[Federal Register Volume 60, Number 124 (Wednesday, June 28, 1995)]
[Rules and Regulations]
[Pages 33333-33336]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-15298]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-NM-252-AD; Amendment 39-9285; AD 95-13-05]


Airworthiness Directives; Boeing Model 747 Series Airplanes 
Equipped with Rolls Royce Model RB211 Series 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 [[Page 33334]] 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 July 28, 1995.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of July 28, 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 February 7, 1995 (60 
FR 7140). 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.
    Two commenters support the proposed rule.

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 in the 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.
    This same commenter provides additional 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.
    This commenter also provides further clarification of the 
description of the requirements of the existing AD's that address 
unsafe conditions associated with the strut attachment assemblies on 
Model 747 series airplanes equipped with Rolls Royce Model RB211 series 
engines. The description in the Discussion section of the preamble to 
the proposal states that the existing AD's require ``sections of the 
strut, and strut-to-wing attachment structure.'' The commenter states 
that a more complete description of the existing AD's would be 
``inspections of the strut fuse pins, and strut-to-wing attachment 
structure.'' The FAA concurs that the commenter's wording is clearer. 
However, the following provides a more complete description: The 
existing AD's require ``inspections of the diagonal brace and midspar 
fuse pins, and strut-to-wing attachment structure.'' Since the 
Discussion section is not restated in this final rule, no change to the 
final rule is necessary.

AD's Terminated by this Final Rule

    Additionallly, this commenter requests a revision of proposed 
paragraph (c), which lists the AD's that will be terminated upon 
accomplishment of the proposed modification of the nacelle strut and 
wing structure. The commenter states that since AD 79-17-07, amendment 
39-3533, is not applicable to Model 747 series airplanes equipped with 
Rolls Royce Model RB211 series engines, that AD should be removed from 
the list. The FAA concurs; paragraph (c) of the final rule has been 
revised accordingly.
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 Estimate

    Currently, there are no Model 747 series airplanes of the affected 
design, equipped with Rolls Royce Model RB211 series engines, on the 
U.S. Register. However, should an affected airplane be imported and 
placed on the U.S. Register in the future, it will require 
approximately 6,545 work hours to accomplish the required actions, at 
an average labor charge of $60 per work hour. The manufacturer will 
incur the cost of labor, on a pro-rated basis, with 20 years being the 
expected life of these airplanes. The median age for the fleet of Model 
747 series airplanes equipped with Rolls Royce Model RB211 series 
engines is estimated to be 6 years. Required parts will be supplied by 
the manufacturer at no cost to operators. Based on these figures, the 
total cost impact of this AD will be $117,810 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 5 of Boeing Alert Service Bulletin 747-54A2157, dated January 12, 
1995, 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 requirements of this AD 
action, and that no operator would accomplish [[Page 33335]] those 
actions in the future if this AD were not adopted.
    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 these 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-
beneficial. When the FAA, as in this AD action, 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:

95-13-05  Boeing: Amendment 39-9285. Docket 94-NM-252-AD.

    Applicability: Model 747 series airplanes having line positions 
292 through 1033 inclusive, equipped with Rolls Royce Model RB211 
series engines; certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must use the authority 
provided in paragraph (d) of this AD 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-
54A2157, dated January 12, 1995, 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 5 of Boeing Alert Service Bulletin 747-54A2157, dated 
January 12, 1995, 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 Model 747-400 series airplanes having line positions 705 
through 1033 inclusive, equipped with Rolls Royce Model RB211-524G 
and H engines: Within 80 months after the effective date of this AD.
    (2) For all other Model 747 series airplanes equipped with Rolls 
Royce Model RB211 series engines not subject to the requirements of 
paragraph (a)(1) of this AD: Within 56 months after the effective 
date of this AD.
    (b) Perform the inspections and checks specified in paragraph 
III, NOTES 8, 9, and 13 of the Accomplishment Instructions on pages 
109 and 110 of Boeing Alert Service Bulletin 747-54A2157, dated 
January 12, 1995, 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-
54A2157, dated January 12, 1995, constitutes terminating action for 
the inspections required by the following AD's:

                                                                        
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                     Amendment    Federal Register                      
       AD No.           No.           citation       Date of publication
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93-17-07               39-8678  58 FR 45827          Aug. 31, 1993.     
93-03-14               39-8518  58 FR 14513          Mar. 18, 1993.     
92-24-51               39-8439  57 FR 60118          Dec. 18, 1992.     
90-20-20               39-6725  55 FR 37859          Sept. 14, 1990.    
89-07-15               39-6167  54 FR 11693          Mar. 22, 1989      
[[Page 33336]]
                                                                        
87-04-13 R1            39-5836  53 FR 2005           Jan. 26, 1988.     
86-05-11 R1            39-5334  51 FR 21900          June 17, 1986.     
86-23-01               39-5450  51 FR 37712          Oct. 26, 1986.     
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  (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 2: 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 747-54A2157, dated January 12, 1995. 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 August 28, 1995.

    Issued in Renton, Washington, on June 16, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-15298 Filed 6-27-95; 8:45 am]
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