# Airworthiness Directives; Sandel Avionics Incorporated Model ST3400 Terrain Awareness Warning System/Radio Magnetic Indicator (TAWS/RMI) Units Approved Under Technical Standard Order(s) C113, C151a, or C151b; Installed on Various Small and Transport Category Airplanes
> **Rule** · Final rule. · Published 2006-08-21 · Effective 2006-09-25 · 71 FR 48461
## Document
- **Document number:** E6-13447
- **Category:** airworthiness
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 71 FR 48461
- **Publication date:** 2006-08-21
- **Effective date:** 2006-09-25
- **FAA docket:** Docket No. FAA-2006-24101
## Abstract

The FAA is adopting a new airworthiness directive (AD). The new AD is for Sandel Avionics Incorporated Model ST3400 TAWS/RMI units as described above. This AD requires installing a warning placard on the TAWS/RMI and revising the Limitations section of the airplane flight manual (AFM). This AD also requires installing upgraded software in the TAWS/RMI. This AD results from a report that an in-flight bearing error occurred in a Model ST3400 TAWS/RMI configured to receive bearing information from a very high frequency omnidirectional range (VOR) receiver interface via a composite video signal, due to a combination of input signal fault and software error. We are issuing this AD to prevent a bearing error, which could lead to an airplane departing from its scheduled flight path, which could result in a reduction in separation from, and a possible collision with, other aircraft or terrain.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2006/08/21/E6-13447/airworthiness-directives-sandel-avionics-incorporated-model-st3400-terrain-awareness-warning)
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