[Federal Register Volume 61, Number 206 (Wednesday, October 23, 1996)]
[Proposed Rules]
[Pages 54969-54972]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-27238]


-----------------------------------------------------------------------


DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-NM-235-AD]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model DC-9 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to certain

[[Page 54970]]

McDonnell Douglas DC-9 series airplanes, that currently requires 
repetitive visual inspections to detect corrosion and cracking of the 
fuselage upper skin and frames in the area of the loop antenna 
assemblies of the automatic direction finder (ADF), and repair, if 
necessary. This action would add a requirement to perform a visual and 
an eddy current inspection of the fuselage forward upper skin under the 
antennas, followed by the reinstallation of the ADF antennas using an 
improved procedure. This proposal is prompted by the development of a 
modification of the ADF antenna installation that would constitute 
terminating action for the required repetitive visual inspections. The 
actions specified by the proposed AD are intended to prevent rapid 
decompression of the fuselage, significant structural damage, and 
subsequent reduced structural integrity of the airplane, due to 
problems associated with corrosion and fatigue cracking in the subject 
area.

DATES: Comments must be received by December 3, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-235-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: Wahib Mina, Aerospace Engineer, 
Airframe Branch, ANM-120L, FAA, Los Angeles Aircraft Certification 
Office, 3960 Paramount Boulevard, Lakewood, California 90712; telephone 
(310) 627-5324; 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-235-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-235-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On March 28, 1996, the FAA issued AD 96-07-51, amendment 39-9562 
(61 FR 15882, April 10, 1996), applicable to certain McDonnell Douglas 
DC-9 series airplanes, to require repetitive internal visual 
inspections to detect corrosion and cracking of the fuselage forward 
upper skin and to detect cracking of the fuselage frames in the subject 
area. That AD also requires repair of any corrosion or cracking found. 
That action was prompted by a report indicating that severe corrosion 
and a 39-inch crack of the forward fuselage upper skin was found during 
scheduled maintenance on a McDonnell Douglas Model DC-9-31 series 
airplane. Additionally, subsequent inspection of the adjacent structure 
revealed cracking of the fuselage frame at fuselage station 275. The 
cracking found has been attributed to fatigue. Corrosion and fatigue 
cracking in these areas, if not detected and corrected in a timely 
manner, could result in rapid decompression of the fuselage, 
significant damage to adjacent structure, and subsequent reduced 
structural integrity of the airplane.

Actions Since Issuance of Previous Rule

    Since the issuance of that AD, McDonnell Douglas has developed a 
new procedure for the installation of the ADF antennas. Installation of 
the antennas using the improved installation procedure will eliminate 
the need for repetitive inspections to detect corrosion and cracking of 
the fuselage upper skin for cracks and corrosion under the ADF loop 
antenna.

Explanation of Relevant Service Information

    The FAA has reviewed and approved McDonnell Douglas Service 
Bulletin DC-9-53-284, dated August 20, 1996, which describes procedures 
for a one-time visual and a one-time high frequency eddy current 
inspection to detect corrosion and cracking of the fuselage forward 
upper skin under the antennas. The service bulletin also describes 
procedures for repair of certain corrosion or cracking that is within 
the limits specified by the service bulletin. In addition, the service 
bulletin describes procedures for modification of the ADF antennas 
using an improved installation procedure. Accomplishment of the 
inspections and installation procedure eliminates the need for 
repetitive visual inspections of the area.

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 supersede AD 96-07-51 to continue to require 
repetitive internal visual inspections to detect corrosion and cracking 
of the fuselage forward upper skin and to detect cracking of the 
fuselage frame in the area of the forward and aft loop antenna 
assemblies of the automatic direction finder (ADF).
    The proposed AD would add a requirement for removing the ADF 
antennas and performing a one-time visual and a one-time high frequency 
eddy current inspection to detect corrosion and cracking of the 
fuselage forward upper skin under the antennas; reinstallation of the 
ADF antennas using an improved installation procedure would constitute 
terminating action for the previously required repetitive visual 
inspections. The proposed AD also would require repair of any corrosion 
or cracking detected that is within the limits specified by the service 
bulletin. Those actions would be required to be accomplished in 
accordance with the service bulletin described previously.
    If any corrosion or cracking is detected that is beyond the limits 
specified in the service bulletin, the repair would be required to be

[[Page 54971]]

accomplished in acordance with a method approved by the FAA.

FAA's Determination Regarding Terminating Actions

    The FAA has determined 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 569 McDonnell Douglas Model DC-9 series 
airplanes of the affected design in the worldwide fleet. The FAA 
estimates that 403 airplanes of U.S. registry would be affected by this 
proposed AD.
    The actions that are currently required by AD 96-07-51 take 
approximately 5 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact on U.S. operators of the actions currently required is estimated 
to be $120,900, or $300 per airplane, per inspection.
    The new actions that are proposed in this AD action would take 
approximately 16 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact on U.S. operators of the proposed requirements of this AD is 
estimated to be $386,880, or $960 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or 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 removing amendment 39-9562 (61 FR 
15882, April 10, 1996), and by adding a new airworthiness directive 
(AD), to read as follows:

McDonnell Douglas: Docket 96-NM-235-AD. Supersedes AD 96-07-51, 
Amendment 39-9562.

    Applicability: Model DC-9 series airplanes having fuselage 
numbers 001 through 631 inclusive, 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 (c)(1) 
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 rapid decompression of the fuselage, significant 
structural damage, and subsequent reduced structural integrity of 
the airplane, due to problems associated with corrosion and fatigue 
cracking, accomplish the following:
    (a) Within 15 days after April 15, 1996 (the effective date of 
AD 96-07-51, amendment 39-9562): Perform an internal visual 
inspection to detect corrosion and cracking of the fuselage forward 
upper skin and to detect cracking of the fuselage frame in the area 
of the forward and aft loop antenna assemblies of the automatic 
direction finder (ADF), in accordance with McDonnell Douglas Alert 
Service Bulletin DC9-53A282, dated March 20, 1996.
    (1) If no corrosion or cracking is detected: Repeat the visual 
inspection required by paragraph (a) of this AD thereafter at 
intervals not to exceed six months.
    (2) If any corrosion or cracking is detected that is within the 
limits specified in Chapter 53-04, Figure 29, of the DC-9 Structural 
Repair Manual (SRM): Prior to further flight, repair in accordance 
with Chapter 53-04, Figure 29, of the SRM. Repeat the visual 
inspection required by paragraph (a) of this AD thereafter at 
intervals not to exceed six months.
    (3) If any corrosion or cracking is detected in the fuselage 
forward upper skin, or if any cracking is detected in the fuselage 
frame, and that corrosion or cracking is outside the limits 
specified in Chapter 53-04, Figure 29, of the SRM: Prior to further 
flight, repair in accordance with a method approved by the Manager, 
Los Angeles Aircraft Certification Office (ACO), FAA, Transport 
Airplane Directorate.
    (b) Within 24 months after the effective date of this AD: Remove 
the ADF antennas and perform visual and high frequency eddy current 
inspections to detect corrosion and cracking of the fuselage forward 
upper skin under the antennas, in accordance with McDonnell Douglas 
Service Bulletin DC9-53-284, dated August 20, 1996; and accomplish 
the requirements of paragraph (b)(1), (b)(2), or (b)(3) of this AD, 
as applicable, at the times specified. Accomplishment of the actions 
specified in paragraph (b)(1) or (b)(2) of this AD constitute 
terminating action for the requirements of paragraphs (a)(1) and 
(a)(2) of this AD.
    (1) If no cracking or corrosion is detected: Prior to further 
flight, reinstall the ADF antennas using the improved installation 
procedure in accordance with the service bulletin.
    (2) If any cracking or corrosion is detected that is within the 
limits specified in Chapter 53-04 of the DC-9 Structural Repair 
Manual (SRM): Prior to further flight, repair in accordance with 
Chapter 53-04 of the DC-9 SRM, and reinstall the ADF antennas using 
the improved installation procedure in accordance with the service 
bulletin.
    (3) If any cracking or corrosion is detected that is outside the 
limits specified in Chapter 53-04 of the SRM: Prior to further 
flight, repair in accordance with a method approved by the Manager, 
Los Angeles Certification Office (ACO), FAA, Transport Airport 
Directorate.
    (c)(1) An alternative method of compliance or adjustment of the 
compliance time that

[[Page 54972]]

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.

    (2) Alternative methods of compliance, approved in accordance 
with AD 96-07-71, amendment 39-9562, are approved as alternative 
methods of compliance with this AD.
    (d) 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 October 17, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-27238 Filed 10-22-96; 8:45 am]
BILLING CODE 4910-13-U