Flight Controls, Rudder Control System

1 FAA Aviation Safety SPECIAL AIRWORTHINESS INFORMATION BULLETIN SUBJ: Flight Controls, Rudder Control System SAIB: CE-18-06 Date: December 1, 2017 This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin (SAIB) informs registered owners/operators of an airworthiness concern for Air Tractor, Inc. Models AT-401B, AT-402B, AT-502A, AT-502B, AT-504, AT-602, AT-802, and AT-802A having serial numbers prior to 401B/402B-1347, 502A/502B-3059, 504-4029, 602-1278, and 802/802A-0661 airplanes (under Type Certificate Data Sheets A17SW and A19SW) of an airworthiness concern. Specifically, this SAIB specifies and recommends the use of procedures for replacement of the bolts and nuts through the vertical fin rear spar.

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

Background

Air Tractor, Inc. issued Snow Engineering Co. Service Letter (SL) #359, Revision A, dated November 29, 2017, for the Air Tractor airplanes referenced in the Introduction section of this SAIB. The SL was issued after an in-flight failure of the bolts at the vertical fin rear spar attach connection, which caused the rudder boost trim mounting bracket to migrate out of its normal position. To date, there have been two failures of these bolts. Failure of these bolts may lead to difficulty controlling the airplane. The SL specifies instructions for replacement of the nuts and bolts through the vertical fin rear spar attach point.

Recommendations

The FAA recommends that the affected owners of the Air Tractor airplanes referenced in the Introduction section of this SAIB replace the six bolts and nuts through the vertical fin rear spar with NAS1303 bolts and MS21042-3 nuts at the next annual inspection using the procedures in SL #359, Revision A, dated November 29, 2017. Before the next flight, the FAA also recommends that affected owners remove the surrounding skin to visually inspect both the forward and aft sides of the bolts for damage. The FAA recommends that you report any findings of damaged bolts to the FAA points of contact listed below. Providing this information is strictly voluntary as indicated below:

A federal agency may not conduct or sponsor, and a person is not required to respond to, nor shall a person be subject to a penalty for failure to comply with a collection of information subject to the requirements of the Paperwork Reduction Act unless that collection of information displays a current valid OMB Control Number. Under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.), the OMB has approved the information collection contained in this SAIB, and assigned OMB Control Number 2120-0731. Public reporting for this collection of information is estimated to be approximately 5 minutes per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, completing and reviewing the collection of information. All responses to this collection of information are

2 voluntary. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to the FAA at: 800 Independence Ave. SW, Washington, DC 20591, Attn: Information Collection Clearance Officer, ASP-110.

For Further Information Contact

Kristi Bradley, Aerospace Engineer, AIR-7F2, Fort Worth ACO Branch, 10101 Hillwood Pkwy, Fort Worth, TX 76177; phone: (817) 222-5485; email: [email protected]

Kenneth Cook, Aerospace Engineer, AIR-7F1, Fort Worth ACO Branch, 10101 Hillwood Pkwy, Fort Worth, TX 76177; phone: (817) 222-5475; e-mail: [email protected]

For Related Service Information Contact

Air Tractor, Inc., P.O. Box 485, Olney, Texas, 76374; phone: (940) 564-5616; fax: (940) 564-5612; email: [email protected].