[Federal Register Volume 72, Number 4 (Monday, January 8, 2007)]
[Proposed Rules]
[Pages 666-669]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-41]


-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2003-SW-37-AD]
RIN 2120-AA64


Airworthiness Directives; MD Helicopters, Inc. Model 369A, 369D, 
369E, 369F, 369FF, 369H, 369HE, 369HS, 369HM, 500N, and OH-6A 
Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Supplemental notice of proposed rulemaking; reopening of 
comment period.

-----------------------------------------------------------------------

SUMMARY: This document revises an earlier proposed airworthiness 
directive (AD) for MD Helicopters, Inc. (MDHI) Model 369A, 369D, 369E, 
369F, 369FF, 369H, 369HE, 369HS, 369HM, 500N, and OH-6A helicopters 
that would have required replacing or reworking certain forward (fwd) 
and aft landing gear assemblies. That proposal was prompted by five 
reports of landing gear strut (strut) failures. This action revises 
that action by proposing to mandate both the creation of an access hole 
to facilitate inspections and a recurring inspection. The proposed AD 
also would exclude from the applicability certain helicopters modified 
with a certain Supplemental Type Certificate (STC) and would provide a 
terminating action for the proposed requirements. This proposal also 
includes clarifying changes. The actions specified by this proposed AD 
are intended to detect a crack that could result in the failure of a 
strut and subsequent loss of control of the helicopter during landing.

DATES: Comments must be received on or before March 9, 2007.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 2003-SW-37-AD, 2601 Meacham Blvd., Room 
663, Fort Worth, Texas 76137. You may also send comments electronically 
to the Rules Docket at the following address: [email protected]. 
Comments may be inspected at the Office of the Regional Counsel between 
9 a.m. and 3 p.m., Monday through Friday, except Federal holidays.
    The service information referenced in the proposed rule may be 
obtained 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. This information may be examined at the FAA, 
Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., 
Room 663, Fort Worth, Texas.

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.

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 document 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 mailed 
comments submitted in response to this proposal must submit a self-
addressed, stamped postcard on which the following statement is made: 
``Comments to Docket No. 2003-SW-37-AD.'' The postcard will be date 
stamped and returned to the commenter.

Discussion

    A proposal to amend 14 CFR part 39 to add an AD for the specified 
MDHI model helicopters was published in the Federal Register on August 
4, 2004 (69 FR 47040). That proposal would have required removing all 
landing gear fairings; determining the number and location of rivets 
that attach the landing gear fairing support assembly to the landing 
gear strut; and if three rivets (fwd, aft and inboard) are present, 
replacing or reworking the landing gear assembly. If only the fwd and 
aft rivets are present, no rework would be required by the proposed AD. 
That proposal was prompted by five reports of strut failures. Operators 
of the helicopters with failed struts do not fall into any clear 
category of service. For example, one was a tour operator in Niagara 
Falls, New York and another was a police department operator in 
Calgary, Canada. In its original design, the fairing support was 
attached to the strut with three rivets (forward, aft, and outboard). 
In 1994, the manufacturer released a design change to attach the 
fairing support assembly with only forward and aft rivets because of 
the possibility of reduced service life of the strut if the third rivet 
was located on the inboard side of the strut. Some landing gear struts 
entered service with an additional rivet hole drilled on the inboard 
side of the strut. This additional rivet hole results in decreased 
fatigue strength of the strut and subsequent

[[Page 667]]

cracking. That condition, if not corrected, could result in cracking of 
the fwd and aft struts, failure of a strut, and subsequent loss of 
control of the helicopter during landing.
    Since issuing that proposal, we received several comments from 2 
commenters and agree that we should make some changes to our proposed 
AD. We have determined that it is necessary to reopen the comment 
period to provide additional opportunity for public comment since we 
are making changes that expand the scope of the originally proposed 
rule. Due consideration was given to all of the comments received.
    One commenter, the manufacturer, states that we need to mandate the 
installation of the landing gear fairing inspection hole rather than 
specifically excluding it from the proposed requirements as we did in 
the notice of proposed rulemaking (NPRM). The commenter also states 
that we should have the operators commence the periodic crack 
inspection per the maintenance manual. The commenter states that 
without these two critical additions the likelihood of a strut failure 
due to fatigue still exists.
    After further consideration, we agree that having an inspection 
hole in the fairing would be preferable to removing the fairings every 
100 hours time-in-service (TIS) or annually in order to do the 
inspection of the inboard rivet hole. We have also determined that our 
decision not to propose to mandate the repetitive crack inspection in 
the NPRM was an error. Therefore, we are now proposing to mandate the 
drilling of the access hole as well as the repetitive crack inspections 
of the inboard rivet. We have also added Notes in this proposal that 
include information for doing the inspections.
    The same commenter provided us with a marked-up proposal that 
contains suggested word changes or additional information, but did not 
provide justification for those changes. We have made only those 
changes that clarify or correct the proposal.
    One of those suggested changes was a request to change the wording 
we use to describe the intent of the proposed actions. The commenter 
writes that the intent of the proposed AD is to detect cracks of the 
fwd and aft struts, remove cracked struts from service prior to 
failure, and preclude subsequent extensive damage to the helicopter 
during landing. Although we agree that the proposal is intended 
primarily to detect cracks, we maintain that such cracking could lead 
to fatigue failure of the strut and loss of control of the helicopter 
during landing; therefore we have not made any changes to the proposal.
    Another requested change is that we change the number of work hours 
to determine the number of rivets from 7 to 2, that we include the 
fairing as a part that may need to be reworked, and that we reduce the 
cost impact of the proposed AD from $438,800 to $227,225. In the NPRM, 
we erroneously estimated that it would take 7 work hours to determine 
the number of rivets; we agree with the commenter's suggestion that 2 
hours is more appropriate and have revised the proposal accordingly. 
Also, since we are now proposing to mandate these actions, we have 
added the work hours and costs associated with both drilling the 
inspection hole in the fairing and accomplishing the repetitive 
inspections.
    The commenter also requests that we add the address for obtaining 
service information. It is not appropriate to include the 
manufacturer's address within the regulatory text of the AD and we have 
not done so; however, we have included that address in the ADDRESSES 
section of this proposal and will add the address in the Incorporation 
by Reference paragraph of the Final Rule when it is issued.
    Also requested is that we more specifically identify the ``three 
rivets'' in the Discussion of the proposal and that part of the intent 
of the AD is to ``clean up the inboard rivet hole (de-burr). We agree 
only to more specifically identify the ``three rivets'' and have 
modified the proposal accordingly.
    Finally, the commenter requests that we change the proposal to 
mandate only the recording of the initial inspection in the logbook but 
not any subsequent periodic landing gear inspections. We do not agree 
with this comment; all required inspections must be recorded. For the 
subsequent landing gear inspections proposed by this action, a Part 91 
operator, for example, would be required by 39.7 to comply with the 
requirements of the AD, would be required by 43.11 to make entries in 
the maintenance records after any required inspection is performed, and 
would be required by 91.417 to keep maintenance records of required 
inspections. Therefore, we have not made the requested change.
    Another commenter, a manufacturer, suggests that operators who can 
verify that their helicopters have an Aerometals strut (P/N 369XH6001-
41, -42, -51, -52) that was ``installed'' under STC No. SR00981LA 
should not have to take any further actions at the strut locations 
because those struts are only approved to have fairing supports 
attached with two rivets (forward and aft) and they have never been 
approved for a third, inboard rivet. The commenter states that 
excluding the struts that they manufactured will result in a 
substantial savings to operators because their landing gear fairings 
will not have to be removed from a strut to verify the number of rivets 
attaching the fairing support since their installation should be 
annotated in the maintenance records. We agree with the commenter and 
have excluded those struts from the applicability of this proposal.
    Because some of these changes expand the scope of the originally 
proposed rule, we have determined that it is necessary to reopen the 
comment period to provide additional opportunity for public comment.
    The FAA estimates that this proposed AD would affect 651 
helicopters of U.S. registry. Determining the number of rivets and 
initially inspecting each affected ``3-hole'' strut and fairing would 
take approximately 2 work hours, installing a new strut would take 
approximately 1.5 work hours, and reworking a strut would take 1 work 
hour. Each repetitive inspection would take \1/4\ work hour per strut 
(1 hour per helicopter for each of 4 struts). The average labor rate is 
$80 per work hour. Required parts (new struts) would cost approximately 
$2,838 for each forward strut, $2,574 for each aft strut, and $97 for a 
modification kit to install an inspection hole. Assuming that each 
helicopter would get the initial inspection, that all 651 helicopters 
would be modified, that 325 helicopters would need two struts reworked, 
that 5 helicopters would require 2 new forward struts, and that 2 
repetitive inspections would be required per year, the total estimated 
cost of the proposed AD on U.S. operators would be about $353,047 
($248,887 for the initial inspections, modification, and parts, and 
$104,160 for the repetitive inspections).

Regulatory Findings

    The regulations proposed herein 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. Therefore, it 
is determined that this proposal would not have federalism implications 
under Executive Order 13132.
    For the reasons discussed above, I certify that 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

[[Page 668]]

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.

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.

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:

MD Helicopters, Inc.: Docket No. 2003-SW-37-AD.

    Applicability: Model 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 
369HS, 369HM, 500N, and OH-6A helicopters, with any of the 
components listed in the Applicability Table installed, excluding 
any model with Aerometals strut (part number (P/N) 369XH6001-41, -
42, -51, or -52) installed in accordance with Supplemental Type 
Certificate (STC) No. SR00981LA, certificated in any category:

                           Applicability Table
------------------------------------------------------------------------
            Component name                Component part number (P/N)
------------------------------------------------------------------------
Mid Aft Fairing Assembly.............  369H6200-61, -62, standard gear.
Aft Support Assembly.................  369H6200-23, -24 (-23 to be
                                        reinstalled on the right-hand
                                        side and -24 to be reinstalled
                                        on the left-hand side, all
                                        configurations).
Aft Fairing Assembly.................  369H92113-91, -92, extended gear.
Aft Filler Assembly..................  369H92113-131, -132, extended
                                        gear.
Aft Fillet Assembly..................  369A6200-45, -46, standard gear.
Aft Fillet Assembly..................  369H92113-111, -112, extended
                                        gear.
Mid Fwd Fairing Assembly.............  369H6200-41, -42, standard gear.
Fwd Fairing Assembly.................  369H92113-81, -82, extended gear.
Fwd Support Assembly.................  369H6200-23, -24 (-23 becomes
                                        right-hand side and -24 becomes
                                        left-hand side).
Fwd Filler Assembly..................  369H92113-121, -122, extended
                                        gear.
Fwd Fillet Assembly..................  369A6200-57, -58, standard gear.
Fwd Fillet Assembly..................  369H92113-101, -102, extended
                                        gear.
------------------------------------------------------------------------

    Compliance: Required as indicated.
    To detect a crack that could result in the failure of a strut 
and subsequent loss of control of the helicopter during landing, 
accomplish the following:
    (a) Within 4 months, unless accomplished previously, remove all 
landing gear fairings (fairings) and inspect each landing gear 
fairing support assembly (support assembly) to determine the number 
and location of the rivets attaching the support assembly to the 
landing gear strut assembly (strut assembly).
    (1) If three rivets (forward, aft and inboard) are used to 
attach the support assembly to the strut assembly,
    (i) For each FORWARD landing gear assembly, remove the landing 
gear fillet assembly (fillet assembly), the three rivets, and the 
support assembly, and clean and dye-penetrant inspect the area in 
and around the 0.125 (3.18mm) diameter hole in the inboard surface 
of the strut assembly.
    (A) If the strut assembly is cracked, replace the cracked strut 
assembly with an airworthy strut assembly and install the other 
landing gear components in accordance with steps (6) through (11) of 
paragraph C of the Accomplishment Instructions of MD Helicopters 
Service Bulletin SB369H-244, SB369E-094, SB500N-022, SB369D-200, and 
SB369F-078, dated April 7, 2000 (SB).
    (B) If the strut assembly is not cracked, rework the landing 
gear assembly and install the other landing gear components in 
accordance with steps (5) through (11) of paragraph C of the 
Accomplishment Instructions of the SB.
    (ii) For each AFT landing gear assembly, remove the fillet 
assembly, the three rivets, and the support assembly, and clean and 
dye-penetrant inspect the area in and around the 0.125 (3.18mm) 
diameter hole in the inboard surface of the strut assembly.
    (A) If the strut assembly is cracked, replace the cracked strut 
assembly with an airworthy strut assembly and install the other 
landing gear components in accordance with steps (6) through (13) of 
paragraph B of the Accomplishment Instructions of the SB.
    (B) If the strut assembly is not cracked, rework the landing 
gear assembly and install the other landing gear components in 
accordance with steps (5) through (13) of Paragraph B of the 
Accomplishment Instructions of the SB.
    (2) If only two rivets (forward and aft) are used to attach the 
support assembly to the strut assembly and a third rivet hole has 
not been drilled in the strut, neither the inspection of the strut 
assembly nor the rework of those landing gear assemblies is required 
by this AD.
    (b) At intervals not to exceed 100 hours TIS or during each 
annual inspection, whichever occurs first, for any strut assembly 
that has a third rivet hole, remove the fairing inspection button 
plug and clean and inspect the area in and around the rivet hole for 
cracks using a bright light and 1 10x or higher magnifying glass.
    (1) If any FORWARD strut assembly is cracked, replace the 
cracked strut with an airworthy strut assembly.
    (2) If any AFT strut assembly is cracked, replace the cracked 
strut with an airworthy strut assembly.
    (c) Installing a strut assembly that has only 2 rivet holes is 
terminating action for the requirements of this AD.


[[Page 669]]


    Note 1: For the Model 369D, 369E, 369F, 369FF, and 500N 
helicopters, the Handbook of Maintenance Instruction, Servicing and 
Maintenance, HMI, CSP-HMI-2, Chapter 32, Section 32-10-00, ``Landing 
Gear Strut Inspection'' pertains to the subject of this AD.


    Note 2: For the Model 369(A) (OH-6A), 369H, 369HE, 369HS, and 
369HM helicopters, the Basic Handbook of Maintenance Instructions 
CSP-H-2, Section 6, ``Landing Gear'' pertains to the subject of this 
AD.

    (d) 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 Los Angeles Aircraft Certification Office, Transport 
Airplane Directorate, FAA, for information about previously approved 
alternative methods of compliance.

    Issued in Fort Worth, Texas, on December 26, 2006.
David A. Downey,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. E7-41 Filed 1-5-07; 8:45 am]
BILLING CODE 4910-13-P