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[Federal Register Volume 62, Number 221 (Monday, November 17, 1997)]
[Rules and Regulations]
[Pages 61223-61225]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-30058]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-SW-17-AD; Amendment 39-10206; AD 97-12-02]
RIN 2120-AA64

Airworthiness Directives; McDonnell Douglas Helicopter Systems 
MD900 Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment supersedes an existing priority letter 
airworthiness

[[Page 61224]]

directive (AD), applicable to McDonnell Douglas Helicopter Systems 
(MDHS) Model MD900 helicopters, which prohibits flight or ground 
operations of helicopters with a certain adjustable collective drive 
link assembly (link assembly) installed. This amendment requires 
installation of a redesigned airworthy link assembly after which 
further operations are permitted. This amendment is prompted by recent 
incidents in which the link assembly failed during flight. The actions 
specified by this AD are intended to prevent failure of the link 
assembly, which could result in loss of control of the helicopter.

DATES: Effective December 2, 1997.
    Comments for inclusion in the Rules Docket must be received on or 
before January 16, 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-17-AD, 2601 Meacham Blvd., Room 663, 
Fort Worth, Texas 76137.

FOR FURTHER INFORMATION CONTACT: Mr. Greg DiLibero, Aerospace Engineer, 
FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Blvd., 
Lakewood, California 90712, telephone (562) 627-5231, fax (562) 627-
5210.

SUPPLEMENTARY INFORMATION: On May 29, 1997, the FAA issued priority 
letter AD 97-12-02, applicable to MDHS Model MD900 helicopters with 
collective drive link assembly (link assembly) part number (P/N) 
900C2010233-103 and P/N 900C2010233-105, installed, which prohibits 
flight or ground operations of the helicopters. That action was 
prompted by recent incidents in which the link assembly failed during 
flight. The link assembly is part of the primary collective flight 
control system. Based on these incidents and further testing by the 
manufacturer, the FAA determined that further operations with either 
affected link assembly installed constituted an unsafe condition. That 
condition, if not corrected, could result in failure of the link 
assembly and subsequent loss of control of the helicopter.
    Since the issuance of that AD, MDHS has issued MDHS Service 
Bulletin (SB) No. SB900-055R1, dated June 5, 1997, for the installation 
of a redesigned link assembly. The FAA has determined that installation 
of redesigned link assembly, P/N 900C2010233-107, will correct the 
unsafe condition. Additionally, in AD 97-12-02, the FAA has noted that 
the applicability section incorrectly stated that the AD applied to 
Model MD900 helicopters with P/N 900C2010233-103 and P/N 900C2010233-
105 installed. The AD should have stated that it applied to Model MD900 
helicopters with P/N 900C2010233-103 or P/N 900C2010233-105 installed. 
This imprecision in word choice is corrected in this AD.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other MDHS Model MD900 helicopters of the same type 
design, this AD supersedes AD 97-12-02 to require installation of a 
redesigned link assembly. This AD also clarifies the applicability 
statement that could be incorrectly interpreted to mean that two link 
assemblies must be installed in order for the AD to be applicable.
    Since a situation exists that requires the immediate adoption of 
this regulation, 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 should 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 No. 97-SW-17-AD.'' The postcard will be date stamped and 
returned to the commenter.
    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, 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. 106(g), 40113, 44701.

Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding a new airworthiness directive 
to read as follows:

97-12-02  McDonnell Douglas Helicopter Systems: Amendment 39-10206. 
Docket No. 97-SW-17-AD. Supersedes priority letter AD 97-12-02.

    Applicability: Model MD900 helicopters, with adjustable 
collective drive link assembly (link assembly), part number (P/N) 
900C2010233-103 or -105, installed, certificated in any category.

[[Page 61225]]

    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 (b) 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 as indicated, unless accomplished 
previously.
    To prevent failure of the link assembly, which could result in 
loss of control of the helicopter, accomplish the following:
    (a) Before further flight, remove the link assembly, P/N 
900C2010233-103 or -105, and replace with link assembly, P/N 
900C2010233-107.
    (b) 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. 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 2: 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.

    (c) Special flight permits will not be issued.
    (d) This amendment becomes effective on December 2, 1997.

    Issued in Fort Worth, Texas, on November 6, 1997.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 97-30058 Filed 11-14-97; 8:45 am]
BILLING CODE 4910-13-U
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