AD/CF34/9 - High Pressure Compressor Forward Spool

This directive requires removal from service of GE CF34 high-pressure compressor forward spools P/N 6078T56P03 and P/N 6078T56P04 for specified CF34 engine models, with removal at the first piece-part exposure after 6,000 cycles‑since‑new but no later than 20,000 or 22,000 CSN depending on variant. It also prohibits installing P/N 6078T56P03 and forbids installing P/N 6078T56P04 unless it has 0 CSN. It affects aircraft operators, maintenance organisations and parts suppliers for the listed Bombardier types to reduce low‑cycle fatigue crack risk and prevent uncontained engine failure.