Powerplant, Engine Mount Section

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FAA Aviation Safety SPECIAL AIRWORTHINESS INFORMATION BULLETIN SAIB: CE-11-57 SUBJ: Powerplant, Engine Mount Section Date: September 14, 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. Models AT-400, AT-400A, AT-402, AT-402A, and AT-402B airplanes (under Type Certificate Data Sheets A9SW and A17SW) of an airworthiness concern. Specifically, this SAIB provides for general and detailed inspection for fatigue cracking of the engine mount tube.

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 a report of a fatigue crack in a Model AT-402 airplane engine mount tube at the left hand firewall attach location. The crack started in the tip of the weld where the tubes intersect at the attach bolt lug location (see photo below). This crack area is separate from the engine mount area required to be inspected by AD 2009-11-05 effective on June 1, 2009.

In response Air Tractor, Inc. issued Snow Engineering Co. Service Letter #297 directing recurring visual inspections of the right and left hand engine mount attach tubes at the firewall, focusing on where the tubes join at the weld tip. The first inspection is performed before continued flight, with recurring inspections at each annual inspection thereafter. Contact the Air Tractor, Inc. Service Department if any cracks are found to obtain a repair or replacement method prior to continued flight.

Left unaddressed, cracks can continue around the perimeter of the engine mount attach tube and result in loss of connection of the attach tube at the firewall, leading to reduction in structural integrity.

Recommendations

The FAA recommends that all owners and operators of Air Tractor, Inc. ModelsAT-400, AT-400A, AT-402, AT-402A, and AT-402B airplanes inspect the engine mount attach tubes at the time intervals and using the inspection procedures directed in Snow Engineering Co. Service Letter #297. Repair or replace any engine mount found cracked during any inspection in accordance with Air Tractor, Inc. Service Department instructions prior to continued flight.

In addition, we recommend you report any engine mount found cracked during any inspection, to include crack location and size, to the FAA using the Further Information point of contact listed below. Under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.), the Office of Management and Budget (OMB) has approved the information collection contained in this SAIB, and assigned OMB Control Number 2120-0731.

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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].

For Related Service Information Contact

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