FR Doc E8-9925

[Federal Register: May 8, 2008 (Volume 73, Number 90)]
[Rules and Regulations]
[Page 25967-25970]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr08my08-3]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-0258; Directorate Identifier 2007-CE-090-AD;
Amendment 39-15518; AD 2008-10-12]
RIN 2120-AA64

Airworthiness Directives; Air Tractor, Inc. AT-400, AT-500, AT-
600, and AT-800 Series Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) to
supersede AD 2007-13-17, which applies to certain Air Tractor, Inc.
(Air Tractor) Models AT-602, AT-802, and AT-802A airplanes. AD 2007-13-
17 currently requires you to repetitively inspect the engine mount for
any cracks, repair or replace any cracked engine mount, and report any
cracks found to the FAA. Since we issued AD 2007-13-17, Air Tractor has
learned of a Model AT-502B with a crack located where the lower engine
mount tube is welded to the engine mount ring. In addition, Air Tractor
has developed gussets that, when installed according to their service
letter, terminate the repetitive inspection requirement. Consequently,
this AD would retain the inspection actions of AD 2007-13-17 for Model
AT-602, AT-802, and AT-802A airplanes, including the compliance times
and effective dates; establish new inspection actions for the AT-400
and AT-500 series airplanes; incorporate a mandatory terminating action
for all airplanes; and terminate the reporting requirement of AD 2007-
13-17. We are issuing this AD to detect and correct cracks in the
engine mount, which could result in failure of the engine mount. Such
failure could lead to separation of the engine from the airplane.

DATES: This AD becomes effective on June 12, 2008.
On June 12, 2008, the Director of the Federal Register approved the
incorporation by reference of Snow Engineering Co. Service Letter
253, Rev. C, dated April 17, 2008; Snow Engineering Co.
Service Letter 253, Rev. B, dated November 30, 2007; and Snow
Engineering Co. Service Letter 253 Rev. A, dated October 16,
2007, as listed in this AD.
As of August 10, 2007 (72 FR 36863, July 6, 2007), the Director of
the Federal Register approved the incorporation by reference of Snow
Engineering Co. Service Letter 253, revised January 22, 2007,
as listed in this AD.

ADDRESSES: For service information identified in this AD, contact Air
Tractor Inc., P.O. Box 485, Olney, Texas 76374; telephone: (940) 564-
5616; fax: (940) 564-5612.
To view the AD docket, go to U.S. Department of Transportation,
Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200
New Jersey Avenue, SE., Washington, DC 20590, or on the Internet at
http://www.regulations.gov. The docket number is FAA-2007-0258;
Directorate Identifier 2007-CE-090-AD.

FOR FURTHER INFORMATION CONTACT: Andy McAnaul, Aerospace Engineer,
10100 Reunion Pl., Suite 650, San Antonio, Texas 78216; telephone:
(210) 308-3365; fax: (210) 308-3370.

SUPPLEMENTARY INFORMATION:

Discussion

On November 23, 2007, 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 all Air Tractor AT-400, AT-500, AT-600, and AT-800
series airplanes. This proposal was published in the Federal Register
as a notice of proposed rulemaking (NPRM) on November 30, 2007 (72 FR
67687). The NPRM proposed to supersede AD 2007-13-17 with a new AD that
would retain the inspection actions of AD 2007-13-17 for Models AT-602,
AT-802, and AT-802A airplanes, including the compliance times and
effective dates; establish new inspection actions for the AT-400 and
AT-500 series airplanes; incorporate a mandatory terminating action for
all airplanes; and terminate the reporting requirement of AD 2007-13-
17. That proposed AD would have required you to use Snow Engineering
Co. Service Letter 253 Rev. A, dated October 16, 2007.
Air Tractor revised the Snow Engineering Co. Service Letter
253 to the Rev. B level (dated November 30, 2007), and:
The FAA determined the actions in the revised service
letter were necessary and needed to be incorporated into the proposed
AD; and
Because incorporating the revision increased the burden
upon the public over that proposed in the NPRM, the FAA issued a
supplemental NPRM to give the public an additional opportunity to
comment.
The supplemental NPRM was published in the Federal Register on
December 14, 2007 (72 FR 71086).

Comments

The following presents the comment received on the proposal and
FAA's response to that comment:

Comment Issue: Delay the Terminating Action

Mr. Leland Snow, President of Air Tractor, and five other
commenters recommend some kind of delay in mandating the terminating
action in the proposed AD. Mr. Snow and one other commenter believe
that the compliance time to install welded gussets on the engine mounts
can be adjusted from before the airplane reaches 5,000 total hours
time-in-service (TIS) to before the airplane reaches 8,000 hours total
TIS. In order to get through the current spray season, three commenters
believe the compliance time should be delayed 12 months or when the
engine is removed.

[[Page 25968]]

The other commenter recommends shorter interval repetitive inspections
with no mandatory terminating action.
The FAA partially agrees. Our review of the current service history
does not support allowing the installation of welded gussets to be
extended from before the airplane reaches 5,000 total hours TIS to
before the airplane reaches 8,000 hours total TIS. We have received no
additional data to substantiate the airworthiness aspects of such an
extension and show that the unsafe condition is addressed.
After further evaluation of the service history and the risk
involved, we have determined that terminating action can be delayed
until the beginning of the 2009 spray season (May 1, 2009) provided
100-hour TIS repetitive inspections are done and no cracks are found.
Therefore, we are changing the final rule AD action to allow for the
option of delaying the terminating action until April 30, 2009, with
the provisions described above.
In addition, Air Tractor has revised Snow Engineering Co. Service
Letter 253 to the Revision C level (dated April 17, 2008).
This revision incorporates new gusset part numbers for the AT-400 and
AT-500 series airplanes. The gusset part numbers provided in Revision B
or Revision C of the service letter address the unsafe condition. We
will incorporate this service letter revision into the final rule.

Conclusion

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 change and addition described above and minor editorial
corrections. We have determined that the change, addition, and minor
corrections:
Are consistent with the intent that was proposed in the
NPRM or supplemental NPRM for correcting the unsafe condition; and
Do not add any additional burden upon the public than was
already proposed in the NPRM or supplemental NPRM.

Costs of Compliance

We estimate that this AD affects 1,264 airplanes in the U.S.
registry.
We estimate the following costs to do the inspection:

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Total cost per Total cost on
Labor cost Parts cost airplane U.S. operators
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1.5 work-hours x $80 per hour = $120............................ $0 $120 $151,680
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We estimate the following costs to do the repair/modification:

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Total cost per Total cost on
Labor cost Parts cost airplane U.S. operators
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24 work-hours x $80 per hour = $1,920........................... $80 $2,000 $2,528,000
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The estimated total cost on U.S. operators includes the cumulative
costs associated with AD 2007-13-17 and those airplanes and actions
being added in this AD.

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 AD.

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 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-2007-0258; Directorate Identifier 2007-CE-090-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. The FAA amends Sec. 39.13 by removing Airworthiness Directive (AD)
2007-13-17, Amendment 39-15121 (72 FR 36863, July 6, 2007), and adding
the following new AD:

2008-10-12 Air Tractor, Inc.: Amendment 39-15518; Docket No. FAA-
2007-0258; Directorate Identifier 2007-CE-090-AD.

Effective Date

(a) This AD becomes effective on June 12, 2008.

[[Page 25969]]

Affected ADs

(b) This AD supersedes AD 2007-13-17, Amendment 39-15121.

Applicability

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Models Serial Nos.
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AT-400, AT-400A, AT-402, AT-402A, -0001 through -1175.
and AT-402B.
AT-502, AT-502A, AT-502B, and AT- -0001 through -2597.
503A.
AT-602............................. -0001 through -1141.
AT-802 and AT-802A................. -0001 through -0227.
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Unsafe Condition

(d) This AD results from a report of a Model AT-502B airplane
with a crack located where the lower engine mount tube is welded to
the engine mount ring. The airplane had 8,436 total hours time-in-
service (TIS). We are issuing this AD to detect and correct cracks
in the engine mount, which could result in failure of the engine
mount. Such failure could lead to separation of the engine from the
airplane.

Compliance

(e) To address this problem, you must do the following, unless
already done:
(1) For all airplanes with less than 5,000 hours total TIS that
do not have gussets installed on the engine mount in accordance with
Snow Engineering Co. Service Letter #253 Rev. A, dated October 16,
2007; Snow Engineering Co. Service Letter #253 Rev. B, dated
November 30, 2007; or Snow Engineering Co. Service Letter #253 Rev.
C, dated April 17, 2008: Visually inspect the engine mount as
follows:

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Affected airplanes Compliance Procedures
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(i) For all Models AT-602, Initially before the Follow one of the
AT-802, and AT-802A airplane reaches a following:
airplanes. total of 1,300 (A) Snow Engineering
hours TIS or within Co. Service Letter
the next 100 hours 253, Rev.
TIS after August C, dated April 17,
10, 2007 (the 2008;
effective date of (B) Snow Engineering
AD 2007-13-17), Co. Service Letter
whichever occurs 253, Rev.
later. Repetitively B, dated November
thereafter at 30, 2007;
intervals not to (C) Snow Engineering
exceed 300 hours Co. Service Letter
TIS. 253, Rev.
A, dated October
16, 2007;
or
(D) Snow Engineering
Co. Service Letter
253,
revised January 22,
2007.
(ii) For all Model AT-502A Initially before the Follow one of the
airplanes. airplane reaches a following:
total of 1,300 (A) Snow Engineering
hours TIS or within Co. Service Letter
the next 100 hours 253, Rev.
TIS after June 12, C, dated April 17,
2008 (the effective 2008; or
date of this AD), (B) Snow Engineering
whichever occurs Co. Service Letter
later. Repetitively 253, Rev.
thereafter at B, dated November
intervals not to 30, 2007.
exceed 300 hours
TIS.
(iii) For all Models AT-400, Initially within the Follow one of the
AT-400A, AT-402, AT-402A, next 12 months following:
AT-402B, AT-502, AT-502B, after June 12, 2008 (A) Snow Engineering
and AT-503A airplanes. (the effective date Co. Service Letter
of this AD). 253, Rev.
Repetitively C, dated April 17,
thereafter at 2008; or
intervals not to (B) Snow Engineering
exceed 12 months. Co. Service Letter
253, Rev.
B, dated November
30, 2007.
------------------------------------------------------------------------

(2) For all airplanes: Before further flight after any
inspection required by paragraph (e)(1) of this AD where crack
damage is found, repair and modify the engine mount by installing
gussets following Snow Engineering Co. Service Letter 253,
Rev. C, dated April 17, 2008; or Snow Engineering Co. Service Letter
253, Rev. B, dated November 30, 2007. This modification
terminates the repetitive inspections required in paragraphs
(e)(1)(i), (e)(1)(ii), and (e)(1)(iii) of this AD.
(3) For all airplanes: Unless already done (mandated by
paragraph (e)(2) of this AD when crack damage was found) inspect,
repair if cracked, and modify the engine mount by installing gussets
following Snow Engineering Co. Service Letter 253, Rev. C,
dated April 17, 2008; or Snow Engineering Co. Service Letter
253, Rev. B, dated November 30, 2007, at whichever of the
following compliance times that occurs later. This modification
terminates the repetitive inspections required in paragraphs
(e)(1)(i), (e)(1)(ii), and (e)(1)(iii) of this AD.
(i) Before the airplane reaches 5,000 hours total TIS; or
(ii) Within the next 100 hours TIS after June 12, 2008 (the
effective date of this AD).
(4) For all airplanes: You may delay the modification specified
in paragraph (e)(3) above until April 30, 2009, provided you do the
following in accordance with the service information provided in the
Procedures column of the table presented in paragraph (e)(1) of this
AD:
(i) Initially inspect upon reaching the applicable time in
paragraph (e)(3)(i) or (e)(3)(ii) of this AD, unless already done
within the last 100 hours TIS;
(ii) Repetitively inspect thereafter at intervals not to exceed
100 hours TIS; and
(iii) If cracks are found during any inspection, before further
flight, repair the cracked part and install the gussets.

Note: As a terminating action to the repetitive inspections
required in paragraphs (e)(1)(i), (e)(1)(ii), and (e)(1)(iii) of
this AD, you may install the gussets before finding cracks or
reaching the times specified above provided you inspect to assure
the area is crack free before installing the gussets.

Alternative Methods of Compliance (AMOCs)

(f) The Manager, Fort Worth Airplane Certification Office, FAA,
has the authority to approve AMOCs for this AD, if requested using
the procedures found in 14 CFR 39.19. Send information to ATTN: Andy
McAnaul, Aerospace Engineer, ASW-150, FAA San Antonio MIDO-43, 10100
Reunion Place, Suite 650, San Antonio, Texas 78216; phone: (210)
308-3365; fax: (210) 308-3370. Before using any approved AMOC on any
airplane to which the AMOC applies, notify your appropriate
principal inspector (PI) in the FAA Flight Standards District Office
(FSDO), or lacking a PI, your local FSDO.

Material Incorporated by Reference

(g) You must use Snow Engineering Co. Service Letter
253, Rev. C, dated April 17, 2008; Snow Engineering Co.
Service Letter 253, Rev. B, dated November 30, 2007; Snow
Engineering Co. Service Letter 253, Rev. A, dated October
16, 2007; or Snow Engineering Co. Service Letter 253,
revised January 22, 2007, to do the actions required

[[Page 25970]]

by this AD, unless the AD specifies otherwise.
(1) The Director of the Federal Register approved the
incorporation by reference of Snow Engineering Co. Service Letter
253, Rev. C, dated April 17, 2008; Snow Engineering Co.
Service Letter 253, Rev. B, dated November 30, 2007; and
Snow Engineering Co. Service Letter 253 Rev. A, dated
October 16, 2007, under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) On August 10, 2007 (72 FR 36863, July 6, 2007), the Director
of the Federal Register approved the incorporation by reference of
Snow Engineering Co. Service Letter 253, revised January
22, 2007.
(3) For service information identified in this AD, contact Air
Tractor Inc., P.O. Box 485, Olney, Texas 76374; telephone: (940)
564-5616; fax: (940) 564-5612.
(4) You may review copies at the FAA, Central Region, Office of
the Regional Counsel, 901 Locust, Kansas City, Missouri 64106; or at
the National Archives and Records Administration (NARA). For
information on the availability of this material at NARA, call 202-
741-6030, or go to http://www.archives.gov/federal_register/code_
of_federal_regulations/ ibr_locations.html.

Issued in Kansas City, Missouri, on April 30, 2008.
Patrick R. Mullen,
Acting Manager, Small Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E8-9925 Filed 5-7-08; 8:45 am]

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