[Federal Register Volume 63, Number 149 (Tuesday, August 4, 1998)]
[Proposed Rules]
[Pages 41479-41481]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-20678]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-197-AD]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model DC-10 Series 
Airplanes and KC-10 (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-10 series airplanes and KC-10 (military) airplanes. This proposal 
would require repetitive inspections to detect fatigue cracking of the 
rear spar cap of the horizontal stabilizer; and repair, if necessary. 
The proposed AD also would require a preventive modification of the 
rear spar cap of the horizontal stabilizer, which would constitute 
terminating action for the repetitive inspections. This proposal is 
prompted by reports of fatigue cracking of the rear spar cap of the 
horizontal stabilizer. The actions specified by the proposed AD are 
intended to prevent fatigue cracking of the rear spar cap of the 
horizontal stabilizer, which could result in reduced structural 
integrity of the horizontal stabilizer, and consequent reduced 
controllability of the airplane.

DATES: Comments must be received by September 18, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-197-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 (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 98-NM-197-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. 98-NM-197-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports indicating that, on several in-service 
McDonnell Douglas Model DC-10 series airplanes, cracking has been 
discovered on the vertical leg of the rear spar cap of the horizontal 
stabilizer, near the junction of the operating bulkhead. The cracking 
originated in the counterbore transition area. The affected airplanes 
had accumulated more than 46,000 total flight hours and 19,134 total 
landings.

[[Page 41480]]

The cause of the cracking has been attributed to fatigue. Such 
cracking, if not corrected, could result in reduced structural 
integrity of the horizontal stabilizer, and consequent reduced 
controllability of the airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved McDonnell Douglas Alert Service 
Bulletin DC10-55A028, dated April 27, 1998, which describes procedures 
for repetitive penetrant inspections or high frequency eddy current 
inspections to detect fatigue cracking of the rear spar cap of the 
horizontal stabilizer; and repair, if necessary. This alert service 
bulletin also describes procedures for a preventive modification of the 
rear spar cap of the horizontal stabilizer. The modification involves 
the installation of doublers on the rear spar cap, which would 
eliminate the need for the repetitive inspections. Accomplishment of 
the actions specified in the alert service bulletin is intended to 
adequately address the identified unsafe condition.

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 penetrant inspections or high 
frequency eddy current inspections to detect fatigue cracking of the 
rear spar cap of the horizontal stabilizer; and repair, if necessary. 
The proposed AD also would require a preventive modification of the 
rear spar cap of the horizontal stabilizer, which would constitute 
terminating action for the repetitive inspections. The actions would be 
required to be accomplished in accordance with the alert service 
bulletin described previously, except as discussed below.

Differences Between Proposed Rule and Alert Service Bulletin

    Operators should note that, for airplanes that have accumulated 
18,000 or more total landings, although the alert service bulletin 
recommends accomplishing the penetrant inspection or high frequency 
eddy current inspection within 60 days (after the release of the alert 
service bulletin), the FAA has determined that an interval of 1,500 
landings would address the identified unsafe condition in a timely 
manner, and would allow the airplanes to be inspected during a routine 
maintenance period. In developing an appropriate compliance time for 
this proposed AD, the FAA considered not only the manufacturer's 
recommendation, but the fail-safe features of the Model DC-10 series 
airplane, the degree of urgency associated with addressing the subject 
unsafe condition, the average utilization of the affected fleet, and 
the time necessary to perform the inspection (two hours). In light of 
all of these factors, the FAA finds a 1,500-landing compliance time 
(for airplanes that have accumulated 18,000 or more total landings) for 
the required actions to be warranted, in that it represents an 
appropriate interval of time allowable for affected airplanes to 
continue to operate without compromising safety.
    Operators should note that this AD proposes to mandate, within 5 
years after the effective date of this AD, the preventive modification 
described in the alert service bulletin, as terminating action for the 
repetitive inspections. The alert service bulletin provides for 
accomplishment of the preventive modification as an option only.
    The FAA has determined that long-term continued operational safety 
would be better assured by 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 continual inspections, has 
led the FAA to consider placing less emphasis on inspections and more 
emphasis on design improvements. The proposed preventive modification 
requirement is in consonance with these conditions.

Cost Impact

    There are approximately 420 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 242 airplanes of U.S. registry 
(124 Group 1 airplanes; 118 Group 2 airplanes) would be affected by 
this proposed AD.
    It would take approximately 2 work hours per airplane to accomplish 
the proposed inspections, at an average labor rate of $60 per work 
hour. Based on these figures, the cost impact of the inspections 
proposed by this AD on U.S. operators for Groups 1 and 2 airplanes is 
estimated to be $29,040, or $120 per airplane, per inspection cycle.
    It would take approximately 34 work hours per airplane to 
accomplish the proposed modification, at an average labor rate of $60 
per work hour. Required parts would cost approximately $6,236 per 
airplane for Group 1 airplanes, or $6,349 per airplane for Group 2 
airplanes. Based on these figures, the cost impact of the modification 
proposed by this AD on U.S. operators of Group 1 airplanes is estimated 
to be $1,026,224, or $8,276 per airplane; and, for Group 2 airplanes, 
$989,902, or $8,389 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.


[[Page 41481]]




Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

McDonnell Douglas: Docket 98-NM-197-AD.

    Applicability: Model DC-10 series airplanes and KC-10 (military) 
airplanes, as listed in McDonnell Douglas Alert Service Bulletin 
DC10-55A028, dated April 27, 1998; 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 prevent fatigue cracking of the rear spar cap of the 
horizontal stabilizer, which could result in reduced structural 
integrity of the horizontal stabilizer, and consequent reduced 
controllability of the airplane, accomplish the following:
    (a) Prior to the accumulation of 18,000 total landings, or 
within 1,500 landings after the effective date of this AD, whichever 
occurs later: Perform a penetrant inspection or a high frequency 
eddy current inspection to detect fatigue cracking of the rear spar 
cap of the horizontal stabilizer, in accordance with McDonnell 
Douglas Alert Service Bulletin DC10-55A028, dated April 27, 1998.
    (1) If no cracking is detected, repeat the inspection thereafter 
at intervals not to exceed 2,200 landings until accomplishment of 
the requirements of paragraph (b) of this AD.
    (2) If any cracking is detected, prior to further flight, repair 
in accordance with the alert service bulletin. Repeat the inspection 
thereafter at intervals not to exceed 2,200 landings until 
accomplishment of the requirements of paragraph (b) of this AD.
    (b) Within 5 years after the effective date of this AD, perform 
a penetrant inspection or a high frequency eddy current inspection 
to detect fatigue cracking of the rear spar cap of the horizontal 
stabilizer, in accordance with McDonnell Douglas Alert Service 
Bulletin DC10-55A028, dated April 27, 1998.
    (1) If no cracking is detected, prior to further flight, perform 
the preventive modification of the rear spar cap of the horizontal 
stabilizer, in accordance with the alert service bulletin. 
Accomplishment of this modification constitutes terminating action 
for the requirements of this AD.
    (2) If any cracking is detected, prior to further flight, 
repair, and perform the preventive modification of the rear spar cap 
of the horizontal stabilizer, in accordance with the alert service 
bulletin. Accomplishment of the modification constitutes terminating 
action for the requirements of this AD.
    (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 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.

    (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 July 27, 1998.
S.R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-20678 Filed 8-3-98; 8:45 am]
BILLING CODE 4910-13-U