[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