This is additional information concerning the Airworthiness Directive  AD 2004-08-16.

 

The FAA has issued an AD concerning the Narco Avionics AT150. The AD addresses 2599 AT150's which were manufactured in 1977. The FAA has made a change in their ATC Radar System which caused a problem with the AT150's involved. Over the past 26 years many of the affected AT150's may have already been modified by AT150 service bulletin #1. This was standard procedure for AT150's serviced at the factory. Affected AT150's that have been modified will have their chassis level marking changed from 'A_' to' B_'. The FAA has asked us to re-issue Service Bulletin No. 1 as Service Bulletin #6 addressing the NEW REASON for modifying the AT150's. AT150's with serial numbers greater than 12598 already have the modification installed and do not need to be re-modified. If you have any concerns or questions about your particular AT150 please contact us at sb6@narcoavionics.com .