[Federal Register Volume 72, Number 76 (Friday, April 20, 2007)]
[Rules and Regulations]
[Pages 19788-19790]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-7438]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-27343; Directorate Identifier 2007-SW-05-AD; 
Amendment 39-15030; AD 2007-05-51]
RIN 2120-AA64


Airworthiness Directives; MD Helicopters Inc. (MDHI) Model MD600N 
Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This document publishes in the Federal Register an amendment 
adopting Airworthiness Directive (AD) 2007-05-51, which was sent 
previously to all known U.S. owners and operators of MDHI Model MD600N 
helicopters by individual letters. This AD requires, before further 
flight, a visual and eddy current inspection of each lateral mixer 
output link assembly (mixer link) and replacing any cracked mixer link. 
This AD also requires performing an eddy current inspection on each 
mixer link before installing it on any helicopter. This amendment is 
prompted by the discovery of 3 cracked mixer links. The actions 
specified by this AD are intended to detect a crack in the mixer link, 
which could result in failure of the mixer link and subsequent loss of 
control of the helicopter.

DATES: Effective May 7, 2007, to all persons except those persons to 
whom it was made immediately effective by Emergency AD 2007-05-51, 
issued on February 17, 2007, which contained the requirements of this 
amendment.
    Comments for inclusion in the Rules Docket must be received on or 
before June 19, 2007.

ADDRESSES: Use one of the following addresses to submit comments on 
this AD:
    <bullet> DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically;
    <bullet> Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically;
    <bullet> Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590;
    <bullet> Fax: (202) 493-2251; or
    <bullet> Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    You may get the service information identified in this AD from MD 
Helicopters Inc., Attn: Customer Support Division, 4555 E. McDowell 
Rd., Mail Stop M615, Mesa, Arizona 85215-9734, telephone 1-800-388-
3378, fax 480-346-6813, or on the Web at http://www.mdhelicopters.com.

Examining the Docket

    You may examine the docket that contains the AD, any comments, and 
other information on the Internet at http://dms.dot.gov, or in person 
at the Docket Management System (DMS) Docket Offices between 9 a.m. and 
5 p.m., Monday through Friday, except Federal holidays. The Docket 
Office (telephone (800) 647-5227) is located on the plaza level of the 
Department of Transportation Nassif Building at the street address 
stated in the ADDRESSES section. Comments will be available in the AD 
docket shortly after the DMS receives them.

FOR FURTHER INFORMATION CONTACT: Jon Mowery, Aviation Safety Engineer, 
FAA, Los Angeles Aircraft Certification Office, Airframe Branch, 3960 
Paramount Blvd., Lakewood, California 90712, telephone (562) 627-5322, 
fax (562) 627-5210.

SUPPLEMENTARY INFORMATION: On February 17, 2007 we issued Emergency AD 
2007-05-51 for MDHI Model MD600N helicopters, which requires, before 
further flight, a visual and eddy current inspection of each mixer link 
and replacing any cracked mixer link.

[[Page 19789]]

The Emergency AD also requires performing an eddy current inspection on 
each mixer link before installing it on any helicopter. That action was 
prompted by the discovery of a cracked mixer link, part number (P/N) 
600N7636-1, on an in-service MDHI Model MD600N helicopter. Cracks were 
also found on two additional mixer links, P/N 600N7636-3, which were 
being held as spares. The cracks on all three mixer links run through 
the bearing end area of the mixer link and emanate from staking marks 
in the mixer link. Cracks in the mixer link, if not detected, could 
result in failure of the mixer link and subsequent loss of control of 
the helicopter.
    We have reviewed MDHI Service Bulletin No. SB600N-044, dated 
February 16, 2007 (SB), which describes procedures for a one-time 
visual inspection and an eddy current inspection of the mixer link. The 
SB includes only P/Ns 600N7636-1, and -3 in its effectivity, however, 
because the exact cause of the cracks is unknown, and the -9 and -11 
are similar designs, we have included them in the applicability of this 
AD. We are also requiring an eddy current inspection of each affected 
mixer link before installing it on any helicopter.
    Since the unsafe condition described is likely to exist or develop 
on other MDHI Model MD600N helicopters of the same type design, we 
issued Emergency AD 2007-05-51 to detect a crack in the mixer link, 
which could result in failure of the mixer link and subsequent loss of 
control of the helicopter. The AD requires, before further flight, the 
following for each mixer link, P/N 600N7636-1, -3, -9, and -11:
    <bullet> Removing each mixer link, and visually inspecting, with a 
bright light and a 10x or higher magnifying glass, the areas on the 
ends of the mixer link on both sides around the bearing bore for any 
crack,
    <bullet> Performing an eddy current inspection of each mixer link 
in the bearing end areas, and
    <bullet> Replacing any cracked mixer link with an airworthy mixer 
link on which an eddy current inspection has been performed.
The AD also requires performing an eddy current inspection on each 
mixer link before installing it on any helicopter.
    The short compliance time involved is required because the 
previously described critical unsafe condition can adversely affect the 
structural integrity and controllability of the helicopter. Therefore, 
the actions described previously are required before further flight, 
and this AD must be issued immediately.
    A one-time flight permit is allowed for flying the helicopter to a 
location where the eddy current inspection can be performed, provided 
that no crack is found during the visual inspection required in 
paragraph (a) of this AD and that the helicopter's airspeed does not 
exceed 100 knots.
    The requirements of this AD are interim actions; the manufacturer 
continues to investigate the cause of the cracks and, based on that 
investigation, we will determine either follow-on actions or a 
terminating action for the requirements of this AD.
    Since it was found that immediate corrective action was required, 
notice and opportunity for prior public comment thereon were 
impracticable and contrary to the public interest, and good cause 
existed to make the AD effective immediately by individual letters 
issued on February 17, 2007 to all known U.S. owners and operators of 
MDHI Model MD600N helicopters. These conditions still exist, and the AD 
is hereby published in the Federal Register as an amendment to 14 CFR 
39.13 to make it effective to all persons.
    We estimate that this AD will affect 26 helicopters of U.S. 
registry. It will take approximately:
    <bullet> 2 work hours to remove, inspect, and replace both mixer 
links on each helicopter,
    <bullet> 5 work hours for an eddy current inspection of both mixer 
links,
    <bullet> $80 per work hour, and
    <bullet> $865 for a mixer link, if necessary.
    Based on these figures, we estimate the total cost impact of the AD 
on U.S. operators to be $18,885, assuming that a visual and eddy 
current inspection are performed on each mixer link installed on a 
helicopter and that 5 of the 52 mixer links are cracked and need to be 
replaced.

Comments Invited

    This AD is a final rule that involves requirements that affect 
flight safety and was not preceded by notice and an opportunity for 
public comment; however, we invite you to submit any written data, 
views, or arguments regarding this AD. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2007-27343; 
Directorate Identifier 2007-SW-05-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the AD. We will consider 
all comments received by the closing date and may amend the AD in light 
of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this AD. Using the search function of our docket 
web site, you can find and read the comments to any of our dockets, 
including the name of the individual who sent the comment. You may 
review the DOT's complete Privacy Act Statement in the Federal Register 
published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov.

Regulatory Findings

    We have determined that this AD will not have federalism 
implications under Executive Order 13132. This AD will not have a 
substantial direct effect 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.
    For the reasons discussed above, I certify that the 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. 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.
    We prepared an economic evaluation of the estimated costs to comply 
with this AD. See the DMS to examine the economic evaluation.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, Section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

[[Page 19790]]

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

Adoption of the Amendment

0
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

0
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]

0
2. Section 39.13 is amended by adding a new airworthiness directive to 
read as follows:

2007-05-51 MD Helicopters Inc. (MDHI): Amendment 39-15030. Docket 
No. FAA-2007-27343; Directorate Identifier 2007-SW-05-AD.

    Applicability: Model MD600N helicopters, with a lateral mixer 
output link assembly (mixer link), part number (P/N) 600N7636-1, -3, 
-9, or -11 installed, certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To detect a crack in the mixer link, which could result in 
failure of the mixer link and subsequent loss of control of the 
helicopter, accomplish the following:
    (a) Before further flight:
    (1) Remove each mixer link and visually inspect, with a bright 
light and a 10x or higher magnifying glass, the shaded areas around 
the bearing bore for any crack as depicted in the following Figure 
1:
[GRAPHIC] [TIFF OMITTED] TR20AP07.003

    (2) Perform an eddy current inspection of each mixer link in the 
bearing end areas.
    (3) Replace any cracked mixer link with an airworthy mixer link 
on which an eddy current inspection has been performed.

    Note: MDHI Service Bulletin No. SB600N-044, dated February 16, 
2007, pertains to the subject of this AD.

    (b) Perform an eddy current inspection on each mixer link before 
installing it on any helicopter.
    (c) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Contact the Manager, Los Angeles Aircraft Certification Office, FAA, 
ATTN: Jon Mowery, Aviation Safety Engineer, Airframe Branch, 3960 
Paramount Blvd., Lakewood, California 90712, telephone (562) 627-
5322, fax (562) 627-5210, for information about previously approved 
alternative methods of compliance.
    (d) A one-time special flight permit may be issued in accordance 
with 14 CFR 21.197 and 21.199 to operate the helicopter to a 
location where the eddy current inspection requirements of this AD 
can be accomplished provided that no crack is found during the 
visual inspection required in paragraph (a) of this AD and that the 
helicopter's airspeed does not exceed 100 knots.
    (e) This amendment becomes effective on May 7, 2007, to all 
persons except those persons to whom it was made immediately 
effective by Emergency AD 2007-05-51, issued February 17, 2007, 
which contained the requirements of this amendment.

    Issued in Fort Worth, Texas, on April 5, 2007.
Mark R. Schilling,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. E7-7438 Filed 4-19-07; 8:45 am]
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