[Federal Register Volume 64, Number 207 (Wednesday, October 27, 1999)]
[Proposed Rules]
[Pages 57789-57790]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-28079]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-209-AD]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model MD-90 Series 
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 certain McDonnell Douglas Model 
MD-90 series airplanes. This proposal would require a one-time detailed 
visual inspection to detect fatigue cracking of certain longerons and 
the attaching frames of the lower left nose; and repair, if necessary. 
The proposal also would require installation of a preventive 
modification. This proposal is prompted by several reports of fatigue 
cracking of certain longerons and the attaching frames. The actions 
specified by the proposed AD are intended to prevent such fatigue 
cracking, which could result in reduced structural integrity of the 
fuselage, and consequent loss of pressurization of the airplane.

DATES: Comments must be received by December 13, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-209-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 The Boeing Company, Douglas Products Division, 3855 
Lakewood Boulevard, Long Beach, California 90846, Attention: Technical 
Publications Business Administration, Dept. C1-L51 (2-60). This 
information may be examined at the FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Transport 
Airplane Directorate, Los Angeles Aircraft Certification Office, 3960 
Paramount Boulevard, Lakewood, California.

FOR FURTHER INFORMATION CONTACT: Carl Fountain, Aerospace Engineer, 
Airframe Branch, ANM-120L; FAA, Los Angeles Aircraft Certification 
Office, 3960 Paramount Boulevard, Lakewood, California 90712; telephone 
(562) 627-5222; fax (562) 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 99-NM-209-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-114, Attention: Rules 
Docket No. 99-NM-209-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports indicating that cracking of the 
fuselage longerons-to-frame attachment holes occurred on three 
McDonnell Douglas Model DC-9 series airplanes. The fatigue cracking was 
found between longerons 22 though 26 on the left side at stations 
Y=160.000 and Y=200.000. These airplanes had accumulated between 59,110 
and 74,445 total flight cycles. The cracking of the longeron segments 
has been attributed to fatigue. Such fatigue cracking, if not 
corrected, could result in reduced structural integrity of the 
fuselage, and consequent loss of pressurization of the airplane.
    The fuselage longerons-to-frame attachments of McDonnell Douglas 
Model MD-90 series airplanes are similar to those of the affected 
McDonnell Douglas Model DC-9 series airplanes. Therefore, the Model MD-
90 may be subject to the same unsafe condition.

Other Relevant Rulemaking

    On November 20, 1998, the FAA issued AD 98-24-33, amendment 39-
10919 (63 FR 66739, December 3, 1998), applicable to certain McDonnell 
Douglas DC-9 and MD-88 series airplanes, to require a one-time visual 
inspection to detect fatigue cracks between longerons 22 through 26 and 
the attaching frames, and corrective action, if necessary. However, 
this proposed AD would not affect the current requirements of that 
previously issued AD.

Explanation of Relevant Service Information

    The FAA has reviewed and approved McDonnell Douglas Service 
Bulletin MD90-53-004, dated August 20, 1998, which describes procedures 
for a one-time detailed visual inspection to detect cracking of 
longerons 22 through 26 and the attaching frames at stations Y=160.000 
and Y=200.000 of the lower left nose, and repair, if necessary. The 
service bulletin also provides procedures for a preventive modification 
(i.e., installation of clips and doublers under longeron flanges and 
shims longeron) to relieve preloads.

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 accomplishment of the actions specified in 
the service bulletin described previously.

Cost Impact

    There are approximately 7 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 6 airplanes of U.S. registry 
would be affected by this proposed AD.

[[Page 57790]]

    It would take approximately 1 work hour per airplane to accomplish 
the proposed inspection, at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of the inspection proposed by 
this AD on U.S. operators is estimated to be $360, or $60 per airplane.
    It would take approximately 6 work hours per airplane to accomplish 
the proposed modification, at an average labor rate of $60 per work 
hour. Parts would cost approximately $312 per airplane. Based on these 
figures, the cost impact of the modification proposed by this AD on 
U.S. operators is estimated to be $4,032, or $672 per airplane.
    The cost impact figures discussed above are 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 99-NM-209-AD.

    Applicability: Model MD-90 series airplanes, as listed in 
McDonnell Douglas Service Bulletin MD90-53-004, dated August 20, 
1998; 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 request approval for an 
alternative method of compliance in accordance with paragraph (b) 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 fatigue cracking of longerons 22 through 26 and the 
attaching frames, which could result in reduced structural integrity 
of the fuselage, and consequent loss of pressurization of the 
airplane; accomplish the following:

Inspection and Modification

    (a) Prior to the accumulation of 40,000 total landings, or 
within 24 months after the effective date of this AD, whichever 
occurs later: Perform a detailed visual inspection to detect 
cracking of longerons 22 through 26 (inclusive) and the respective 
attaching frames at station frames Y=160.000 and Y=200.000 of the 
left lower nose, in accordance with McDonnell Douglas Service 
Bulletin MD90-53-004, dated August 20, 1998.

    Note 2: For the purposes of this AD, a detailed visual 
inspection is defined as: ``An intensive visual examination of a 
specific structural area, system, installation, or assembly to 
detect damage, failure, or irregularity. Available lighting is 
normally supplemented with a direct source of good lighting at 
intensity deemed appropriate by the inspector. Inspection aids such 
as mirror, magnifying lenses, etc., may be used. Surface cleaning 
and elaborate access procedures may be required.''

    (1) If no cracking is detected: Prior to further flight, install 
clips and doublers under the longeron flanges and shim the longerons 
in accordance with the service bulletin.
    (2) If any cracking is detected: Prior to further flight, repair 
the cracks and install clips and doublers under the longeron flanges 
and shim the longerons in accordance with the service bulletin.

Alternative Methods of Compliance

    (b) 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 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Manager, Los Angeles ACO.

Special Flight Permits

    (c) 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 October 21, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-28079 Filed 10-26-99; 8:45 am]
BILLING CODE 4910-13-U