Garmin has resumed shipments of the GRS 77 attitude heading reference system (AHRS), a key component in the company's G1000 primary flight display unit, after resolving part problems responsible for a string of failures uncovered during factory testing of the new units at Garmin and at aircraft manufacturers earlier this month.

The G1000 is increasingly used as the backbone for integrated avionics suites for general aviation and business aviation new-builds, with high-profile clients such as Cessna for the Mustang and Embraer for the Phenom 100.

According to Garmin, a faulty part installed in the GRS 77 AHRS, a subassembly provided by a vendor that Garmin has not identified, had caused "a sudden increase in failure rates during aircraft manufacturer product flight tests of new GRS 77 AHRS", leading the manufacturer to halt deliveries of the subassembly.

Garmin alerted operators in the field using the G1000 that "a continual "red-x" of attitude information on the primary flight display" would indicate that an internal system monitor had detected the component failure in their system, and that back-up attitude instruments should be used. No failures had been reported in delivered units.

After an investigation of the failures, Garmin and its vendors determined that the increased failure rate was due to a "production process change by a component supplier". The company says it will issue a service bulletin "in the near future" providing instructions on how to have the affected GRS 77 units updated under warranty.

Source: Flight International