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

[Federal Register Volume 64, Number 139 (Wednesday, July 21, 1999)]
[Proposed Rules]
[Pages 39104-39106]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-18629]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-14-AD]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model DC-10-10, -15, 
and -30 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 to revise an existing airworthiness 
directive (AD), applicable to certain McDonnell Douglas Model DC-10-10, 
-15, and -30 airplanes and KC-10A (military) airplanes, that currently 
requires inspections to determine the condition of the lockwires on the 
forward engine mount bolts and correction of any discrepancies found. 
That action also provides for termination of the inspections for some 
airplanes by installing retainers on the bolts. That AD was prompted by 
reports of stretched or broken lockwires on the forward engine mount 
bolts. The actions specified by that AD are intended to prevent broken 
lockwires, which could result in loosening of the engine mount bolts, 
and subsequent separation of the engine from the airplane. This new 
action would provide an additional optional terminating modification, 
clarification of the requirements of the previous optional terminating 
modification, and would remove the reporting requirements for the 
repetitive inspections.

DATES: Comments must be received by September 7, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-14-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, 3936 
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

[[Page 39105]]

statement is made: ``Comments to Docket Number 99-NM-14-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. 99-NM-14-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On February 16, 1995, the FAA issued AD 95-04-07, amendment 39-9159 
(60 FR 11617, March 2, 1995), applicable to certain McDonnell Douglas 
Model DC-10-10, -15, and -30 series airplanes and KC-10A (military) 
airplanes. That AD required inspections to determine the condition of 
the lockwires on the forward engine mount bolts and correction of any 
discrepancies found. That action also provided for termination of the 
inspections for some airplanes by installing retainers on the bolts. 
That AD was prompted by reports of stretched or broken lockwires on the 
forward engine mount bolts. The actions specified by that AD are 
intended to prevent broken lockwires, which could result in loosening 
of the engine mount bolts, and subsequent separation of the engine from 
the airplane.

Actions Since Issuance of Previous Rule

    Since the issuance of AD 95-04-07, the FAA issued AD 95-04-07 R1, 
amendment 39-9317 (60 FR 38477, July 27, 1995), that clarifies the 
procedures for accomplishing the optional terminating action on engines 
1, 2, and 3.
    Additionally, since the issuance of that AD, the FAA has received 
reports indicating that the lockwires of the forward engine mount bolts 
have failed since the incorporation of McDonnell Douglas DC-10 Service 
Bulletin 71-133, Revision 6, dated June 30, 1992 (which is referenced 
in the existing AD as the appropriate source of information for 
accomplishment of installation of retainers on the engine mount bolts 
of the engine 1, 2, or 3). The exact cause of the failures has not yet 
been determined.
    That service bulletin segregates the affected airplanes into three 
groups and provides each group (two of which are relatively similar) 
with an option for accomplishing the modification of the forward engine 
mount bolts of engines 1, 2, and 3, as listed below:
    •  For airplanes listed as Groups I and III, the service 
bulletin describes procedures for replacing the bolts on pylons 1 and 
3; the washers with tabs on pylon 2 (for Group III--include bolts); and 
the H-11 steel material bolt, washers, and nuts on the engine 1, 2, and 
3 forward and aft mounts with improved material.
    •  For airplanes listed as Group II, the service bulletin 
describes procedures for replacing the bolts on pylons 1 and 3; the 
washers with tabs on pylon 2; and the H-11 steel material bolt, 
washers, and nuts on the engine 1, 2, and 3 forward and aft mounts with 
improved material. Additionally, the modification includes installing 
four retention brackets (retainers) on the aft engine mounts on engines 
1, 2, and 3.
    As mentioned previously, failed lockwires have been reported. The 
failed lockwires occurred on airplanes that had incorporated the 
requirements for Groups I and III of the service bulletin. No reports 
of failed lockwires have been reported on airplanes that have 
incorporated the retainers in accordance with the service bulletin. In 
light of this, the FAA has determined that the installation of the 
retainers in accordance with the McDonnell Douglas service bulletin 
(previously described) should be incorporated in order to terminate the 
repetitive inspections required by this proposed AD. This clarification 
of the previous optional terminating action is specified in paragraph 
(b) of this proposed AD.
    The FAA has reviewed and approved McDonnell Douglas Service 
Bulletins DC10-71-159, dated September 6, 1995, and Revision 01, dated 
July 28, 1997, as additional sources of service information for 
accomplishment of an optional terminating action. These service 
bulletins describe procedures for modification of the forward engine 
mount bolts of engines 1, 2, and 3. This involves removal of the 
existing lockwires from the forward engine mount bolts, modification 
and reidentification of the anti-ice duct, and installation of 
retainers on the forward engine mount bolts.
    Accomplishment of this optional terminating modification would 
eliminate the need for the repetitive inspections.

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 revise AD 95-04-07 R1 to continue to require 
inspections to determine the condition of the lockwires on the forward 
engine mount bolts and correction of any discrepancies found. It also 
would continue to provide for termination of the inspections for some 
airplanes by installing retainers on the bolts. This proposed AD would 
provide an additional optional terminating modification, clarification 
of the requirements of the previous optional terminating action, and 
would remove the reporting requirements for the repetitive inspections.

Differences Between Proposed Rule and Service Information

    Operators should note that McDonnell Douglas Service Bulletins 
DC10-71-159, and Revision 01, recommend accomplishment of the 
modification of the forward engine mount bolts at the earliest 
practical maintenance period, but not to exceed 18 months from the 
issue date of the service bulletin. However, this proposed AD would 
allow operators the option of accomplishing the modification at their 
discretion.
    The FAA has determined that, for this proposed AD, repetitive 
inspections of the lockwires of the forward engine mount bolts safely 
addresses the unsafe condition. The FAA has determined that repetitive 
inspections of an area may be permitted to continue indefinitely, 
although a positive fix to the problem exists, for the following 
reasons:
    1. The inspection area of the forward engine mount bolts is easily 
accessible; and
    2. In the event of a broken lockwire, it is easily detected; and
    3. Since a single broken lockwire would not result in loss of an 
engine, the consequences of a single broken lockwire are not likely to 
be catastrophic.
    In light of these reasons, the FAA has determined that the 
circumstances warranting continual repetitive inspections meet these 
three criteria.

Cost Impact

    There are approximately 389 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 229 airplanes of U.S. registry 
would be affected by this proposed AD.
    The inspections that are currently required by AD 95-04-07 R1 and 
retained in this proposed AD, would take approximately 2 work hours per 
airplane to accomplish, at an average labor rate of $60 per hour. Based 
on these figures, the cost impact of the currently required inspections 
on U.S. operators is estimated to be approximately $27,480, or $120 per 
airplane, per inspection cycle.
    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

[[Page 39106]]

accomplish those actions in the future if this AD were not adopted.
    Should an operator elect to accomplish the optional terminating 
modification as specified in AD 95-04-07 R1, and the requirements 
clarified in this proposed AD, it would take approximately 4 work hours 
per airplane to accomplish, at an average labor rate of $60 per hour. 
Required parts would cost between $2,744 and $2,822 per airplane. Based 
on these figures, the cost impact of the optional terminating 
modification specified by AD 95-04-07 R1 on U.S. operators is estimated 
to be between $2,984 and $3,062 per airplane.
    Should an operator elect to accomplish the optional terminating 
modification specified in McDonnell Douglas Service Bulletin DC10-71-
159 that would be provided by this AD, it would take approximately 16 
work hours per airplane to accomplish the proposed actions, at an 
average labor rate of $60 per work hour. Required parts would cost 
between $2,744 and $2,822 per airplane. Based on these figures, the 
cost impact of the optional terminating modification proposed by this 
AD on U.S. operators is estimated to be between $3,704 and $3,782 per 
airplane.

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.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-9317 (60 FR 
38477, July 27, 1995), and by adding a new airworthiness directive 
(AD), to read as follows:

McDonnell Douglas: Docket 99-NM-14-AD. Revises AD 95-04-07 R1, 
Amendment 39-9317.

    Applicability: Model DC-10-30 and KC-10A (military) airplanes on 
which bolt retainers have not been installed on the engine mount in 
accordance with McDonnell Douglas DC-10 Service Bulletin 71-133, 
Revision 6, dated June 30, 1992; and all Model DC-10-10 and -15 
airplanes; 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 (d) 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 broken lockwires, which could result in loosening of 
the engine mount bolts, and subsequent separation of the engine from 
the airplane, accomplish the following:

Restatement of Requirements of AD 95-04-07 R1, Amendment 39-9317

    (a) Within 120 days after March 17, 1995 (the effective date of 
AD 95-04-07 R1, amendment 39-9317), unless accomplished previously 
within the last 750 flight hours prior to March 17, 1995, perform a 
visual inspection to detect broken lockwires on the forward engine 
mount bolts on engines 1, 2, and 3, in accordance with McDonnell 
Douglas Alert Service Bulletin DC10-71A159, Revision 1, dated 
January 31, 1995.
    (1) If no lockwire is found broken, repeat the inspection 
thereafter at intervals not to exceed 750 flight hours.
    (2) If any lockwire is found broken, prior to further flight: 
Check the torque of the bolt, install a new lockwire, and install a 
torque stripe on the bolt, in accordance with the alert service 
bulletin. Thereafter at intervals not to exceed 750 flight hours, 
perform a visual inspection to detect misalignment of the torque 
stripes, and repeat the inspection to detect broken lockwires, in 
accordance with the alert service bulletin.

Optional Terminating Actions

    (b) For Model DC-10-30 airplanes and KC-10A (military) airplanes 
only: Installation of retainers on the engine mount bolts of engines 
1, 2, or 3 in accordance with the precedures depicted in Figure 6 of 
Revision 6 of McDonnell Douglas DC-10 Service Bulletin 71-133, dated 
June 30, 1992, constitutes terminating action for the requirements 
of this AD for that engine.
    (c) For Model DC-10-10, -15, and -30 airplanes and KC-10A 
(military) airplanes: Modification of the forward engine mount bolts 
for engine 1, 2, or 3 in accordance with McDonnell Douglas Service 
Bulletin DC10-71-159, dated September 6, 1995, or Revision 01, dated 
July 28, 1997, constitutes terminating action for the requirements 
of this AD for that engine.

Alternative Methods of Compliance

    (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 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles ACO.

Special Flight Permits

    (e) 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.

    Issued in Renton, Washington, on July 15, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-18629 Filed 7-20-99; 8:45 am]
BILLING CODE 4910-13-U