[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