Airworthiness Directive · Amendment 39-11837 · Air Tractor, Inc. Models AT-501, AT-502, and AT-502A Airplanes
Air Tractor, Inc. Models AT-501, AT-502, and AT-502A Airplanes
Superseded. A later AD replaced this one: AD 2001-10-04, AD 2001-10-04 R1. Comply with the one in force.
This AD applies to the following Air Tractor airplane models and serial numbers:
| Model | Serial numbers |
|---|---|
| AT-501 | 501-002 through 501-0060 that have been converted to turboprop power. |
| AT-502 | 502-003 through 502-0061, except those that have been upgraded to the 8,000-pound gross weight configuration through the incorporation of Snow Engineering Co. Service Letter #80J. |
| AT-502A | All serial numbers. |
This document publishes in the Federal Register an amendment adopting emergency Airworthiness Directive (AD) 2000-14-51. The Federal Aviation Administration (FAA) previously sent emergency AD 2000-14-51 to all known U.S. owners and operators of Air Tractor Models AT-501, AT-502, and AT-502A airplanes. This AD requires you to inspect the wing lower spar cap for cracks and modify or replace any cracked lower spar cap. This AD is the result of an accident report of an Air Tractor Model AT-502A airplane where the wing separated in flight. The actions specified by this AD are intended to detect and correct fatigue cracks in the wing lower spar cap, which could result in an in-flight separation of the wing from the airplane.
To address this problem, you must accomplish the following:
| Action | When | Procedures |
|---|---|---|
| (1) Initial Inspection: Visually inspect the wing lower spar cap at the wing center splice connection for cracks | At whichever of the following that is applicable: (i) For the Models AT-501 and AT-502 airplanes: Upon accumulating 4,000 hours time-in-service (TIS) on each wing or within the next 10 hours TIS after the effective date of this AD, whichever occurs later; or (ii) For the Model AT-502A airplanes: Upon accumulating 3,000 hours TIS on each wing or within the next 10 hours TIS after the effective date of this AD, whichever occurs later | Accomplish this inspection in accordance with the Inspection Requirements section of Snow Engineering Co. Service Letter #197, dated June 13, 2000. |
| (2) Repetitive Inspections: Inspect using visual or ultrasonic methods the wing lower spar cap at center splice connection for cracks | For all affected airplanes, accomplish the repetitive inspections as follows: (i) Visually: Within 50 hours TIS after the initial inspection and thereafter at intervals not to exceed 50 hours TIS; or | Accomplish these inspections in accordance with the Inspection Requirements section of Snow Engineering Co. the Service Letter # 197, dated June 13, 2000. |
| (ii) Using ultrasonic methods: Within 400 hours TIS after the initial inspection and thereafter at intervals not to exceed 400 hours TIS | ||
| (3) Replace or modify any cracked wing lower spar cap, as specified in the service information | Prior to further flight after the inspection where the crack is found | Accomplish the replacement and modification as follows: |
| (i) Replacement: Remove the wing with the cracked lower spar cap and return to Air Tractor for spar cap replacement. Immediately notify Air Tractor that you are sending the wing if the cracked spar cap can not be modified. | ||
| (ii) Modification: In accordance with the TERMINATING ACTION section of Snow Engineering Co. Service Letter #197, dated June 13, 2000. | ||
| (4) Modifying each lower spar cap is considered terminating action for the repetitive inspection requirement. This modification can only be accomplished if the lower spar caps are inspected before the modification is incorporated and: | This terminating action may be accomplished at any time provided the lower spar caps are not cracked | Accomplish in accordance with the TERMINATING ACTION section of Snow Engineering Co. Service Letter #197, dated June 13, 2000. |
| (i) no cracks are found; or | ||
| (ii) any crack found can be removed by drilling the hole to the next larger size |
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
