414A and 421C aircraft with S-TEC Corporation (S-TEC) Supplemental Typ

414A and 421C aircraft with S-TEC Corporation (S-TEC) Supplemental Typ

This Special Airworthiness Information Bulletin (SAIB) informs registered owners/operators of Cessna Aircraft Company (Cessna) 414A and 421C aircraft with S-TEC Corporation (S-TEC) Supplemental Type Certificate (STC) SA08996AC-D (system 55/55X) with optional Trim installed, Cessna 414A and 421C aircraft with S-TEC STC SA7787SW-D (system 65) with optional Trim installed, and Cessna 414A and 421C aircraft with S-TEC STC SA7790SW-D (system 60) with optional Trim installed, of an airworthiness concern. Specifically, this SAIB provides guidance on procedures for inspection of the rudder trim tab blocks which were relocated during the installation of the STC. This SAIB also provides guidance on inspecting phenolic blocks for wear along the flight control system.
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.
During an inspection of an elevator trim installation per S-TEC STC SA08996AC-D, it was found that the elevator trim cables pass through a bulkhead with about five degrees of deflection. A phenolic block is installed to prevent wear on the cable. Additionally, the cable impacts the floor aft of the bulkhead. A phenolic strip is installed to prevent contact between the cable and the floor. Currently, there are no directed inspections of the phenolic block and strip. The routing of the cables and location of the phenolic components are installed by Cessna and is not modified by the installation of these S-TEC STCs.
S-TEC is currently planning an update to their STC that would install a pulley to move the cable off the bulkhead pass through. Cessna may be providing a similar modification.
Also, during the installation inspection, it was noticed that the rudder trim tab blocks were not properly relocated in accordance with the S-TEC STCs. This prevented the rudder system from obtaining full travel. There was no approval for the location and installation of the trim tab blocks for this particular installation.
The Federal Aviation Administration (FAA) recommends you inspect your rudder trim tab blocks and flight control cables in accordance with S-TEC Service Bulletin (SB) 11-001R1. If during the inspections listed in the SB, it is determined that the rudder trim tab blocks were not relocated in accordance with the STC, you should relocate in accordance with the STC as reflected in paragraph 3 of SB 11-001R1 or any other method approved by the FAA.
For Further Information Contact
Garry Sills, Aerospace Engineer, 2601 Meacham Boulevard, Fort Worth, TX 76137; phone: (817) 222-5154; fax: (817) 222-5960; e-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
For Related Service Information Contact
S-TEC Corporation, One S-TEC Way, Municipal Airport, Mineral Wells, TX, 76067; phone: (800) 872-7832; fax: (940) 325-3904; website: www.s-tec.com

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