with the Boeing Alert Service Bulletin 747-54A2152, dated December 
23, 1992, or Revision 1, dated July 15, 1993, instead of Revision 2, 
dated September 16, 1993; and excluding the modification described 
in Boeing Service Bulletin 747-54-2118, dated July 25, 1986:
    (A) Within 56 months after the effective date of this AD, 
accomplish the modification of the nacelle strut and wing structure 
and perform the inspections of the adjacent structure that has not 
been replaced by the modification.
    (B) Repeat the ultrasonic inspections to detect cracking of the 
aft-most two fastener holes in both strut midspar fittings on the 
inboard and outboard nacelle struts, as required by AD 87-04-13 R1, 
within 4,000 landings following the immediately preceding inspection 
performed in accordance with AD 87-04-13 R1, or within 1,000 
landings after the effective date of this AD, whichever occurs 
earlier, in accordance with Boeing Service Bulletin 747-54-2118, 
dated July 25, 1986, until the modification of the nacelle strut and 
wing structure is accomplished in accordance with Boeing Alert 
Service Bulletin 747-54A2159, dated November 3, 1994. Repeat this 
inspection thereafter at intervals not to exceed 1,000 landings.
    (C) Prior to the accumulation of 3 years since rework of the 
inboard lugs, or within 6 months after the effective date of this 
AD, whichever occurs later, perform an ultrasonic inspection to 
detect cracking of the midspar fitting lugs of the inboard struts, 
and repeat the inspection thereafter as required by AD 93-17-07, 
until the modification of the nacelle strut and wing structure is 
accomplished in accordance with Boeing Alert Service Bulletin 747-
54A2159, dated November 3, 1994.

    Note 5: Notes 3 and 4 are also applicable to this paragraph.

    (v) For all other airplanes not subject to the requirements of 
paragraph (a)(2)(i), (a)(2)(ii), (a)(2)(iii), or (a)(2)(iv) of this 
AD: Within 32 months after the effective date of this AD, accomplish 
the modification of the nacelle strut and wing structure and perform 
the inspections of the adjacent structure that has not been replaced 
by the modification.

    Note 6: The following table graphically illustrates the 
applicability and compliance times for accomplishing the 
modification of the nacelle strut and wing structure as required by 
paragraph (a)(2) of this AD.

------------------------------------------------------------------------
                                                              Compliance
          Paragraph              Accomplishment of service       time   
                                         bulletins             (months) 
------------------------------------------------------------------------
(i)-.........................  All in paragraph I.D.-......           56
(ii).........................  All except 747-54-2118......           56
(iii)........................  All except 747-54A2152,                56
                                Revision 2-.                            
(iv).........................  All except 747-54-2118 and             56
                                747-54A2152, Revision 2.                
(v)-.........................  (*).........................          32 
------------------------------------------------------------------------
*Paragraph (a)(2)(v) of this AD is applicable to all airplanes, other   
  than those addressed in paragraphs (a)(2)(i), (a)(2)(ii), (a)(2)(iii),
  and (a)(2)(iv) of this AD. As such, these airplanes may have          
  accomplished some or none of the service bulletins listed in paragraph
  I.D. of Boeing Alert Service Bulletin 747-54A2159, dated November 3,  
  1994.                                                                 

    (b) Perform the inspections and checks specified in paragraph 
III, NOTES 8, 9, 10, and 11 of the Accomplishment Instructions on 
pages 149 and 150 of Boeing Alert Service Bulletin 747-54A2159, 
dated November 3, 1994, concurrently with the modification of the 
nacelle strut and wing structure required by paragraph (a) of this 
AD. Prior to further flight, correct any discrepancies found, in 
accordance with the alert service bulletin.

    (c) Accomplishment of the modification of the nacelle strut and 
wing structure in accordance with Boeing Alert Service Bulletin 747-
54A2159, dated November 3, 1994, constitutes terminating action for 
the inspections required by the following AD's:


----------------------------------------------------------------------------------------------------------------
                                                                  Federal Register                              
                    AD No.                       Amendment No.        citation            Date of publication   
----------------------------------------------------------------------------------------------------------------
94-17-17......................................         39-9012  59 FR 44903           August 31, 1994.          
94-10-05......................................         39-8912  59 FR 25288           May 16, 1994.             
93-17-07......................................         39-8678  58 FR 45827           August 31, 1993.          
93-03-14......................................         39-8518  58 FR 14513           March 18, 1993.           
92-24-51......................................         39-8439  57 FR 60118           December 18, 1992.        
92-07-11......................................         39-8207  57 FR 10415           March 26, 1992.           
90-20-20......................................         39-6725  55 FR 37859           September 14, 1990.       
90-17-18......................................         39-6702  55 FR 33279           August 15, 1990.          
89-07-15......................................         39-6167  54 FR 11693           March 22, 1989.           
87-04-13 R1...................................         39-5546  54 FR 3421            February 4, 1987.         
                                                                                                                
[[Page 27016]]
                                                                                                                
86-08-03......................................         39-5289  51 FR 12836           April 16, 1986.           
86-07-06......................................         39-5270  51 FR 10821           March 31, 1986.           
86-05-11......................................         39-5255  51 FR 8479            March 12, 1986.           
86-23-01......................................         39-5450  51 FR 37712           October 24, 1986.         
82-22-02......................................         39-4476  47 FR 46842           October 21, 1982.         
80-08-02......................................        39-3738-  45 FR 24450           April 10, 1980.           
79-17-07......................................        39-3533-  44 FR 50033           August 27, 1979.          
----------------------------------------------------------------------------------------------------------------

  (d) 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.

    Note 7: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (e) 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.
    (f) The modification, inspections, checks, and correction of 
discrepancies shall be done in accordance with Boeing Alert Service 
Bulletin 747-54A2159, 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.
    (g) This amendment becomes effective on June 21, 1995.
    Issued in Renton, Washington, on May 10, 1995.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-11968 Filed 5-19-95; 8:45 am]
BILLING CODE 4910-13-U