[Federal Register Volume 63, Number 17 (Tuesday, January 27, 1998)]
[Proposed Rules]
[Pages 3852-3854]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-1858]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-99-AD]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model DC-9-31 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 
DC-9-31 series airplanes.
    This proposal would require a one-time visual inspection to 
determine if all corners of the forward service door doorjamb have been 
modified previously, various follow-on repetitive inspections, and 
modification, if necessary. This proposal is prompted by reports of 
fatigue cracks found in the fuselage skin and doubler at the corners of 
the forward service door 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 March 13, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 97-NM-99-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; 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 
(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-99-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-99-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 forward service door doorjamb on 
Model DC-9-31 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 forward service door 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 DC9-53-288, dated February 10, 1997. The service bulletin 
describes the following procedures:
    1. Performing a one-time visual inspection to determine if the 
corners of the forward service door doorjamb have been modified;
    2. For airplanes on which the modification specified in Service 
Bulletin DC9-53-288 has not been accomplished: Performing a low 
frequency eddy current (LFEC) or x-ray inspection to detect cracks of 
the fuselage skin and doubler at all corners of the forward service 
door doorjamb;
    3. Conducting repetitive inspections, or modifying the corner skin 
of the doorjamb of the forward service door and performing follow-on 
action high frequency eddy current (HFEC) inspections, if no cracking 
is detected;
    4. Performing repetitive HFEC 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 HFEC inspections.
    Accomplishment of the modification will minimize the possibility of 
cracks in the fuselage skin and doubler.

[[Page 3853]]

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 a one-time visual inspection to determine if 
all corners of the forward service door doorjamb have been modified 
previously, various follow-on repetitive inspections, and modification, 
if necessary. The one-time visual inspection, follow-on repetitive 
inspections, and modification would be required to be accomplished in 
accordance with the service bulletin described previously.

Differences Between the Proposed Rule and the Relevant Service 
Information

    Operators 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 FAA.

Cost Impact

    There are approximately 64 McDonnell Douglas Model DC-9-31 series 
airplanes of the affected design in the worldwide fleet. The FAA 
estimates that 51 airplanes of U.S. registry would be affected by this 
proposed AD, that it would take approximately 1 work hour per airplane 
to accomplish the proposed one-time visual inspection, and that the 
average labor rate is $60 per work hour. Based on these figures, the 
cost impact of the one-time visual inspection of the proposed AD on 
U.S. operators is estimated to be $3,060, or $60 per airplane.
    The cost impact figure discussed above is 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.
    Should an operator be required to accomplish the LFEC or x-ray 
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 any necessary LFEC or x-ray 
inspection is estimated to be $60 per airplane, per inspection cycle.
    Should an operator be required to accomplish the HFEC 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 any necessary HFEC inspection is estimated to be $60 per 
airplane, per inspection cycle.
    Should an operator be required to accomplish the modification, it 
would take approximately 30 work hours per airplane to accomplish, at 
an average labor rate of $60 per work hour. Required parts would cost 
approximately $4,800 per airplane. Based on these figures, the cost 
impact of any necessary modification is estimated to be $6,600 per 
airplane.

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-99-AD.

    Applicability: Model DC-9-31 series airplanes, as listed in 
McDonnell Douglas Service Bulletin DC9-53-288, dated February 10, 
1997, 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 (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 detect and correct fatigue cracking in the fuselage skin or 
doubler at the corners of the forward service door 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: The words ``repair'' and ``modify/modification'' in this 
AD and the referenced service bulletin are used interchangeably.
    Note 4: This AD will affect Principal Structural Element (PSE) 
53.09.033 of the DC-9 Supplemental Inspection Document (SID).

    (a) Prior to the accumulation of 50,000 total landings, or 
within 3,225 landings after the effective date of this AD, whichever 
occurs later, perform a one-time visual inspection to determine if 
the corners of the forward service door doorjamb have been modified. 
Perform the inspection in accordance with McDonnell Douglas Service 
Bulletin DC9-53-288, dated February 10, 1997.
    (b) For airplanes identified as Group 1 in McDonnell Douglas 
Service Bulletin DC9-53-288, dated February 10, 1997: If the visual 
inspection required by paragraph (a) of this AD reveals that the 
corners of the forward service door doorjamb have not been modified, 
prior to further flight, perform a low frequency eddy currrent 
(LFEC) or x-ray inspection to detect cracks of the fuselage skin and 
doubler at all corners of the forward service door doorjamb, in 
accordance with McDonnell Douglas Service Bulletin DC9-53-288, dated 
February 10, 1997.
    (1) Group 1, Condition 1. If no crack is detected during any 
LFEC or x-ray inspection required by paragraph (b) of this AD, 
accomplish the requirements of either paragraph (b)(1)(i) or 
(b)(1)(ii) of this AD, in accordance with the service bulletin.
    (i) Option 1. Repeat the LFEC inspection required by this 
paragraph thereafter at intervals not to exceed 3,225 landings, or 
the x-ray inspection required by this paragraph thereafter at 
intervals not to exceed 3,075 landings; or
    (ii) Option 2. Prior to further flight, modify the corner skin 
of the forward service door

[[Page 3854]]

doorjamb in accordance with the service bulletin. Prior to the 
accumulation of 28,000 landings after accomplishment of the 
modification, perform a high frequency eddy current (HFEC) 
inspection to detect cracks on the skin adjacent to the 
modification, in accordance with the service bulletin.
    (A) If no crack is detected on the skin adjacent to the 
modification during the HFEC required by this paragraph, repeat the 
HFEC 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 HFEC inspection required by this paragraph, 
prior to further flight, repair it in accordance with a method 
approved by the Manager, Los Angeles Aircraft Certification Office 
(ACO), FAA, Transport Airplane Directorate.
    (2) Group 1, Condition 2. If any crack is found during any LFEC 
or x-ray inspection required by paragraph (b) of this AD, and the 
crack is 2 inches or less in length: Prior to further flight, 
modify/repair the corners of the doorjamb of the forward service 
door in accordance with the service bulletin. Prior to the 
accumulation of 28,000 landings after accomplishment of the 
modification, perform a HFEC 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 HFEC inspection required 
by this paragraph, repeat the HFEC inspection thereafter at 
intervals not to exceed 20,000 landings.
    (ii) If any crack is detected during any HFEC inspection 
required by this paragraph, prior to further flight, repair it in 
accordance with a method approved by the Manager, Los Angeles ACO.
    (3) Group 1, Condition 3. If any crack is found during any LFEC 
or x-ray inspection required by paragraph (b) of this AD, 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) Group 2, Condition 1. For airplanes identified as Group 2 in 
McDonnell Douglas Service Bulletin DC9-53-288, dated February 10, 
1997: If the visual inspection required by paragraph (a) of this AD 
reveals that the corners of the forward service door doorjamb have 
been modified previously in accordance with the McDonnell Douglas 
DC-9 Structural Repair Manual, using a steel doubler, accomplish 
either paragraph (c)(1) or (c)(2) of this AD in accordance with 
McDonnell Douglas Service Bulletin DC9-53-288, dated February 10, 
1997.
    (1) Option 1. Prior to the accumulation of 6,000 landings after 
accomplishment of that modification, or within 3,225 landings after 
the effective date of this AD, whichever occurs later, perform an 
HFEC 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 HFEC inspection required 
by paragraph (c)(1) of this AD, repeat the HFEC inspection 
thereafter at intervals not to exceed 3,000 landings.
    (ii) If any crack is detected during any HFEC inspection 
required by paragraph (c)(1) of this AD, prior to further flight, 
repair it in accordance with a method approved by the Manager, Los 
Angeles ACO.
    (2) Option 2. Prior to further flight, modify the corner skin of 
the forward service door doorjamb in accordance with the service 
bulletin. Prior to the accumulation of 28,000 landings after 
accomplishment of the modification, perform an HFEC inspection to 
detect cracks on the skin adjacent to the modification, in 
accordance with the service bulletin.
    (i) If no crack is detected on the skin adjacent to the 
modification during the HFEC required by this paragraph, repeat the 
HFEC inspection thereafter at intervals not to exceed 20,000 
landings.
    (ii) If any crack is detected on the skin adjacent to the 
modification during any HFEC inspection required by this paragraph, 
prior to further flight, repair it in accordance with a method 
approved by the Manager, Los Angeles Aircraft Certification Office 
(ACO), FAA, Transport Airplane Directorate.
    (d) Group 2, Condition 2. For airplanes identified as Group 2 in 
McDonnell Douglas Service Bulletin DC9-53-288, dated February 10, 
1997: If the visual inspection required by paragraph (a) of this AD 
reveals that the corners of the forward service door doorjamb have 
been modified previously in accordance with McDonnell Douglas DC-9 
Structural Repair Manual, using an aluminum doubler, prior to the 
accumulation of 28,000 landings after accomplishment of that 
modification, or within 3,225 landings after the effective date of 
this AD, whichever occurs later, perform an HFEC inspection to 
detect cracks on the skin adjacent to the modification, in 
accordance with McDonnell Douglas Service Bulletin DC9-53-288, dated 
February 10, 1997.
    (1) If no crack is detected on the skin adjacent to the 
modification during the HFEC required by this paragraph, repeat the 
HFEC inspection thereafter at intervals not to exceed 20,000 
landings.
    (2) If any crack is detected on the skin adjacent to the 
modification during any HFEC inspection required by this paragraph, 
prior to further flight, repair it in accordance with a method 
approved by the Manager, Los Angeles Aircraft Certification Office 
(ACO), FAA, Transport Airplane Directorate.
    (e) Group 2, Condition 3. For airplanes identified as Group 2 in 
McDonnell Douglas Service Bulletin DC9-53-288, dated February 10, 
1997: If the visual inspection required by paragraph (a) of this AD 
reveals that the corners of the forward service door doorjamb have 
been modified previously, but not in accordance with McDonnell 
Douglas Structural Repair Manual, prior to further flight, repair 
the corners in accordance with a method approved by the Manager, Los 
Angeles ACO.
    (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 ACO. 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 5: 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 January 20, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-1858 Filed 1-26-98; 8:45 am]
BILLING CODE 4910-13-U