[Federal Register Volume 62, Number 45 (Friday, March 7, 1997)]
[Proposed Rules]
[Pages 10490-10492]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-5573]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 96-NM-201-AD]
RIN 2120-AA64
Airworthiness Directives; McDonnell Douglas Model MD-90-30
Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to all McDonnell Douglas Model MD-90-
30 airplanes. This proposal would require revising the Airworthiness
Limitations Section of the Instructions for Continued Airworthiness
[MD-90-30 Airworthiness Limitations Instructions (ALI)]. The revision
would incorporate certain compliance times for inspections to detect
fatigue cracking of principal structural elements (PSE) and to add
PSE's to the ALI. This proposal is prompted by analysis of data that
identified reduced initial inspection thresholds, reduced repetitive
inspection intervals for PSE's, and other PSE's to be added to the ALI.
The actions specified by the proposed AD are intended to ensure that
fatigue cracking of various PSE's are detected and corrected; such
fatigue cracking could adversely affect the structural integrity of
these airplanes.
DATES: Comments must be received by April 16, 1997.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 96-NM-201-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056. Comments may be inspected at this
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except
Federal holidays.
The service information referenced in the proposed rule may be
obtained from McDonnell Douglas Corporation, 3855 Lakewood Boulevard,
Long Beach, California 90846, Attention: Technical Publications
Business Administration, Department C1-L51 (2-60). This information may
be examined at the FAA, Transport Airplane Directorate, 1601 Lind
Avenue, SW., Renton, Washington.
FOR FURTHER INFORMATION CONTACT: Brent Bandley, Aerospace Engineer,
Airframe Branch, ANM-120L, FAA, Los Angeles Aircraft Certification
Office, 3960 Paramount Boulevard, Lakewood, California 90712; telephone
(310) 627-5237; fax (310) 627-5210.
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 shall 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 96-NM-201-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, Transport Airplane Directorate, ANM-103, Attention: Rules
Docket No. 96-NM-201-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
In accordance with airworthiness standards requiring ``damage
tolerance assessments'' [reference current section 1529 of parts 23,
25, 27, and 29 of the Federal Aviation Regulations (FAR); section 4 of
parts 33 and 35 of the FAR; section 82 of part 31 of the FAR; and the
Appendices referenced in those sections], all products certificated to
comply with those sections must have Instructions for Continued
Airworthiness (or, for some products, maintenance manuals), that
include an Airworthiness Limitations Section. That section must set
forth:
mandatory replacement times for structural components,
structural inspection intervals, and
[[Page 10491]]
related approved structural inspection procedures
necessary to show compliance with the damage-tolerance requirements.
Compliance with the terms specified in the Airworthiness
Limitations Sections is required by FAR sections 43.16 (for persons
maintaining products) and 91.403 (for operators).
As airplanes gain service experience, or as the result of post-
certification testing and evaluation, it may become necessary to add
additional life limits or structural inspections in order to ensure the
continued structural integrity of the airplane. The manufacturer may
revise the Airworthiness Limitations Section to include new or more
restrictive life limits and inspections. However, in order to require
compliance with those revised life limits and/or inspection intervals,
the FAA must engage in rulemaking.
Because loss of structural integrity would result in an unsafe
condition, it is appropriate to impose these requirements through the
AD process.
Actions Taken by the Manufacturer
McDonnell Douglas recently has completed extensive analyses and
testing of fatigue cracking of Principal Structural Elements (PSE) on
Model MD-90-30 airplanes, which included:
crack growth analysis,
service experience analysis,
crack growth testing,
fatigue testing, and
analysis of the effectiveness of applicable non-
destructive inspection techniques to detect cracking and other
anomalies.
The analyses and testing were similar to methods used to develop
the initial MD-90 Airworthiness Limitations Instructions (ALI),
Document No. MDC-94K9000, dated November 1994.
The results of the testing and analyses demonstrated the need to
revise certain inspections contained in the current ALI.
New Revisions of Airworthiness Limitations Instructions (ALI)
The FAA has reviewed and approved MD-90 ALI, Revision 1, dated
January 1995, and Revision 2, dated July 1996. These revisions describe
specific reduced initial inspection thresholds and reduced repetitive
inspection intervals for certain PSE's. They also include additional
PSE's to be inspected.
Explanation of Requirements of Proposed Rule
Since an unsafe condition has been identified that is likely to
exist or develop on other products of this same type design, the
proposed AD would require operators to revise the MD-90 ALI to
incorporate Revision 1, dated January 1995, and Revision 2, dated July
1996.
Explanation of Action Taken by the FAA
As stated previously, in order to require compliance with these
inspection intervals and life limits, the FAA must engage in
rulemaking, namely the issuance of an AD. For products certificated to
comply with the referenced part 25 requirements, it is within the
authority of the FAA to issue an AD requiring a revision to the
Airworthiness Limitations Section that includes reduced life limits, or
new or different structural inspection requirements. These revisions
then are mandatory for operators under section 91.403(c) of the FAR,
which prohibits operation of an airplane for which Airworthiness
Limitations have been issued unless the inspection intervals specified
in those limitations have been complied with.
Once that document is revised, as required, and the AD has been
fully complied with, the life limit or structural inspection change
remains enforceable as a part of the Airworthiness Limitations. (This
is analogous to AD's that require changes to the Limitations Section of
the Airplane Flight Manual.)
Requiring a revision of the Airworthiness Limitations, rather than
requiring individual inspections, is advantageous for operators because
it allows them to record AD compliance status only once--at the time
they make the revision--rather than after every inspection. It also has
the advantage of keeping all Airworthiness Limitations, whether imposed
by original certification or by AD, in one place within the operator's
maintenance program, thereby reducing the risk of non-compliance
because of oversight or confusion.
Cost Impact
There are approximately 15 Model MD-90 series airplanes of the
affected design in the worldwide fleet. The FAA estimates that 11
airplanes of U.S. registry would be affected by this proposed AD, that
it would take approximately 1 work hour per airplane to accomplish the
proposed actions, and that the average labor rate is $60 per work hour.
Based on these figures, the cost impact of the proposed AD on U.S.
operators is estimated to be $660, or $60 per airplane.
The cost impact figure discussed above is based on assumptions that
no operator has yet accomplished any of the proposed requirements of
this AD action, and that no operator would accomplish those actions in
the future if this AD were not adopted.
Regulatory Impact
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:
McDonnell Douglas: Docket 96-NM-201-AD.
Applicability: All Model MD-90-30 series airplanes, 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
[[Page 10492]]
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 request
approval for an alternative method of compliance in accordance with
paragraph (d) 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 ensure continued structural integrity of these airplanes,
accomplish the following:
(a) Within 180 days after the effective date of this AD, revise
the Airworthiness Limitations Section of the Instructions for
Continued Airworthiness [Airworthiness Limitations Instructions
(ALI), McDonnell Douglas Report No. MDC-94K9000, dated November
1994] to incorporate the Item, Location, and Inspection Interval of
the following principal structural elements: This may be
accomplished by inserting a copy of Revision 1 of the ALI, dated
January 1995, or a copy of this AD into the ALI.
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Inspection interval (in
landings)
Item Location -------------------------
Initial Repeat
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Item 53.30.02.3......... Skin Panels, STA 237 60,000 11,000
to 1395 Fuselage
Skin in Constant
Section from
Longeron 3 Left to
Longeron 3 Right.
Item 53.30.02.4......... Skin Panels, STA 237 60,000 30,000
to 1395 Fuselage
Hoop Skin Splice in
Constant Section
from Longeron 5
Left to Longeron 5
Right.
Item 54.10.04.1......... Thrust Bulkhead, 15,000 4,500
Pylon--STA Yn
170.5--Rear Spar
and Engine Thrust
Support Fitting
(Upper and Lower).
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(b) Within 180 days after the effective date of this AD, revise the
Airworthiness Limitations Section of the Instructions for Continued
Airworthiness [Airworthiness Limitations Instructions (ALI), McDonnell
Douglas Report No. MDC-94K9000, dated November 1994] to incorporate the
Item, Location, and Inspection Interval of the following principal
structural elements: This may be accomplished by inserting a copy of
Revision 2 to the ALI, dated July 1996, or a copy of this AD into the
ALI.
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Inspection interval (in
landings)
Item Location -------------------------
Initial Repeat
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Item 55.13.01.1......... Plates/Skin--Upper 60,000 8,100
STA Xh 27.2 Left to
Xh 27.2 Right--
Upper Aft Skin
Plank with Integral
Stringers from Xh
7.234 to Xh 26.859.
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(c) Except as provided in paragraph (d) of this AD: After the
actions specified in paragraphs (a) and (b) of this AD have been
accomplished, no alternative inspections or inspection intervals may be
approved for the parts specified in paragraphs (a) and (b) of this AD.
(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, Los Angeles 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, Los
Angeles ACO.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Los Angeles ACO.
(e) 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.
Issued in Renton, Washington, on February 28, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 97-5573 Filed 3-6-97; 8:45 am]
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