FAA 2020-12-15

Requires a measurement of the trunnion nut torque of the cabin pressure control system's V-band clamp, an inspection of the safety valve and airplane bulkhead flange area for any cracking and deformations, and any necessary corrective actions. Prompted by a report that certain safety valves at the left- and right-hand sides of the cabin pressure control system were not installed correctly and that the trunnion nuts used to fasten the V -band clamp were over-torqued.