FR Doc 05-12177

[Federal Register: June 22, 2005 (Volume 70, Number 119)]
[Rules and Regulations]
[Page 36005-36008]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr22jn05-9]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2004-19837; Directorate Identifier 2004-CE-43-AD;
Amendment 39-14149; AD 2005-13-12]
RIN 2120-AA64

Airworthiness Directives; Air Tractor, Inc. Models AT-300, AT-
301, AT-302, AT-400, AT-400A, AT-401, AT-402, AT-602, AT-802, and AT-
802A Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA adopts a new airworthiness directive (AD) for certain
Air Tractor, Inc. (Air Tractor) Models AT-300, AT-301, AT-302, AT-400,
AT-400A, AT-401, AT-402, AT-602, AT-802, and AT-802A airplanes. This AD
requires you to repetitively tighten the four eyebolts that attach the
front and rear spar of the horizontal stabilizer to the respective
stabilizer strut to the specified torque, and repetitively replace at
specified intervals any eyebolts that attach the front and rear spar of
the horizontal stabilizer to the respective stabilizer strut. An option
for replacing the steel brace assembly inside the stabilizer with a new
steel brace assembly with larger bushings and stronger eyebolts that
increases the interval for replacement of eyebolts for AT-602, AT-802,
and AT-802A airplanes is also included in this AD. This AD results from
reports of failures of the subject eyebolt. We are issuing this AD to
detect, correct, and prevent future fatigue failure in any eyebolt that
attaches the front and rear spar of the horizontal stabilizer to the
respective stabilizer strut. Failure of the eyebolt could lead to an
abrupt change or complete loss of pitch control and/or the airplane
departing from controlled flight.

DATES: This AD becomes effective on August 5, 2005.
As of August 5, 2005, the Director of the Federal Register approved
the incorporation by reference of certain publications listed in the
regulation.

ADDRESSES: To get the service information identified in this AD,
contact Air Tractor, Incorporated, P.O. Box 485, Olney, Texas 76374.
To view the AD docket, go to the Docket Management Facility; U.S.
Department of Transportation, 400 Seventh Street, SW., Nassif Building,
Room PL-401, Washington, DC 20590-001 or on the Internet at http://dms.dot.gov.
The docket number is FAA-2004-19837; Directorate

Identifier 2004-CE-43-AD.

FOR FURTHER INFORMATION CONTACT: Andrew D. McAnaul, Aerospace Engineer,
FAA, Fort Worth Airplane Certification Office (ACO), ASW-150, 2601
Meacham Boulevard, Fort Worth, Texas 76193-0150. Current duty station:
San Antonio Manufacturing Inspection District Office (MIDO-43), 10100
Reunion Place, Suite 650, San Antonio, Texas 78216; telephone: (210)
308-3365; facsimile: (210) 308-3370.

SUPPLEMENTARY INFORMATION:

Discussion

What events have caused this AD? In December 1985, Snow Engineering
Co. issued Service Letter 62 to recommend the inspection of
eyebolts. This was in response to several reports of eyebolt failures
on Models AT-301 and AT-400 airplanes.
In response to another failure of an eyebolt on an AT-400 airplane,
Snow Engineering Co. issued Service Letter 129 in September
1994. This service letter recommended eyebolt replacement every 2,000
hours time-in-service (TIS) for Models AT-301 and AT-400 airplanes.
After a report of an eyebolt failure on a Model AT-602 airplane, Snow
Engineering Co. revised Service Letter 129 in November 2003 to
recommend replacing eyebolts for Models AT-602, AT-802, and AT-802A
airplanes every 1,350 hours TIS.
In December 2003, FAA issued Special Airworthiness Information
Bulletin (SAIB) CE-04-23. This SAIB recommended periodic eyebolt
replacement following Snow Engineering Co. Service Letter 129.
In April 2004, we received a report of both eyebolts that attach
the left hand stabilizer failing in flight on a Model AT-602 airplane.
These eyebolts had accumulated 1,675 hours TIS.
Engineering analysis concludes that the eyebolts failed as a result
of high-cycle, low-nominal stress. This is most likely due to the loss
of torque during service.
Air Tractor has since redesigned the horizontal stabilizer
structure for Models AT-802 and AT-602 airplanes to accommodate a new,
stronger eyebolt.
Snow Engineering Co. also revised Service Letter 129 with
new eyebolt replacement intervals and issued Service Letter
129A to include procedures for optional replacement of the
steel brace assembly inside the stabilizer with a new steel brace
assembly with larger bushings to accommodate new stronger eyebolts on

[[Page 36006]]

existing Models AT-602, AT-802, and AT-802A airplanes. This
modification provides for increased safety and extends eyebolt
replacement intervals.
What is the potential impact if FAA took no action? Failure of an
eyebolt could lead to an abrupt change or complete loss of pitch
control and/or aircraft departure from controlled flight.
Has FAA taken any action to this point? We issued a proposal to
amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to
include an AD that would apply to certain Air Tractor, Inc. (Air
Tractor) Models AT-300, AT-301, AT-302, AT-400, AT-400A, AT-401, AT-
402, AT-602, AT-802, and AT-802A airplanes. This proposal was published
in the Federal Register as a notice of proposed rulemaking (NPRM) on
March 4, 2005 (70 FR 10513). The NPRM proposed to require you to
repetitively tighten the four eyebolts that attach the front and rear
spar of the horizontal stabilizer to the respective stabilizer strut to
the specified torque, and repetitively replace at specified intervals
any eyebolts that attach the front and rear spar of the horizontal
stabilizer to the respective stabilizer strut. An option for replacing
the steel brace assembly inside the stabilizer with a new steel brace
assembly with larger bushings and stronger eyebolts that increases the
interval for replacement of eyebolts for AT-602, AT-802, and AT-802A
airplanes was also included in this proposed AD.

Comments

Was the public invited to comment? We provided the public the
opportunity to participate in developing this AD. The following
presents the comments received on the proposal and FAA's response to
each comment:

Comment Issue No. 1: Correct the Date for Service Letter 129
in Discussion

What is the commenter's concern? One commenter writes that the
original date of Snow Engineering Co. Service Letter 129 is
September 1994 (not September 1995) and requests use of the correct
date in the Discussion section.
What is FAA's response to the concern? We concur. We will correct
all reference in the final rule of the service letter to read, ``Snow
Engineering Co. issued Service Letter 129 in September 1994.''

Comment Issue No. 2: Cases of Cracks in Model AT-802 Airplane Eyebolts

What is the commenter's concern? Mr. Leland Snow, Air Tractor,
Inc., writes that the Discussion section of the NPRM is incorrect in
reporting, ``The FAA also received two service difficulty reports
(SDRs) in November 2003. Both SDRs referenced Model AT-802 airplane
eyebolt cracks.'' Also, Mr. Snow notes that Air Tractor inspected
eyebolts that were reported to be cracked and found that the eyebolts
were not cracked but instead had a groove caused by washer edge
contact.
What is FAA's response to the concern? The FAA is not able to
verify with certainty that the eyebolts that Air Tractor inspected are
the same or not as those eyebolts identified in the two SDRs. However,
both the eyebolts Air Tractor inspected and the eyebolts reported to
FAA were from the same sources, making Air Tractor's claim a strong
possibility.
We have deleted the reference to the two SDRs from the Discussion
section of the final rule.

Comment Issue No. 3: Initial and Repetitive Tightening of the Eyebolts

What is the commenter's concern? Mr. Leland Snow, Air Tractor,
requests that the compliance times for initial and repetitive
tightening of the eyebolts follow the times required in Snow
Engineering Service Letter 129, initial inspection and
tightening of the eyebolts within 100 hours TIS, and repetitively
tighten the eyebolts every 12 calendar months thereafter.
What is FAA's response to the concern? We agree to add the
requirement to initially inspect within 100 hours TIS after the
effective date of the AD. However, we will retain the initial 12
calendar months requirement with whichever occurs first as the
prevalent time. We agree the repetitive inspections should remain every
12 calendar months thereafter.

Conclusion

What is FAA's final determination on this issue? We have carefully
reviewed the available data and determined that air safety and the
public interest require adopting the AD as proposed except for the
changes discussed above and minor editorial corrections. We have
determined that these changes and minor corrections:

--Are consistent with the intent that was proposed in the NPRM for
correcting the unsafe condition; and
--Do not add any additional burden upon the public than was already
proposed in the NPRM.

Changes to 14 CFR Part 39--Effect on the AD

How does the revision to 14 CFR part 39 affect this AD? On July 10,
2002, the FAA published a new version of 14 CFR part 39 (67 FR 47997,
July 22, 2002), which governs the FAA's AD system. This regulation now
includes material that relates to altered products, special flight
permits, and alternative methods of compliance. This material
previously was included in each individual AD. Since this material is
included in 14 CFR part 39, we will not include it in future AD
actions.

Costs of Compliance

How many airplanes does this AD impact? We estimate that this AD
affects 1,011 airplanes in the U.S. registry.
What is the cost impact of this AD on owners/operators of the
affected airplanes? We estimate the following costs to do the
tightening of the four eyebolt nuts to the specified torque:

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Total cost per
Labor cost Parts cost airplane Total cost on U.S. operators
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1 workhour x $65 per hour = $65.... No parts required.... $65 $65 x 1,011= $65,715
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We estimate the following costs to do any necessary replacement of
the four eyebolts for the Models AT-300, AT-301, AT-302, AT-400, AT-
400A, AT-401, AT-402 AT-602, AT-802, and AT-802A airplanes:

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Average total
Average labor cost Average parts cost per Average total cost on U.S. operators
cost airplane
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1 workhour x $65 per hour = $65.. $186.30 $251.30 1,011 x $251.30 = $254,064.30
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[[Page 36007]]

We estimate the following costs to do any necessary replacement of
the steel brace assembly inside the stabilizer with a new steel brace
assembly with larger bushings on existing Models AT-602, AT-802, and
AT-802A airplanes:

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Average total
Average labor cost Average parts cost per Average total cost on U.S. operators
cost airplane
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22 workhours x $65 per hour = $901.65 $2,331.65 312 x $2,331.65 = $727,474.80
$1,430.
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Authority for This Rulemaking

What authority does FAA have for issuing this rulemaking action?
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 AD.

Regulatory Findings

Will this AD impact various entities? 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.
Will this AD involve a significant rule or regulatory action? For
the reasons discussed above, I certify that this AD:
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 summary of the costs to comply with this AD (and
other information as included in the Regulatory Evaluation) and placed
it in the AD Docket. You may get a copy of this summary by sending a
request to us at the address listed under ADDRESSES. Include ``Docket
No. FAA-2004-19837; Directorate Identifier 2004-CE-43-AD'' in your
request.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

Adoption of the Amendment

0
Accordingly, under 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. FAA amends Sec. 39.13 by adding a new AD to read as follows:

2005-13-12 Air Tractor, Inc.: Amendment 39-14149; Docket No. FAA-
2004-19837; Directorate Identifier 2004-CE-43-AD.

When Does This AD Become Effective?

(a) This AD becomes effective on August 5, 2005.

What Other ADs Are Affected by This Action?

(b) None.

What Airplanes Are Affected by This AD?

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Models Serial Nos.
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AT-300, AT-301, AT-302, AT-400, All serial numbers.
and AT-400A.
AT-401/AT-402..................... All through 401-0700.
AT-602............................ All through 602-0695 that have any 7/
16-inch eyebolt (part number (P/N)
AN47-22A) installed; all beginning
with 602-0703; and all that have
any 9/16-inch eyebolt (P/N 30774-1)
installed.
AT-802 and AT-802A................ All through 802A-0188 that have any
7/16-inch eyebolt (P/N AN47-30A)
installed; all beginning with 802A-
0189; and all that have any 9/16-
inch eyebolt (P/N 30775-1)
installed.
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What Is the Unsafe Condition Presented in This AD?

(d) This AD is the result of reports of failures of the subject
eyebolt. The actions specified in this AD are intended to detect,
correct, and prevent future fatigue failure in any eyebolt that
attaches the front and rear spar of the horizontal stabilizer to the
respective stabilizer strut. Failure of the eyebolt could lead to an
abrupt change or complete loss of pitch control and/or the airplane
departing from controlled flight.

What Must I Do To Address This Problem?

(e) To address this problem, you must do the following:

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Actions Compliance Procedures
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(1) Tighten the four Within the next 100 Follow Snow
eyebolts that attach the hours time-in- Engineering Co.
front and rear spar of the service (TIS) or 12 Service Letter
horizontal stabilizer to calendar months 129,
the respective stabilizer after August 5, Issued September
strut using the torque 2005 (the effective 26, 1994, Revised
values referenced in Snow date of this AD), October 21, 2004.
Engineering Co. Service whichever occurs
Letter 129, first, unless
revised October 21, 2004. already done.
Repetitively
tighten thereafter
at every 12
calendar months
after the date of
the initial
tightening to the
specified torque.
-----------------------------

[[Page 36008]]

(2) Repetitively replace any Initially replace Follow Snow
eyebolts that attach the upon accumulating Engineering Co.
front and rear spar of the the applicable Service Letter
horizontal stabilizer to number of hours TIS 129,
the respective stabilizer referenced in Snow Issued September
strut. Engineering Co. 26, 1994, Revised
Service Letter October 21, 2004.
129,
revised October 21,
2004, or within 50
hours TIS after
August 5, 2005 (the
effective date of
this AD), whichever
occurs later.
Replace
repetitively
thereafter at the
intervals
referenced in Snow
Engineering Co.
Service Letter
129,
revised October 21,
2004.
-----------------------------
(3) For Model AT-602 At any time after Follow Snow
airplanes through serial August 5, 2005 (the Engineering Co.
number 602-0695 and AT-802, effective of this Service Letter
and 802A airplanes through AD). Use the 129A,
serial number 802A-0188: As applicable time in Dated August 7,
an alternative in order to Snow Engineering 2004.
use the increased Co. Service Letter
replacement compliance 129A,
times in paragraph (e)(2) dated August 7,
of this AD, you may replace 2004. The
the steel brace assembly repetitive
inside the stabilizer with replacement of
a new steel brace assembly paragraph (e)(2) of
with larger bushings, and this AD is still
(i) For the Model AT-602 required.
airplane: replace any 7/16-
inch eyebolt with the 9/16-
inch eyebolt (P/N 30774-1)
(ii) For the Model AT-802
and AT-802A airplanes:
replace any 7/16-inch
eyebolt with the 9/16-inch
eyebolt (P/N 30775-1)
-----------------------------
(4) Do not install any 5/16- As of August 5, 2005 Not Applicable.
inch eyebolt (P/N AN44-17A (the effective date
or AN44-21A), 7/16-inch of this AD).
eyebolt (AN47-22A or AN47-
30A), or 9/16-inch eyebolt
(P/N 30774-1 or 30775-1)
that exceeds the
corresponding cumulative
hours TIS specified in
paragraphs (e)(2) or (e)(3)
of this AD.
------------------------------------------------------------------------

May I Request an Alternative Method of Compliance?

(f) You may request a different method of compliance or a
different compliance time for this AD by following the procedures in
14 CFR 39.19. Unless FAA authorizes otherwise, send your request to
your principal inspector. The principal inspector may add comments
and will send your request to the Manager, Fort Worth Airplane
Certification Office (ACO), FAA. For information on any already
approved alternative methods of compliance, contact Andrew D.
McAnaul, Aerospace Engineer, FAA, Fort Worth ACO, ASW-150, 2601
Meacham Boulevard, Fort Worth, Texas 76193-0150. Current duty
station: San Antonio Manufacturing Inspection District Office (MIDO-
43), 10100 Reunion Place, Suite 650, San Antonio, Texas 78216;
telephone: (210) 308-3365; facsimile: (210) 308-3370.

Does This AD Incorporate Any Material by Reference?

(g) You must do the actions required by this AD following the
instructions in Snow Engineering Co. Service Letter 129,
Issued September 26, 1994, Revised October 21, 2004, and Snow
Engineering Co. Service Letter 129A, dated August 7, 2004.
The Director of the Federal Register approved the incorporation by
reference of this service bulletin in accordance with 5 U.S.C.
552(a) and 1 CFR part 51. To get a copy of this service information,
contact Air Tractor, Incorporated, P.O. Box 485, Olney, Texas 76374.
To review copies of this service information, go to the National
Archives and Records Administration (NARA). For information on the
availability of this material at NARA, go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html
or call (202) 741-6030. To view the AD docket,

go to the Docket Management Facility; U.S. Department of
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-
401, Washington, DC 20590-001 or on the Internet at http://dms.dot.gov.
The docket number is FAA-2004-19837; Directorate

Identifier 2004-CE-43-AD.

Issued in Kansas City, Missouri, on June 14, 2005.
John R. Colomy,
Acting Manager, Small Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 05-12177 Filed 6-21-05; 8:45 am]

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