[Federal Register Volume 62, Number 17 (Monday, January 27, 1997)]
[Proposed Rules]
[Pages 3837-3840]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-1620]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-NM-244-AD]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model DC-9-10, -20, -
30, -40, and -50 Series Airplanes and C-9 (Military) 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 
DC-9 and C-9 (military) series airplanes. This proposal would require 
eddy current inspections to detect cracking of the frame-to-longeron 
attachment area, the frame-to-skin shear clips at certain fuselage 
stations, and the fuselage bulkhead at the front spar of the engine 
pylon in the aft fuselage; and repair, if necessary. This proposal also 
would require certain modifications, which, when accomplished, would 
terminate the requirement for inspections. This proposal is prompted by 
reports indicating that fatigue cracking has occurred at those areas. 
The actions specified by the proposed AD are intended to prevent such 
fatigue cracking, which could cause damage to adjacent structure and 
result in reduced structural integrity of the airplane.

DATES: Comments must be received by February 24, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-244-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00

[[Page 3838]]

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; or at the FAA, Transport Airplane 
Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount 
Boulevard, Lakewood, California.

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-244-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-244-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On May 8, 1996, the FAA issued AD 96-10-11, amendment 39-9618 (61 
FR 24675, May 16, 1996), which requires, among other actions, a one-
time visual inspection to detect fatigue cracking of the frame-to-
longeron attachment area and frame-to-skin shear clips in the aft 
fuselage. It also requires an eventual modification (within 86,000 
total landings) that entails installing formers, plates, doublers, and 
angles at certain fuselage stations, and installation of a doubler, 
splice, filler, and strap on the fuselage bulkhead at the front spar of 
the engine pylon of the aft fuselage. Those actions are required to be 
accomplished in accordance with McDonnell Douglas Service Bulletins 
DC9-53-140, Revision 03, dated March 12, 1986; and DC9 53-150, Revision 
2, dated February 27, 1991. That AD was prompted by reports indicating 
that fatigue cracking had occurred in the frame-to-longeron attachment 
area, the frame-to-skin shear clips of certain fuselage stations, and 
the fuselage bulkhead at the front spar of the engine pylon of the aft 
fuselage. That AD was issued to prevent degradation in the structural 
capabilities of the airplane.
    However, after the release of McDonnell Douglas Service Bulletins 
DC9-53-140, Revision 03, and DC9 53-150, Revision 2, the manufacturer 
conducted additional fatigue analyses of the same frame-to-longeron 
attachment area, the frame-to-skin shear clips at certain fuselage 
locations, and the fuselage bulkhead at the front spar of the engine 
pylon of the aft fuselage. The analyses revealed that a one-time visual 
inspection is not an effective method of detecting fatigue cracking in 
this case, and that repetitive inspections using a more comprehensive 
inspection method are necessary. Subsequently, the manufacturer 
developed eddy current inspection procedures to ensure that such 
fatigue cracking is identified and corrected before it reaches critical 
lengths.
    Upon consideration of these new data, the FAA finds that the one-
time visual inspection required by AD 96-10-11 is not adequate to 
detect fatigue cracking in a timely manner. Such fatigue cracking, if 
not detected and corrected in a timely manner, could cause damage to 
the adjacent structure, and, consequently, result in loss of the 
capability of the engine pylon to support engine loads and possible 
separation of the engine from the airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved McDonnell Douglas Service 
Bulletin DC9-53-140, Revision 05, dated February 15, 1996, which 
describes procedures for repetitive eddy current inspections to detect 
fatigue cracking in the longeron-to-frame attachment area and frame-to-
skin shear clips of certain fuselage stations, and repair, if 
necessary. That service bulletin also describes procedures for a 
modification that entails installing formers, plates, doublers, and 
angles at certain fuselage stations.
    Additionally, the FAA previously reviewed and approved McDonnell 
Douglas Service Bulletin DC9 53-150, Revision 2, dated February 27, 
1991, which describes procedures for visual and eddy current 
inspections to detect cracks in the fuselage bulkhead at the front spar 
of the engine pylon of the aft fuselage, and repair, if necessary. That 
service bulletin also describes procedures for a modification that 
entails installing a doubler, splice, filler, and strap on the fuselage 
bulkhead of the front spar of the engine pylon.
    Accomplishment of the described modifications eliminates the need 
to repeat the visual and eddy current inspections.
    (McDonnell Douglas Service Bulletins DC9-53-140, Revision 03, and
    DC9 53-150, Revision 2, were referenced in AD 96-10-11 as 
appropriate sources of service information.)

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 visual and eddy current 
inspections to detect fatigue cracking of the frame-to-longeron 
attachment area and frame-to-skin shear clips and the fuselage bulkhead 
of the front spar of the engine pylon, and repair, if necessary. The 
eddy current inspections described in McDonnell Douglas Service 
Bulletin DC9-53-140, Revision 05, must be accomplished prior to or in 
conjunction with the visual and eddy current inspections described in 
McDonnell Douglas Service Bulletin 53-150, Revision 2, for all 
airplanes that are specified in the effectivity listing of both of 
these service bulletins.
    This proposed AD also would require eventual modifications that 
entail installing formers, plates, doublers, and angles at certain 
fuselage stations; and

[[Page 3839]]

installing a doubler, splice, filler, and a strap on the fuselage 
bulkhead of the front spar of the engine pylon.These modifications 
would consitutute terminating action for the required repetitive 
inspections.
    The actions would be required to be accomplished in accordance with 
the service bulletins described previously.

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, that it would take approximately 6 work hours per airplane 
to accomplish the proposed inspections, and that the average labor rate 
is $60 per work hour. Based on these figures, the cost impact of these 
inspections on U.S. operators is estimated to be $145,080, or $360 per 
airplane, per inspection cycle.
    The FAA estimates that it would take approximately 174 work hours 
per airplane to accomplish the proposed modification of longeron-to-
frame attachment area and the frame-to-skin shear clips of the aft 
fuselage. The cost of required parts would differ, depending on whether 
the airplane is categorized as a Group 1 airplane or a Group 2 
airplanes, as defined in the applicable service bulletin. Required 
parts would cost approximately $13,669 per airplane for Group 1 
airplanes, and $10,285 per airplane for Group 2 airplanes. Based on 
these figures, the cost impact of this modification on U.S. operators 
is estimated to be $24,109 per airplane for Group 1 airplanes, and 
$20,725 per airplane for Group 2 airplanes.
    The FAA estimates that it would take approximately 229 work hours 
per airplane for Group 1 airplanes, and 137 work hours per airplane for 
Group 2 airplanes, to accomplish the proposed modification of the 
fuselage bulkhead at the front spar of the engine pylon of the aft 
fuselage. Required parts would cost approximately $5,871 per airplane 
for Group 1 airplanes, and $5,014 per airplane for Group 2 airplanes. 
Based on these figures, the cost impact of this modification on U.S. 
operators is estimated to be $19,611 per airplane for Group 1 
airplanes, and $13,234 per airplane for Group 2 airplanes.
    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-244-AD.

    Applicability: Model DC-9-10, -20, -30, -40, -50 series 
airplanes, and C-9 (military) 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 
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 (g) 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 that fatigue cracking of the frame-to-longeron 
attachment area and the frame-to-skin shear clips in the aft 
fuselage is detected and corrected in a timely manner so as to 
prevent damage to adjacent structure, which could result in loss of 
the capability of the engine pylon to support engine loads and 
possible separation of the engine from the airplane, accomplish the 
following:
    (a) For airplanes that are specified in both McDonnell Douglas 
Service Bulletin DC9-53-140, Revision 05, dated February 15, 1996, 
and McDonnell Douglas Service Bulletin DC9-53-150, Revision 2, dated 
February 27, 1991: Prior to the accumulation of 30,000 total 
landings or within 4,000 landings after the effective date of this 
AD, whichever occurs later, accomplish the requirements of paragraph 
(a)(1) and (a)(2) of this AD. The requirements of paragraph (a)(1) 
of this AD must be accomplished prior to or in conjunction with the 
requirements of paragraph (a)(2) of this AD.
    (1) Perform an eddy current inspection to detect cracking of the 
longeron-to-frame attachment area and frame-to-skin shear clips of 
the aft fuselage, in accordance with the Accomplishment Instructions 
of McDonnell Douglas Service Bulletin DC9-53-140, Revision 05, dated 
February 15, 1996. If no cracking is detected, repeat these 
inspections thereafter at intervals not to exceed 12,500 landings, 
until the modification specified in paragraph (f)(1) of this AD is 
accomplished.
    (2) Perform a visual and eddy current inspection to detect 
cracking of the fuselage bulkhead at the front spar of the engine 
pylon of the aft fuselage, in accordance with the Accomplishment 
Instructions of McDonnell Douglas Service Bulletin DC9 53-150, 
Revision 2, dated February 27, 1991. If no cracking is detected, 
repeat these inspections thereafter at intervals not to exceed 4,000 
landings, until the modification specified in paragraph (f)(2) of 
this AD is accomplished.
    (b) For airplanes listed in McDonnell Douglas Service Bulletin 
DC9-53-140 that have been previously inspected using visual 
inspection techniques in accordance with McDonnell Douglas Corrosion 
Prevention Control Program (CPCP), Document MDC-K4606, Revision 1, 
dated December 1990: Within 8,500 landings after the previous visual 
inspection or within 4,000 landings after the effective date of this 
AD, whichever occurs later, accomplish the requirements of paragraph 
(a)(1) of this AD.
    (c) For airplanes that are specified in McDonnell Douglas 
Service Bulletin DC9-53-140, Revision 05, dated February 15, 1996, 
and not subject to paragraph (a) or (b) of this AD: Prior to the 
accumulation of 30,000 total landings or within 4,000 landings after 
the effective date of this AD, whichever occurs later, perform an 
eddy

[[Page 3840]]

current inspection to detect cracking of the longeron-to-frame 
attachment area and frame-to-skin shear clips of the aft fuselage, 
in accordance with the Accomplishment Instructions of McDonnell 
Douglas Service Bulletin DC9-53-140, Revision 05, dated February 15, 
1996. If no cracking is detected, repeat these inspections 
thereafter at intervals not to exceed 12,500 landings, until the 
modification specified in paragraph (f)(1) of this AD is 
accomplished.
    (d) For airplanes that are specified in McDonnell Douglas 
Service Bulletin DC9-53-150, Revision 2, dated February 27, 1991, 
and not subject to paragraph (a) of this AD: Prior to the 
accumulation of 30,000 total landings or within 4,000 landings after 
the effective date of this AD, whichever occurs later, perform a 
visual and eddy current inspection to detect cracking of the 
fuselage bulkhead at the front spar of the engine pylon of the aft 
fuselage, in accordance with the Accomplishment Instructions of 
McDonnell Douglas Service Bulletin DC9 53-150, Revision 2, dated 
February 27, 1991. If no cracking is detected, repeat these 
inspections thereafter at intervals not to exceed 4,000 landings, 
until the modifications required by paragraph (f)(2) of this AD is 
accomplished.
    (e) If any cracking is detected during any inspection required 
by this AD: Prior to further flight, repair the cracking in 
accordance with either McDonnell Douglas Service Bulletin DC9-53-
140, Revision 05, dated February 15, 1996; or McDonnell Douglas DC-9 
Service Bulletin 53-150, Revision 2, dated February 27, 1991; as 
applicable. Thereafter, perform the inspections required by 
paragraph (a) of this AD.
    (f) Prior to the accumulation of 86,000 total landings, or 
within 4 years after the effective date of this AD, whichever occurs 
later, accomplish the requirements of paragraps (f)(1) and paragraph 
(f)(2) of this AD, as applicable.
    (1) For airplanes that are subject to the requirements of 
paragraph (a), (b), or (c) of this AD: Accomplish the modification 
of the longeron-to-frame attachment area and frame-to-skin shear 
clips, in accordance with McDonnell Douglas Service Bulletin DC9-53-
140, Revision 05, dated February 15, 1996. Accomplishment of this 
modification constitutes terminating action for the repetitive 
inspection requirements of paragraphs (a)(1), (b), and (c) of this 
AD.
    (2) For airplanes that are subject to the requirements of 
paragraph (a)(2) or (d) of this AD: Accomplish the modification of 
the fuselage bulkhead at the front spar of the engine pylon of the 
aft fuselage, in accordance with McDonnell Douglas Service Bulletin 
DC9 53-150, Revision 2, dated February 27, 1991. Accomplishment of 
this modification constitutes terminating action for the repetitive 
inspection requirements of paragraphs (a)(2) and (d) of this AD.
    (g) Accomplishment of the requirements of this AD constitutes 
terminating action for the requirements of AD 96-10-11, amendment 
39-9618, which requires modifications as specified in McDonnell 
Douglas Report No. MDC K1572, `DC-9/MD-80 Aging Aircraft Service 
Action Requirements Document'' (SARD), Revision B, dated January 15, 
1993. (Both McDonnell Douglas Service Bulletin DC9-53-140, Revision 
03, dated March 12, 1986; and McDonnell Douglas Service Bulletin DC9 
53-150, Revision 2, dated February 27, 1991; are specified in that 
Douglas report.)
    (h) 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.

    (i) 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 January 16, 1997.
S.R. Miller,
Acting Manager,Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-1620 Filed 1-24-97; 8:45 am]
BILLING CODE 4910-13-U