[Federal Register Volume 59, Number 191 (Tuesday, October 4, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-24199]


  Federal Register / Vol. 59, No. 191 / Tuesday, October 4, 1994 /
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[[Page Unknown]]

[Federal Register: October 4, 1994]


                                                   VOL. 59, NO. 191

                                           Tuesday, October 4, 1994

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 93-NM-221-AD; Amendment 39-9039; AD 94-20-10]

 

Airworthiness Directives; McDonnell Douglas Model DC-10-10, -15, 
-30, and -40 Series Airplanes and KC-10A (Military) Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain McDonnell Douglas Model DC-10-10, -15, -30, and -
40 series airplanes and KC-10A (military) airplanes, that requires 
inspections to detect fatigue-related cracking in certain areas of the 
horizontal stabilizer; and repair of cracked parts. It also requires 
installation of terminating modifications, which, when accomplished, 
would eliminate the repetitive inspections. This amendment is prompted 
by reports of fatigue-related cracks found on the horizontal 
stabilizer. The actions specified by this AD are intended to prevent 
loss of the load carrying and fail safe capability of the horizontal 
stabilizer, damage to the adjacent structure, and subsequent reduced 
structural integrity of the airplane, due to the problems associated 
with fatigue cracking.

DATES: Effective October 31, 1994.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of November 3, 1994.

ADDRESSES: The service information referenced in this AD may be 
obtained from McDonnell Douglas Corporation, P.O. Box 1771, Long Beach, 
California 90801-1771, Attention: Business Unit Manager, Technical 
Administrative Support, Dept. L51, M.C. 2-98. This information may be 
examined at the Federal Aviation Administration (FAA), Transport 
Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, 
Washington; or at the FAA, Transport Airplane Directorate, Los Angeles 
Aircraft Certification Office, 3229 East Spring Street, Long Beach, 
California; or at the Office of the Federal Register, 800 North Capitol 
Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Wahib Mina, Aerospace Engineer, 
Airframe Branch, ANM-121L, FAA, Transport Airplane Directorate, Los 
Angeles ACO, 3229 East Spring Street, Long Beach, California 90806-
2425; telephone (310) 988-5324; fax (310) 988-5210.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to certain McDonnell Douglas Model 
DC-10-10, -15, -30, and -40 series airplanes and KC-10A (military) 
airplanes was published as a notice of proposed rulemaking (NPRM) in 
the Federal Register on March 30, 1994 (59 FR 14800). That action 
proposed to require inspections to detect fatigue-related cracking in 
certain areas of the horizontal stabilizer; and repair of cracked 
parts. It also proposed to require the installation of certain 
terminating modifications that would eliminate the need for the 
repetitive inspections.

Immediate Adoption of This Regulation

    Since issuance of the NPRM, one operator has reported finding a 
crack in the area of the forward spar upper cap on the horizontal 
stabilizer on a Model DC-10-10 series airplane that had accumulated 
approximately 16,000 landings. This evidence indicates that fatigue 
cracking may begin in this area much earlier than what was previously 
considered. In light of this, the FAA has reconsidered the compliance 
time proposed for the initiation of inspections to detect cracking in 
this subject area on these airplanes. The FAA now has determined that 
the initiation of inspections of Model DC-10-10 and -15 series 
airplanes must begin prior to the accumulation of 12,000 total landings 
or 90 days after the effective date of this AD, whichever occurs later. 
(The compliance time for this action that was proposed in the notice 
was 18,000 total landings.) The lowered threshold of 12,000 total 
landings is necessary to ensure that cracking is detected and corrected 
in a timely manner, and to prevent the loss of load-carrying and fail 
safe capability of the horizontal stabilizer due to the problems 
associated with fatigue cracking. The compliance time for the 
inspections specified in paragraph (a) of this final rule has been 
revised accordingly.
    In making this revision, the FAA finds that, with respect to the 
reduced compliance threshold, a situation exists that requires the 
immediate adoption of this regulation. Therefore, it is found that 
notice and opportunity for prior public comment hereon are 
impracticable, and that good cause exists for making this amendment 
effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 93-NM-221-AD.'' The postcard will be date stamped and 
returned to the commenter.

Discussion of Comments Received to the NPRM

    Interested persons have been afforded an opportunity to participate 
in the making of a portion of this amendment. Due consideration has 
been given to the comments received.
    One commenter supports the proposal.
    Several commenters request that the proposed rule be revised to 
exclude the Models DC-10-30 and -40 from the applicability until more 
information is gathered to substantiate that these airplanes are 
subject to the addressed unsafe condition. These commenters point out 
that cracks have been reported on Model DC-10-10 series airplanes only. 
One commenter states that the airframe manufacturer previously had 
requested that operators of Model DC-10 series airplanes inspect their 
airplanes for cracking and, as a result, none was found on any models 
other than the Model DC-10-10 and -15 series. Another commenter 
suggests that the spar cap and skin panel installed on Models DC-10-30 
and -40 are thicker than those on Models DC-10-10 and -15; therefore, 
the possibility of these items cracking on the Model DC-10-30 and -40 
airplanes is very low.
    The FAA does not concur with these commenters' request. Although 
fatigue cracking may not have been detected on in-service Model DC-10-
30 and -40 series airplanes, the airframe manufacturer has conducted 
load, fatigue, and damage-tolerance analyses, which indicate that 
fatigue-related cracking is likely to occur on all Model DC-10 series 
airplanes as these airplanes accumulate flight cycles. The compliance 
thresholds specified in this AD, as well as the compliance times for 
the required initial and repetitive inspections, were developed in 
consideration of these analyses and with the participation of the 
airframe manufacturer.
    Several commenters request that the rule be revised to give credit 
for visual inspections of the area that were performed previously, and 
to add a visual inspection as an option for accomplishment of the 
initial eddy current inspection. These commenters state that a damage 
tolerance assessment conducted by the airframe manufacturer has shown 
that an initial visual inspection will ensure that the structural 
integrity of the horizontal stabilizer spar cap and skin is maintained. 
Additionally, by permitting a visual inspection to be performed, which 
takes less time and materials than an eddy current inspection, the 
economic impact of non-scheduled maintenance and removal of aircraft 
from service would be reduced for operators, as well as the 
corresponding inconvenience for the traveling public.
    The FAA concurs with these commenters' request. Subsequent to the 
issuance of the notice, the FAA reviewed and approved Revision 1 to 
McDonnell Douglas DC-10 Service Bulletins 55-24 and 55-25, both dated 
August 3, 1994. These revised service bulletins contain revised 
instructions for accomplishing the eddy current inspection (to make it 
less complicated), and instructions for performing an optional visual 
inspection in lieu of the initial eddy current inspection to determine 
if cracks exist in the horizontal stabilizer forward cap and skin 
panel. The FAA has revised the final rule to permit operators to 
perform this optional visual inspection as the initial inspection only. 
All repetitive inspections must be performed using eddy current 
techniques.
    Several commenters request that the proposed rule be revised to 
eliminate the compliance time for the terminating modifications. These 
commenters consider that these modifications should be optional instead 
of mandatory. Other commenters indicate that fatigue-related cracks are 
cycle-dependent, not calendar time-dependent; therefore, it is 
inappropriate to impose a calendar time compliance time on a cycle-
dependent phenomenon. The commenters also consider that the proposed 
compliance time of five years for installation of the terminating 
modifications could be unfair to operators of low-time airplanes, 
since, in some cases, an operator could be required to install the 
terminating modifications before the airplane has reached the threshold 
for the initial inspection.
    The FAA does not concur with the commenters' request to allow the 
terminating action to be optional. The FAA has determined that long 
term continued operational safety will 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 modifications required by this AD are in consonance 
with these considerations.
    The FAA does acknowledge, however, that the proposed compliance 
time for installation of the terminating modifications could present an 
unfair situation to operators of low-time airplanes. This was not the 
FAA's intent. Therefore, the FAA has revised paragraph (d) of the final 
rule to specify modification prior to the accumulation of a certain 
number of cycles (depending upon airplane model) or within 5 years, 
whichever occurs later.
    The FAA has revised paragraphs (a)(1), (b)(1), and (c)(1) of the 
final rule to delete the previously proposed requirement to continue 
inspections after installation of a repair that has been approved by 
the Manager of the Los Angeles Aircraft Certification Office. The FAA 
has determined that deletion of this requirement is appropriate, since 
some repairs that have been approved have incorporated a terminating 
action, thereby eliminating the need for continuing repetitive 
inspections.

Cost Impact

    There are approximately 427 Model DC-10-10, -15, -30, and -40 
series airplanes and KC-10A (military) airplanes of the affected design 
in the worldwide fleet. The FAA estimates that 241 airplanes of U.S. 
registry will be affected by this AD.
    The accomplishment of the optional initial visual inspection will 
take approximately 1 workhour per airplane per inspection, at an 
average labor charge of $55 per workhour. Based on these figures, the 
total cost impact of this optional inspection on U.S. operators who 
elect to accomplish it is estimated to be $55 per airplane.
    The accomplishment of the eddy current inspections will take 
approximately 3 workhours per airplane per inspection, at an average 
labor charge of $55 per workhour. Based on these figures, the total 
cost impact of the inspection requirement on U.S. operators is 
estimated to be $39,765, or $165 per airplane, per inspection cycle.
    The accomplishment of the modification of the forward spar upper 
cap will take approximately 248 workhours per airplane. Likewise, the 
accomplishment of the modification of the forward upper skin panel will 
take approximately 248 workhours per airplane. The average labor rate 
is $55 per workhour. Required parts will cost approximately $10,600 per 
airplane. Based on these figures, the total cost impact of the 
modification actions AD on U.S. operators is estimated to be 
$9,129,080, or $37,880 per airplane.
    The FAA recognizes that the required modifications require a large 
number of workhours to accomplish. However, the 5-year compliance time 
specified in paragraph (d) of this proposed AD should allow ample time 
for the modifications to be accomplished coincidentally with scheduled 
major airplane inspection and maintenance activities, thereby 
minimizing the costs associated with special airplane scheduling.
    The total cost impact figures discussed above are based on 
assumptions that no operator has yet accomplished any of the 
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 adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, may be obtained from the Rules Docket at the 
location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

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

94-20-10 McDonnell Douglas: Amendment 39-9039. Docket 93-NM-221-AD.

    Applicability: Model DC-10-10, -15, -30, and -40 series 
airplanes and KC-10A (military) airplanes; as listed in McDonnell 
Douglas DC-10 Service Bulletins 55-24 and 55-25, Revision 1, both 
dated August 3, 1994; certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent reduced structural integrity of the airplane, 
accomplish the following:
    (a) For Model DC-10-10 and -15 series airplanes: Prior to the 
accumulation of 12,000 total landings, or within 90 days after the 
effective date of this AD, whichever occurs later, unless previously 
accomplished within the last 4,500 landings, perform either an 
initial an eddy current inspection or visual inspection to detect 
fatigue-related cracking of the forward spar upper caps on the 
horizontal stabilizer, in accordance with McDonnell Douglas DC-10 
Service Bulletin 55-24, Revision 1, dated August 3, 1994.

    Note 1: Eddy current inspections accomplished in accordance with 
McDonnell Douglas DC-10 Service Bulletin 55-24, dated October 25, 
1993, are considered acceptable for compliance with this paragraph.

    (1) If any crack is detected, prior to further flight, repair 
the crack in accordance with a method approved by the Manager, Los 
Angeles Aircraft Certification Office (ACO), FAA, Transport Airplane 
Directorate.
    (2) If no crack is detected, perform repetitive inspections 
thereafter in accordance with the service bulletin and in accordance 
with the following schedule:
    (i) If the initial inspection was performed using visual 
techniques, perform an eddy current inspection within 1,000 landings 
after the visual inspection. Thereafter, repeat the eddy current 
inspection at intervals not to exceed 4,500 landings.
    (ii) If the initial inspection was performed using eddy current 
techniques, repeat the eddy current inspection thereafter at 
intervals not to exceed 4,500 landings.
    (b) For Model DC-10-10 and -15 series airplanes: Prior to the 
accumulation of 10,000 total landings, or within 120 days after the 
effective date of this AD, whichever occurs later, unless previously 
accomplished within the last 4,500 landings, perform either an 
initial eddy current inspection or visual inspection to detect 
fatigue-related cracking of the forward upper skin panel of the 
horizontal stabilizer, in accordance with McDonnell Douglas DC-10 
Service Bulletin 55-25, Revision 1, dated August 3, 1994.

    Note 2: Eddy current inspections performed in accordance with 
McDonnell Douglas DC-10 Service Bulletin 55-25, dated October 25, 
1993, are considered acceptable for compliance with this paragraph.

    (1) If any crack is detected, prior to further flight, repair 
the crack in accordance with a method approved by the Manager, Los 
Angeles ACO, FAA, Transport Airplane Directorate.
    (2) If no crack is detected, perform repetitive eddy current 
inspections thereafter in accordance with the service bulletin and 
in accordance with the following schedule:
    (i) If the initial inspection was performed using visual 
techniques, perform an eddy current inspection within 1,000 landings 
after the visual inspection. Thereafter, repeat the eddy current 
inspection at intervals not to exceed 4,500 landings.
    (ii) If the initial inspection was performed using eddy current 
techniques, repeat the eddy current inspection thereafter at 
intervals not to exceed 4,500 landings.
    (c) For Model DC-10-30 and -40 series airplanes: Prior to the 
accumulation of 17,500 total landings, or within 120 days after the 
effective date of this AD, whichever occurs later, unless previously 
accomplished within the last 4,500 landings, perform either an 
initial eddy current inspection or visual inspection to detect 
fatigue-related cracking of the forward upper skin panel of the 
horizontal stabilizer, in accordance with McDonnell Douglas DC-10 
Service Bulletin 55-25, Revision 1, dated August 3, 1994.

    Note 3: Eddy current inspections performed in accordance with 
McDonnell Douglas DC-10 Service Bulletin 55-25, dated October 25, 
1993, are considered acceptable for compliance with this paragraph.

    (1) If any crack is detected, prior to further flight, repair 
the crack in accordance with a method approved by the Manager, Los 
Angeles ACO, FAA, Transport Airplane Directorate.
    (2) If no crack is detected, perform repetitive eddy current 
inspections thereafter in accordance with the service bulletin and 
in accordance with the following schedule:
    (i) If the initial inspection was performed using visual 
techniques, perform an eddy current inspection within 1,000 landings 
after the visual inspection. Thereafter, repeat the eddy current 
inspection at intervals not to exceed 4,500 landings.
    (ii) If the initial inspection was performed using eddy current 
techniques, repeat the eddy current inspection thereafter at 
intervals not to exceed 4,500 landings.
    (d) For all airplanes: Install the preventative modifications 
specified in McDonnell Douglas DC-10 Service Bulletin 55-24, 
Revision 1, dated August 3, 1994; and McDonnell Douglas DC-10 
Service Bulletin 55-25, Revision 1, dated August 3, 1994; in 
accordance with the following schedule. Accomplishment of these 
preventative modifications constitutes terminating action for the 
repetitive inspections required by this AD.

    Note 4: Accomplishment of these preventative modifications in 
accordance with McDonnell Douglas DC-10 Service Bulletin 55-24, 
dated October 25, 1993; or McDonnell Douglas DC-10 Service Bulletin 
55-25, dated October 25, 1993; as applicable; is considered 
acceptable for compliance with this paragraph.

    (1) For Model DC-10-10 and -15 series airplanes:
    (i) Prior to the accumulation of 21,000 total landings, or 
within 5 years after the effective date of this AD, whichever occurs 
later, accomplish the preventative modifications of the forward spar 
upper cap on the horizontal stabilizer in accordance with McDonnell 
Douglas DC-10 Service Bulletin 55-24, Revision 1, dated August 3, 
1994.
    (ii) Prior to the accumulation of 19,000 total landings, or 
within 5 years after the effective date of this AD, whichever occurs 
later, accomplish the modification of the forward upper skin panel 
on the horizontal stabilizer in accordance with McDonnell Douglas 
DC-10 Service Bulletin 55-25, Revision 1, dated August 3, 1994.
    (2) For Model DC-10-30 and -40 series airplanes:
    (i) Prior to the accumulation of 44,250 total landings, or 
within 5 years after the effective date of this AD, whichever occurs 
later, accomplish the modification of the forward spar upper cap on 
the horizontal stabilizer in accordance with McDonnell Douglas DC-10 
Service Bulletin 55-24, Revision 1, dated August 3, 1994.
    (ii) Prior to the accumulation of 26,500 total landings, or 
within 5 years after the effective date of this AD, whichever occurs 
later, accomplish the modification of the forward upper skin panel 
on the horizontal stabilizer in accordance with McDonnell Douglas 
DC-10 Service Bulletin 55-25, Revision 1, dated August 3, 1994.
    (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 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 5: 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 
Secs. 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.
    (g) The inspections and modifications shall be done in 
accordance with McDonnell Douglas DC-10 Service Bulletin 55-24, 
Revision 1, dated August 3, 1994; and McDonnell Douglas DC-10 
Service Bulletin 55-25, Revision 1, dated August 3, 1994. This 
incorporation by reference was approved by the Director of the 
Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 
51. Copies may be obtained from McDonnell Douglas Corporation, P.O. 
Box 1771, Long Beach, California 90801- 1771, Attention: Business 
Unit Manager, Technical Administrative Support, Dept. L51, M.C. 2-
98. Copies may be inspected at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the 
FAA, Transport Airplane Directorate, Los Angeles Aircraft 
Certification Office, 3229 East Spring Street, Long Beach, 
California; or at the Office of the Federal Register, 800 North 
Capitol Street, NW., suite 700, Washington, DC.
    (h) This amendment becomes effective on October 31, 1994.

    Issued in Renton, Washington, on September 26, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-24199 Filed 10-3-94; 8:45 am]
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