[Federal Register Volume 64, Number 158 (Tuesday, August 17, 1999)]
[Proposed Rules]
[Pages 44667-44670]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-21331]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 99-NE-07-AD]
RIN 2120-AA64
Airworthiness Directives; Allison Engine Company AE 3007A and AE
3007C Series Turbofan Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This proposal would require revisions to the Airworthiness
Limitations Section of the Allison Engine Company AE 3007A and AE 3007C
Engine Manuals to include required enhanced inspection of selected
critical life-limited parts at each piece-part exposure. This proposal
would also require an air carrier's approved continuous airworthiness
maintenance program to incorporate these inspection procedures. Air
carriers with an approved continuous airworthiness maintenance program
[[Page 44668]]
would be allowed to either maintain the records showing the current
status of the inspections using the record keeping system specified in
the air carrier's maintenance manual, or establish an acceptable
alternate method of record keeping. This proposal is prompted by an FAA
study of in-service events involving uncontained failures of critical
rotating engine parts that indicated the need for improved inspections.
The improved inspections are needed to identify those critical rotating
parts with conditions, which if allowed to continue in service, could
result in uncontained failures. The actions specified by this proposed
AD are intended to prevent critical life-limited rotating engine part
failure, which could result in an uncontained engine failure and damage
to the airplane.
DATES: Comments must be received by September 16, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Regional
Counsel, Attention: Rules Docket No. 99-NE-07-AD, 12 New England
Executive Park, Burlington, MA 01803-5299. Comments may also be sent
via the Internet using the following address: ``adcomment@faa.gov''. Comments sent via the Internet must contain the
docket number in the subject line. Comments may be inspected at this
location between 8:00 a.m. and 4:30 p.m., Monday through Friday, except
Federal holidays.
FOR FURTHER INFORMATION CONTACT: Chung-Der Young, Aerospace Engineer
Chicago Aircraft Certification Office, FAA, Small Airplane Directorate,
2300 East Devon Avenue, Des Plaines, IL 60018; telephone (847) 294-
7309, fax (847) 294-7834.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of the
proposed rule by submitting such written data, views, or arguments as
they may desire. Communications should identify the Rules Docket number
and be submitted in triplicate to the address specified above. All
communications received on or before the closing date for comments,
specified above, will be considered before taking action on the
proposed rule. The proposals contained in this notice may be changed in
light of the comments received.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with
the substance of this proposal will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this notice must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 99-NE-07-AD.'' The postcard will be date stamped and
returned to the commenter.
Availability of NPRMs
Any person may obtain a copy of this NPRM by submitting a request
to the FAA, New England Region, Office of the Regional Counsel,
Attention: Rules Docket No. 99-NE-07-AD, 12 New England Executive Park,
Burlington, MA 01803-5299.
Discussion
A recent FAA study analyzing 15 years of accident data for
transport category airplanes identified several failure mode root
causes that can result in serious safety hazards to transport category
airplanes. This study identified uncontained failure of critical life-
limited rotating engine parts as the leading engine-related safety
hazard to airplanes. Uncontained engine failures have resulted from
undetected cracks in rotating parts that initiated and propagated to
failure. Cracks can originate from causes such as unintended excessive
stress from the original design, or they may initiate from stresses
induced from material flaws, handling damage, or damage from machining
operations. The failure of rotating parts can present a significant
safety hazard to the airplanes by release of high energy fragments that
could injure passengers or crew by penetration of the cabin, damage
flight control surfaces, sever flammable fluid lines, or otherwise
compromise the airworthiness of the airplane.
Accordingly, the FAA has developed an intervention strategy to
significantly reduce uncontained engine failures. This intervention
strategy was developed after consultation with industry and will be
used as a model for future initiatives. This intervention strategy is
to conduct enhanced, nondestructive inspections of fan disks which
could most likely result in a safety hazard to the airplane in the
event of a disk fracture. The FAA is also considering the need for
additional rule making. Future ADs may be issued introducing additional
intervention strategies to further reduce or eliminate uncontained
engine failures.
Properly focused enhanced inspections require identification of the
parts whose failure presents the highest safety hazard to the airplane,
identifying the most critical features to inspect on these parts, and
utilizing inspection procedures and techniques that improve crack
detection. The FAA, with close cooperation of the engine manufacturers,
has completed a detailed analysis that identifies the most safety
significant parts and features, and the most appropriate inspection
methods.
Critical life-limited high-energy rotating parts are currently
subject to some form of recommended crack inspection when exposed
during engine maintenance or disassembly. As a result of this AD, the
inspections currently recommended by the manufacturer will become
mandatory for those parts listed in the compliance section.
Furthermore, the FAA intends that additional mandatory enhanced
inspections resulting from this AD serve as an adjunct to the existing
inspections. The FAA has determined that the enhanced inspections will
significantly improve the probability of crack detection while the
parts are disassembled during maintenance. All mandatory inspections
must be conducted in accordance with detailed inspection procedures
prescribed in the manufacturer's Engine Manuals.
Additionally, this AD allows for air carriers operating under the
provisions of 14 CFR part 121 with an FAA-approved continuous
airworthiness maintenance program, and entities with whom those air
carriers make arrangements to perform this maintenance, to verify
performance of the enhanced inspections by retaining the maintenance
records that include the inspections resulting from this AD, provided
that the records include the date and signature of the person
performing the maintenance action. These records must be retained with
the maintenance records of the part, engine module, or engine until the
task is repeated. This will establish a method of record preservation
and retrieval typical to those in existing continuous airworthiness
maintenance programs. Instructions must be included in an air carrier's
maintenance manual providing procedures on how this record preservation
and retrieval system will be implemented and integrated into the air
carrier's record keeping system.
This proposal would require, within the next 30 days after the
effective date of this AD, revisions to the
[[Page 44669]]
Airworthiness Limitations Section in the Allison Engine Company AE
3007A and AE 3007C Engine Manuals, and, for air carriers, the approved
continuous airworthiness maintenance program. Allison Engine Company,
the manufacturer of AE 3007A and AE 3007C series turbofan engines, used
on 14 CFR part 25 airplanes, has provided the FAA with a detailed
proposal that identifies and prioritizes the critical life-limited
rotating engine parts with the highest potential to hazard the airplane
in the event of failure, along with instructions for enhanced, focused
inspection methods. The enhanced inspections resulting from this AD
will be conducted at piece-part opportunity, as defined below in the
compliance section, rather than specific time inspection intervals.
The FAA estimates that 450 engines installed on airplanes of U.S.
registry would be affected by this proposed AD, that it would take
approximately 1 work hour per engine to accomplish the proposed
actions. The average labor rate is $60 per work hour. Based on these
figures, the total cost impact of the proposed AD on U.S. operators is
estimated to be $27,000.
The regulations proposed herein would 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
proposal would not have sufficient federalism implications to warrant
the preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this proposed
regulation (1) is not a ``significant regulatory action'' under
Executive Order 12866; (2) is not a ``significant rule'' under the DOT
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979);
and (3) if promulgated, 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 copy of the draft
regulatory evaluation prepared for this action is contained in the
Rules Docket. A copy of it may be obtained by contacting the Rules
Docket at the location provided under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
The Proposed Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration proposes to amend
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. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
Allison Engine Company: Docket 99-NE-07-AD.
Applicability: Allison Engine Company AE 3007A, A1/1, A1/2,
A1and AE 3007C series turbofan engines, installed on but not limited
to EMBRAER EMB-145 series and Cessna Citation X series airplanes.
Note 1: This airworthiness directive (AD) applies to each engine
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 engines that have been
modified, altered, or repaired so that the performance of the
requirements of this AD is affected, the owner/operator must request
approval for an alternative method of compliance in accordance with
paragraph (c) of this AD. The request should include an assessment
of the effect of the modification, alteration, or repair on the
unsafe condition addressed by this AD; and, if the unsafe condition
has not been eliminated, the request should include specific
proposed actions to address it.
Compliance: Required as indicated, unless accomplished
previously.
To prevent critical life-limited rotating engine part failure,
which could result in an uncontained engine failure and damage to
the airplane, accomplish the following:
(a) Within the next 30 days after the effective date of this AD,
revise the Airworthiness Limitations Section of the Allison Engine
Company AE 3007A and AE 3007C Engine Manuals, and for air carrier
operations revise the approved continuous airworthiness maintenance
program, by adding the following:
``Mandatory Inspections
(1) Perform inspections of the following parts at each piece-part
opportunity in accordance with the instructions provided in the
applicable manual provisions:
----------------------------------------------------------------------------------------------------------------
Part nomenclature Part No. (P/N) Inspect per engine manual chapter
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Wheel, Fan.......................... All................... 72-21-21 (Task 72-21-21-200-801)
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(2) For the purposes of these mandatory inspections, piece-part
opportunity means:
(i) The part is completely disassembled when done in accordance
with the disassembly instructions in the engine manufacturer's Heavy
Maintenance Manual; and
(ii) The part has accumulated more than 100 cycles in service
since the last piece-part opportunity inspection, provided that the
part was not damaged or related to the cause for its removal from
the engine.''
(b) Except as provided in paragraph (c) of this AD, and
notwithstanding contrary provisions in Sec. 43.16 of the Federal
Aviation Regulations (14 CFR 43.16), these mandatory inspections
shall be performed only in accordance with the Airworthiness
Limitations Section of the Allison Engine Company AE 3007A and AE
3007C Engine Manuals.
(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 Engine Certification Office. Operators shall
submit their requests through an appropriate FAA Principal
Maintenance Inspector (PMI), who may add comments and then send it
to the Engine Certification Office.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this airworthiness directive,
if any, may be obtained from the Engine Certification Office.
(d) Special flight permits may be issued in accordance with
Secs. 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) FAA-certificated air carriers that have an approved
continuous airworthiness maintenance program in accordance with the
record keeping requirement of Sec. 121.369(c) of the Federal
Aviation Regulations [14 CFR 121.369(c)] of this chapter must
maintain records of the mandatory inspections that result from
revising the Airworthiness Limitations Section and the air carrier's
continuous airworthiness program. Alternately, certificated air
carriers may establish an approved system of record retention that
provides a method for preservation and retrieval of the maintenance
records that include the inspections resulting
[[Page 44670]]
from this AD, and include the policy and procedures for implementing
this alternate method in the air carrier's maintenance manual
required by Sec. 121.369(c) of the Federal Aviation Regulations [14
CFR 121.369(c)]; however, the alternate system must be accepted by
the appropriate PMI and require the maintenance records be
maintained either indefinitely or until the work is repeated.
Records of the piece-part inspections are not required under
Sec. 121.380(a)(2)(vi) of the Federal Aviation Regulations [14 CFR
121.380(a)(2)(vi)]. All other Operators must maintain the records of
mandatory inspections required by the applicable regulations
governing their operations.
Note 3: The requirements of this AD have been met when the
engine manual changes are made and air carriers have modified their
continuous airworthiness maintenance plans to reflect the
requirements in the Engine Manuals.
Issued in Burlington, Massachusetts, on August 9, 1999.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 99-21331 Filed 8-16-99; 8:45 am]
BILLING CODE 4910-13-U
