
[Federal Register: May 6, 2008 (Volume 73, Number 88)]
[Rules and Regulations]               
[Page 24858-24864]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr06my08-4]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0490; Directorate Identifier 2008-SW-26-AD; 
Amendment 39-15509; AD 2008-10-03]
RIN 2120-AA64

 
Airworthiness Directives; Bell Helicopter Textron Model 204B, 
205A, 205A-1, 205B, 210, 212, 412, 412CF, and 412EP Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) for 
the specified Bell Helicopter Textron (Bell) model helicopters. This 
action requires certain checks and inspections of each tail rotor blade 
assembly (T/R blade) at specified intervals and repairing or replacing, 
as applicable, any unairworthy T/R blade. This amendment is prompted by 
three failures of a T/R blade occurring during flight and a recent 
incident of a cracked T/R blade discovered during a scheduled visual 
inspection. The actions specified in this AD are intended to detect 
damage to a T/R blade that could lead to cracking of a T/R blade and 
subsequent loss of control of the helicopter.

DATES: Effective May 21, 2008.
    Comments for inclusion in the Rules Docket must be received on or 
before July 7, 2008.

ADDRESSES: Use one of the following addresses to submit comments on 
this AD:
     Federal eRulemaking Portal: Go to http://
www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590, 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 Bell 
Helicopter Textron, Inc., P.O. Box 482, Fort Worth, Texas 76101, 
telephone (817) 280-3391, fax (817) 280-6466.
    Examining the Docket: You may examine the docket that contains the

[[Page 24859]]

AD, any comments, and other information 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 Docket Operations office (telephone (800) 647-5527) is 
located in Room W12-140 on the ground floor of the West Building at the 
street address stated in the ADDRESSES section. Comments will be 
available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Michael Kohner, Aviation Safety 
Engineer, FAA, Rotorcraft Directorate, Rotorcraft Certification Office, 
Fort Worth, Texas 76193-0170, telephone (817) 222-5447, fax (817) 222-
5783.

SUPPLEMENTARY INFORMATION: A proposal to amend 14 CFR part 39 to 
include an AD for the specified model helicopters was published in the 
Federal Register as Docket No. FAA-2006-26219, Directorate Identifier 
2004-SW-49-AD on November 2, 2006 (71 FR 64484). That Notice of 
Proposed Rulemaking (NPRM) was prompted by eight reports of fatigue 
cracking of T/R blades installed on Bell Model 212 and 412 helicopters 
(three failures on the Bell Model 212 and five failures on the Bell 
Model 412) with a blade assembly, part number (P/N) 212-010-750-009, -
105, and -107. Six of the cracks initiated between blade stations 30 to 
33.5; one crack initiated at blade station 21.9; and one crack 
initiated at blade station 27.6. Three of these T/R blades failed 
during flight and all were installed on Bell Model 412 series 
helicopters. In one of the in-flight failures, the T/R blade failed due 
to a fatigue crack that initiated in the blade skin from a nick .060 
inches long by .008 inches deep. The initial damage was above the 
maximum allowable damage limit for the blade skin provided in the 
maintenance manual. That failed blade had accumulated 1,478 hours time-
in-service (TIS). In another in-flight failure, a section of the T/R 
blade separated from the helicopter during cruise flight at 5,500 feet. 
The helicopter was reported to have violently turned down and to the 
left. The helicopter ``leveled out'' at approximately 1,000 feet before 
setting down in the water. The blade failed due to a cracked stainless 
steel leading edge spar that originated from a corrosion pit .001 
inches deep. The corrosion area extended .003 inches along the surface 
of the origin location. That blade had accumulated 4,643 hours TIS. In 
the third in-flight failure, sanding on the spar and chem-milling was 
found during a post-accident investigation. The crack had initiated at 
blade station 21.9 and the blade had accumulated 1,232 hours TIS. Also, 
the following blades were found cracked:

--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                 Blade        Crack
                Model                     Year     P/N 212-010-   Hours TIS     station       length      Initial damage part      Initial damage size
                                                       750-                      (in.)        (in.)             and type
--------------------------------------------------------------------------------------------------------------------------------------------------------
212.................................         1973          -009        3,224         32.2          6.5  Skin--Corrosion........  .030 in. wide.
212.................................         1985          -009          279         31.5         13.0  Spar--Manufacturing      .090 in. wide.
                                                                                                         Notch.
212.................................         1991          -105          423         30.8          8.0  Skin--Non Sharp Dent...  .75 in. long.
412.................................         1990          -009        3,876         27.6          8.0  Skin--Corrosion........  Unknown.
412.................................         1996          -105        1,235         30.0          8.3  Skin--Scratch..........  .45 in. long by .005
                                                                                                                                  in. deep.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The NPRM proposed to require the following interim actions until 
either a more rigorous inspection is developed or a new blade that is 
more damage tolerant is designed:
     Before each start of the engines, visually checking each 
T/R blade for a crack;
     Within 25 hours TIS or 15 days, whichever occurs first, 
and thereafter at intervals not to exceed 25 hours TIS or 15 days, 
whichever occurs first, cleaning and visually inspecting each T/R blade 
for a crack, corrosion, nick, scratch, or dent using a 3-power or 
higher magnifying glass and a bright light;
     If certain damage is found, inspecting for a crack or 
corrosion using a 10-power or higher magnifying glass and measuring the 
depth of any damage; and
     Before further flight, replacing any cracked T/R blade and 
repairing or replacing any otherwise unairworthy T/R blade.
    Since the issuance of that NPRM, we were notified that a crack was 
found on another T/R blade, P/N 212-010-750-105 FM, installed on a Bell 
Model 412EP helicopter. The crack was discovered while the helicopter 
was on the ground during a scheduled visual inspection. The T/R blade 
is now being examined at the manufacturer's field investigation lab. 
The crack is located approximately in the center of the TR blade span 
and extends across the majority of the chord. The T/R blade had 
accumulated 2,076 hours TIS. Because P/N 212-010-750-105 FM was not 
included in the applicability of the NPRM, and because a crack growth 
analysis using the striation count data from one of the failed T/R 
blades predicted a crack propagation rate of approximately 77 hours TIS 
from damage initiation to blade failure, we will withdraw that NPRM and 
issue this AD as a Final rule; request for comments. This AD contains 
the proposed requirements from the NPRM; however, we've included 
additional P/Ned blades and made other changes based on the comments to 
the NPRM. In response to the NPRM we received several comments from 4 
commenters; the manufacturer, the Canadian National Defence 
Headquarters, and 2 individuals.
    Two commenters suggest changing the compliance time for the 
proposed actions. One of the commenters suggests changing the proposed 
initial inspection from 25 hours TIS or 15 days to 25 hours TIS or 30 
days and changing the recurring inspection from 25 hours TIS or 15 days 
to 25 hours TIS or 30 days. The other commenter believes that a visual 
inspection before the first flight of each day would be adequate and 
that a limit of 10 hours between visual inspections in any one day 
could be added. The same commenter states that it is not always 
practical (e.g. carrying a suitable safe ladder for conducting an 
adequate inspection and carry passengers) and might also be hazardous 
(e.g. doing an inspection from an offshore oil field platform where 
there is no ladder or stand available or where there is restricted 
space and the possibility of high wind speeds) to do a visual 
inspection before each engine start. Finally, one commenter, the 
manufacturer, states that it is impractical to require inspection of 
the T/R blades before each flight or engine start unless we are 
referring to a ground-level visual inspection because a ladder, which 
is not available in the field, would be required for a hands-on 
inspection. It recommends an

[[Page 24860]]

inspection in accordance with the maintenance manual. The manufacturer 
further recommends an inspection for more than just ``cracks'', that 
is, any damage beyond limits in accordance with the published schedule 
and requirements in the maintenance manual.
    We concur with the recommendation to change the initial and 
recurring inspections from 25 hours TIS or 15 days to 25 hours TIS or 
30 days. The 15-day interval was originally proposed because a 
corrosion pit was the initiation point for one of the failures and that 
interval is consistent with FAA advisory material relating to the 
detection of corrosion. Since the proposal was published, we have 
reevaluated the need for the interval and determined that a 30-day 
interval is adequate for this inspection and the AD is revised 
accordingly. We do not concur that a visual inspection before the first 
flight of each day would be adequate and that a limit of 10 hours 
between visual inspections in any one day should be added. 
Additionally, we do not agree with the manufacturer that a 60-day 
interval would be appropriate because of the quick degradation in the 
T/R blade strength. However, we do agree that it is not always 
practical to require a detailed visual inspection of the T/R blades 
using a ladder before each flight or engine start. The proposed owner/
operator (pilot) check was only intended to be a ``walk around'' check 
to detect any large cracks. Although the Canadian commenter states that 
their inspection from the ground is not considered effective, we have 
received reports that two cracked blades were discovered during checks 
performed from the ground. The initial and recurring inspections 
performed by a mechanic are detailed, up-close inspections.
    One commenter also suggests that instead of requiring a mandatory 
daily log book entry stating compliance with the AD that ``the blade 
inspection be made a required preflight checklist item with no daily 
log book entry required.'' If a logbook entry is required, the 
commenter suggests that it be a separate entry made at the time the 25 
hour is signed off. We have determined that this critical check needs 
to be mandated. This determination is based on the critical nature of 
this failure and that the length of a crack is predicted to grow 
quickly once it is detectable based on the service history of these T/R 
blades. All required inspections, including the pilot checks 
specifically approved by this AD, must be recorded at the time they are 
performed. That recording evidences that the required AD actions have 
been performed. If it is not recorded, the aircraft is not in 
compliance with the AD and is unairworthy.
    In addition to comments regarding the inspection times and types, 
the manufacturer provided other comments to the NPRM. Those comments 
and our responses follow:

------------------------------------------------------------------------
                Comment                              Response
------------------------------------------------------------------------
The AD lists a 1991 Model 212 with a     The cracked T/R blade in
 .75'' crack * * * that Bell questions    question is found in the FAA
 since they have no conclusive            service difficulty database.
 technical data on it. They also          An approximate 8-inch crack
 question our references to a 77 hour     was found in the T/R blade
 crack propagation from striation count   installed on a Bell Model 212
 and state that the 77 hour value is      helicopter during a daily
 actually from a crack growth analysis    inspection. The crack was
 that simply includes striation count     located 20.25 inches inboard
 data. Bell also states that they are     from the tip of the T/R blade
 aware of only 4, not 8, existing         running through a .75 inch
 M205Bs that are of FAA certified         long smooth dent. The part
 configuration.                           number of the T/R blade was
                                          212-010-750-105 with a total
                                          time of 423 hours.
                                         We agree with the comment about
                                          the reference to the 77 hour
                                          crack propagation and the
                                          number of existing M205B
                                          helicopters and have revised
                                          this AD accordingly.
The listed tail rotor dash numbers       While the standard Model 204B
 appear to be incorrect. The Model 204B   helicopter may not use this
 does not use the 212-010-750 tail        particular T/R blade, the 212-
 rotor blade and there also appears to    010-750 T/R blade may be on a
 be several of the later dash numbers     modified Model 204B helicopter
 missing from various models.             that does use this blade. To
                                          assure that we have covered
                                          all affected blades, the
                                          applicability now encompasses
                                          all affected dash-numbered T/R
                                          blades.
Recommend changing areas called out for  Agree with this change and have
 special attention to Stations 25.0 to    revised this AD accordingly.
 35.0 (both sides) for damage/corrosion
 and include inboard blade butt area
 surrounding balance weights/screws for
 cracks.
There have not been eight reported       A crack in a blade makes that
 failures, there have been three. All     blade unable to safely perform
 others are reported cracks in the        its intended function. Thus,
 blade skin, not ``failures.'' The term   there are now 9 T/R blades
 ``failure'' can be misleading.           that meet that criteria.
Bell objects to our statement in the     As we understand this objection
 NPRM that ``The requirements of the      by the manufacturer, it
 proposed AD would be interim actions     believes that a redesigned
 until either a more rigorous             blade is unnecessary and that
 inspection is developed or a new blade   the current inspections are
 that is more damage tolerant is          adequate. We do not agree.
 designed.'' Bell states ``Although we    Based on the fracture
 are in concept discussions with DND,     analysis, once the crack
 completion and certification of this     reaches a size that is
 blade is many months away and could be   detectable by inspection, it
 misleading to the commercial             is predicted to grow quickly.
 community.''                             Therefore, for the affected T/
                                          R blades, it is critical to
                                          find a crack or damage that
                                          could lead to a crack at the
                                          earliest opportunity. The
                                          service history of these
                                          affected T/R blades has shown
                                          that the current inspections
                                          are inadequate to reveal these
                                          cracks before blade failure.
                                          One T/R blade failed and
                                          another one cracked because of
                                          manufacturing damage on the
                                          inside of the T/R blade. That
                                          damage was not initially
                                          detectable by external
                                          inspection. Another T/R blade
                                          failed during flight due to
                                          cracking that initiated from a
                                          corrosion pit in the leading
                                          edge spar that was too small
                                          to be readily detected.
                                          Therefore, replacing the
                                          affected T/R blades with a
                                          redesigned, more damage-
                                          tolerant T/R blade is
                                          anticipated as terminating
                                          action for the requirements of
                                          this AD.
------------------------------------------------------------------------

    Another commenter, the Canadian National Defence Headquarters, 
views the proposed actions as a ``good first step'' but offers several 
recommendations. Those recommendations and our responses follow:

[[Page 24861]]



------------------------------------------------------------------------
             Recommendation                          Response
------------------------------------------------------------------------
``Promulgate to other aviation           Our standard practice is to
 regulation agencies worldwide because    send our ADs to aviation
 there are many more airframes affected   authorities with which we have
 than the `388 helicopters of U.S.        a bilateral agreement. In
 registry'.''                             turn, it is then at their
                                          discretion whether or not to
                                          follow up with similar action.
Adjust the inspection frequency as a     We agree that the risk of
 function of the operations               incurring damage in the T/R
 environment, e.g., a 12.5 hours          blade would be less for those
 inspection frequency using the 10x       helicopters operated on paved
 magnification (noting that deployments   landing fields versus ``harsh
 of small numbers of aircraft take the    & rough'' landing fields.
 minimum support equipment required)      Defining and enforcing such an
 visual inspection for operations using   inspection interval, however,
 ``harsh & rough'' landing fields and     would be difficult because
 an interval of 25 hours inspection for   helicopters operate in so many
 paved landing fields.                    varied environments. We
                                          believe the commet to use a 10-
                                          power magnifying glass may be
                                          a typographical error because
                                          the Canadian National Defense
                                          uses a 2-power magnifying
                                          glass and a good source of
                                          light every 12.5 hours TIS for
                                          the visual inspection of the T/
                                          R blades on their Model 412CF
                                          helicopters. Regardless, we
                                          have determined that a 25-hour
                                          TIS inspection using a 3x or
                                          higher magnifying glass is
                                          best for the overall safe
                                          operation of these helicopters
                                          in the U.S.
Specify that the visual check be         We do not believe that further
 carried out by an appropriately          information regarding who can
 qualified person.                        carry out this visual check is
                                          necessary. The visual check is
                                          only intended to detect a
                                          large-scale crack and we
                                          believe an owner/operator
                                          (pilot) is qualified to
                                          perform this ``walk-around''
                                          function.
Define what constitutes a ``bright       The illumination levels are
 light''.                                 historically not given for
                                          visual inspections that are
                                          mandated by an AD. We believe
                                          what constitutes a bright
                                          light can be adequately
                                          determined by the individuals
                                          who are qualified to do the
                                          inspection. We also did not
                                          want to create additional
                                          calibration and recordkeeping
                                          requirements.
Implement damage mapping as a means to   Inspection of the T/R blade
 increase detectability of new damage     records and recording any
 and decrease the maintenance burden.     damage found within the repair
                                          limits are in the maintenance
                                          instructions for the T/R blade
                                          inspection on the applicable
                                          helicopters. These steps are
                                          currently in the applicable
                                          maintenance procedures.
                                          Operators are free to
                                          implement such mapping if they
                                          believe it will reduce their
                                          maintenance burden.
Carry out a Type 1, Method C, Level III  We believe the requirement to
 dye-penetrant inspection in cases        use of a 10-power magnifying
 where difficulties are encountered in    glass is adequate.
 determining the presence of a crack by
 visual inspection.
------------------------------------------------------------------------

    We have reviewed the following Bell documents:
     Operations Safety Notice OSN 205-02-37, OSN 205B-02-10, 
OSN 212-02-39, OSN 412-02-25, OSN 412CF-02-05, and OSN UH-1H-II-02-3, 
dated August 27, 2002. These Operations Safety Notices apply to all 
owners and operators of Bell 205, 205B, 212, 412, 412CF, and UH-1H-II 
helicopters and were written to remind operators of the following:
     The importance of accomplishing a complete inspection of 
the T/R blades at specified inspection intervals;
     That the blades must be cleaned in order to perform an 
adequate visual inspection to determine their condition; and
     That maintenance manuals and component repair and overhaul 
manuals are to be consulted for damage limits and repair criteria as 
required.
     Alert Service Bulletin No. 412CF-03-20, dated February 6, 
2003, which applies to Model 412CF helicopters and provides 
instructions for doing a visual inspection of certain T/R blades 
immediately and every 25 hours TIS in accordance with the Model 412CF 
maintenance manual and instructions for sending the affected tail rotor 
blade to DND ``Calgary Supply Center'' for refinishing and 
reidentification.
     Bell Maintenance Document C-12-146-000/MF-001, Mod 4, 
dated February 12, 2004, which applies to Model 412CF helicopters and 
specifies a tail rotor blade damage records check and a visual 
inspection for dents, nicks, cracks, paint chips, or blisters using a 
2-power magnifying glass and a good source of light in specified areas 
of the tail rotor blades (reference 64-00-00, section 64-38, page 42).
    This unsafe condition is likely to exist or develop on other 
helicopters of these same type designs. Therefore, this AD is being 
issued to detect damage to a T/R blade that could lead to cracking of a 
T/R blade and subsequent loss of control of the helicopter. This AD 
requires:
     Before each start of the engines, visually checking each 
T/R blade for a crack. An owner/operator (pilot) holding at least a 
private pilot certificate may perform this visual check and must enter 
compliance with paragraph (a) of this AD into the aircraft maintenance 
records in accordance with 14 CFR 43.11 and 91.417(a)(2)(v). A pilot 
may do this check because it requires no special tools and can be 
performed equally well by a pilot or a mechanic.
     Within 25 hours TIS or 30 days, whichever occurs first, 
unless accomplished previously, and thereafter at intervals not to 
exceed 25 hours TIS or 30 days, whichever occurs first, cleaning and 
visually inspecting the T/R blade skins, leading edge spar, doublers, 
grip plates, and trailing edge for a crack, corrosion (may be indicated 
by blistering, peeling, flaking, bubbling, or cracked paint) and any 
other damage (including a nick, scratch, or dent) using a 3x or higher 
magnifying glass.
     If certain damage is found, inspecting the affected area 
using a 10-power or higher magnifying glass and measuring the depth of 
the damage.
     Before further flight, repairing or replacing, as 
applicable, any unairworthy T/R blade. The short compliance time 
involved is required because a cracked or damaged T/R blade creates an 
unsafe condition that can adversely affect the structural integrity and 
controllability of the helicopter. Therefore the required actions 
within the specified short time intervals require that this AD 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.
    We estimate that this AD will affect 384 helicopters of U.S. 
registry. There

[[Page 24862]]

are approximately 184 Model 205A and 205A-1 helicopters, 4 Model 205B 
helicopters, 101 Model 212 helicopters, 80 Model 412, 412CF, and 412EP 
helicopters, and 15 modified Model 204B helicopters. Each visual check 
will take .125 hours, each visual inspection will take .5 hours, and 6 
hours to remove and replace each T/R blade assembly, if necessary. The 
average labor rate is $80. Replacement parts will cost $11,243 for each 
T/R blade assembly. Based on these figures, the estimated cost impact 
of the AD for all of the affected models will be $1,828,855 assuming an 
average of 600 hours TIS per year for each helicopter resulting in 365 
visual checks, 24 inspections, and 5 T/R blade assembly replacements 
for the total fleet.

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-2008-0490; Directorate 
Identifier 2008-SW-26-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://
www.regulations.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).

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 AD docket 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.

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:

2008-10-03 Bell Helicopter Textron: Amendment 39-15509. Docket No. 
FAA-2008-0490; Directorate Identifier 2008-SW-26-AD.

Applicability

    The following model helicopters, with the specified tail rotor 
blade assembly (T/R blade) installed, certificated in any category:

------------------------------------------------------------------------
                                         With T/R blade, part number (P/
            Helicopter model                            N)
------------------------------------------------------------------------
204B, 205A, 205A-1, 212, 412, 412CF,     212-010-750-(all dash numbers).
 and 412EP.
205B...................................  212-010-750-(all dash numbers).
                                         212-015-501-(all dash numbers).
210....................................  210-010-001-(all dash numbers).
                                         212-010-750-(all dash numbers).
------------------------------------------------------------------------

Compliance

    Required as indicated.
    To detect any damage in a T/R blade, prevent cracking of a T/R 
blade leading to failure from static overload, and subsequent loss 
of control of the helicopter, accomplish the following:
    (a) Before each start of the engines, visually check both sides 
of each T/R blade for a crack. An owner/operator (pilot) holding at 
least a private pilot certificate may perform this visual check and 
must enter compliance with this paragraph into the aircraft 
maintenance records in accordance with 14 CFR 43.11 and 
91.417(a)(2)(v).
    (b) Within 25 hours time-in-service (TIS) or 30 days, whichever 
occurs first, unless accomplished previously, and thereafter at 
intervals not to exceed 25 hours TIS or 30 days, whichever occurs 
first:
    (1) Clean each T/R blade by hand using a mild degreaser and 
water to remove soot and grime on both sides of the blade using a 
coarse, loosely woven cotton cloth in a spanwise direction. Use a 
cloth with a color that contrasts with the color of the T/R blade so 
that a snag will be visible.
    (2) Using a 3-power or higher magnifying glass and a bright 
light, visually inspect the T/R blade skins, leading edge spar, 
doublers, grip plates, and trailing edge for a crack, corrosion (may 
be indicated by blistering, peeling, flaking, bubbling, or cracked 
paint) and any other damage (including a nick, scratch, or dent). 
See Figure 1 of this AD. Pay particular attention to both sides of 
the T/R blade in the area located 16 to 26 inches from the T/R blade 
tip (blade station 25 to 35--the T/R blade tip is located at blade 
station 51) and to the inboard blade butt area near the attachment 
of the external balance weights

[[Page 24863]]

and screws. Also pay particular attention to any blade surface that 
was snagged by the cloth, as that may be an indication of a crack or 
paint chip that could lead to corrosion.
BILLING CODE 4910-13-P
[GRAPHIC] [TIFF OMITTED] TR06MY08.182

BILLING CODE 4910-13-C

[[Page 24864]]

    (3) If any blistering, peeling, flaking, bubbling, or cracked 
paint is detected, remove the paint from the affected area and 
visually inspect the affected area for corrosion or a crack using a 
10-power or higher magnifying glass. If any corrosion is found, 
measure the depth of the corrosion (a digital optical micrometer is 
one tool that can be used for this measurement).
    (4) If a nick, scratch, or dent is found, visually inspect for a 
crack using a 10-power or higher magnifying glass and measure the 
depth of the damage (a digital optical micrometer is one tool that 
can be used for this measurement).
    (c) Before further flight:
    (1) Replace any T/R blade that has a crack with an airworthy 
blade.
    (2) Replace any T/R blade that has any corrosion, nick, scratch, 
dent, or other damage that exceeds any maximum repair limit with an 
airworthy blade.

    Note 1: The maximum repair limits are specified in the 
applicable maintenance manual.

    (3) Repair or replace with an airworthy blade any T/R blade that 
has any corrosion, nick, scratch, dent or other damage that is 
within the maximum repair limits.

    Note 2: The repair procedures are specified in the applicable 
maintenance manual and component repair and overhaul manuals.

    (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 Manager, Rotorcraft Certification Office, Rotorcraft 
Directorate, FAA, ATTN: Michael Kohner, Aviation Safety Engineer, 
Fort Worth, Texas 76193-0170, telephone (817) 222-5447, fax (817) 
222-5783, for information about previously approved alternative 
methods of compliance.
    (e) This amendment becomes effective on May 21, 2008.

    Issued in Fort Worth, Texas, on April 22, 2008.
Mark R. Schilling,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. E8-9790 Filed 5-5-08; 8:45 am]

BILLING CODE 4910-13-P
