November 24, 2004

This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin informs you, registered owners and operators of Cessna 206 series airplanes equipped with the S-TEC autopilot of possible cracking at the right wing rear spar shear web, and requests that you inspect the roll servo mounting location at the shear web.

S-TEC has distributed service information to all registered owners or operators of Cessna 206 series airplanes that are currently modified with S-TEC autopilot and/or float or amphibian and/or tip tank. The autopilot reference is System 20/30, 40/50, 55/55X, 60-1, 60-2, and 65 autopilot installed following one of these supplemental type certificates (STCs):
 

System Model	STC Number
System 20/30	SA09404AC-D,SA09389AC-D,SA09379AC-D, andSA09377AC-D
System 40/50	SA5216SW-D, SA5223SW-D, SA6040SW-D, and SA09431AC-D
System 55/55X	SA8406SW-D, SA8886SW-D, and SA09403AC-D
System 60-1	SA5156SW-D, and SA5152SW-D
System 60-2	SA5140SW-D, SA5157SW-D, and SA5399SW-D
System 65	SA7135SW-D, and SA7158SW-D

Background

During routine inspections on two Cessna 206 airplanes modified with floats and tip tanks, operators discovered cracks at the fasteners’ holes of the right wing rear spar shear web where the roll servo was installed. Shortly thereafter in September 2003, S-TEC released service letter (SL) 03-003 and service bulletin (SB) 03-001. This service information notifies customers of potential cracks at a right wing rear spar shear web (at roll servo mounting location). The SL 03-003 outlines the inspection process and identifies a point of contact should you find cracks in this area. The SB provides a modification kit and a procedure to re-enforce the roll servo installation and the rear wing spar shear web.

Originally this process was limited to Cessna 206 series airplanes with the S-TEC autopilot installation and equipped with float, or amphibian and/or tip tanks. To ensure that all aircraft are modified, S-TEC issued SB 03-001 Revision 4 to include all Cessna 206 configurations (land-based, float/amphibian, tip tank) equipped with S-TEC autopilot per the above mentioned STCs.

Recommendation

We recommend that within the next 100 hour or at the next annual inspection, whichever is shortest, you inspect the right wing aft spar shear web at the roll servo mounting location for cracks. You should inspect by following STEC SL 03-003, revision 3, dated August 25, 2004, for all Cessna 206 series airplanes with S-TEC System 20/30, 40/50, 55/55X, 60-1, 60-2, and 65 autopilot installed per the above mentioned STCs. If a crack is found, you should contact S-TEC for an FAA-approved repair scheme. For safety reasons, you must never operate an aircraft with any known crack.

If crack(s) is/are not found, we recommend that you install a structural kit to strengthen the roll servo mounting. You should do this installation following S-TEC SB 03-001, revision 4, dated September 21, 2004, or later FAA approved revision.

For Further Information Contact

Hung V. Nguyen, Aerospace Engineer, FAA, Fort Worth ACO, ASW-150, 2601 Meacham Blvd, Fort Worth, TX 76193, telephone: (817) 222-5155, fax: (817) 222-5960, e-mail: hung.v.nguyen@faa.gov

To obtain a copy of the service information, please contact S-TEC customer service at (940) 325-9406.