[Federal Register Volume 59, Number 234 (Wednesday, December 7, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-29919]
[[Page Unknown]]
[Federal Register: December 7, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 94-NM-207-AD; Amendment 39-9085; AD 94-25-01]
Airworthiness Directives; Boeing Model 747 Series Airplanes
Equipped with Pratt & Whitney Model JT9D-70 Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
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SUMMARY: This amendment adopts a new airworthiness directive (AD) that
is applicable to certain Model 747 series airplanes. This action
requires inspections to detect cracking of the surfaces of the outboard
strut spring beam, and replacement of cracked spring beams. It also
requires an inspection to detect damage to the structure that is
adjacent to the cracked spring beam, and replacement of any cracked
parts. This amendment is prompted by a report of failure of a spring
beam due to cracking that was propagated by fatigue. The actions
specified in this AD are intended to prevent failure of a spring beam,
which could lead to loss of an outboard strut.
DATES: Effective on December 22, 1994.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of December 22, 1994.
Comments for inclusion in the Rules Docket must be received on or
before February 6, 1995.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 94-NM-207-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056.
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 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.
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: Recently, the FAA received a report that the
spring beam on a Boeing Model 747-200 series airplane equipped with
Pratt & Whitney (P&W) Model JT9D-70 engines was severed (failed)
forward of the mid pivot bolt housing at the outboard spring beam on
the number 4 outboard strut. Investigation revealed that cracking
initiated at a flaw (porosity) in the material of the spring beam and
propagated due to fatigue. The subject airplane was operated as a
freighter and had accumulated 15,809 total flight cycles on the struts.
This airplane was originally delivered with P&W Model JT9D-3 engines
and struts, but was later reconfigured with P&W Model JT9D-70 engines
and struts.
Spring beams are used in place of midspar fittings on the outboard
struts of all Model 747 series airplanes, except those equipped with
P&W Model JT9D-3 and -7 engines. (The P&W Model JT9D-3 and -7 engines
have midspar fittings at the outboard strut.) Airplanes equipped with
P&W Model JT9D-70 engines have spring beams that are made of titanium.
All other spring beams are made of steel, which analyses and tests have
shown to be more resistant to fatigue cracking than titanium spring
beams.
Fatigue cracking, if not corrected, could result in failure of a
spring beam, which could lead to the loss of an outboard strut.
The FAA has reviewed and approved Boeing Alert Service Bulletin
747-54A2171, dated October 31, 1994, which describes procedures for
repetitive detailed visual inspections to detect cracking of the upper,
lower, and side surfaces of the spring beam, and replacement of cracked
spring beams with new spring beams.
Since an unsafe condition has been identified that is likely to
exist or develop on other airplanes of the same type design, this AD is
being issued to prevent failure of a spring beam due to fatigue
cracking, which could lead to the loss of an outboard strut. This AD
requires repetitive detailed visual inspections to detect cracking of
the surfaces of the spring beam from the root of the clevis lugs to the
forward journal, and replacement of cracked spring beams with new
spring beams. This AD also requires an additional detailed visual
inspection to detect damage of the adjacent spring beam and all support
fittings of the affected strut, and replacement of any cracked parts
with new parts. The actions are required to be accomplished in
accordance with the alert service bulletin described previously.
As an alternative to the repetitive detailed visual inspections,
this AD also provides for an optional terminating action, which entails
removing the spring beam, accomplishing a fluorescent dye penetrant
inspection, and accomplishing a zero-time overhaul of the spring beam,
in accordance with Section 54-00-01 of the Boeing Overhaul Manual, and
reinstalling that spring beam.
As a result of recent communications with the Air Transport
Association (ATA) of America, the FAA has learned that, in general,
some operators may misunderstand the legal effect of AD's on airplanes
that are identified in the applicability provision of the AD, but that
have been altered or repaired in the area addressed by the AD. The FAA
points out that all airplanes identified in the applicability provision
of an AD are legally subject to the AD. If an airplane has been altered
or repaired in the affected area in such a way as to affect compliance
with the AD, the owner or operator is required to obtain FAA approval
for an alternative method of compliance with the AD, in accordance with
the paragraph of each AD that provides for such approvals. A note has
been included in this rule to clarify this requirement.
Since a situation exists that requires the immediate adoption of
this regulation, it is found that notice and opportunity for prior
public comment hereon are impracticable, and that good cause exists for
making this amendment effective in less than 30 days.
Comments Invited
Although this action is in the form of a final rule that involves
requirements affecting flight safety and, thus, was not preceded by
notice and an opportunity for public comment, comments are invited on
this rule. Interested persons are invited to comment on this rule by
submitting such written data, views, or arguments as they may desire.
Communications shall identify the Rules Docket number and be submitted
in triplicate to the address specified under the caption ADDRESSES. All
communications received on or before the closing date for comments will
be considered, and this rule may be amended in light of the comments
received. Factual information that supports the commenter's ideas and
suggestions is extremely helpful in evaluating the effectiveness of the
AD action and determining whether additional rulemaking action would be
needed.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the rule that might
suggest a need to modify the rule. All comments submitted will be
available, both before and after the closing date for comments, in the
Rules Docket for examination by interested persons. A report that
summarizes each FAA-public contact concerned with the substance of this
AD will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this rule must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 94-NM-207-AD.'' The postcard will be date stamped and
returned to the commenter.
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.
The FAA has determined that this regulation is an emergency
regulation that must be issued immediately to correct an unsafe
condition in aircraft, and that it is not a ``significant regulatory
action'' under Executive Order 12866. It has been determined further
that this action involves an emergency regulation under DOT Regulatory
Policies and Procedures (44 FR 11034, February 26, 1979). If it is
determined that this emergency regulation otherwise would be
significant under DOT Regulatory Policies and Procedures, a final
regulatory evaluation will be prepared and placed in the Rules Docket.
A copy of it, if filed, 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.
39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
94-25-01 Boeing: Amendment 39-9085. Docket 94-NM-207-AD.
Applicability: Model 747 series airplanes having line numbers
202 through 396 inclusive, equipped with Pratt & Whitney 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 (c) 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 a spring beam, which could lead to the
loss of an outboard strut, accomplish the following:
(a) Prior to the accumulation of 10,000 total flight cycles or
within 30 days after the effective date of this AD, whichever occurs
later, perform a detailed visual inspection to detect cracking of
the upper, lower, and side surfaces of the spring beam from the root
of the clevis lugs to the forward journal, in accordance with Boeing
Alert Service Bulletin 747-54A2171, dated October 31, 1994. (Remove
the gap covers and fairing access panels to perform this
inspection.)
Note 2: The area of inspection is illustrated in Figure 3 of the
service bulletin.
(1) If no cracking is detected, repeat the inspection thereafter
at intervals not to exceed 300 flight cycles.
(2) If any cracking is detected, prior to further flight,
accomplish the requirements of paragraphs (a)(2)(i), (a)(2)(ii), and
(a)(2)(iii) of this AD, in accordance with the service bulletin.
(i) Replace the cracked spring beam with a new spring beam.
(ii) Perform the detailed visual inspection required by
paragraph (a) of this AD to detect cracking of the other spring beam
on the affected strut. Also perform a detailed visual inspection to
detect damage of all spring beam support fittings of the affected
strut. Prior to further flight, replace any cracked or damaged parts
with new parts.
(iii) Repeat the inspection of the surfaces of the spring beam
required by paragraph (a) of this AD thereafter at intervals not to
exceed 300 flight cycles.
(b) Accomplishment of all of the following actions in accordance
with Boeing Overhaul Manual, Section 54-00-01, constitutes
terminating action for the requirements of this AD.
(1) Remove the spring beam.
(2) Accomplish a fluorescent dye penetrant inspection.
(3) Zero-time overhaul the spring beam.
(4) Reinstall that spring beam.
(c) 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 3: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
(d) 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.
(e) The inspections and replacement shall be done in accordance
with Boeing Alert Service Bulletin 747-54A2171, dated October 31,
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.
(f) This amendment becomes effective on December 22, 1994.
Issued in Renton, Washington, on November 30, 1994.
James V. Devany, Acting Manager,
Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 94-29919 Filed 12-6-94; 8:45 am]
BILLING CODE 4910-13-U
