[Federal Register Volume 63, Number 58 (Thursday, March 26, 1998)]
[Proposed Rules]
[Pages 14654-14656]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-7879]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-288-AD]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model DC-10 Series 
Airplanes and KC-10A (Military) Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain McDonnell Douglas Model 
DC-10 series airplanes and KC-10A (military) airplanes. This proposal 
would require repetitive inspections to detect cracking of the lower 
cap of the wing rear spar, and repair, if necessary. This proposal is 
prompted by reports of fatigue cracks found in the lower cap of the 
wing rear spar. The actions specified by the proposed AD are intended 
to detect and correct fatigue cracking of the lower cap of the wing 
rear spar, which could result in reduced structural integrity of the 
airplane.

DATES: Comments must be received by May 11, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 97-NM-288-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 The Boeing Company, Douglas Products Division, 3855 
Lakewood Boulevard, Long Beach, California 90846, Attention: Technical 
Publications Business Administration, Dept. C1-L51

[[Page 14655]]

(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: Ron Atmur, Aerospace Engineer, 
Airframe Branch, ANM-120L, FAA, Transport Airplane Directorate, Los 
Angeles Aircraft Certification Office, 3960 Paramount Boulevard, 
Lakewood, California 90712-4137; telephone (562) 627-5224; 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-288-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-114, Attention: Rules 
Docket No. 97-NM-288-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports of four instances of crack development 
in the lower cap of the wing rear spar. In all four instances, a single 
crack on the left or right wing had propagated from the aft leg into 
both the vertical and forward legs of the spar cap. All affected 
airplanes had accumulated over 32,000 flight hours and over 18,000 
landings. The cause of the cracking has been attributed to fatigue. 
Such fatigue cracking, if not detected and corrected in a timely 
manner, could result in reduced structural integrity of the airplane.

Other Relevant Rulemaking

    The subject area is designated as Principal Structural Element 
(PSE) No. 57.10.007/.008 in McDonnell Douglas Report No. L26-012, ``DC-
10 Supplemental Inspection Document (SID),'' Volume I, Revision 5, 
dated October 1994; Volume II, Revision 5, dated October 1994; and 
Volume III-94, dated November 1994. Inspections of that PSE are 
required by AD 95-23-09, amendment 39-9429 (60 FR 61649, December 1, 
1995). The inspections required for this PSE follow the fleet leader 
sampling criteria with a fatigue life threshold (Nth) greater than 
34,000 landings, which corresponds to a probability of failure per 
flight of 10-9; i.e., failure is extremely improbable. All 
of the cracks have been detected on airplanes with fewer than 34,000 
landings. Additionally, a PSE is defined as structure on which 
undetected failure could lead to loss of the structural integrity of 
the airplane. Therefore, the FAA has determined that an additional AD 
is warranted to require inspection of the lower cap of the wing rear 
spar on Model DC-10 series airplanes and KC-10A (military) airplanes 
after accumulation of 7,000 total landings. Such inspections would 
ensure that fatigue cracking is detected in a timely manner, well in 
advance of cracking reaching a critical length.

Explanation of Relevant Service Information

    The FAA has reviewed and approved McDonnell Douglas Alert Service 
Bulletin DC10-57A137, dated July 31, 1997, which describes procedures 
for repetitive eddy current surface inspections to detect cracking in 
the lower cap of the wing rear spar.

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 accomplishment of the actions specified in 
the alert service bulletin described previously, except as discussed 
below.

Differences Between the Alert Service Bulletin and This Proposed AD

    Operators should note that, although the alert service bulletin 
specifies that the manufacturer may be contacted for disposition of 
repair conditions, this proposal would require the repair of those 
conditions to be accomplished in accordance with a method approved by 
the FAA.
    Operators also should note that, although the alert service 
bulletin recommends a compliance time of 60 days for accomplishment of 
the initial inspection for airplanes that have accumulated more than 
7,000 total landings, this proposed AD would require that the initial 
inspection be accomplished within 18 months after the effective date of 
the AD. In developing the proposed compliance time, the FAA determined 
that a compliance time of 18 months is appropriate in consideration of 
the safety implications, the average utilization rate of the affected 
fleet, and the practical aspects of an orderly inspection of the fleet 
during regular maintenance periods.

Cost Impact

    There are approximately 283 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 201 airplanes of U.S. registry 
would be affected by this proposed AD, that it would take approximately 
8 work hours per airplane to accomplish the proposed inspection, and 
that the average labor rate is $60 per work hour. Based on these 
figures, the cost impact of the proposed AD on U.S. operators is 
estimated to be $96,480, or $480 per airplane, per inspection cycle.
    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.

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''

[[Page 14656]]

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-288-AD.

    Applicability: Model DC-10 series airplanes and KC-10A 
(military) airplanes, as listed in McDonnell Douglas Alert Service 
Bulletin DC10-57A137, dated July 31, 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 (c) 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 of the lower cap of the 
wing rear spar, which could result in reduced structural integrity 
of the airplane, accomplish the following:
    (a) Conduct an eddy current surface inspection to detect 
cracking of the lower cap of the wing rear spar, in accordance with 
the Accomplishment Instructions of McDonnell Douglas Alert Service 
Bulletin DC10-57-A137, dated July 31, 1997; at the later of the 
times specified in paragraphs (a)(1) and (a)(2) of this AD. 
Thereafter, repeat this inspection at intervals not to exceed 1,500 
landings.
    (1) Prior to the accumulation of 7,000 total landings, or within 
18 months after the effective date of this AD, whichever occurs 
later. Or
    (2) Within 1,500 landings after the accomplishment of the 
inspection of Principal Structural Elements 57.10.007 and 57.10.008, 
in accordance with AD 95-23-09, amendment 39-9429.
    (b) If any crack is found during any inspection required by this 
AD, prior to further flight, repair in accordance with a method 
approved by the Manager, Los Angeles Aircraft Certification Office 
(ACO), FAA, Transport Airplane Directorate.
    (c) 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, 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.

    (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 March 19, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-7879 Filed 3-25-98; 8:45 am]
BILLING CODE 4910-13-U