Challenger 300 operators should be aware that Honeywell Category 1 Safety-related SB AS907-76-9031 and Bombardier SB 100-72-01 are nearing the deadline for compliance with approximately only 30% of the fleet having performed the SBs.

These Service Bulletins are effective for all Bombardier Challenger 300 aircraft equipped with Honeywell HTF7000 (AS907-1-1A) engines and relate to necessary upgrades to the ECU (Electronic Control Unit) software.

This upgrades the ECU (Electronic Control Unit) software from V10B to V11B. It also changes the P/N of the ECU from 2119576-1011 to P/N 2119576-1013. This new software addresses the susceptibility to engine surge during takeoff climb out if a significant temp inversion exists that was identified and classified as a safety issue. This is the main upgrade; refer to the SB for a complete list of upgrades included in software V11B.

Operators should be aware that the SBs will be completed at no charge to the operator if taken to a Honeywell Authorized AS907 Service Center, like West Star Aviation and are enrolled in MSP.

Be aware, in some circumstances, the software will not upload successfully and an Overhauled or new ECU will be required. ECUs may be in short supply, so WSA recommends complying with this SB sooner rather than later. Operators should schedule this upgrade at their next scheduled engine or airframe maintenance, but no later than November 27, 2023.