[Federal Register Volume 62, Number 45 (Friday, March 7, 1997)]
[Proposed Rules]
[Pages 10492-10494]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-5572]


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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-203-AD]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model DC-9 and DC-9-
80 Series Airplanes, Model MD-88 Airplanes, and C-9 (Military) 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 McDonnell Douglas Model DC-9 and 
DC-9-80 series airplanes, Model MD-88 airplanes, and C-9 (military) 
series airplanes. This proposal would require repetitive high frequency 
eddy current inspections of the external areas of the fuselage to 
detect cracks of the skin and/or longeron, and various follow-on 
actions. The proposal also would require the installation of a 
preventative modification, which would terminate the repetitive 
inspections. This proposal is prompted by reports indicating that, due 
to material fatigue caused by installation preload and cabin 
pressurization cycles, fatigue cracks were found in the skin and 
longerons of the fuselage. The actions specified by the proposed AD are 
intended to prevent such fatigue cracks, which could result in loss of 
the structural integrity of the fuselage and, consequently, lead to 
rapid depressurization of the airplane.

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-203-AD, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056. Comments may be inspected at this

[[Page 10493]]

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-203-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-203-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received several reports indicating that, on certain 
McDonnell Douglas Model DC-9 series airplanes, cracks were found in the 
skin and longerons of the fuselage. The cracked fuselage skin was found 
on airplanes that had accumulated 61,345 or more total landings. The 
cracked fuselage longerons were found on airplanes that had accumulated 
45,850 or more total landings. The cracking occurred between longeron 5 
left and longeron 8 right, between stations Y=160.000 and Y=218.000. 
Investigation revealed that the apparent cause of such cracking has 
been attributed to material fatigue, as a result of installation 
preload and cabin pressurization cycles. This condition, if not 
detected and corrected in a timely manner, could result in loss of the 
structural integrity of the fuselage and, consequently, lead to rapid 
depressurization of the airplane.
    The subject area on certain McDonnell Douglas Model DC-9-80 series 
airplanes, Model MD-88 airplanes, and C-9 (military) series airplanes 
is identical to that on the affected Model DC-9 series airplanes. 
Therefore, all of these airplanes may be subject to the same unsafe 
condition.

Explanation of Relevant Service Information

    The FAA has reviewed and approved McDonnell Douglas Service 
Bulletin 53-235, dated September 15, 1993. The service bulletin 
describes procedures for performing repetitive high frequency eddy 
current (HFEC) inspections of the external areas of the fuselage skin 
to detect cracks of the skin and/or longeron between stations Y=160.000 
and Y=218.000 and various follow-on actions. (These follow-on actions 
include repetitive inspections or installation of a preventative 
modification, and repair of cracked skin or longerons.) The service 
bulletin also describes procedures for installation of a preventative 
modification, which would eliminate the need for repetitive 
inspections. The preventative modification involves installation of 
clips and doublers between certain stations. Accomplishment of the 
preventative modification will minimize the possibility of further 
crack development.

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 repetitive HFEC inspections of the external 
areas of the fuselage skin to detect cracks of the skin and/or longeron 
between stations Y=160.000 and Y=218.000, and various follow-on 
actions. The proposed AD also would require the installation of a 
preventative modification, which would constitute terminating action 
for the repetitive inspection requirements. The actions would be 
required to be accomplished in accordance with the service bulletin 
described previously.

Differences Between the Proposal and the Referenced Service 
Information

    This proposed AD would differ from the referenced service bulletin 
in that it would mandate the accomplishment of the terminating 
preventative modification for the repetitive inspections. The service 
bulletin provides that action only as optional procedure.
    Mandating the terminating action is based on the FAA's 
determination that long term continued operational safety will be 
better assured by modifications or design changes to remove the source 
of the problem, rather than by repetitive inspections. Long term 
inspections may not be providing the degree of safety assurance 
necessary for the transport airplane fleet. This, coupled with a better 
understanding of the human factors associated with numerous repetitive 
inspections, has led the FAA to consider placing less emphasis on 
special procedures and more emphasis on design improvements. The 
proposed modification requirement is in consonance with these 
considerations.

Cost Impact

    There are approximately 1,728 McDonnell Douglas Model DC-9 and DC-
9-80 series airplanes, Model MD-88 airplanes, and C-9 (military) series 
airplanes of the affected design in the worldwide fleet. The FAA 
estimates that 1,152 airplanes of U.S. registry would be affected by 
this proposed AD.
    It would take approximately 16 work hours per airplane to 
accomplish the proposed HFEC inspection, at an average labor rate of 
$60 per work hour. Based on these figures, the cost impact of the HFEC 
inspection proposed by this AD on U.S. operators is estimated to be 
$1,105,920, or $960 per airplane, per inspection cycle.
    It would take approximately 89 work hours per airplane to 
accomplish the proposed modification, at an average labor rate of $60 
per work hour. The cost of required parts would range from $13,771 to 
$15,292 per airplane. Based on these figures, the cost impact of the 
proposed AD on U.S. operators is estimated to be between $22,015,872

[[Page 10494]]

($19,111 per airplane) and $23,768,064 ($20,632 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 96-NM-203-AD.

    Applicability: Model DC-9-10, -20, -30, -40, and -50 series 
airplanes; Model DC-9-81 (MD-81), -82 (MD-82), -83 (MD-83), and -87 
(MD-87) series airplanes; Model MD-88 airplanes; and C-9 (military) 
series airplanes; as listed in McDonnell Douglas DC-9 Service 
Bulletin 53-235, dated September 15, 1993; certificated in any 
category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise 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 (f) 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 cracks in the skin and longerons of the 
fuselage, which could result in loss of the structural integrity of 
the fuselage and, consequently, lead to rapid depressurization of 
the airplane, accomplish the following:
    (a) Prior to the accumulation of 30,000 total landings, or 
within 8,000 landings after the effective date of this AD, whichever 
occurs later, perform a high frequency eddy current (HFEC) 
inspection of the external areas of the fuselage to detect cracks of 
the skin and/or longeron between stations Y=160.000 and Y=218.000, 
in accordance with McDonnell Douglas DC-9 Service Bulletin 53-235, 
dated September 15, 1993.
    (b) Condition 1 (No Cracks). If no crack is detected during any 
inspection required by this AD, accomplish either paragraph (b)(1) 
or (b)(2) of this AD, in accordance with McDonnell Douglas DC-9 
Service Bulletin 53-235, dated September 15, 1993.
    (1) Condition 1, Option I (Repetitive Inspection). Repeat the 
HFEC inspection required by paragraph (a) of this AD, and the aided 
visual inspection specified in paragraph 2.E. of the Accomplishment 
Instructions of the service bulletin, at intervals not to exceed 
10,000 landings.
    (2) Condition 1, Option II (Terminating Action Modification). 
Accomplish the preventative modification installation of clips and 
doublers between stations Y=160.000 and Y=218.000, in accordance 
with the service bulletin. Accomplishment of the modification 
constitutes terminating action for the repetitive inspection 
requirements of this AD.
    (c) Condition 2 (Skin Cracks). If any skin crack is detected 
during any inspection required by this AD, prior to further flight, 
repair it in accordance with McDonnell Douglas DC-9 Service Bulletin 
53-235, dated September 15, 1993. After repair, accomplish either 
paragraph (b)(1) or (b)(2) of this AD.
    (d) Condition 3 (Longeron Cracks). If any longeron crack is 
detected during any inspection required by this AD, prior to further 
flight, repair it in accordance with McDonnell Douglas DC-9 Service 
Bulletin 53-235, dated September 15, 1993. After repair, accomplish 
either paragraph (b)(1) or (b)(2) of this AD.
    (e) Prior to the accumulation of 100,000 total landings, or 
within 4 years after the effective date of this AD, whichever occurs 
later, accomplish the preventative modification specified in 
paragraph 2.J. of the Accomplishment Instructions of McDonnell 
Douglas DC-9 Service Bulletin 53-235, dated September 15, 1993. 
Accomplishment of the modification constitutes terminating action 
for the requirements of this AD.
    (f) 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.

    (g) 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.

    Issued in Renton, Washington, on February 28, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-5572 Filed 3-6-97; 8:45 am]
BILLING CODE 4910-13-U