300 ECU software upgrade for TT2 lockout

Effectivity: all Challenger 300 aircraft (aircraft 20003 through 20500)

ATA: 76

It has been previously reported in the Forum newsletter that some Challenger 300 aircraft have experienced loss of thrust during take-off climb due to engine surge. The reported surges, which were all self-recovering, happened during taking off into strong, low altitude temperature inversions up to 400 ft. above ground level (AGL) due to a feature called TT2 lockout. Following these reports, an Advisory Wire AW300-76-0363 was published in May 2020 to provide all the details and to advise operators that until a permanent solution is implemented, all Challenger 300 operators are required to take-off with engine bleed ON for ECS in order to significantly reduce the likelihood of surges. This procedure was introduced on May 12, 2020 in the AFM CSP 100-1 via TR 87 against revision 59.

Since last year, Bombardier and Honeywell have worked on a permanent solution that is close to being deployed. More specifically, Honeywell has developed a new ECU software called “V11B” to maintain a consistent level of thrust from the engines throughout the takeoff phase. Bombardier and Honeywell will be rolling out at the beginning of December this year the Service Bulletins SB 100-72-01 and SB AS907-76-9031 to allow operators to upload the V11B software on ECUs p/n 2119576−1011. ECUs with the V11B software implemented will be re-identified as p/n 2119576−1013 and aircraft in the post SB configuration will no longer be required to take-off with engine bleed ON for ECS. The Advisory Wire AW300-76-0363 will be revised shortly to provide all the details.

Operators will be required to implement the SB before November 27, 2023 so plan on having these service bulletins completed at your next service center visit!