
[Federal Register Volume 78, Number 27 (Friday, February 8, 2013)]
[Rules and Regulations]
[Pages 9309-9311]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-02582]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2012-0746; Directorate Identifier 2008-SW-035-AD; 
Amendment 39-17337; AD 2013-03-03]
RIN 2120-AA64


Airworthiness Directives; MD Helicopters, Inc., Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for MD 
Helicopters, Inc. (MDHI) Model 500N, 600N and MD900 helicopters to 
require determining the cure date for each NOTAR fan blade tension-
torsion strap (T-T strap), establishing a calendar-time retirement life 
for certain T-T straps, reducing the retirement life of certain T-T 
straps, marking each T-T strap with the expiration date, creating a 
component record card for each T-T strap, and revising the 
airworthiness limitations section of the maintenance manual to reflect 
the changes to the retirement life. This AD was prompted by a report 
from the T-T strap manufacturer that, over a period of time, moisture 
may reduce the strength of a T-T strap. The actions are intended to 
prevent failure of a T-T strap, loss of directional control and 
subsequent loss of control of the helicopter.

DATES: This AD is effective March 15, 2013.

ADDRESSES: For service information identified in this AD, contact 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. 
You may review a copy of the referenced service information at the FAA, 
Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., 
Room 663, Fort Worth Texas 76137.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov or in person at the Docket Operations Office 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this AD, any incorporated-by-reference 
service information, the economic evaluation, any comments received, 
and other information. The street address for the Docket Operations 
Office (phone: 800-647-5527) is U.S. Department of Transportation, 
Docket Operations Office, M-30, West Building Ground Floor, Room W12-
140, 1200 New Jersey Avenue SE., Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: John Cecil, Aviation Safety Engineer, 
Los Angeles Aircraft Certification Office, Transport Airplane 
Directorate, FAA, 3960 Paramount Blvd., Lakewood, California 90712; 
telephone (562) 627-5228; email john.cecil@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

    On July 19, 2012, at 77 FR 42459, the Federal Register published 
our notice of proposed rulemaking (NPRM), which proposed to amend 14 
CFR part 39 to include an AD that would apply to MDHI Model 500N and 
600N helicopters with a NOTAR fan blade T-T strap part number (P/N) 
500N5311-5 and MDHI Model MD900 helicopters with a T-T strap, P/N 
500N5311-5, P/N 900R3442009-101, P/N 900R3442009-103, or P/N

[[Page 9310]]

900R6442009-103. That NPRM proposed to require determining the cure 
date for each T-T strap, establishing a calendar-time retirement life 
for certain T-T straps, reducing the retirement life of certain T-T 
straps, marking each T-T strap with the expiration date, creating a 
component record card for each T-T strap, and revising the 
airworthiness limitations section of the maintenance manual to reflect 
the changes to the retirement life. This AD was prompted by information 
from the T-T strap manufacturer indicating that, over time, the T-T 
straps can absorb moisture, which can weaken the T-T strap and cause it 
to fail. The proposed requirements were intended to prevent failure of 
a T-T strap, loss of directional control and subsequent loss of control 
of the helicopter.

Comments

    We gave the public the opportunity to participate in developing 
this AD, but we received no comments on the NPRM (77 FR 42459, July 19, 
2012).

FAA's Determination

    We have reviewed the relevant information and determined that an 
unsafe condition exists and is likely to exist or develop on other 
products of these same type designs and that air safety and the public 
interest require adopting the AD requirements as proposed.

Related Service Information

    We have reviewed one MDHI service bulletin, which contains two 
service bulletin numbers, SB500N-029R3, applicable to MDHI Model 500N 
helicopters; and SB600N-046R3, applicable to MDHI Model 600N 
helicopters, dated July 9, 2008. We have also reviewed MDHI SB900-
107R1, dated March 14, 2008, applicable to MDHI Model MD900 
helicopters. The service bulletins describe procedures for establishing 
a retirement life for each affected T-T strap by determining the 
manufacturer's cure date and marking the T-T strap with an expiration 
date; creating a component record card for each affected T-T strap; 
replacing T-T straps that have been in service beyond their revised 
life limit; and recording compliance with the service information in 
the Rotorcraft Log Book.

Differences Between This AD and the Service Information

    This AD differs from the previously described service bulletins as 
follows:
     This AD contains requirements for T-T straps that are 
installed or will be installed on the affected helicopters, but does 
not address a part that is in storage.
     For a T-T strap with five or more calendar years from the 
manufacturer's cure date, this AD requires, before further flight, 
replacing the T-T strap with an airworthy T-T strap. The service 
bulletins specify the T-T strap to be replaced within six, 12, or 24 
months, depending on the manufacturing cure date.
     The service bulletins specify sending removed parts to the 
manufacturer. This AD does not require such action.
     This AD requires reducing the life limit for any T-T 
strap, P/N 500N5311-5, to 2500 hours TIS if the T-T strap has been 
installed on a MDHI Model MD900 helicopter.

Costs of Compliance

    We estimate that this AD will affect 111 helicopters of U.S. 
Registry, including 73 helicopters in the combined MDHI Model 500N and 
MDHI Model 600N fleet, and 38 MDHI Model MD900 helicopters. Determining 
the manufacturer's cure date, the expiration date, marking an 
expiration date on the T-T strap, creating the component record card, 
revising the applicable airworthiness limitations section of the 
maintenance manual, and re-installing the T-T strap will take about 40 
work-hours per helicopter for Model 500N and Model 600N helicopters, 
and 32 work-hours per helicopter for Model MD900 helicopters, at an 
average labor rate of $85 per work-hour. Required parts will cost about 
$1,340 per T-T strap. Based on these figures, the total cost impact of 
the AD on U.S. operators will be about $543,180 for the entire fleet, 
assuming all T-T straps will be marked, and assuming 11 helicopters 
will need T-T straps replaced (13 T-T straps per helicopter).

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.

Regulatory Findings

    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 this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866;
    (2) Is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979);
    (3) Will not affect intrastate aviation in Alaska to the extent 
that it justifies making a regulatory distinction; and
    (4) 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 and placed it in the AD docket.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends 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. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive (AD):

2013-03-03 MD Helicopters, Inc. (MDHI): Amendment 39-17337; Docket 
No. FAA-2012-0746; Directorate Identifier 2008-SW-035-AD.

(a) Applicability

    MDHI Model 500N and 600N helicopters, with a NOTAR fan blade 
tension-torsion strap (T-T strap), part number (P/N) 500N5311-5; and 
MDHI Model MD900 helicopters, with a T-T strap, P/N 500N5311-5, P/N 
900R3442009-101, P/N 900R3442009-103, or P/N 900R6442009-103; 
certificated in any category.

[[Page 9311]]

(b) Unsafe Condition

    This AD defines the unsafe condition as a decrease, over time, 
in the strength of a T-T strap caused by moisture. This condition 
could result in failure of a T-T strap, loss of directional control, 
and subsequent loss of control of the helicopter.

(c) Effective Date

    This AD becomes effective March 15, 2013.

(d) Compliance

    You are responsible for performing each action required by this 
AD within the specified compliance time unless it has already been 
accomplished prior to that time.

(e) Required Actions

    (1) Within six months, determine the manufacturer's cure date of 
each of the 13 T-T straps.
    (i) For a T-T strap with five or more calendar years from the 
manufacturer's cure date, before further flight, replace the T-T 
strap with an airworthy T-T strap.
    (ii) For a T-T strap with less than five calendar years from the 
manufacturer's cure date, mark the expiration date on the T-T strap 
face in permanent ink.
    (2) Thereafter, before installing a T-T strap, mark the 
expiration date on the T-T strap using permanent ink. The expiration 
date is five years from the date the T-T strap package was opened, 
or if that date was not recorded, five years from the manufacturer's 
cure date.
    (3) On or before the date you comply with paragraph (e)(1) or 
(e)(2) of this AD, create a component record card for each T-T strap 
and record on the card the manufacturer's cure date or the date that 
the T-T strap package was opened, if that date was recorded 
previously, and the T-T strap expiration date.
    (4) Revise the Airworthiness Limitations section of the 
maintenance manual by establishing:
    (i) A calendar life limit for the T-T straps, P/N 500N5311-5, 
900R3442009-101, 900R3442009-103, and 900R6442009-103 of five years 
from the date the T-T strap package was opened, or if that date was 
not recorded, five years from the manufacturer's cure date.
    (ii) A 2,500 hour time-in-service (TIS) life limit for any T-T 
straps, P/N 500N5311-5, installed on a Model 500N or Model 600N 
helicopter that was previously installed on a Model MD900 
helicopter.

    Note to paragraph (e) of this AD: For the MDHI Model MD900 
helicopters, AD 2006-18-01 (71 FR 51095, August 29, 2006) contains 
additional TIS life limits for T-T straps, P/N 900R3442009-103 and 
P/N 900R6442009-103 and additional inspection requirements for all 
four affected T-T straps, P/N 500N5311-5, P/N 900R3442009-101, P/N 
900R3442009-103, and P/N 900R6442009-103.

(f) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Los Angeles Aircraft Certification Office, FAA, 
may approve AMOCs for this AD. Send your proposal to: John Cecil, 
Aviation Safety Engineer, Los Angeles Aircraft Certification Office, 
Transport Airplane Directorate, FAA, 3960 Paramount Blvd., Lakewood, 
California 90712; telephone (562) 627-5228; email 
john.cecil@faa.gov.
    (2) For operations conducted under a 14 CFR part 119 operating 
certificate or under 14 CFR part 91, subpart K, we suggest that you 
notify your principal inspector, or lacking a principal inspector, 
the manager of the local flight standards district office or 
certificate holding district office before operating any aircraft 
complying with this AD through an AMOC.

(g) Additional Information

    MDHI has issued one service bulletin with two numbers, SB500N-
029R3 for the Model 500N helicopters, and SB600N-046R3 for the Model 
600N helicopters, dated July 9, 2008. MDHI has also issued SB900-
107R1, dated March 14, 2008, for the Model MD900 helicopters. These 
service bulletins, which are not incorporated by reference, contain 
information related to the subject of this AD. For service 
information identified in this AD, contact 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. You may 
review a copy of this service information at the FAA, Office of the 
Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, 
Fort Worth, Texas 76137.

(h) Subject

    Joint Aircraft Service Component (JASC) Code: 6410, Tail rotor 
blades.

    Issued in Fort Worth, Texas, on January 29, 2013.
Lance T. Gant,
Acting Directorate Manager, Rotorcraft Directorate, Aircraft 
Certification Service.
[FR Doc. 2013-02582 Filed 2-7-13; 8:45 am]
BILLING CODE 4910-13-P


