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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.

AFFECTED ADS

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

APPLICABILITY

(c) This AD  applies to the  following airplane models  and serial numbers
    that are certificated in any category:
    ______________________________________________________________________
    MODELS                                                SERIAL NUMBERS  
    ______________________________________________________________________
    AT-400, AT-400A, AT-402, AT-402A, and AT-402B      -0001 through -1175
    AT-502, AT-502A, AT-502B, and AT-503A              -0001 through -2597
    AT-602                                             -0001 through -1141
    AT-802 and AT-802A                                 -0001 through -0227
    ______________________________________________________________________

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:

    ______________________________________________________________________


    AFFECTED AIRPLANES » » »

    (i) For all Models AT-602, AT-802, and AT-802A airplanes.

                    COMPLIANCE » » »

                    Initially before the airplane reaches a total of 1,300
                    hours  TIS  or within  the  next 100  hours  TIS after
                    August 10, 2007 (the effective date of AD 2007-13-17),
                    whichever  occurs  later.  Repetitively  thereafter at
                    intervals not to exceed 300 hours TIS.

                                PROCEDURES » » »

                                Follow one of the following:

                                (A) Snow Engineering  Co.  Service  Letter
                                    #253, Rev. C, dated April 17, 2008;

                                (B) Snow Engineering  Co.  Service  Letter
                                    #253, Rev. B, dated November 30, 2007;

                                (C) Snow Engineering  Co.  Service  Letter
                                    #253 Rev. A,  dated  October 16, 2007;
                                    or

                                (D) Snow Engineering  Co.  Service  Letter
                                    #253, revised January 22, 2007.

    ______________________________________________________________________


    AFFECTED AIRPLANES » » »

    (ii) For all Model AT-502A airplanes.

                    COMPLIANCE » » »

                    Initially before the airplane reaches a total of 1,300
                    hours TIS or within the next 100 hours TIS after  June
                    12, 2008  (the effective  date of  this AD), whichever
                    occurs later. Repetitively thereafter at intervals not
                    to exceed 300 hours TIS.

                                PROCEDURES » » »

                                Follow one of the following:

                                (A) Snow Engineering  Co.  Service  Letter
                                    #253, Rev. C, dated April 17, 2008; or

                                (B) Snow Engineering  Co.  Service  Letter
                                    #253, Rev. B, dated November 30, 2007.

    ______________________________________________________________________


    AFFECTED AIRPLANES » » »

    (iii) For  all Models  AT-400, AT-400A,  AT-402, AT-402A,  AT-402B, AT
          -502, AT-502B, and AT-503A airplanes.

                    COMPLIANCE » » »

                    Initially within  the next  12 months  after June  12,
                    2008  (the effective  date of  this AD).  Repetitively
                    thereafter at intervals not to exceed 12 months.

                                PROCEDURES » » »

                                Follow one of the following:

                                (A) Snow Engineering  Co.  Service  Letter
                                    #253, Rev. C, dated April 17, 2008; or

                                (B) Snow Engineering  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  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.

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

ACTION: Final rule.

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. 

DATES: This AD becomes effective on June 12, 2008. 

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. 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: 
 
Labor Cost
Parts Cost
Total Cost Per Airplane
Total Cost on U.S. Operators
1.5 work-hours X $80 per hour = $120
$ 0
$120
$151,680

We estimate the following costs to do the repair/modification: 
 
Labor Cost
Parts Cost
Total Cost Per Airplane
Total Cost on U.S. Operators
24 work-hours X $80 per hour = $1,920
$80
$2,000
$2,528,000

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

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

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. 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: