[Federal Register: October 17, 2005 (Volume 70, Number 199)]
[Rules and Regulations]
[Page 60206-60211]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr17oc05-3]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 2004-SW-13-AD; Amendment 39-14340; AD 2005-21-02]
RIN 2120-AA64
Airworthiness Directives; MD Helicopters, Inc. Model 369D, 369E,
369F, 369FF, 500N, and 600N Helicopters
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
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SUMMARY: This amendment supersedes an existing airworthiness directive
(AD) for the MD Helicopters, Inc. (MDHI) Model 369A, H, HE, HM, HS, D,
and E helicopters with a certain part-numbered main rotor blade (blade)
and modified with a Helicopter Technology Company, LLC (HTC),
Supplemental Type Certificate (STC) No. SR09172RC, SR09074RC, or
SR09184RC. That AD currently requires recording on the component
history card or equivalent record (record) each torque event (TE) on
each blade, inspecting both surfaces of the blade, and replacing any
cracked blade with an airworthy blade. Also, that AD establishes life
limits for certain part-numbered blades. This amendment revises the
model applicability, adds MDHI part-numbered blades, removes any
reference to the life limits of the blades, changes the requirements
for inspecting the blades, and revises the STC applicability. This
amendment also provides that compliance with portions of certain
documents constitutes alternative methods of compliance with portions
of this AD, contains editorial changes for clarification, and makes
some corrections. This amendment is prompted by additional reports of
cracked blades and by the comments received in response to AD 2003-24-
01. The actions specified in this AD are intended to detect fatigue
cracking of the blade to prevent blade failure and subsequent loss of
control of the helicopter.
DATES: Effective November 1, 2005. Comments for inclusion in the Rules
Docket must be received on or before December 16, 2005.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Office of the Regional Counsel, Southwest Region,
Attention: Rules Docket No. 2004-SW-13-AD, 2601 Meacham Blvd., Room
663, Fort Worth, Texas 76137. You may also send comments electronically
to the Rules Docket at the following address: 9-asw-adcomments@faa.gov.
The service information referenced in this AD may be obtained from
the following addresses: 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 and Helicopter Technology Company, LLC,
12902 South Broadway, Los Angeles, CA 90061, telephone 310-523-2750,
fax 310-523-2745.
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.
[[Page 60207]]
SUPPLEMENTARY INFORMATION: On November 17, 2003, the FAA issued AD
2003-24-01, Amendment 39-13370 (68 FR 66004, November 25, 2003), to
require recording TE and inspecting certain blades with 13,720 TEs and
750 hours TIS. The AD also requires replacing any cracked blade with an
airworthy blade. Also, the AD revises the Limitations and Conditions of
HTC, LLC, STC Nos. SR09172RC, SR09074RC, and SR09184RC by establishing
life limits for certain part-numbered blades. The AD was prompted by
reports of certain blades cracking due to a higher number of TEs per
hour than originally calculated. This condition, if not corrected,
could result in fatigue cracking of the blade, blade failure, and
subsequent loss of control of the helicopter.
Interested persons were afforded an opportunity to participate in
the making of AD 2003-24-01. The FAA received several comments from 10
commenters. We have given due consideration to the comments received.
One commenter, the manufacturer (MDHI), states the scope of the AD
should be expanded to add the OH-6A designation immediately after the
model to read ``Model 369A (OH-6A), H, etc.''
The FAA disagrees that we should add the Model OH-6A. We included
STC No. SR09184RC and the Model 369A (OH-6A), H, HE, HM, and HS
helicopters to AD 2003-24-01 in error. We have reviewed reports,
summaries about rates of use, incident reports, certification data,
weight limits, and other information from the manufacturer. These
models may have the affected part-numbered blades installed. However,
the data shows that even with a higher than expected number of TEs,
these models have approved operating limitations that assume operations
at maximum gross weight and are conservative enough to compensate for
the higher TEs. We have received no reports of these blades cracking in
the areas affected by this AD. These blades should reach their
retirement lives based on hours TIS before the number of TEs results in
cracks in the affected area. Also, we have determined that we should
have included STC No. SR01050LA and the Model 369F, FF, 500N, and 600N
helicopters in the AD applicability. Our data shows the unsafe
condition addressed by this AD correlates to a flight profile with a
higher number of TEs than expected during certification (six TEs per
hour). The Model 369D, E, F, FF, 500N and 600N helicopters, with a
higher gross weight limit, fit that profile. Therefore, we have
determined that this AD should apply only to the Model 369D, E, F, FF,
500N and 600N helicopters.
Five commenters state the new definition of a TE in AD 2003-24-01
is inconsistent with the definition given in other ADs and in a service
letter. One commenter, MDHI, states the new definition is likely to
cause confusion.
The FAA agrees. The definition introduced in AD 2003-24-01 is
inconsistent with previously issued ADs and could unnecessarily burden
and confuse the operators. Therefore, we have changed the definition to
make it consistent with the definition of a TE as that term is defined
in AD 98-15-26, Amendment 39-10675, Docket 98-SW-22-AD. The TE
definition in AD 98-15-26 is also consistent with the definition in
MDHI Service Letter SL369H-132R1, SL369D-111R1, SL369E-063R1, SL369F-
056R1, SL500N-008R1, and SL600N-005R1, dated May 15, 2001.
One commenter asks that the word ``reliably'' be added to the AD
paragraph requiring operators to determine the number of TEs. The
commenter states that FAA approved service information reads,
``operators who cannot reliably determine the actual number of TEs for
a blade * * *.''
The FAA does not agree. The word ``reliably'' is subjective and
does not assist operators in determining accumulated TEs. The
requirement is that operators determine actual TEs or assume 13,720
accumulated TEs.
One commenter, MDHI, states the actions in the AD do not prevent
cracks but mandate a 35-hour repetitive inspection to detect cracks
before blade failure.
The FAA agrees. The AD wording is revised to read: ``The actions
specified in this AD are intended to detect fatigue cracking to prevent
* * *''
Four commenters do not agree with the blade inspection
requirements. One commenter states the inspection is unnecessary. The
four commenters state the use of a 10X or higher magnifying glass is
unnecessary and that cracks have been found without the use of a
magnifying glass. Three commenters ask if pilots can do the inspections
instead of a mechanic.
The FAA disagrees and has determined the inspection is necessary
because the affected blades on these model helicopters continue to
crack. The manufacturer has not identified a permanent modification but
has identified TE counting or replacing the blade as a corrective
measure. The FAA has also determined that a 10X or higher magnifying
glass is necessary to detect a chord-wise crack protruding from under
the root fitting and doubler on the bottom-side of the blade to prevent
blade failure because these cracks may not be detectable without a 10X
magnifying glass until they are near failure. Current FAA policy does
not allow pilots to do these inspections. Pilots may only perform
simple visual checks authorized by the AD. Pilots may perform checks
that do not require the use of tools, precision measuring equipment,
training, pilot logbook endorsements, or the use of or reference to
technical data not contained in the body of the AD. The inspection in
the AD requires the use of a 10X or higher magnifying glass, which is
not considered a simple visual check.
One commenter states that an eddy current inspection is effective
in detecting cracks in the ``C'' channel of certain blades. The
commenter states the FAA may want to consider having the manufacturer
incorporate an eddy current inspection into the maintenance
instructions for all blades.
The FAA does not agree that an eddy current inspection is necessary
to detect a crack in the blade in the areas specified in this AD. We
have determined the cracks can be detected in the specified areas by
inspecting the blades using a 10X or higher magnifying glass.
Two commenters suggest the service bulletins and their amendments,
created by MDHI and HTC, are adequate to address the unsafe condition.
One of those commenters states that normally an AD is coordinated with
the manufacturer who produces a service bulletin (SB) and the FAA backs
it up with an AD stating the operators must comply. That commenter
further states that the idea of an AD should be to address an issue the
manufacturer is either unaware of or has not addressed.
The FAA is responsible for determining which portions, if any, of
an SB to incorporate in an AD and any additional requirements necessary
to correct the unsafe condition. Even though an SB may address an
unsafe condition, an AD mandates compliance with the actions specified
in the SB by all affected operators. While we generally seek technical
information from the manufacturer, we neither solicit the
manufacturer's assistance in drafting an AD nor its consent before
issuing an AD. However, we do note in this AD that complying with
certain portions of certain documents constitutes an approved
alternative method of compliance for certain parts of this AD.
One commenter states that only a few companies consistently have
cracked blades. That commenter suggests that we should look at those
companies. The same commenter states an AD is not
[[Page 60208]]
needed because the maintenance manual criteria are sufficient to detect
a cracked blade.
The FAA partially concurs with the commenter. The commenter is
correct in that most cracked blades do appear to occur as a result of
the operations of a relatively few operators. However, the affected
blades from these relatively few operators may be placed on any of the
affected model helicopters regardless of their previous use. Thus, the
AD must include all affected model helicopters. Although we agree that
the maintenance manual criteria are sufficient to detect a cracked
blade, we do not agree that the AD is not needed. The AD requires
determining and recording the number of TEs accumulated on each blade
and provides the required time intervals to perform the inspections. We
have determined the affected blades must be inspected to determine if a
crack exists at the required TEs or hours TIS.
One commenter, MDHI, states that it disagrees that specific blade
station inspections are any more meaningful than the area described as
``* * * around the root fitting, doubler and skin * * *.''
The FAA, upon reconsideration, agrees and no longer refers to the
six blade stations because the reference is not necessary to identify
the required inspection area.
One commenter, the blade manufacturer, HTC, states the instructions
in paragraph (b)(2) of AD 2003-24-01 ``(parallel to the blade) from the
center of the root fitting and lead lag attach bolt-holes closest to
the trailing edge,'' are confusing. The commenter asks if the direction
is perhaps ``span wise'' and states that the trailing edge of the blade
is not relevant. The commenter also states the instructions will cause
many operators to perform the inspection in the wrong areas.
The FAA included the specific measurements, reference points, and
directions in paragraph (b)(2) of AD 2003-24-01 to provide the mechanic
the location of the specific blade stations stated in HTC SB No. 2100-
3R2. To simplify these instructions, we have decided to remove the
specific locations from the AD and include a figure that depicts the
blade inspection area.
Six commenters commented on the cost analysis stating the AD poses
an economic burden on operators. One commenter states it will cause a
hardship on the industry. Another commenter states it will not be
economically feasible. Another commenter states the AD will put
operators out of work and force them to switch to other aircraft types.
Another commenter states the AD will cause an increase in paperwork.
Another commenter asks what is the basis for the cost of the blades and
the number of additional inspections. Another commenter states the
economic impact should be redone using realistic blade rejections due
to fatigue cracks.
While the FAA must consider the economic burdens caused by issuing
an AD, the primary purpose of an AD is to correct an unsafe condition.
We did, however, reassess the cost analysis as a result of the
comments. Therefore, we are assuming a total of 9000 TE inspections and
blade replacements will be required for 10 percent of the fleet. Also,
we have determined the paperwork costs will be negligible.
A commenter, HTC, states the AD establishes life limits for certain
blades that already have published service lives, the action is FAA
approved, and the life limits are contained in Maintenance Manual HTCM-
001.
The FAA agrees with the commenters statements. When the life limits
were originally issued, they were inadvertently omitted from the
Limitations and Conditions of HTC, LLC, STC Nos. SR09172RC, SR01050LA,
and SR09184RC. The STCs were amended and now include the life limits.
However, the life limits can only be established in an AD because a
change to a life limit appearing only in a manual or on type
certificate data sheets, even if FAA-approved, does not require
compliance by the pilot or operator. To be legally required, the change
must be made through an AD. We are addressing the issue of establishing
life limits in another AD. Therefore, the paragraph establishing life
limits is excluded from this AD.
A commenter, HTC, notes the AD states that this proposal is
prompted by several reports. The commenter states there are two known
reports, both from the same Canadian operator, and they received only
one of those two reports.
The FAA agrees there were two reports when AD 2003-24-01 was
issued, and we also note that we inadvertently called the ``action''
required by the AD a ``proposal''. However, since the AD was issued, we
have received additional reports. We have reviewed a total of five
reports in making our decision to issue this AD.
Three commenters question the statement in AD 2003-24-01, paragraph
(a)(2), about recording the total number of TEs. One commenter asks
whether the AD intent is to require that the pilots land or record the
100 TEs by taking their hands off the controls. Another commenter wants
to know the basis for the 100 external lifts. Another commenter states
that requiring the operator to record TEs after 100 external lifts will
add a burden and a penalty to the operator in having to land and record
the TEs. That same commenter suggests that they be allowed to record TE
at the end of daily operations.
The FAA partially agrees with the comments. The AD does not dictate
the flight profile of the helicopter when recording TEs. It's up to the
operator to record the TEs. The time required to record the number of
TEs is a negligible burden. The basis for our initial assessment was
that in any given day there would be 100 external lift operations. We
have since determined the use of 100 external lift operations is not
realistic given that some operators often exceed that number before a
single day of operation. Therefore, after additional analysis, we have
determined that recording the TEs at the end of each day's operation or
on or before accumulating an additional 200 TEs, whichever occurs
first, is sufficient.
One commenter states that AD 98-15-26 requires recording unknown
TEs using a formula to determine TE against TIS. In AD 2003-24-01, the
operator must assume a penalty of 13,720 TEs for blades with unknown
TEs. The commenter expresses concern that at some future date, the FAA
will decide that these HTC blades must be retired at a similar TE as
the MD blades now have. The commenter further states that this could
cost operators about $44,000,000.
The FAA has determined that because of the critical nature of the
unsafe condition, the formula for TEs as required in AD 98-15-26 would
not adequately address the unsafe condition. While we cannot rule out
further AD action related to this unsafe condition, any such action
would require justification and consideration of the financial impact
of that action.
One commenter states the paragraph in the preamble of the AD that
begins with the statement, ``This unsafe condition is likely to exist
or develop on other helicopters * * *'' seems to indicate that only
HTC-built blades could cause the condition.
The FAA issues an AD when it believes there is an unsafe condition
in a product and that an unsafe condition is likely to exist or develop
in other products of the same type design. In AD 2003-24-01, the unsafe
condition was identified as fatigue cracking of the part-numbered
blades listed in the ``applicability'' section and installed as part of
the three listed STCs. These helicopter models, listed in the
``applicability section'' with the affected blades installed, are
susceptible to fatigue cracking of the blades. These
[[Page 60209]]
blades include both MDHI and HTC blades. Therefore, this AD retains
similar wording for the revised model helicopters and STCs for
helicopters with blades installed, which are susceptible to fatigue
cracking.
One commenter, HTC, states the comment period for an NPRM is 1
year. The commenter asks why is this AD so urgent when the FAA was so
unconcerned before. The same commenter also states that they requested
an NPRM more than 16 months ago.
The FAA comment period for an NPRM is usually 60 days. We issued AD
2003-24-01 as a final rule; request for comments with a typical 60-day
comment period. Since the original incident, we have been evaluating
the reports and data as it becomes available to determine the necessary
corrective action. In addition to the reports of cracked blades that
prompted the AD, we have received additional reports of cracked blades.
We have determined that this critical unsafe condition and the short
compliance time to correct it require an immediate AD.
Two commenters suggest the January 26, 2003, date for receipt of
comments for inclusion in the rules docket may be a typographical
error.
The FAA agrees the date was a typographical error and should have
been January 26, 2004.
Finally, two commenters state the FAA should include and cross-
reference the blades specified in the HTC and MDHI SBs so that
operators understand that the new AD affects both HTC and MDHI part
number (P/N) blades.
The FAA agrees. In this AD, we include both MDHI and HTC part-
numbered blades and cross-reference the part numbers and the STCs to
clearly show the affected helicopters, blades, and STC's.
Since issuing AD 2003-24-01, the FAA has reviewed MDHI SB369H-
245R2, SB369E-095R2, SB500N-023R2, SB369D-201R2, SB369F-079R2, SB600N-
031R2, dated February 4, 2004. The SB contains information about the
blade TEs and determining an inspection interval. Also, the SB lists
certain MDHI helicopter models and HTC and MDHI blade part numbers.
HTC superseded Mandatory Notice No. 2100-3R2, dated December 20,
2002, with Notice No. 2100-3R3, dated January 5, 2004. Notice No. 2100-
3R3 contains information about blade TE inspections and determining an
inspection interval. The notice references the information contained in
MDHI CSP-HMI-2, Section 62-10-00, Main Rotor Blade Torque Event
Inspection. Also, Notice No. 2100-3R3 ``revises the model effectivity
and the scope of the additional inspection with a 10X glass.''
Also since issuing AD 2003-24-01, the FAA determined that STC
SR09184RC approves the installation of blades, P/N 500P2100-301 and -
303, only, on the MDHI 369A, H, HE, HM, and HS model helicopters. Based
on our determination, this AD will not apply to these five model
helicopters. Likewise, the AD will not apply to STC SR09184RC and
blades, P/N 500P2100-301 and -303. However, we will establish life
limits for these blades in a subsequent AD.
Also, after further review of the service information, the FAA has
determined that helicopters modified under STC SR01050LA, STC
SR09172RC, and STC SR09074RC may have the affected blades installed.
Therefore, they are included in the applicability of this AD.
In addition, since issuing AD 2003-24-01, the FAA has received
three additional reports of incidents of cracked blades in 2004 and
2005. A preliminary evaluation of the cracked blades continues to
indicate that the cracking is related to a high number of TEs
accumulated by the blades. None of the blades identified in incident
reports that caused the FAA to publish AD 2003-24-01 or this final rule
involved helicopters modified with STC SR09184RC. Therefore, exclusion
of STC SR09184RC is appropriate because none of the blades used in that
modification, based on a review of technical data and accident records,
should be affected by this AD.
An unsafe condition is likely to exist or develop on other Model
369D, 369E, 369F, 369FF, 500N, and 600N helicopters of these same type
designs modified with an HTC STC No. SR09172RC, SR09074RC, or
SR01050LA. Therefore, this AD supersedes AD 2003-24-01 to require:
On or before the next 50-hours time-in-service (TIS),
unless accomplished previously, determine and record the number of TEs
accumulated on each blade. A TE is the transition to a hover from
forward flight or any external lift operation. Each transition to a
hover from forward flight is recorded as a TE, and any external lift
operation is recorded as two TEs. Forward flight is considered to be
flight at any airspeed (or direction) after attaining translational
lift. If you cannot determine the number of TEs, assume 13,720.
Continue to record the number of TEs accumulated (actual usage)
throughout the life of the blades and the hours TIS. On or before
accumulating an additional 200 TEs or at the end of each day's
operation, whichever occurs first, record and update the accumulated
TEs total.
For each blade that has accumulated 13,720 or more TEs and
750 or more hours TIS, before further flight, unless accomplished
previously, and thereafter at intervals not to exceed 200 TEs or 35
hours TIS, whichever occurs first, perform a main rotor blade torque
event inspection.
If a crack is found, replace the blade with an airworthy
blade before further flight.
The short compliance time involved is required because the
previously described critical unsafe condition can adversely affect the
controllability and structural integrity of the helicopter. Some
operators not affected by AD 2003-24-01 may have already exceeded the
13,720 TEs and 750 hours TIS. Therefore, based on the high usage rate
of some of these model helicopters, the 35-hour TIS or 200 TE
inspections may occur in a short time span, and this AD must be issued
immediately.
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.
The FAA estimates that this AD will:
Affect 886 helicopters of U.S. registry;
Take about 1 work hour per helicopter for inspecting
blades, assuming 9000 TE inspections for 10 percent of the fleet, at an
average labor rate of $65 per work hour;
Cost about $50,000 for one set of blades (on condition),
assuming 10 percent of the fleet has blades that are replaced; and
Have paperwork costs that are negligible.
Based on these figures, we estimate the total cost impact of the AD
on U.S. operators is $56,261,000, assuming 10 percent of the fleet is
affected.
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 FAA, Office of the Regional Counsel, Southwest
Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas. All
communications
[[Page 60210]]
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 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 mailed
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. 2004-SW-13-AD.'' The postcard will be date
stamped and returned to the commenter.
Regulatory Findings
The regulations adopted herein 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. Therefore, it
is determined that this final rule does not have federalism
implications under Executive Order 13132.
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.
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.
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 removing Amendment 39-13370 (68 FR
66004, November 25, 2003), and by adding a new airworthiness directive
(AD), Amendment 39-14340, to read as follows:
2005-21-02 MD Helicopters, Inc.: Amendment 39-14340. Docket No.
2004-SW-13-AD. Supersedes AD 2003-24-01, Amendment 39-13770, Docket
No. 2003-SW-16-AD.
Applicability: Models 369D, 369E, 369F, 369FF, 500N, or 600N
with either an MD Helicopter, Inc. (MDHI) main rotor blade (blade)
installed or modified with Helicopter Technology Company, LLC (HTC),
Supplemental Type Certificate (STC) No. SR09172RC, SR09074RC, or
SR01050LA with an HTC blade installed as listed in the following
table, certificated in any category:
--------------------------------------------------------------------------------------------------------------------------------------------------------
Helicopter model MDHI blade part No. (P/N) HTC blade P/N HTC STC Nos.
--------------------------------------------------------------------------------------------------------------------------------------------------------
369D............................................................... 369D21100 Basic, -516, -517, -523 500P2100-BSC, -BSC-1 SR09172RC
369E............................................................... 369D21120-501, -503 500P2100-101, -103 SR09074RC
369F, FF........................................................... 369D21102 Basic, -503, -517, -523 500P2300-501, -503 SR01050LA
369D21121-501, -503 ............................ .................
500N............................................................... 369D21102-503, -517, -523 500P2300-501, -503 SR01050LA
369D21121-501, -503 ............................ .................
600N............................................................... 369D21102-517, -523 500P2300-501, -503 SR01050LA
369D21121-501, -503
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note 1: The terms ``BSC'' and ``Basic'' are interchangeable when
identifying blades produced by MDHI and HTC.
Compliance: Required as indicated.
To detect fatigue cracking of the blade to prevent blade failure
and subsequent loss of control of the helicopter, accomplish the
following:
(a) On or before the next 50 hours time-in-service (TIS), unless
accomplished previously:
(1) Determine and record the number of torque events accumulated
on each blade. A torque event (TE) is the transition to a hover from
forward flight or any external lift operation. Each transition to a
hover from forward flight is recorded as a TE, and any external lift
operation is recorded as two TEs. Forward flight is considered to be
flight at any airspeed (or direction) after attaining translational
lift. If you cannot determine the number of TEs, use 13,720 TEs.
(2) Continue to record the number of TEs accumulated (actual
usage) throughout the life of the blades along with hours TIS. On or
before accumulating an additional 200 TEs or at the end of each
day's operations, whichever occurs first, record and update the
accumulated TEs total.
(b) For each blade that has accumulated 13,720 or more TEs and
750 or more hours TIS, before further flight, unless accomplished
previously, and thereafter at intervals not to exceed 200 TEs or 35
hours TIS, whichever occurs first, perform a main rotor blade torque
event inspection.
Note 2: MD Helicopters, Inc. Maintenance Manual CSP-HMI-2,
Revision 36, section 62-10-00, paragraph 8, Main Rotor Blade Torque
Event Inspection, pertains to the subject of this AD.
(c) If a crack is found, replace the blade with an airworthy
blade before further flight.
[[Page 60211]]
Note 3: MDHI Maintenance Manual CSP-HMI-2, Section 20-30-00 Main
Rotor Blade Painting pertains to the subject of this AD. This
section of the maintenance manual recommends painting the inboard 24
inches (not to be exceeded) of the blade gloss white to aid in
detecting a crack; and if this is done, painting all blades alike
and rebalancing them.
Note 4: TEs are used only to establish an additional inspection
interval and not to establish an alternative retirement life.
(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, for information about previously approved
alternative methods of compliance.
Note 5: Complying with the inspection procedures in the
Accomplishment Instructions, paragraphs 2.B.(2). and 2.B.(3)., of MD
Helicopter Inc. Service Bulletin (SB) SB369H-245R2, SB369E-095R2,
SB500N-023R2, SB369D-201R2, SB369F-079R2, SB600N-031R2, dated
February 4, 2004, constitutes an approved alternative method of
conducting the inspection required by paragraph (b) of this AD.
Note 6: Complying with the Inspection Instructions procedures in
paragraphs 2 and 3 of HTC Mandatory SB, Notice No. 2100-3R3, dated
January 5, 2004, constitutes an approved alternative method of
conducting the inspection required by paragraph (b) of this AD.
(e) This amendment becomes effective on November 1, 2005.
Issued in Fort Worth, Texas, on October 7, 2005.
David A. Downey,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 05-20678 Filed 10-14-05; 8:45 am]
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