
[Federal Register Volume 77, Number 139 (Thursday, July 19, 2012)]
[Proposed Rules]
[Pages 42459-42462]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-17616]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2012-0746; Directorate Identifier 2008-SW-35-AD]
RIN 2120-AA64


Airworthiness Directives; MD Helicopters, Inc. (MDHI) Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

[[Page 42460]]


ACTION: Notice of Proposed Rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for 
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 proposal is 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 proposed actions are intended to prevent failure of a T-T 
strap, loss of directional control and subsequent loss of control of 
the helicopter.

DATES: We must receive comments on this proposed AD by September 17, 
2012.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Docket: Go to http://www.regulations.gov. Follow the online instructions for sending your 
comments electronically.
     Fax: 202-493-2251.
     Mail: Send comments to the U.S. Department of 
Transportation, Docket Operations, M-30, West Building Ground Floor, 
Room W12-140, 1200 New Jersey Avenue SE., Washington, DC 20590-0001.
     Hand Delivery: Deliver to the ``Mail'' address between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    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 proposed AD, the 
economic evaluation, any comments received, and other information. The 
street address for the Docket Operations Office (telephone 800-647-
5527) is in the ADDRESSES section. Comments will be available in the AD 
docket shortly after receipt.
    For service information identified in this proposed 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.

FOR FURTHER INFORMATION CONTACT: John Cecil, Aviation Safety Engineer, 
FAA, Los Angeles Aircraft Certification Office, Airframe Branch, 3960 
Paramount Blvd., Lakewood, California 90712-4137; telephone 562-627-
5228, fax 562- 627-5210; email: john.cecil@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to participate in this rulemaking by submitting 
written comments, data, or views. We also invite comments relating to 
the economic, environmental, energy, or federalism impacts that might 
result from adopting the proposals in this document. The most helpful 
comments reference a specific portion of the proposal, explain the 
reason for any recommended change, and include supporting data. To 
ensure the docket does not contain duplicate comments, commenters 
should send only one copy of written comments, or if comments are filed 
electronically, commenters should submit only one time.
    We will file in the docket all comments that we receive, as well as 
a report summarizing each substantive public contact with FAA personnel 
concerning this proposed rulemaking. Before acting on this proposal, we 
will consider all comments we receive on or before the closing date for 
comments. We will consider comments filed after the comment period has 
closed if it is possible to do so without incurring expense or delay. 
We may change this proposal in light of the comments we receive.

Discussion

    The manufacturer has issued service information that indicates that 
it and its supplier, Lord Corporation, have determined that certain T-T 
straps can, over time, absorb moisture that can weaken the T-T strap. 
It indicates that a T-T strap failure can cause decreased directional 
control of the helicopter. Accordingly, it specifies, in addition to 
the current time-in-service (TIS) retirement life limit, an additional 
calendar-time retirement life limit for four part-numbered T-T straps 
and a reduced retirement life of 2,500 hours TIS for T-T strap, part 
number (P/N) 500N5311-5, if it is installed on a Model 500N or 600N 
helicopter after it has been installed on a Model MD900 helicopter. The 
calendar life would start when the package was opened.
    This action proposes to adopt these new calendar-life limits for T-
T straps, P/N 500N5311-5, P/N 900R3442009-101, P/N 900R3442009-103, and 
P/N 900R6442009-103, measured from the manufacturer's cure date or the 
date the package containing the T-T strap was opened exposing it to the 
environment outside the package. We are also proposing to adopt 
requirements that a component record card be created and that the T-T 
straps be marked with the retirement life limit calendar date 
(expiration date).
    For the MDHI Model MD900 helicopters, AD 2006-18-01 (71 FR 51095, 
August 29, 2006) already contains a revised 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. 
The requirements of that AD 2006-18-01 would remain in effect.

FAA's Determination

    We are proposing this AD because we evaluated all known relevant 
information and determined that an unsafe condition exists and is 
likely to exist or develop on other products of these same type 
designs.

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. All of 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 their service 
information in the Rotorcraft Log Book.

Proposed AD Requirements

    This proposed AD would require, within six months:
     Determining the manufacturer's cure date for T-T strap, P/
N 500N5311-5 (installed on MDHI Model 500N and

[[Page 42461]]

MDHI 600N helicopters), and P/N 500N5311-5, P/N 900R3442009-101, P/N 
900R3442009-103, or P/N 900R6442009-103 (installed on MDHI Model MD900 
helicopters);
     Creating a component record card for each affected T-T 
strap and recording the expiration date on the card;
     Revising the Airworthiness Limitations Section of the 
applicable maintenance manual with the additional or revised retirement 
life limit for the T-T straps; and
     Before a T-T strap is installed on any Model 500N, 600N, 
or MD900 helicopter, the T-T strap be marked with the expiration date.

Differences Between This Proposed AD and the Service Information

    This proposed AD differs from the previously described service 
bulletins as follows:
     This AD proposes 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 proposes, 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 to send removed parts to the 
manufacturer, and this proposed AD does not require this action.
     This AD proposes 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 proposed AD would 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 would 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 would cost 
about $1,340 per T-T strap. Based on these figures, the total cost 
impact of the proposed AD on U.S. operators would be about $543,180 for 
the entire fleet, assuming all T-T straps would be marked, and assuming 
11 helicopters would need T-T strap 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

    We determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would 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, I certify 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);
    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 proposed 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.

The Proposed Amendment

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

MD Helicopters, Inc. (MDHI): Docket No. FAA-2012-0746; Directorate 
Identifier 2008-SW-35-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.

(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) 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.

(d) 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 (d)(1) or 
(d)(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) This AD revises 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

[[Page 42462]]

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 (d) 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.

 (e) Alternative Methods of Compliance (AMOC)

    (1) The Manager, Los Angeles Aircraft Certification Office, FAA, 
may approve AMOCs for this AD. Send your proposal to: John Cecil, 
Aviation Safety Engineer, FAA, Los Angeles Aircraft Certification 
Office, Airframe Branch, 3960 Paramount Blvd., Lakewood, California 
90712-4137; telephone 562-627-5228, fax 562-627-5210; 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.

(f) 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. MD Helicopters, Inc. 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 this service information, 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 information at the FAA, Office of the Regional 
Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, 
Texas 76137.

(g) Subject

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


    Issued in Fort Worth, Texas, on July 10, 2012.
Kim Smith,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 2012-17616 Filed 7-18-12; 8:45 am]
BILLING CODE 4910-13-P


