[Federal Register Volume 62, Number 154 (Monday, August 11, 1997)]
[Proposed Rules]
[Pages 42949-42951]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-21096]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-49-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-9-10, -20, -30, -40, and -50 series airplanes, and C-9 (military) 
airplanes. This proposal would require a one-time visual inspection to 
determine if all corners of the aft lower cargo doorjamb have been 
previously modified. This proposal also would require low frequency 
eddy current inspections to detect cracks of the fuselage skin and 
doubler at all corners of the aft lower cargo doorjamb, various follow-
on repetitive inspections, and modification, if necessary. This 
proposal is prompted by fatigue cracks found in the fuselage skin and 
doubler at the corners of the aft lower cargo doorjamb. The actions 
specified by the proposed AD are intended to detect and correct such 
fatigue cracking, which could result in rapid decompression of the 
fuselage and consequent reduced structural integrity of the airplane.

DATES: Comments must be received by September 22, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 97-NM-49-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 
(562) 627-5324; 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 97-NM-49-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. 97-NM-49-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports of fatigue cracks in the fuselage skin 
and doubler at the corners of the aft lower cargo doorjamb on Model DC-
9 series airplanes. These cracks were discovered during inspections 
conducted as part of the Supplemental Structural Inspection Document 
(SSID) program, required by AD 96-13-03, amendment 39-9671 (61 FR 
31009, June 19, 1996). Investigation revealed that such cracking was 
caused by fatigue-related stress. Fatigue cracking in the fuselage skin 
or doubler at the corners of the aft lower cargo doorjamb, if not 
detected and corrected in a timely manner, could result in rapid 
decompression of the fuselage and consequent reduced structural 
integrity of the airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved McDonnell Douglas Service 
Bulletin DC9-53-278, dated November 4, 1996. The service bulletin 
describes the following procedures:
    1. For certain airplanes: Performing low frequency eddy current 
(LFEC) inspections to detect cracks of the fuselage skin and doubler at 
all corners of the aft lower cargo doorjamb;
    2. For certain other airplanes: Contacting the manufacturer for 
disposition of certain conditions;
    3. Conducting repetitive inspections, or modifying the corner skin 
of the aft lower cargo doorjamb and performing follow-on LFEC 
inspections, if no cracking is detected;
    4. Performing repetitive LFEC inspections to detect cracks on the 
skin adjacent to any corner that has been modified; and
    5. Modifying any crack that is found to be 2 inches or less in 
length at all corners that have not been modified and performing 
follow-on repetitive LFEC inspections.
    Accomplishment of the modification will minimize the possibility of 
cracks in the fuselage skin and doubler.

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, for certain airplanes, LFEC inspections to 
detect cracks of the fuselage skin and doubler at all corners of the 
aft lower cargo doorjamb, various follow-on repetitive inspections, and 
modification, if necessary. The actions would be required to be 
accomplished in accordance with the service bulletin described 
previously.
    The proposed AD also would require a one-time visual inspection to 
determine if all corners of the aft lower cargo doorjamb have been 
previously modified. The FAA finds that the LFEC inspections described 
in the referenced service bulletin are dependent on

[[Page 42950]]

whether the corners have been modified or not, and dependent on what 
service documents the operators used to accomplish the modification. 
The FAA finds that an initial one-time visual inspection is necessary 
to make such a determination.
    Operators also should note that, although the service bulletin 
specifies that the manufacturer must be contacted for disposition of 
certain conditions, this proposal would require the repair of those 
conditions to be accomplished in accordance with a method approved by 
the Manager, Los Angeles Aircraft Certification Office (ACO), FAA, 
Transport Airplane Directorate.

Cost Impact

    There are approximately 899 McDonnell Model DC-9-10, -20, -30, -40, 
and -50 series airplanes, and C-9 (military) airplanes of the affected 
design in the worldwide fleet. The FAA estimates that 622 airplanes of 
U.S. registry would be affected by this proposed AD.
    It would take approximately 1 work hour per airplane to accomplish 
the proposed visual inspection, at an average labor rate of $60 per 
work hour. Based on these figures, the cost impact of the visual 
inspection proposed by this AD on U.S. operators is estimated to be 
$37,320, or $60 per airplane.
    Should an operator be required to accomplish the proposed LFEC 
inspection, it would take approximately 1 work hour per airplane to 
accomplish, at an average labor rate of $60 per work hour. Based on 
these figures, the cost impact of the LFEC inspection proposed by this 
AD on U.S. operators is estimated to be $37,320, or $60 per airplane.
    Should an operator be required to accomplish the proposed 
modification, it would take approximately 14 work hours per airplane to 
accomplish, at an average labor rate of $60 per work hour. Required 
parts would cost between $692 to $990 per airplane, depending on the 
service kit purchased. Based on these figures, the cost impact of the 
modification proposed by this AD on U.S. operators is estimated to be 
$1,532 or $1,830 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 97-NM-49-AD.

    Applicability: Model DC-9-10, -20, -30, -40, and -50 series 
airplanes, and C-9 (military) airplanes, as listed in McDonnell 
Douglas DC-9 Service Bulletin DC9-53-278, dated November 4, 1996; 
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 (e) 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 detect and correct fatigue cracking in the fuselage skin or 
doubler at the corners of the aft lower cargo doorjamb, which could 
result in rapid decompression of the fuselage and consequent reduced 
structural integrity of the airplane, accomplish the following:

    Note 2: Where there are differences between the service bulletin 
and the AD, the AD prevails.
    Note 3: This AD is related to AD 96-13-03, amendment 39-9671, 
(61 FR 31009, June 19, 1996), and will affect Principal Structural 
Element (PSE) 53.09.035 of the DC-9 Supplemental Inspection Document 
(SID).

    (a) Prior to the accumulation of 48,000 total landings, or 
within 3,575 landings after the effective date of this AD, whichever 
occurs later, perform a one-time visual inspection to determine if 
the corners of the aft lower cargo doorjamb have been modified prior 
to the effective date of this AD.
    (b) If the visual inspection required by paragraph (a) of this 
AD reveals that the corners of the aft lower cargo doorjamb have not 
been modified, prior to further flight, perform a low frequency eddy 
current (LFEC) or x-ray inspection to detect cracks of the fuselage 
skin and doubler at all corners of the aft lower cargo doorjamb, in 
accordance with McDonnell Douglas Service Bulletin DC9-53-278, dated 
November 4, 1996.
    (1) If no crack is detected during the LFEC or x-ray inspection 
required by this paragraph, accomplish the requirements of either 
paragraph (b)(1)(i) or (b)(1)(ii) of this AD.
    (i) Option 1. Repeat the inspections as follows until paragraph 
(b)(1)(ii) of this AD is accomplished:
    (A) If the immediately preceding inspection was conducted using 
LFEC techniques, conduct the next inspection within 3,575 landings.
    (B) If the immediately preceding inspection was conducted using 
x-ray techniques, conduct the next inspection within 3,075 landings.
    (ii) Option 2. Prior to further flight, modify the corners of 
the aft lower cargo doorjamb, in accordance with the service 
bulletin. Prior to the accumulation of 28,000 landings after 
accomplishment of that modification, perform a LFEC inspection to 
detect cracks on the skin adjacent to the modification, in 
accordance with the service bulletin. Repeat the LFEC inspection 
thereafter at intervals not to exceed 20,000 landings.
    (A) If no crack is detected on the skin adjacent to the 
modification during any LFEC or x-ray inspection required by this 
paragraph, repeat the LFEC inspection thereafter at intervals not to 
exceed 20,000 landings.
    (B) If any crack is detected on the skin adjacent to the 
modification during any LFEC or x-ray inspection required by this 
paragraph, prior to further flight, repair it in accordance with a 
method approved by the

[[Page 42951]]

Manager, Los Angeles Aircraft Certification Office (ACO), FAA, 
Transport Airplane Directorate.
    (2) If any crack is found during any LFEC or x-ray inspection 
required by this paragraph and the crack is 2 inches or less in 
length: Prior to further flight, modify it in accordance with the 
service bulletin. Prior to the accumulation of 28,000 landings after 
accomplishment of the modification, perform a LFEC inspection to 
detect cracks on the skin adjacent to the modification, in 
accordance with the service bulletin.
    (i) If no crack is detected during the LFEC inspection required 
by this paragraph, repeat the LFEC inspection thereafter at 
intervals not to exceed 20,000 landings.
    (ii) If any crack is detected during the LFEC inspection 
required by this paragraph, prior to further flight, repair it in 
accordance with a method approved by the Manager, Los Angeles ACO.
    (3) If any crack is found during any LFEC or x-ray inspection 
required by this paragraph and the crack is greater than 2 inches in 
length: Prior to further flight, repair it in accordance with a 
method approved by the Manager, Los Angeles ACO.
    (c) If the visual inspection required by paragraph (a) of this 
AD reveals that the corners of the aft lower cargo doorjamb have 
been modified, but not in accordance with the DC-9 Structural Repair 
Manual (SRM) or Service Rework Drawing, prior to further flight, 
repair it in accordance with a method approved by the Manager, Los 
Angeles ACO.
    (d) If the visual inspection required by paragraph (a) of this 
AD reveals that the corners of the aft lower cargo doorjamb have 
been modified in accordance with DC-9 SRM or Service Rework Drawing, 
prior to the accumulation of 28,000 landings since accomplishment of 
that modification, or within 3,500 landings after the effective date 
of this AD, whichever occurs later, perform a LFEC inspection to 
detect cracks on the skin adjacent to the modification, in 
accordance with McDonnell Douglas Service Bulletin DC9-53-278, dated 
November 4, 1996. Repeat the LFEC inspection thereafter at intervals 
not to exceed 20,000 landings.
    (1) If no crack is detected during any LFEC inspection required 
by this paragraph, repeat the LFEC inspection thereafter at 
intervals not to exceed 20,000 landings.
    (2) If any crack is detected during any LFEC inspection required 
by this paragraph, prior to further flight, repair it in accordance 
with a method approved by the Manager, Los Angeles ACO.
    (e) 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 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles ACO.

    (f) 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 August 5, 1997.
John J. Hickey,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-21096 Filed 8-8-97; 8:45 am]
BILLING CODE 4910-13-U