[Federal Register Volume 63, Number 94 (Friday, May 15, 1998)]
[Proposed Rules]
[Pages 27011-27012]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-12936]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-SW-61-AD]


Airworthiness Directives; McDonnell Douglas Helicopter Systems 
Model 369D, 369E, 369FF, 369H, MD500N, and MD600N Helicopters

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 McDonnell Douglas Helicopter 
Systems (MDHS) Model 369D, 369E, 369FF, 369H, MD500N, and MD600N 
helicopters. This proposal would require a one-time visual inspection 
of certain input shaft coupling assemblies for pitting. This proposal 
is prompted by three operators' reports of discovering pitting on the 
internal spline teeth. The actions specified by the proposed AD are 
intended to prevent failure of the spline teeth in the input shaft 
coupling assembly, loss of drive to the main rotor system, and 
subsequent loss of control of the helicopter.

DATES: Comments must be received by July 14, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 97-SW-61-AD, 2601 Meacham Blvd., Room 663, 
Fort Worth, Texas 76137. Comments may be inspected at this location 
between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal 
holidays.

FOR FURTHER INFORMATION CONTACT: Mr. Bruce Conze, Aerospace Engineer, 
Los Angeles Aircraft Certification Office, 3960 Paramount Blvd., 
Lakewood, California, 90712, telephone (562) 627-5261, 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 should 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 No. 97-SW-61-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, Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 97-SW-61-AD, 2601 Meacham Blvd., Room 663, 
Fort Worth, Texas 76137.

Discussion

    This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to MDHS Model 369D, 369E, 369FF, 
369H, MD500N, and MD600N helicopters. This proposal would require a 
one-time visual inspection of certain input shaft coupling assemblies 
for pitting below the solid film lubricant layer in the spline area. 
This proposal is prompted by three operators' reports of discovering 
pitting on the internal spline teeth. The actions specified by the 
proposed AD are intended to prevent failure of the spline teeth in the 
input shaft coupling assembly, loss of drive to the main rotor system, 
and subsequent loss of control of the helicopter.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other MDHS Model 369D, 369E, 369FF, 369H, MD500N, 
and MD600N helicopters of the same type design, the proposed AD would 
require a one-time visual inspection of affected input shaft coupling 
assemblies for pitting below the solid film lubricant layer in the 
spline area.
    The FAA estimates that 82 helicopters of U.S. registry would be 
affected by this proposed AD, that it would take approximately 3 work 
hours per helicopter to accomplish the proposed actions, and that the 
average labor rate is $60 per work hour. Required parts would cost 
approximately $638 per coupling assembly. Based on these figures, the 
total cost impact of the proposed AD on U.S. operators is estimated to 
be $67,076 if the coupling assembly is replaced in all 82 helicopters.
    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''

[[Page 27012]]

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 adding a new airworthiness directive 
to read as follows:

McDonnell Douglas Helicopter Systems: Docket No. 97-SW-61-AD.

    Applicability: Model 369D, 369E, 369FF, 369H, MD500N, and MD600N 
helicopters, with input shaft coupling assemblies, part number (P/N) 
369F5133-1, serial number (S/N) 030829-0126 through 030829-0207, 
installed on main transmission, P/N 369F5100-503, and on overrunning 
clutch, P/N 369F5450, certificated in any category.

    Note 1: This AD applies to each helicopter 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 helicopters that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must use the authority 
provided in paragraph (c) to request approval from the FAA. This 
approval may address either no action, if the current configuration 
eliminates the unsafe condition, or different actions necessary to 
address the unsafe condition described in this AD. Such a request 
should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any helicopter from the applicability of this AD.

    Compliance: Required within 100 hours time-in-service after the 
effective date of this AD, unless accomplished previously.
    To prevent failure of the spline teeth in each input shaft 
coupling assembly (coupling assembly), loss of drive to the main 
rotor system, and subsequent loss of control of the helicopter, 
accomplish the following:
    (a) Visually inspect the coupling assemblies, P/N 369F5133-1, 
installed on main transmission, P/N 369F5100-503, and on overrunning 
clutch, P/N 369F5450, for pitting under the solid film lubricant in 
the spline area of the coupling.
    (b) If there is pitting in the splines, replace the coupling 
assembly with an airworthy coupling assembly, P/N 369F5133-1, that 
has been inspected as required by paragraph (a) of this AD.

    Note 2: Boeing Service Bulletin SB369H-240, SB369E-085, SB500N-
013, SB369D-192, SB369F-072, SB600N-003, dated September 26, 1997, 
pertains to 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, FAA. Operators shall submit their requests through an FAA 
Principal Maintenance Inspector, who may concur or comment and then 
send it to the Manager, Los Angeles Aircraft Certification Office.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles Aircraft Certification Office.

    (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 helicopter to a location where 
the requirements of this AD can be accomplished.

    Issued in Fort Worth, Texas, on May 7, 1998.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 98-12936 Filed 5-14-98; 8:45 am]
BILLING CODE 4910-13-U