Testing of the re-engined Embraer E2 family has revealed an electrical system anomaly which has spurred Brazilian regulators to order an urgent revision of smoke procedures in the flight manual.

The emergency directive from Brazil’s civil aviation regulator ANAC focuses on the 190-E2 and 195-E2 variants of the regional twinjet.

It states that the aircraft systems were being subjected to failure propagation tests including a deliberate loss of the number 2 essential DC electrical bus.

ANAC says that, during the test, the smoke-detection system of the forward and aft electronics bays erroneously transmitted smoke warnings through the instrument panel’s crew alerting system.

Procedures in the flight manual require the crew to respond by turning off the number 1 and number 3 busses.

This would result in the loss of all essential DC electrical buses, causing a loss of power to the aircraft’s critical systems.

ANAC says this impact on flight safety requires modification, within five days, of the flight manual procedure for addressing smoke warnings from the electronics bay.

This procedure requires checking whether the crew alerting system is displaying a message warning that the number 2 bus is off, and conducting specific actions depending on the status of this alert.