Aircraft Structures

FAA Aviation Safety SPECIAL AIRWORTHINESS INFORMATION BULLETIN SAIB: CE-11-30 SUBJ: Aircraft Structures Date: May 9, 2011 This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin (SAIB) informs registered owners/operators of all Air Tractor, Inc. AT-250, AT-300, AT-400, AT-500, AT-600 and AT-800 model series aircraft (under Type Certificate Data Sheets A9SW, A17SW, and A19SW) of an airworthiness concern. Specifically, this SAIB provides guidance with special emphasis for general and detailed inspection and repair of corrosion that can be expected in the Air Tractor airframe structure under the severe special use environment these airplanes operate in.

At this time, this airworthiness concern has not been determined to be an unsafe condition that would warrant airworthiness directive (AD) action under Title 14 of the Code of Federal Regulations (14 CFR) part 39.

Background

The Federal Aviation Administration (FAA) received reports of severe corrosion affecting various primary structure in Air Tractor, Inc. model airplanes. The range of Air Tractor models shares a similar philosophy in both structural design and materials. The highly corrosive environment these airplanes operate in while dispersing chemicals and performing firebomber operations make them susceptible to corrosion in areas and to a degree not normally seen in other general aviation airplanes. In some cases, corrosion of primary structure can be severe enough to degrade the ability of the affected airframe member(s) to carry required certified loads.

In response to this concern, Air Tractor, Inc. issued Snow Engineering Co. Service Letter #299 to conduct general and specific inspections of all Air Tractor model airframe structure every 6 months and at each annual inspection. Additional guidance on inspecting, identifying, and removing corrosion from airframe structure can be found in FAA Advisory Circular (AC) 43.13-1B, Chapter 6. If corrosion is found in your Air Tractor, Inc. airplane, contact your Air Tractor dealer or the Air Tractor service department for service related support.

Recommendations

The FAA recommends you inspect your Air Tractor, Inc. airplane structure at the time intervals and using the inspection procedures directed in Snow Engineering Co. Service Letter #299. Repair or replace any corroded structure found during any inspection in accordance with Air Tractor service department instructions.

For Further Information Contact

Andrew McAnaul, Aerospace Engineer, 10100 Reunion Place, Ste. 650, San Antonio, TX 78216; phone: (210) 308-3365; fax: (210) 308-3370; e-mail: [email protected].

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2 For Related Service Information Contact

Air Tractor, Inc., 1524 Leland Snow Way, Olney, Texas 76374; phone: (940) 564-5616; fax: (940) 564-5612.