[Federal Register Volume 71, Number 212 (Thursday, November 2, 2006)]
[Proposed Rules]
[Pages 64484-64488]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-18462]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-26219; Directorate Identifier 2004-SW-49-AD]
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: Notice of proposed rulemaking (NPRM).

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

SUMMARY: This document proposes adopting a new airworthiness directive 
(AD) for Bell Helicopter Textron (Bell) Model 204B, 205A, 205A-1, 205B, 
210, 212, 412, 412CF, and 412EP helicopters. The AD would require 
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 proposal is prompted by 
eight reports of T/R blade failures. The actions specified by the 
proposed AD are intended to prevent failure of a T/R blade and 
subsequent loss of control of the helicopter.

DATES: Comments must be received on or before January 2, 2007.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD:
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically;
     Government-wide rulemaking Web site: Go to[hairsp]http://www.regulations.gov and follow the instructions for sending your 
comments electronically;
     Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590;
     Fax: 202-493-2251; or
     Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    You may get the service information identified in this proposed AD 
from Bell Helicopter Textron, Inc., P.O. Box 482, Fort Worth, Texas 
76101, telephone (817) 280-3391, fax (817) 280-6466.
    You may examine the comments to this proposed AD in the AD docket 
on the Internet at http://dms.dot.gov.

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:

Comments Invited

    We invite you to submit any written data, views, or arguments 
regarding this proposed AD. Send your comments to the address listed 
under the caption ADDRESSES. Include the docket number ``FAA-2006-
26219, Directorate Identifier 2004-SW-49-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the proposed AD. We will 
consider all comments received by the closing date and may amend the 
proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also

[[Page 64485]]

post a report summarizing each substantive verbal contact with FAA 
personnel concerning this proposed rulemaking. 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 or 
signed 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) or you may visit http://dms.dot.gov.

Examining the Docket

    You may examine the docket that contains the proposed AD, any 
comments, and other information in person at the Docket Management 
System (DMS) Docket Office between 9 a.m. and 5 p.m., Monday through 
Friday, except Federal holidays. The Docket Office (telephone 1-800-
647-5227) is located at the plaza level of the Department of 
Transportation NASSIF Building in Room PL-401 at 400 Seventh Street, 
SW., Washington, DC. Comments will be available in the AD docket 
shortly after the DMS receives them.

Discussion

    There have been eight reported failures due to 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 the failures were in-flight and the T/R blades 
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 during an inspection:

--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          P/N  212-010-                Blade station   Crack length    Initial damage part and
           Model                Year          750-        Hours TIS        (in.)           (in)                 type               Initial damage size
--------------------------------------------------------------------------------------------------------------------------------------------------------
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.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    A preliminary investigation after one of the in-flight blade 
failures indicated that the operator (Canadian Department of Defense) 
was not using any specific inspection methods to detect small-scale 
damage on the T/R blades as required by the maintenance manual. A daily 
inspection was being conducted from the ground with the tail rotor 
mounted over 10 feet off of the ground. Inquiries to other Model 212 
and 412 helicopter operators indicate that some of them are not 
accomplishing adequate inspections either. The accident investigation 
team concluded that without a detailed visual inspection, the 
probability of detection is extremely low for the kind of damage and 
fatigue crack that results from the tail rotor design and usage.
    The Canadian Department of Defense now uses a 12.5-hour inspection 
interval for the detailed visual inspection using a 2-power magnifying 
glass for the T/R blades on their Model 412CF helicopters. This 
interval was implemented as a result of a risk assessment performed for 
the T/R blade failure. If damage is suspected, this is followed by a 
10-power magnifying glass and appropriate measuring tools (i.e. optical 
micrometer). The striation count for the failed blade indicates a crack 
propagation rate of approximately 77 hours TIS from damage initiation 
to blade failure.
    We have determined that:
     The T/R blades are susceptible to impact damage from 
outside sources (gravel, stone, hail, etc.). The impact damage is the 
originating point for initiating fatigue cracks with subsequent growth 
until the blade fails from overload on the remaining intact structure;
     Fatigue cracks have also initiated from corrosion and 
corrosion pits;
     Model 205A, 205A-1, and certain 204B helicopters with the 
same part-numbered T/R blades as those installed on Model 212 and 412 
helicopters should be included in this proposed AD; and
     Model 205B and 210 helicopters with the same type-designed 
T/R blades as those installed on Model 212 and 412 helicopters should 
also be included in this proposed AD.
    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. That Operations Safety Notice applies to all 
owners and operators of Bell 205, 205B, 212, 412, 412CF, and UH-1H-II 
helicopters and was 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 Model 412CF 
maintenance manual and instructions for sending the affected tail rotor 
blade

[[Page 64486]]

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 the same type designs. Therefore, the proposed AD would 
require the following actions:
     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.
    The requirements of the proposed AD would be interim actions until 
either a more rigorous inspection is developed or a new blade that is 
more damage tolerant is designed. The manufacturer is currently 
considering a redesign of these T/R blades.
    We estimate that this proposed AD would affect 388 helicopters of 
U.S. registry. There are approximately 184 Model 205A and 205A-1 
helicopters, 8 Model 205B helicopters, 101 Model 212 helicopters, 80 
Model 412, 412CF, and 412EP helicopters, and 15 modified Model 204B 
helicopters. Each visual check would take .125 hours, each visual 
inspection would 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 would cost $11,243 for each T/R blade assembly. Based 
on these figures, the estimated cost impact of the proposed AD for all 
of the affected models would be $1,847,295 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.

Regulatory Findings

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. Additionally, this proposed 
AD would not have a substantial direct effect on the States, on the 
relationship between the national Government and the States, or on the 
distribution of power and responsibilities among the various levels of 
government.
    For the reasons discussed above, I certify that the proposed 
regulation:
    1. Is not a ``significant regulatory action'' under Executive Order 
12866;
    2. Is not a ``significant rule'' under the DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979); 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 a draft economic evaluation of the estimated costs to 
comply with this proposed AD. See the DMS to examine the draft 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.

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:

Bell Helicopter Textron: Docket No. FAA-2006-26219; Directorate 
Identifier 2004-SW-49-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 assembly, part number
         Helicopter model                           (P/N)
------------------------------------------------------------------------
204B..............................  212-010-750-009, -105, or -113.
205A and 205A-1...................  212-010-750-009, -105, or -113.
205B..............................  212-010-750-109, -111, -117, -125,
                                     or -135
                                    212-015-501-115 or -121.
210...............................  212-010-001-101.
212...............................  212-010-750-009, -105, or -113.
412...............................  212-010-750-009, -011, -105, -107, -
                                     113, or -115.
412CF.............................  212-010-750-009, -011, -105, -107, -
                                     113, or -115.
412EP.............................  212-010-750-009, -011, -105, -107, -
                                     113, or -115.
------------------------------------------------------------------------

Compliance

    Required as indicated.
    To prevent failure of a T/R blade 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 15 days, whichever 
occurs first, unless accomplished previously, and thereafter at 
intervals not to exceed 25 hours TIS or 15 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

[[Page 64487]]

blade in the area located 10 to 25 inches from the T/R blade tip 
(blade station 26 to 41--the T/R blade tip is located at blade 
station 51). 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.
    1. Pitch Horn Blade Bolts.
    2. Blade Grip Bolt Holes.
    3. External Balance Weights.
    4. Doubler.
    5. Trailing Edge.
    6. Skin.
    7. Honeycomb Core.
    8. Tip Block.
    9. Balance Screws.
    10. Spar.
    11. Grip Plate.
    12. Drain Hole Doubler.
    13. Butt Block.
    14. Inner Grip Plate.
    15. Tip Closure.
    [GRAPHIC] [TIFF OMITTED] TP02NO06.000
    
    (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 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.


[[Page 64488]]


    Issued in Fort Worth, Texas, on October 26, 2006.
Mark R. Schilling,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
 [FR Doc. E6-18462 Filed 11-1-06; 8:45 am]
BILLING CODE 4910-13-P