[Federal Register: November 2, 2006 (Volume 71, Number 212)]
[Proposed Rules]
[Page 64484-64488]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr02no06-16]
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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).
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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:
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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.
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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