Transport Canada CF-2020-16

Requires an inspection of the V-band clamp trunnion nut torque on both the left and right cabin pressure control system safety valves (P/N GG435-3006-3), as well as an inspection of the valve and aircraft bulkhead flange for damage and deformations, replacing the valve and repairing damage if necessary. Prompted by a post-installation inspection at Bombardier that discovered some of the left and right cabin pressure control system safety valves at the pressure bulkhead in the baggage compartment were not being installed correctly—namely, that the trunnion nuts used to fasten the V-band clamp were over-torqued. These V-band clamps hold the valves to the aircraft bulkhead flange and over-torquing can reduce the safety valve fatigue life or cause damage to the safety valve flange.