[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]
BILLING CODE 4910-13-M
