**MANDATORY** SERVICE BULLETIN NO.: 1559 Rev A GTN 650 and GTN 750 Notification of Mod Level 5

[delay  11 November 2015]


All GTN 650 and GTN 750 navigator units marked as Mod Level 4 or previous mod level are affected.


An issue has been identified where the VOR/LOC/GS may stop functioning in the affected units. This will be indicated by a message on the GTN and the Nav frequencies will be replaced by a red X.


This service bulletin provides instructions to inspect and return affected GTN 650/750 units to Garmin for a Mod Level change. This service bulletin also provides optional instructions for marking Mod Level 5 on the nameplate (serial tag) of unaffected GTN 650/750 units.


Mandatory for units listed in Table 2. This Service Bulletin must be accomplished by October 31st, 2016. Optional for units not listed in Table 2.


35 years component-level Aviation/Electronics repair/Avionics retrofit experience. FCC General Radiotelephone with Ship Radar. Navcom-Audio, Transponder-Pulse-Radar, Autopilot expertise. IT Administration since 1983. Private Pilot since 1986. CAD designer since 1990. FAA Certified Repair Station Chief Inspector since 1994. Started 3 Avionics Shops. College: Business Administration/Marketing. Motorcycle enthusiast. 6 year USAF Veteran, Ground Radio Equipment Technician (30474, E-5). WordPress novice.

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