[Federal Register Volume 59, Number 112 (Monday, June 13, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-13627]


[[Page Unknown]]

[Federal Register: June 13, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-NM-90-AD; Amendment 39-8933; AD 94-12-05]

 

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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to all McDonnell Douglas Model DC-10 series airplanes and 
Model KC-10A (military) airplanes, that requires inspections to detect 
cracks in wing stringer number 41; installation of a repair, if 
necessary; and modification of that stringer. This amendment is 
prompted by reports of fatigue cracks in outer wing stringer number 41. 
The actions specified by this AD are intended to prevent reduced 
structural integrity of the wing.

DATES: Effective July 13, 1994.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of July 13, 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: Maureen Moreland, Aerospace Engineer, 
Airframe Branch, ANM-120L, FAA, Transport Airplane Directorate, Los 
Angeles Aircraft Certification Office, 3229 East Spring Street, Long 
Beach, California 90806-2425; telephone (310) 988-5238; fax (310) 988-
5210.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations to include an airworthiness directive (AD) that is 
applicable to all McDonnell Douglas Model DC-10 series airplanes and 
Model KC-10A (military) airplanes was published in the Federal Register 
on September 24, 1993 (58 FR 49946). That action proposed to require 
inspections to detect cracks in wing stringer number 41; installation 
of a repair, if necessary; and modification of that stringer.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.
    One commenter supports the proposed rule.
    The Air Transport Association (ATA) of America, on behalf of one of 
its members, requests that the FAA include a flow diagram in the 
proposal since its provisions are complex. The FAA does not concur. The 
FAA considers that the requirements of this AD are presented in a 
reasonably clear manner in the text of the final rule. In addition, 
McDonnell Douglas DC-10 Service Bulletin 57-114, Revision 1, dated July 
26, 1993, which is referenced in the AD as the appropriate source of 
service information, provides corresponding guidance for accomplishment 
of the actions required by this AD.
    ATA also suggests that, prior to issuance of the final rule, the 
FAA should verify that the service bulletin will not create problems 
for operators, and that accomplishment of the service bulletin should 
be verified by an operator before the AD is finalized. One ATA member 
experienced difficulty accomplishing the permanent repair specified in 
the service bulletin because parts listed did not fit, drawings were 
erroneous, and fastener grip lengths were inadequate for the repair. 
The FAA concurs with the commenter's request. The FAA has conveyed 
these concerns to the manufacturer, and has verified that the initial 
problems expressed by the commenter have been corrected in Revision 1 
of the service bulletin. Since Revision 1 of the service bulletin was 
cited in the proposal as the appropriate source of service information, 
the FAA finds that no change to the AD is necessary.
    One commenter requests that the FAA allow visual inspection methods 
to be used in lieu of the proposed eddy current inspection methods. The 
commenter indicates that fastener accessibility enables accomplishment 
of a visual inspection and provides an equivalent level of crack 
detection. The FAA does not concur. Based on the results of crack 
growth analysis, the FAA has determined that a visual inspection of the 
stringer cannot provide an acceptable level of crack detection. In 
addition, the FAA based the repetitive inspection intervals on the 
crack growth analysis results based upon the minimum crack length 
detectable by eddy current inspection.
    The commenter also requests that credit be given for general visual 
inspections accomplished previously. A second commenter supports the 
proposed rule, but requests that the AD be revised to state that 
inspections accomplished within 1,500 landings prior to the effective 
date of the AD are acceptable in lieu of the initial inspection. The 
commenters provide no justification for these requests. Since the FAA 
has determined that a visual inspection of the stringer does not 
provide an acceptable level of crack detection, as discussed 
previously, the FAA considers that the requirement for eddy current 
inspections is appropriate and credit cannot be extended for general 
visual inspections accomplished previously. However, the phrase 
``unless accomplished previously,'' which appears in the ``Compliance'' 
paragraph of the final rule, provides credit for operators that have 
accomplished the required inspection prior to the effective date of 
this AD in accordance with McDonnell Douglas DC-10 Service Bulletin 57-
114, Revision 1, dated July 26, 1993.
    One commenter requests that the first inspection accomplished to 
comply with this AD be required during the airplane's next heavy 
maintenance visit if a general visual inspection has been accomplished 
prior to the effective date of the AD. The FAA does not concur. A 
general visual inspection of the stringer does not provide an 
acceptable level of crack detection, as discussed previously. In 
developing an appropriate initial compliance time for this action, the 
FAA considered the safety implications and normal maintenance schedules 
for timely accomplishment of the inspection. In consideration of these 
items, the FAA has determined that 6,500 total landings or 1,500 
landings after the effective date of the AD, whichever occurs later, 
represents the maximum interval of time allowable wherein the 
inspection can reasonably be accomplished and an acceptable level of 
safety can be maintained.
    The same commenter states that the service bulletin cited in the AD 
specifies that one reason for accomplishing the actions described in 
the service bulletin is to prevent unscheduled maintenance downtime for 
replacement of a cracked stringer; therefore, the commenter questions 
the need for this AD. The commenter adds that, to date, stringer 41 
cracking has not impacted its maintenance due to the viable maintenance 
program currently in place. The commenter states that imposing an AD at 
this time would only complicate its maintenance program and would 
contribute little toward ensuring that the airplane wing structure is 
operating in good condition.
    The FAA does not concur. As explained in the preamble of the 
proposal, the FAA has received reports of fatigue cracks in outer wing 
stringer number 41 and, in one case, complete failure of the stringer. 
Such fatigue cracking presents an unsafe condition in airplanes, since 
it could eventually lead to failure of the stringer and reduced 
structural integrity of the wing. The FAA has determined that this 
unsafe condition could exist or eventually develop on Model DC-10 
series airplanes and Model KC-10A (military) airplanes, and that 
repetitive inspections of the affected area must be mandated to ensure 
that safety is not degraded. The appropriate vehicle for mandating such 
action to correct an unsafe condition is the airworthiness directive.
    One commenter requests that the proposed compliance time for 
accomplishment of the initial inspection specified in paragraph (b)(1) 
of the proposal be changed from ``[p]rior to the accumulation of 6,500 
total landings, or within 1,500 landings after the effective date of 
the AD, whichever occurs later,'' to ``[p]rior to the accumulation of 
6,500 total landings, or within one year after the effective date of 
this AD, whichever occurs later.'' The commenter operates Model DC-10-
40 series airplanes of non-U.S. registry for training flights for 
cockpit crews. The commenter explains that, during one training flight 
period of a few weeks, the number of flight cycles accumulated may be 
more than 1,500 landings. The commenter adds that the proposed 
inspections and modifications require entry into the fuel tanks; 
therefore, the commenter plans to accomplish the initial inspections 
and the modifications during regularly scheduled maintenance.
    The FAA does not concur with the commenter's request. Compliance 
times for AD's are normally based on a parameter related to failure of 
a particular component. In this case, fatigue cracking in outer wing 
stringer number 41 and subsequent failure of the stringer are 
undoubtedly related to the number of landings. The FAA has determined, 
in this case, that there is no apparent direct relationship between 
failure of the stringer and calendar time. In light of this, and in 
consideration of the average utilization rate of the affected U.S. 
operators and the practical aspects of orderly inspections of the U.S. 
fleet during regular maintenance periods, the FAA established the 
compliance times specified in this AD. The FAA maintains that those 
compliance times are appropriate. However, the FAA would consider a 
request for adjustment of the compliance time, in accordance with the 
provisions of paragraph (c) of this AD, provided that, for example, 
continued operational safety of the airplane could be assured until the 
required action is accomplished.
    One commenter requests that, in order for the AD requirements to 
align with the actions described in the service bulletin, 
accomplishment of the preventative modification should be considered 
optional, and that operators should be permitted to accomplish 
repetitive inspections at intervals of 4,000 landings in lieu of the 
preventative modification. The FAA does not concur. The degree of 
assurance necessary as to the adequacy of inspections needed to 
maintain the safety of the aging transport airplane fleet, coupled with 
a better understanding of the human factors associated with numerous 
repetitive inspections, has caused the FAA to place less emphasis on 
repetitive inspections and more emphasis on design improvements and 
material replacement. Thus, in lieu of its previous position of 
continual inspection, and repair or modification on condition if cracks 
are found, the FAA has decided to require, whenever practicable, 
airplane modifications necessary to remove the source of the particular 
aging phenomena.
    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.
    There are approximately 426 Model DC-10 series airplanes and Model 
KC-10A (military) airplanes of the affected design in the worldwide 
fleet. The FAA estimates that 121 Model DC-10-10 and -15 series 
airplanes of U.S. registry will be affected by this AD, that it will 
take approximately 13.6 work hours per airplane to accomplish the 
required actions, and that the average labor rate is $55 per work hour. 
Required parts for Model DC-10-10 and -15 series airplanes will cost 
approximately $586 per airplane. Based on these figures, the total cost 
impact of the AD on U.S. operators of Model DC-10-10 and -15 series 
airplanes is estimated to be $161,414, or $1,334 per airplane.
    The FAA estimates that 148 Model DC-10-30 and -40 series airplanes 
and Model KC-10A (military) airplanes of U.S. registry will be affected 
by this AD, that it will take approximately 13.6 work hours per 
airplane to accomplish the required actions, and that the average labor 
rate is $55 per work hour. Required parts for Model DC-10-30 and -40 
series airplanes and Model KC-10A (military) airplanes will cost 
approximately $1,420 per airplane. Based on these figures, the total 
cost impact of the AD on U.S. operators of Model DC-10-30 and -40 
series airplanes and Model KC-10A (military) airplanes is estimated to 
be $320,864, or $2,168 per airplane.
    Based on these figures, the total cost impact of the AD on U.S. 
operators is estimated to be $482,278. The total cost impact figure is 
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. -
    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. -
    For the reasons discussed above, I certify that this action: (1) Is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it 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 14 CFR part 
39 of the Federal Aviation Regulations 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:

94-12-05   McDonnell Douglas: Amendment 39-8933. Docket 93-NM-90-AD.

     -Applicability: All Model DC-10-10, -10F, -15, -30, -30F, -40, 
and -40F series airplanes and Model KC-10A (military) airplanes; 
certificated in any category. -
    Compliance: Required as indicated, unless accomplished 
previously. -
    To prevent reduced structural integrity of the wing, accomplish 
the following: -
    (a) For Model DC-10-10, -10F, and -15 series airplanes: 
Accomplish paragraphs (a)(1), (a)(2), (a)(3), and (a)(4) of this AD 
in accordance with McDonnell Douglas DC-10 Service Bulletin 57-114, 
Revision 1, dated July 26, 1993. -
    (1) Prior to the accumulation of 6,500 total landings, or within 
1,500 landings after the effective date of this AD, whichever occurs 
later: Perform an eddy current surface inspection or an eddy current 
bolt hole inspection to detect cracks on stringer number 41 on the 
left- and right-hand wings, in accordance with the service bulletin. 
-
    (2) If no crack is found, repeat the inspection thereafter at 
intervals not to exceed 4,000 landings. -
    (3) If any crack is found, prior to further flight, accomplish 
paragraph (a)(3)(i), (a)(3)(ii), or (a)(3)(iii) of this AD, as 
applicable. -
    (i) If any crack is found that extends upward from the fastener 
hole, and if that crack is outside the limits specified in Condition 
2 of the service bulletin, accomplish a temporary repair in 
accordance with Condition 2, Phase I of the service bulletin, or a 
permanent repair in accordance with Condition 2, Phase II of the 
service bulletin. If the temporary repair is accomplished, prior to 
the accumulation of 5,000 landings after accomplishing that 
temporary repair, accomplish the permanent repair in accordance with 
Condition 2, Phase II of the service bulletin. After accomplishment 
of the permanent repair, no further action is required by this AD. -
    (ii) If any crack is found that extends downward from the 
fastener hole, and if that crack is outside the limits specified in 
Condition 2 of the service bulletin, accomplish the permanent repair 
in accordance with Condition 2, Phase II of the service bulletin. 
After such repair, no further action is required by this AD. -
    (iii) If any crack is found in a fastener hole, and if that 
crack is within the limits specified in Condition 2 of the service 
bulletin, accomplish the preventative modification in accordance 
with Condition 1, Option II of the service bulletin. If the crack 
was detected using techniques other than the eddy current bolt hole 
inspection described in the service bulletin, prior to accomplishing 
the preventative modification, perform an eddy current bolt hole 
inspection to detect cracks, in accordance with the service 
bulletin, and accomplish paragraph (a)(3)(iii)(A), (a)(3)(iii)(B), 
or (a)(3)(iii)(C) of this AD, as applicable. -
    (A) If any crack is found that extends upward from the fastener 
hole, and if that crack is outside the limits specified in Condition 
2 of the service bulletin, accomplish the requirements of paragraph 
(a)(3)(i) of this AD. -
    (B) If any crack is found that extends downward from the 
fastener hole, and if that crack is outside the limits specified in 
Condition 2 of the service bulletin, accomplish the requirements of 
paragraph (a)(3)(ii) of this AD.
    (C) If any crack is found that is within the limits specified in 
Condition 2 of the service bulletin, accomplish the preventative 
modification in accordance with Condition 1, Option II of the 
service bulletin. After accomplishment of the preventative 
modification, no further action is required by this AD.
    (4) Except for airplanes on which the preventative modification 
(Condition 1, Option II) or the permanent repair (Condition 2, Phase 
II) has been accomplished, prior to the accumulation of 6,500 total 
landings, or within 5 years after the effective date of this AD, 
whichever occurs later: Perform an eddy current bolt hole inspection 
to detect cracks in the fastener holes in accordance with the 
service bulletin.
    (i) If no crack is found, or if any crack is found that is 
within the limits specified in Condition 2 of the service bulletin, 
prior to further flight, accomplish the preventative modification in 
accordance with Condition 1, Option II of the service bulletin. 
After accomplishment of the preventative modification, no further 
action is required by this AD.
    (ii) If any crack is found that exceeds the limits specified in 
Condition 2 of the service bulletin, prior to further flight, 
accomplish a permanent repair in accordance with Condition 2, Phase 
II of the service bulletin. After accomplishment of the permanent 
repair, no further action is required by this AD.
    (b) For Model DC-10-30, -30F, -40, and -40F series airplanes and 
Model KC-10A (military) airplanes: Accomplish paragraphs (b)(1), 
(b)(2), (b)(3), and (b)(4) of this AD in accordance with McDonnell 
Douglas DC-10 Service Bulletin 57-114, Revision 1, dated July 26, 
1993. -
    (1) Prior to the accumulation of 6,500 total landings, or within 
1,500 landings after the effective date of this AD, whichever occurs 
later: Perform an eddy current surface inspection or an eddy current 
bolt hole inspection to detect cracks on stringer number 41 on the 
left- and right-hand wings in accordance with the service bulletin.
    (2) If no crack is found, repeat the inspection thereafter at 
intervals not to exceed 3,200 landings.
    (3) If any crack is found, prior to further flight, accomplish 
paragraph (b)(3)(i), (b)(3)(ii), or (b)(3)(iii) of this AD, as 
applicable.
    (i) If any crack is found that extends upward from the fastener 
hole, and if that crack is outside the limits specified in Condition 
2 of the service bulletin, accomplish a temporary repair in 
accordance with Condition 2, Phase I of the service bulletin, or a 
permanent repair in accordance with Condition 2, Phase II of the 
service bulletin. If the temporary repair is accomplished, prior to 
the accumulation of 5,000 landings after accomplishing that 
temporary repair, accomplish the permanent repair in accordance with 
Condition 2, Phase II of the service bulletin. After accomplishment 
of the permanent repair, no further action is required by this AD.
    (ii) If any crack is found that extends downward from the 
fastener hole, and if that crack is outside the limits specified in 
Condition 2 of the service bulletin, accomplish the permanent repair 
in accordance with Condition 2, Phase II of the service bulletin. 
After such repair, no further action is required by this AD.
    (iii) If any crack is found in a fastener hole, and if that 
crack is within the limits specified in Condition 2 of the service 
bulletin, accomplish the preventative modification in accordance 
with Condition 1, Option II of the service bulletin. If the crack 
was detected using techniques other than the eddy current bolt hole 
inspection described in the service bulletin, prior to accomplishing 
the preventative modification, perform an eddy current bolt hole 
inspection to detect cracks, in accordance with the service 
bulletin, and accomplish paragraph (b)(3)(iii)(A), (b)(3)(iii)(B), 
or (b)(3)(iii)(C) of this AD, as applicable.
    (A) If any crack is found that extends upward from the fastener 
hole, and if that crack is outside the limits specified in Condition 
2 of the service bulletin, accomplish the requirements of paragraph 
(b)(3)(i) of this AD.
    (B) If any crack is found that extends downward from the 
fastener hole, and if that crack is outside the limits specified in 
Condition 2 of the service bulletin, accomplish the requirements of 
paragraph (b)(3)(ii) of this AD.
    (C) If any crack is found that is within the limits specified in 
Condition 2 of the service bulletin, accomplish the preventative 
modification in accordance with Condition 1, Option II of the 
service bulletin. After accomplishment of the preventative 
modification, no further action is required by this AD.
    (4) Except for airplanes on which the preventative modification 
(Condition 1, Option II) or the permanent repair (Condition 2, Phase 
II) has been accomplished, prior to the accumulation of 6,500 total 
landings, or within 5 years after the effective date of this AD, 
whichever occurs later: Perform an eddy current bolt hole inspection 
to detect cracks in the fastener holes in accordance with the 
service bulletin.
    (i) If no crack is found, or if any crack is found that is 
within the limits specified in Condition 2 of the service bulletin, 
prior to further flight, accomplish the preventative modification in 
accordance with Condition 1, Option II of the service bulletin. 
After accomplishment of the preventative modification, no further 
action is required by this AD.
    (ii) If any crack is found that exceeds the limits specified in 
Condition 2 of the service bulletin, prior to further flight, 
accomplish a permanent repair in accordance with Condition 2, Phase 
II of the service bulletin. After accomplishment of the permanent 
repair, no further action is required by 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: 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 
Federal Aviation Regulations (FAR) Sec. 21.197 and Sec. 21.199 to 
operate the airplane to a location where the requirements of this AD 
can be accomplished.
    (e) The inspections, repairs, and modification shall be done in 
accordance with McDonnell Douglas DC-10 Service Bulletin 57-114, 
Revision 1, dated July 26, 1993. 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.
    (f) This amendment becomes effective on July 13, 1994.

    Issued in Renton, Washington, on May 31, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-13627 Filed 6-10-94; 8:45 am]
BILLING CODE 4910-13-U