AD19 Motor Drive Temperature Unreliable (2017-8-25)

INTRODUCTION

This Airworthiness Directive (AD) is being issued to alert all Alta users of a potential design flaw associated with the motor drive PCBA that results in an incorrect motor drive PCBA temperature reading.

BACKGROUND

In April 2016, Freefly revised the motor drive PCBA to update the design and remove some unused components.  An unintended consequence of this change was that some motor drive PCBAs used on Alta’s sold after 8-1-2016  now give incorrect temperature readings.

DISCUSSION

Further investigation by the engineering team led to a better understanding of the temperature sensor and the issues with the design.  This investigation has led the team to deem the temperature reading on the Alta motor drive PCBAs shipped after August 1, 2016 to be unreliable.

REQUIRED ACTION

Freefly recommends that users do not reference the motor temperature reading when making decisions regarding machine performance, payload capabilities, or flight worthiness.  Freefly recommends that users reference the weight check functionality within the ‘monitor’ section of the App to ascertain acceptable payload for various altitudes and temperatures.  Additionally, Freefly publishes an allowable gross weight chart in the Alta user manuals to help users understand max allowable gross weight.