[Federal Register Volume 59, Number 128 (Wednesday, July 6, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-15738]
[[Page Unknown]]
[Federal Register: July 6, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 94-NM-85-AD; Amendment 39-8956; AD 94-14-04]
Airworthiness Directives; Boeing Model 757 Series Airplanes
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 Boeing Model 757 series airplanes. This action
requires inspection to detect cracking of the lower spar chord of the
engine strut, removal of the stiffener straps from the mid-chord,
inspection of the fastener holes, and modification or repair. This
amendment is prompted by a report of cracking in the lower spar chord
of an engine strut. The actions specified in this AD are intended to
prevent cracking in the lower spar chord of the engine strut, which
could result in the inability of the strut to carry required engine
support loads.
DATES: Effective July 21, 1994.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of July 21, 1994.
Comments for inclusion in the Rules Docket must be received on or
before September 6, 1994.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 94-NM-85-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: Carrie Sumner, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056; telephone (206) 227-2778; fax (206) 227-1181.
SUPPLEMENTARY INFORMATION: Recently, the FAA received a report from an
operator that cracking was found in the lower spar chord of a strut on
a Boeing Model 757 series airplane equipped with a Rolls Royce Model
RB211-535 series engine. This cracking penetrated through the inboard
flange of the chord and propagated into the skin flange of the chord.
This fatigue crack in the skin flange was approximately five inches in
length.
Analysis indicates that stiffener straps, which were installed on
early production airplanes, increase the likelihood of cracking in the
spar chords. These stiffener straps are no longer installed on later
production airplanes.
Continued operation with the stiffener straps installed will cause
fatigue cracking or propagation of existing cracks in the lower chord.
Such cracking could result in the inability of the strut to carry
required engine support loads, and ultimately could lead to separation
of the engine from the strut.
The FAA has reviewed and approved Boeing Service Bulletin 757-54-
0028, dated March 31, 1994, that describes procedures for eddy current
inspection to detect cracking of the lower spar chord of the engine
strut, removal of the stiffener straps from the mid-chord, open hole
eddy current inspection of the fastener holes, and modification. This
modification, which includes installing fasteners, a strut pneumatic
duct, a fire extinguisher line, a bulkhead coverplate, and a panel,
will decrease the likelihood of fatigue cracking in the lower spar
chord of the engine strut.
Since an unsafe condition has been identified that is likely to
exist or develop on other Boeing Model 757 series airplanes of the same
type design, this AD is being issued to prevent cracking of the lower
spar chord of the engine strut. This AD requires eddy current
inspection to detect cracking of the lower spar chord of the engine
strut, removal of the stiffener straps from the mid-chord, open hole
eddy current inspection of the fastener holes, and modification. The
actions are required to be accomplished in accordance with the service
bulletin described previously. In certain cases, this AD requires
repair of cracking in accordance with an FAA-approved method.
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-85-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 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.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
94-14-04 Boeing: Amendment 39-8956. Docket 94-NM-85-AD.
Applicability: Model 757 series airplanes having airplane line
numbers 2, 4, 5, 9 through 13 inclusive, 21, 26, 114, and 115,
certificated in any category.
Compliance: Required as indicated, unless accomplished
previously.
To prevent cracking in the lower spar chord of the engine strut,
which could result in the inability of the strut to carry required
engine support loads, accomplish the following:
(a) Within 60 days after the effective date of this AD, perform
an eddy current inspection to detect cracking of the lower chord, in
accordance with Boeing Service Bulletin 757-54-0028, dated March 31,
1994.
(b) If no cracking is detected during the inspection required by
paragraph (a) of this AD, prior to the accumulation of 1,500
landings after accomplishment of the inspection, remove the
stiffener straps from the mid-chord of the inboard and outboard
sides of the strut, and perform an open hole eddy current inspection
to detect cracking of the fastener holes in the mid-chord, in
accordance with Boeing Service Bulletin 757-54-0028, dated March 31,
1994.
(1) If no cracking is detected in the mid-chord strut during the
inspection required by paragraph (b) of this AD, prior to further
flight, modify in accordance with the service bulletin.
(2) If cracking is detected in the mid-chord strut during the
inspection required by paragraph (b) of this AD, prior to further
flight, repair in accordance with a method approved by the Manager,
Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane
Directorate.
(c) If cracking is detected during the inspection required by
paragraph (a) of this AD, prior to further flight, remove the
stiffener straps from the mid-chord of the inboard and outboard
sides of the strut, and perform an open hole eddy current inspection
to detect cracking of the fastener holes in the mid-chord, in
accordance with Boeing Service Bulletin 757-54-0028, dated March 31,
1994.
(1) If no cracking is detected in the mid-chord strut during the
inspection required by paragraph (c) of this AD, prior to further
flight, modify in accordance with the service bulletin.
(2) If cracking is detected in the mid-chord strut during the
inspection required by paragraph (c) of this AD, prior to further
flight, repair in accordance with a method approved by the Manager,
Seattle ACO, FAA, Transport Airplane Directorate.
(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 ACO. 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: 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 inspections, strap removal, and modification shall be
done in accordance with Boeing Service Bulletin 757-54-0028, dated
March 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.
(g) This amendment becomes effective on July 21, 1994.
Issued in Renton, Washington, on June 23, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 94-15738 Filed 7-5-94; 8:45 am]
BILLING CODE 4910-13-U
