Air Tractor AT-Series

Airworthiness Directives; Air Tractor, Inc. Airplanes

The FAA is superseding Airworthiness Directive (AD) 2024-16- 06, which applied to all Air Tractor, Inc. (Air Tractor) Model AT-802 and AT-802A airplanes with Wipaire, Inc. Supplemental Type Certificate (STC) No. SA01795CH installed. AD 2024-16-06 required repetitively inspecting the left and right, forward and rear, horizontal stabilizer spars for cracks, replacing any horizontal stabilizer spar found cracked or damaged, installing bathtub fittings, and reporting inspection results to the FAA. Since the FAA issued AD 2024-16-06, additional cracks in the horizontal stabilizer spars were reported where the vertical fin structural support brace mounts to the horizontal stabilizer spar. This AD retains all the actions of AD 2024- 16-06 and adds inspections to another area. The FAA is issuing this AD to address the unsafe condition on these products.

Airworthiness Directives; Air Tractor, Inc. Airplanes

The FAA is superseding Airworthiness Directive (AD) 2023-15- 07, which applied to all Air Tractor, Inc. (Air Tractor) Model AT-802 and AT-802A airplanes with Wipaire, Inc. Supplemental Type Certificate (STC) No. SA01795CH installed. AD 2023-15-07 required repetitively inspecting the left and right forward horizontal stabilizer spars for cracks, replacing any forward horizontal stabilizer spar found cracked, and reporting inspection results to the FAA. This AD requires repetitively inspecting the left and right, forward and rear, horizontal stabilizer spars for cracks at shorter intervals than those required by AD 2023-15-07, replacing any horizontal stabilizer spar found cracked or damaged, installing bathtub fittings, and reporting inspection results to the FAA. This AD was prompted by additional reports of cracks in the horizontal stabilizer spars and the need to incorporate a new finlet attach design on the horizontal stabilizer spars to reduce the cracking. The FAA is issuing this AD to address the unsafe condition on these products.

Airworthiness Directives; Air Tractor, Inc. Airplanes

The FAA is adopting a new airworthiness directive (AD) for all Air Tractor, Inc. (Air Tractor) Model AT-802 and AT-802A airplanes that have Wipaire Supplemental Type Certificate (STC) No. SA01795CH installed. This AD was prompted by reports of cracks found in the forward horizontal stabilizer spar where the vertical finlets tie to the horizontal tail forward spar. This AD requires repetitively inspecting both the left and right forward horizontal stabilizer spars for cracks and replacing any forward horizontal stabilizer spar found cracked. This AD also requires reporting inspection results to the FAA. The FAA is issuing this AD to address the unsafe condition on these products.

Airworthiness Directives; Air Tractor, Inc., Airplanes

The FAA is adopting a new airworthiness directive (AD) for all Air Tractor, Inc., (Air Tractor) Models AT-250, AT-300, AT-301, AT-302, AT-400, AT-400A, AT-401, AT-401A, AT-401B, AT-402, AT-402A, AT-402B, AT-501, AT-502, AT-502A, AT-502B, AT-503, AT-503A, AT-504, AT-602, AT- 802, and AT-802A airplanes. This AD was prompted by reports of cracks in the flap torque tube actuator attachment brackets that may cause the flap actuator to detach from the flap torque tube. This AD requires repetitive visual and dye penetrant inspections of the flap actuator attachment bracket welds for cracks and replacement if cracks are identified. The FAA is issuing this AD to address the unsafe condition on these products.

Airworthiness Directives; Air Tractor, Inc. Airplanes

We are superseding Airworthiness Directive (AD) 2010-17-18 R1, which applies to certain Air Tractor, Inc. Models AT-802 and AT-802A airplanes. AD 2010-17-18 R1 required repetitively inspecting (using the eddy current method) the two outboard fastener holes in both of the wing main spar lower caps at the center splice joint for cracks; repairing or replacing any cracked spar; changing the safe life for certain serial number ranges; and sending the inspection results, only if cracks are found, to the FAA. This new AD retains all actions of AD 2010-17-18 R1 and expands the applicability to include all serial numbers regardless of configuration or operational use. This AD was prompted by our determination that the safe life for the wing main spar lower caps should apply to all Models AT-802 and AT-802A airplanes regardless of configuration or operational use. We are issuing this AD to correct the unsafe condition on these products.

Airworthiness Directives; Air Tractor, Inc. Models AT-802 and AT-802A Airplanes

We are adopting a new airworthiness directive (AD) to supersede AD 2010-13-08, which applies to all Air Tractor, Inc. (Air Tractor) Models AT-802 and AT-802A airplanes. AD 2010-13-08 currently requires you to repetitively inspect (using the eddy current method) the two outboard fastener holes in both of the wing main spar lower caps at the center splice joint for cracks and repair or replace any cracked spar cap. Since we issued 2010-13-08, we evaluated service information issued by Air Tractor and determined we need to add inspections, add modifications, and change the safe life for certain serial number (SN) ranges. Consequently, this AD would retain the actions of AD 2010-13-08 and would add inspections, add modifications, and change the safe life for certain SN ranges. We are issuing this AD to detect and correct cracks in the wing main spar lower cap at the center splice joint, which could result in failure of the spar cap and lead to wing separation and loss of control of the airplane.

Airworthiness Directives; Air Tractor, Inc. Models AT-802 and AT-802A Airplanes

We are adopting a new airworthiness directive (AD) for certain Air Tractor, Inc. Models AT-802 and AT-802A airplanes. This AD requires installing a rudder-aileron interconnect cable system shield kit and securing any items stowed in the baggage compartment, using tie downs and/or a cargo net until the cable shield kit is installed. We are issuing this AD to prevent jamming of the rudder-aileron interconnect cables by unsecured items in the baggage compartment, which could result in failure of the rudder-aileron interconnect cable system. This failure could lead to loss of control.

Airworthiness Directives; Air Tractor, Inc. Models AT-400, AT-400A, AT-402, AT-402A, AT-402B, AT-502, AT-502A, AT-502B, AT-503A, AT-602, AT-802, and AT-802A Airplanes

We are adopting a new airworthiness directive (AD) to supersede AD 2008-10-12, which applies to certain Air Tractor, Inc. AT- 400, AT-500, AT-600, and AT-800 series airplanes. AD 2008-10-12 currently requires repetitively inspecting the engine mounts for cracks, repairing any crack damage found, and installing gussets as a terminating action for the repetitive inspections. This AD results from a report of a Model AT-602 airplane with a crack completely through the gusset that was installed as required in AD 2008-10-12. Consequently, this AD would require you to continue repetitively inspecting the engine mounts for cracks for all previously affected Air Tractor, Inc. AT-400, AT-500, AT-600, and AT-800 series airplanes with or without gussets installed, and repairing any crack damage found. We are issuing this AD to detect and correct cracks in the engine mount, which could result in failure of the engine mount. This failure could lead to separation of the engine from the airplane.

Airworthiness Directives; Air Tractor, Inc. Models AT-400, AT-401, AT-401B, AT-402, AT-402A, and AT-402B Airplanes

We are adopting a new airworthiness directive (AD) to revise AD 2006-08-08, which applies to certain Air Tractor, Inc. (Air Tractor) Models AT-400, AT-401, AT-401B, AT-402, AT-402A, and AT-402B airplanes. AD 2006-08-08 currently requires you to repetitively eddy current inspect the wing lower spar cap in order to reach the safe life and, for certain Models AT-402A and AT-402B airplanes and those that incorporate or have incorporated Marburger Enterprises, Inc. (Marburger) winglets, lowers the safe life for the wing lower spar cap. Since we issued AD 2006-08-08, we have received information to update inspection intervals for the Models AT-401B, AT-402A, and AT-402B airplanes based on a revised damage tolerance analysis. Consequently, this AD would not only retain the actions of AD 2006-08-08, but would reduce the number of repetitive inspections for all affected Model AT- 401B airplanes and certain Models AT-402A and AT-402B airplanes. We are issuing this AD to prevent fatigue cracks from occurring in the wing lower spar cap before the originally established safe life is reached. Fatigue cracks in the wing lower spar cap, if not detected and corrected, could result in wing separation and loss of control of the airplane.

Airworthiness Directives; Air Tractor, Inc. Models AT-200, AT-300, AT-400, AT-500, AT-600, and AT-800 Series Airplanes

We are adopting a new airworthiness directive (AD) to supersede AD 2008-11-17, which applies to certain Air Tractor, Inc. Models AT-200, AT-300, AT-400, AT-500, AT-600, and AT-800 series airplanes. AD 2008-11-17 currently requires you to install an overturn skid plate kit or a modification to the overturn skid plate already installed. Since we issued AD 2008-11-17, the manufacturer has notified us that Model AT-401B airplanes also need a modification to the overturn skid plate. Consequently, this AD would retain the actions of AD 2008-11-17 and add the requirement to modify the overturn skid plate installed on Model AT-401B airplanes. We are issuing this AD to prevent the front and rear connections of the overturn skid plate to the airplane from breaking, which could allow foreign debris to enter the cockpit during an airplane overturn. This condition, if not corrected, could lead to pilot injury.

Airworthiness Directives; Air Tractor, Inc. Models AT-402, AT-402A, and AT-402B Airplanes

We are adopting a new airworthiness directive (AD) for certain Air Tractor, Inc. (Air Tractor) Models AT-402, AT-402A, and AT-402B airplanes. This AD requires you to repetitively visually inspect the rudder and vertical fin hinge attaching structure for loose fasteners and inspect the rudder or vertical fin skins, spars, hinges, or brackets for cracks and/or corrosion. This AD also requires you to replace any damaged parts found as a result of the inspections and install an external doubler at the upper rudder hinge. Installation of the external doubler at the upper rudder hinge is terminating action for the repetitive inspection requirements. This AD results from a report of a Model AT-402 airplane with a loose upper rudder hinge caused by fatigue. We are issuing this AD to detect and correct loose fasteners; any cracks in the rudder or vertical fin skins, spars, hinges, or brackets; or corrosion of the rudder and vertical fin hinge attaching structure. Hinge failure adversely affects ability to control yaw and has led to the rudder folding over in flight. This condition could allow the rudder to contact the elevator and affect ability to control pitch with consequent loss of control.

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

The FAA is adopting a new airworthiness directive (AD) to supersede AD 2003-06-01, which applies to all Air Tractor, Inc. (Air Tractor) Models AT-300, AT-301, AT-302, and AT-400A airplanes that have aluminum spar caps; certain Air Tractor Models AT-400 airplanes that have aluminum spar caps; and all Models AT-300 and AT-301 airplanes that have aluminum spar caps and are or have been converted to turbine power. AD 2003-06-01 requires replacing the wing spar lower caps at a specified safe life limit; allows extending the safe life limit on certain airplanes if a wing lower spar cap splice rework is done; allows a limited time of continued operation beyond the safe life limit provided parts are ordered, the replacement is scheduled, and repetitive inspections reveal no cracks; and requires a report of any cracks found during any inspection to the FAA. This AD results from a recent report of cracks found on a Model AT-301 airplane at hours below the modification time specified in AD 2003-06-01. Consequently, this AD retains the wing spar lower cap replacement and reporting requirements from AD 2003-06-01 and adds a repetitive eddy-current inspection. We are issuing this AD to detect and correct cracks in the wing centerline splice joint. If not detected and corrected, these cracks could result in the wing separating from the airplane during flight.

Airworthiness Directives; Air Tractor, Inc. Model AT-602 Airplanes

We are adopting a new airworthiness directive (AD) for certain Air Tractor, Inc. (Air Tractor) Model AT-602 airplanes. This AD requires you to install access holes to do repetitive detailed visual inspections for cracks in the horizontal stabilizer brace tube assembly, and if any cracks are found as a result of a visual inspection, to replace the horizontal stabilizer brace tube assembly with a new design horizontal stabilizer brace tube assembly. The installation of the new design horizontal stabilizer brace tube assembly is terminating action for the repetitive inspection requirement. This AD results from two reports of Model AT-602 airplanes with cracked horizontal stabilizer brace tube assemblies. We are issuing this AD to detect and correct cracks in the horizontal stabilizer brace tube assembly, which could result in failure of the horizontal stabilizer. This failure could affect the ability to control pitch with consequent loss of control.

Airworthiness Directives; Air Tractor, Inc. Models AT-501, AT-502, AT-502A, AT-502B, and AT-503A Airplanes

We are adopting a new airworthiness directive (AD) for certain Air Tractor, Inc. Models AT-501, AT-502, AT-502A, AT-502B, and AT-503A airplanes, which supersedes AD 2002- 26-05 and AD 2002-11-05 R1. Since we issued AD 2002-26-05 and AD 2002- 11-05 R1, we determined that additional airplanes should be added to the applicability section and determined the safe life for new production airplanes and replacement spar caps should be extended. We also developed an alternative method of compliance (AMOC) to the requirements of this AD. This AD retains the actions required in AD 2002-26-05 and AD 2002-11-05 R1, adds additional airplanes to the Applicability section, extends the safe life for new production airplanes and replacement spar caps, and incorporates an AMOC. We are issuing this AD to prevent fatigue cracks from occurring in the wing lower spar cap before the established safe life is reached. Fatigue cracks in the wing lower spar cap could result in failure of the spar cap and lead to wing separation.

Airworthiness Directives; Air Tractor, Inc. Models AT-502, AT-502A, AT-502B, AT-602, AT-802, and AT-802A Airplanes

The FAA adopts a new airworthiness directive (AD) for certain Air Tractor, Inc. (Air Tractor) Models AT-502, AT-502A, AT-502B, AT- 602, AT-802, and AT-802A airplanes. This AD requires you to repetitively visually inspect the rudder and vertical fin hinge attaching structure (vertical fin skins, spars, hinges, and brackets) for loose fasteners, cracks, and/or corrosion. This AD also requires you to replace any damaged parts found as a result of the inspection and install an external doubler at the upper rudder hinge. This AD results from two reports of in-flight rudder separation from the vertical fin at the upper attach hinge area, and other reports of airplanes with loose hinges, skin cracks, or signs of repairs to the affected area. We are issuing this AD to detect and correct loose fasteners; any cracks in the rudder or vertical fin skins, spars, hinges or brackets; and/or corrosion of the rudder and vertical fin hinge attaching structure. Hinge failure adversely affects ability to control yaw and has led to the rudder folding over in flight. This condition could allow the rudder to contact the elevator and affect ability to control pitch with consequent loss of control.

Airworthiness Directives; Air Tractor, Inc. Model AT-602 Airplanes

The FAA adopts a new airworthiness directive (AD) for all Air Tractor, Inc. (Air Tractor) Model AT-602 airplanes. This AD requires you to repetitively inspect (using the eddy current method) the wing center splice joint two outboard fastener holes on both of the wing main spar lower caps for fatigue cracking; repair or replace any wing main spar lower cap where fatigue cracking is found; and report any fatigue cracking found. This AD results from fatigue cracking at the wing center splice joint outboard fastener hole in one of the wing main spar lower caps. We are issuing this AD to detect and correct cracks in the wing main spar lower cap, which could result in failure of the spar cap and lead to wing separation and loss of control of the airplane.

Airworthiness Directives; Air Tractor, Inc. Models AT-802 and AT-802A Airplanes

We are adopting a new airworthiness directive (AD) for certain Air Tractor, Inc. (Air Tractor) Models AT-802 and AT-802A airplanes. This AD requires you to repetitively inspect the attach angles on the firewall mounted hopper rinse tank shelf for damage and/or cracks and replace damaged and/or cracked attach angles with steel attach angles. Replacing the attach angles with steel attach angles terminates the repetitive inspection requirement. Reports of an uncommanded change in the engine power setting caused by separation of the hopper rinse tank shelf from the firewall prompted this AD. We are issuing this AD to detect and correct damage and/or cracks in the attach angles on the firewall mounted hopper rinse tank shelf, which could result in failure of the attach angles. This failure could lead to shelf movement under maneuver load and shifting of the engine power cables, which could result in an uncommanded engine power setting change.

Airworthiness Directives; Air Tractor, Inc. Models AT-400; AT-401, AT-401B, AT-402, AT-402A, and AT-402B Airplanes

The FAA is adopting a new airworthiness directive (AD) for certain Air Tractor, Inc. (Air Tractor) Models AT-400, AT-401, AT-401B, AT-402, AT-402A, and AT-402B airplanes. This AD requires you to lower the safe life for the wing lower spar cap for certain Models AT-402A and AT-402B airplanes and those that incorporate or have incorporated Marburger Enterprises, Inc. (Marburger) winglets. For Models AT-400, AT-401, AT-401B, AT-402, and certain AT-402A, airplanes, this AD requires you to repetitively inspect the wing lower spar cap in order to reach the safe life. We also developed an alternative method of compliance (AMOC) to the requirements of this Ad for certain Models AT- 402A and AT-402B airplanes. The AMOC includes repetitive eddy current inspections, modification of the center splice connection, and lower spar cap replacement. This AD is the result of reports of cracks in the \3/8\-inch bolt hole of the wing lower spar cap before reaching the approved safe life. We are issuing this AD to prevent fatigue cracks from occurring in the wing lower spar cap before the originally established safe life is reached. Fatigue cracks in the wing lower spar cap, if not detected and corrected, could result in wing separation and loss of control of the airplane.

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

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.

Airworthiness Directives; Air Tractor, Inc. Models AT-401, AT-401B, AT-402, AT-402A, AT-402B, AT-501, AT-502, AT-502A, AT-502B, AT-503A, AT-602, AT-802, and AT-802A Airplanes

The FAA supersedes Airworthiness Directive (AD) 2002-19-10, which applies to certain Air Tractor, Inc. (Air Tractor) Models AT-402, AT-402A, AT-402B, AT-602, AT-802, and AT-802A airplanes. AD 2002-19-10 currently requires you to repetitively inspect the upper longeron and upper diagonal tube on the left hand side of the aft fuselage structure for cracks and contact the manufacturer for a repair scheme if cracks are found. This AD is the result of reports of the same cracks recently found on AT-500 series airplanes. The manufacturer has also issued new and revised service information that incorporates a modification to terminate the repetitive inspection requirements. Consequently, this AD retains the inspection actions required in AD 2002-19-10, adds certain AT-500 series airplanes to the applicability section, changes the compliance times, and incorporates new and revised manufacturer service information that contains a terminating action for the repetitive inspection requirement. We are issuing this AD to detect and correct cracks in the upper aft longeron, which could cause the fuselage to fail. Such failure could result in loss of control of the airplane.

Airworthiness Directives; Air Tractor, Inc. Models AT-300, AT-400, AT-400A, AT-401, AT-401B, AT-402, AT-402A, AT-402B, AT-501, AT-502, and AT-502B Airplanes

This amendment adopts a new airworthiness directive (AD) that applies to certain Air Tractor, Inc. (Air Tractor) Models AT-300, AT- 400, AT-400A, AT-401, AT-401B, AT-402, AT-402A, AT-402B, AT-501, AT- 502, and AT-502B airplanes. This AD requires you to repetitively inspect the vertical fin front spar fitting for cracks and replace any cracked fitting found. This AD also requires you to install a steel doubler as a terminating action for the repetitive inspections. This AD is the result of a report of failure of a \1/4\-inch thick vertical fin front spar fitting. The actions specified by this AD are intended to prevent failure of the vertical fin front spar fitting, which could result in failure of the rear spar fitting. Such failures could lead to loss of directional control of the airplane.

Airworthiness Directives; Air Tractor, Inc. Models AT-502, AT-502A, AT-502B, and AT-503A Airplanes

This amendment supersedes Airworthiness Directive (AD) 2002- 11-03, which applies to certain Air Tractor, Inc. (Air Tractor) Models AT-502, AT-502A, AT-502B, and AT-503A airplanes. AD 2002-11-03 lowered the safe life for the wing lower spar cap and further reduced the safe life for airplanes that incorporate or have incorporated Marburger Enterprises, Inc. winglets. AD 2002-11-03 also currently requires you to eddy-current inspect the wing lower spar cap immediately prior to the replacement/modification to detect and correct any crack in a bolthole before it extends to the modified center section of the wing and report the results of this inspection to the Federal Aviation Administration (FAA). Field inspections on the affected airplanes have revealed wings with cracks below the currently established safe life. This AD would further reduce the safe life of the Models AT502, AT- 502B, and AT-503A airplanes and would add airplanes recently manufactured to the Applicability of the AD. The actions specified by this AD are intended to prevent fatigue cracks from occurring in the wing lower spar cap before the established safe life is reached. Fatigue cracks in the wing lower spar cap, if not detected and corrected, could result in the wing separating from the airplane during flight.

Airworthiness Directives; Air Tractor, Inc. Models AT-802 and AT-802A Airplanes

This amendment adopts a new airworthiness directive (AD) that applies to certain Air Tractor, Inc. (Air Tractor) Models AT-802 and AT-802A airplanes. This AD requires you to replace the rudder control cables and fairleads with parts of improved design. This AD is the result of a report that a rudder control cable broke because of wear at the aft fairlead. The actions specified by this AD are intended to prevent the rudder control cable from breaking because of the rudder control cables wearing in the fairlead area. Broken rudder control cables could result in loss of rudder control.

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

This amendment adopts a new airworthiness directive (AD) that applies to all Air Tractor, Inc. (Air Tractor) Models AT-300, AT-301, AT-302, and AT-400A airplanes that have aluminum spar caps; certain Air Tractor Models AT-400 airplanes that have aluminum spar caps; and all Models AT-300 and AT-301 airplanes that have aluminum spar caps and are or have been converted to turbine power. This AD requires you to inspect (one-time) the wing centerline splice joint for cracks and, if any crack is found, replace the affected wing spar lower cap. This AD also requires you to report the results of the inspection to the Federal Aviation Administration (FAA) and replace the wing spar lower caps after a certain amount of usage. This AD is the result of an incident on one of the affected airplanes where the wing separated from the airplane. Preliminary reports indicate that fatigue caused the lower aluminum spar cap to fail across the \3/8\-inch bolt hole (6.5 inches outboard of the fuselage centerline in the centersplice connection). The actions specified by this AD are intended to detect and correct cracks in the wing centerline splice joint. If not detected and corrected, these cracks could eventually result in the wing separating from the airplane during flight.

Airworthiness Directives; Air Tractor, Inc. Models AT-502, AT-502A, AT-502B, and AT-503A Airplanes

This amendment adopts a new airworthiness directive (AD) that applies to certain Air Tractor, Inc. (Air Tractor) Models AT-502, AT- 502A, AT-502B, and AT-503A airplanes. This AD lowers the safe life for the wing lower spar cap established in AD 2001-10-04 R1 and further reduces the safe life for airplanes that incorporate or have incorporated Marburger Enterprises, Inc. winglets. This AD also requires you to eddy-current inspect the wing lower spar cap immediately prior to the replacement/modification to detect and correct any crack in a bolthole before it extends to the modified center section of the wing and report the results of this inspection to the Federal Aviation Administration (FAA). This AD is the result of reports of several cracks originating in the outboard \3/8\-inch hole of the main spar lower cap on Air Tractor Models AT-502, AT-502A, AT-502B, and AT-503A airplanes at times lower than the established safe life. The actions specified by this AD are intended to prevent fatigue cracks from occurring in the wing lower spar cap before the established safe life is reached. Fatigue cracks in the wing lower spar cap, if not detected and corrected, could result in the wing separating from the airplane during flight.

Airworthiness Directives; Air Tractor, Inc. Models AT-400, AT-401, AT-401B, AT-402, AT-402A, AT-402B, AT-501, AT-802, and AT-802A Airplanes

This amendment supersedes Airworthiness Directive (AD) 2001- 10-04 R1, which lowered the safe life for the wing lower spar cap on certain Air Tractor, Inc. (Air Tractor) AT-400, AT-500, and AT-800 series airplanes. AD 2001-10-04 R1 resulted from numerous reports of cracks in the \3/8\-inch bolthole of the wing lower spar cap on the affected airplanes. This AD retains the safe life for the wing lower spar cap and requires you to eddy-current inspect the wing lower spar cap immediately prior to the replacement/modification in order to detect and correct any crack in a bolthole before it extends to the modified center section of the wing. This AD further reduces the safe life for certain Models AT-401, AT-401B, AT-402, AT-402A, AT-402B, and AT-501 airplanes that incorporate or have incorporated Marburger Enterprises, Inc. winglets and removes the Models AT-502, AT-502A, AT- 502B, and AT-503A airplanes from the applicability. We are issuing another AD action to cover these airplanes. The actions specified by this AD are intended to prevent fatigue cracks from occurring in the wing lower spar cap before the established safe life is reached. Fatigue cracks in the wing lower spar cap, if not detected and corrected, could result in the wing separating from the airplane during flight.

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

This amendment revises AD 2001-10-04, which concerns certain Air Tractor, Inc. (Air Tractor) AT-400, AT-500, and AT-800 series airplanes. AD 2001-10-04 superseded AD 2000-14-51 and lowers the safe life for the wing lower spar cap on these airplanes. The AD was the result of numerous reports of cracks in the 3/8-inch bolthole of the wing lower spar cap on the affected airplanes. We inadvertently included certain AT-800 series airplanes in the Applicability of this AD. Those AT-800 series airplanes that are equipped with the factory- supplied part number 80540 computerized fire gate should not be affected by AD 2001-10-04. This action revises the AD to reflect this change and to provide information for applying for an alternative method of compliance with this AD. The actions specified by this AD are intended to prevent fatigue cracks from occurring in the wing lower spar cap before the originally established safe life is reached. Fatigue cracks in the wing lower spar cap, if not detected and corrected, could result in the wing separating from the airplane during flight.

Airworthiness Directives; Air Tractor Incorporated Models AT-301, AT-401, and AT-501 Airplanes

This amendment adopts a new airworthiness directive (AD) that applies to certain Air Tractor Incorporated (Air Tractor) Models AT- 301, AT-401, and AT-501 airplanes that are equipped with a \3/16\-inch thick aluminum fin front spar fitting and an all metal rudder. This AD requires that you repetitively inspect the vertical fin front spar attachment fittings for fatigue cracks, and rework the vertical fin if any cracks are found. This AD is the result of reports of a vertical fin front spar fitting failure on a Model AT-401 airplane. The actions specified by this AD are intended to detect and correct cracks in the vertical fin front spar attachment fittings, which could result in failure of the vertical fin. This condition could lead to loss of directional control and eventual loss of airplane control.

Airworthiness Directives; Air Tractor, Inc. AT-300, AT-400, and AT-500 Series Airplanes

This amendment supersedes Airworthiness Directive (AD) 96-23- 19, which currently requires installing a new flap actuator overtravel stop and a roll pin through the overtravel stop and jack screw on certain Air Tractor, Inc. (Air Tractor) Models AT-300, AT-400, and AT- 500 series airplanes. This AD requires replacing the existing flap actuator overtravel stop with a new one of improved design. This AD is the result of reports of the jack screw breaking through the roll pin hole on three of the affected airplanes that were already in compliance with AD 96-23-19. The actions specified by this AD are intended to prevent interference between the flap pushrod and the aileron pushrod caused by the flap actuator overtravel nut disengaging, which could result in loss of aileron control.

Airworthiness Directives; Air Tractor Incorporated Models AT-301, AT-302, AT-400, AT-400A, AT-401, AT-402, AT-501, and AT-502 Airplanes

This amendment supersedes Airworthiness Directive AD 95-20-06, which applies to certain Air Tractor Incorporated (Air Tractor) Models AT-301, AT-302, AT-400, AT-400A, AT-401, AT-402, AT-501, and AT-502 airplanes and currently requires repetitively inspecting the front spar attachment lugs and the rear spar for fatigue cracks, and modifying the vertical fin if cracks are found. The modification terminates the repetitive inspection requirement of AD 95-20-06 and may be incorporated at any time, if cracks are not found. The FAA has determined that the Air Tractor Models mentioned above with a \1/4\- inch fin front spar fitting installed should be exempt from the AD. The AD will retain the requirements of AD 95-20-06 for all Air Tractor airplanes that have a \3/16\-inch fin front spar fitting. The actions specified by this AD are intended to prevent in-flight vertical fin cracking, which, if not detected and corrected, could result in structural failure of the front spar attachments and eventually the rear spar attachment and cause loss of directional control of the airplane.

Airworthiness Directives; Air Tractor, Inc. Models AT-802 and AT- 802A Airplanes

This amendment adopts a new airworthiness directive (AD) that applies to certain Air Tractor, Inc. (Air Tractor) Models AT-802 and AT-802A airplanes. This action requires revising the Airworthiness Limitations section of the applicable maintenance manual to change the life limit of the tail landing gear spring. This action results from analysis of the life limits of both the tail landing gear and main landing gear after a fatigue failure of the main landing gear on one of the affected airplanes. This analysis revealed that the life limit of the tail landing gear spring should be 3,000 hours time-in-service (TIS) instead of 3,500 hours TIS to be consistent with the main landing gear spring. The actions specified by this AD are intended to prevent fatigue failure of a tail landing gear spring before the life limit of the part is achieved, which could result in loss of control of the airplane.

Airworthiness Directives; Air Tractor, Inc. Models AT-250, AT- 300, AT-301, AT-302, AT-400, AT-400A, AT-401, AT-402, AT-501, and AT- 502 Airplanes

This amendment adopts a new airworthiness directive (AD) that applies to certain Air Tractor, Inc. (Air Tractor) Models AT-250, AT- 300, AT-301, AT-302, AT-400, AT-400A, AT-401, AT-402, AT-501, and AT- 502 airplanes that are equipped with a Gerdes part number (P/N) A-850-5 or Cleveland P/N 60-9 parking brake valve. This action requires replacing the parking brake valve with a Scott P/N 4500A-2 parking brake valve. This AD results from several reports of the parking brake valve inadvertently slipping to the ``PARK'' position during flight, which causes constant pressure on the brakes. When the pilot applies the brake upon landing, this pressure causes the airplane to overturn. The actions specified by this AD are intended to prevent the airplane from overturning because of extreme pressure applied to the brake if the parking brake valve inadvertently slips to the ``PARK'' position during flight.

Airworthiness Directives; Air Tractor, Inc. AT-300, AT-400, and AT-500 Series Airplanes

This amendment adopts a new airworthiness directive (AD) that applies to certain Air Tractor, Inc. (Air Tractor) Models AT-300, AT- 400, and AT-500 series airplanes. This AD requires installing both a new flap actuator overtravel stop and a roll pin through the overtravel stop and jack screw. This AD results from incidents where the flap actuator overtravel stop nut disengaged from the jack screw. The flap pushrod pressed against the aileron pushrod, which caused difficulty in moving the ailerons. The actions specified by this AD are intended to prevent interference between the flap pushrod and the aileron pushrod caused by the flap actuator overtravel nut disengaging, which could result in loss of aileron control.

Airworthiness Directives; Air Tractor, Incorporated Models AT-802 and AT-802A Airplanes

This amendment adopts a new airworthiness directive (AD) that applies to Air Tractor, Incorporated (Air Tractor) Models AT-802 and AT-802A airplanes. This action requires repetitively replacing the main landing gear legs. Failure of the main landing gear legs on an AT-802A prompted this action. The actions specified by this AD are intended to prevent possible failure of the main landing gear legs, which, if not detected and corrected, could result in loss of control of the airplane during landing operations.