[Federal Register Volume 59, Number 180 (Monday, September 19, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-23100]


[[Page Unknown]]

[Federal Register: September 19, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-NM-79-AD]

 

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).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to all McDonnell Douglas Model DC-10 
series airplanes and KC-10A (military) airplanes. This proposal would 
require inspections to detect cracking of H-11 attach bolts of the 
upper vertical stabilizer and replacement of these bolts and associated 
nuts with Inconel bolts and nuts. This proposal is prompted by reports 
of failure of the attach bolts of the upper vertical stabilizer due to 
stress corrosion. The actions specified by the proposed AD are intended 
to prevent undetected cracked or failed attach bolts that may lead to 
reduced structural integrity of the vertical stabilizer.

DATES: Comments must be received by November 10, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 94-NM-79-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, P.O. Box 1771, Long Beach, 
California 90801-1771, Attention: Business Unit Manager, Technical 
Administrative Support, Department L51, M.C. 2-98. 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, 3229 East 
Spring Street, Long Beach, California.

FOR FURTHER INFORMATION CONTACT: Maureen Moreland, Aerospace Engineer, 
Airframe Branch, ANM-121L, FAA, Transport Airplane Directorate, Los 
Angeles Aircraft Certification Office, 3229 East Spring Street, Long 
Beach, California; telephone (310) 988-5238; fax (310) 988-5210.

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 94-NM-79-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. 94-NM-79-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On August 25, 1993, the FAA issued AD 93-17-09, Amendment 39-8680 
(58 FR 54949, October 25, 1993), which is applicable to McDonnell 
Douglas Model DC-10 series airplanes and KC-10A (military) airplanes. 
That AD requires the implementation of a Structural Inspection Document 
(SID) program of structural inspections to detect fatigue cracking, and 
repair or replacement, as necessary, to ensure the continued 
airworthiness of these airplanes as they approach the manufacturer's 
original fatigue design life goal. AD 93-17-09 requires inspection of 
the attach bolts of the upper vertical stabilizer [designated Principal 
Structural Element (PSE) 55.10.001/002 in McDonnell Douglas Report 
Number L26-012, ``DC-10 Supplemental Inspection Document,'' which is 
referenced in that AD as the appropriate source of service information] 
under the fleet leader operator sampling criteria. The fatigue life for 
these attach bolts is (Nth) 119,334 flight hours. The sampling 
period for this PSE started in September 1989, and will end in June 
2001. Sampling inspections are to be accomplished within that interval 
for airplanes in the candidate fleet that have accumulated more than 
59,667 total flight hours (Nth/2).
    The inspection threshold for the SID program was based upon a 
fatigue analysis conducted by the manufacturer. The FAA is not aware of 
any operator having, as yet, accomplished the inspection of these bolts 
for the purpose of complying with the requirements of AD 93-17-09. 
McDonnell Douglas has advised the FAA that the planning data contained 
in Volume III of the SID will be revised to indicate that H-11 bolts 
have been replaced with new Inconel bolts.
    Since the issuance of that AD, operators of Model DC-10 series 
airplanes have recently reported that the attach bolts of the upper 
vertical stabilizer had failed on several in-service airplanes. These 
failures had occurred on airplanes that had accumulated between 40,000 
total flight hours and 67,000 total flight hours. The attach bolts and 
associated nuts on these airplanes were made of H-11 material, which is 
susceptible to failure due to stress corrosion. The FAA has determined 
that replacement of the H-11 bolts and associated nuts with Inconel 
bolts and associated nuts will eliminate the possibility of failure due 
to stress corrosion. Failure of the attach bolts in the upper vertical 
stabilizer, if not corrected, could compromise the structural integrity 
of the vertical stabilizer.
    The FAA has reviewed and approved Revision 1, dated March 8, 1991, 
and Revision 2, dated August 4, 1994, of McDonnell Douglas DC-10 
Service Bulletin 55-20, which describe procedures for repetitive 
ultrasonic inspections at 12-month intervals to detect cracking in H-11 
attach bolts of the upper vertical stabilizer, and replacement of H-11 
attach bolts and associated nuts with Inconel attach bolts and 
associated nuts.
    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 ultrasonic inspections at 18-month intervals 
to detect cracking in H-11 attach bolts of the upper vertical 
stabilizer, and replacement of H-11 attach bolts and associated nuts 
with Inconel attach bolts and associated nuts. The actions would be 
required to be accomplished in accordance with the procedures specified 
in the service bulletins described previously.
    Although the referenced service bulletins recommend that these 
inspections be performed at 12-month intervals, the FAA has determined 
that 18-month intervals will not adversely affect safety and will allow 
these repetitive inspections to be performed at a base during regularly 
scheduled maintenance where special equipment and trained maintenance 
personnel will be available.
    There are approximately 426 McDonnell Douglas Model DC-10 series 
airplanes and KC-10A (military) airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 269 airplanes of U.S. registry 
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 $55 per work hour. 
Based on these figures, the total cost impact of the inspections 
proposed by this AD on U.S. operators is estimated to be $29,590, or 
$110 per airplane, per inspection cycle.
    It would take approximately 8 work hours per airplane to accomplish 
the proposed replacements at an average labor rate of $55 per work 
hour. Required parts would cost approximately $9,009 per airplane. 
Based on these figures, the total cost impact of the replacements 
proposed by this AD on U.S. operators is estimated to be $2,541,781, or 
$9,449 per airplane.
    Based on the above figures, the total cost impact of the 
inspections and replacements proposed by this AD on U.S. operators is 
estimated to be $2,571,371, or $9,559 per airplane.
    The total 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.
    The FAA recognizes that the obligation to maintain aircraft in an 
airworthy condition is vital, but sometimes expensive. Because AD's 
require specific actions to address specific unsafe conditions, they 
appear to impose costs that would not otherwise be borne by operators. 
However, because of the general obligation of operators to maintain 
aircraft in an airworthy condition, this appearance is deceptive. 
Attributing those costs solely to the issuance of this AD is 
unrealistic because, in the interest of maintaining safe aircraft, most 
prudent operators would accomplish the required actions even if they 
were not required to do so by the AD.
    A full cost-benefit analysis has not been accomplished for this 
proposed AD. As a matter of law, in order to be airworthy, an aircraft 
must conform to its type design and be in a condition for safe 
operation. The type design is approved only after the FAA makes a 
determination that it complies with all applicable airworthiness 
requirements. In adopting and maintaining those requirements, the FAA 
has already made the determination that they establish a level of 
safety that is cost-beneficial. When the FAA, as in this proposed AD, 
makes a finding of an unsafe condition, this means that the original 
cost-beneficial level of safety is no longer being achieved and that 
the proposed actions are necessary to restore that level of safety. 
Because this level of safety has already been determined to be cost-
beneficial, a full cost-benefit analysis for this proposed AD would be 
redundant and unnecessary.
    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. 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:

McDonnell Douglas: Docket 94-NM-79-AD.

    Applicability: All Model DC-10-10, -10F, -15, -30, -30F, -40, 
and -40F series airplanes, and KC-10A (military) airplanes; 
certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent undetected cracked or failed attach bolts that may lead 
to reduced structural integrity of the vertical stabilizer, accomplish 
the following:
    (a) Within 12 months after the effective date of this AD, perform 
an ultrasonic inspection to detect cracking in the attach bolts of the 
upper vertical stabilizer, in accordance with McDonnell Douglas DC-10 
Service Bulletin 55-20, Revision 2, dated August 4, 1994, unless 
accomplished within the last 18 months prior to the effective date of 
this AD in accordance with McDonnell Douglas DC-10 Service Bulletin 55-
20, Revision 1, dated March 8, 1991, or Revision 2, dated August 4, 
1994.
    (1) If no cracking is detected in any bolt, repeat the 
inspection of the uncracked bolt thereafter at intervals not to 
exceed 18 months, until the requirements of paragraph (c) of this AD 
are accomplished.
    (2) If cracking is detected in any bolt, prior to further 
flight, replace the cracked bolt and associated nut with a new 
Inconel attach bolt and associated nut, in accordance with the 
service bulletin. No further action is required by this AD for the 
new Inconel bolts and associated nuts.
    (b) Compliance with the inspections required by paragraph (a) of 
this AD constitutes compliance with the inspections and reports 
required by paragraph (b) of AD 93-17-09, Amendment 39-8680, for 
Principal Structural Element (PSE) 55.10.001/002. However, after 
installation of new Inconel bolts and associated nuts, in accordance 
with the requirements of paragraphs (a) and (c) of this AD, PSE 
55.10.001/002 must continue to be inspected in accordance with AD 
93-17-09.
    (c) Within 5 years after the effective date of this AD, replace 
all H-11 attach bolts and associated nuts of the upper vertical 
stabilizer with new Inconel attach bolts and associated nuts, in 
accordance with McDonnell Douglas DC-10 Service Bulletin 55-20, 
Revision 1, dated March 8, 1991; or Revision 2, dated August 4, 
1994. Such replacement constitutes terminating action for the 
requirements of this AD.
    (d) 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.

    (e) 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 September 13, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-23100 Filed 9-16-94; 8:45 am]
BILLING CODE 4910-13-U