Date: 202103
Local time of day: 1201-1800
Location: ZZZ.TRACON, US
Flight conditions: VMC
Light: Dawn
Aircraft: SA-227 AC Metro III
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb; Initial Climb
Airspace: Class B ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Pressurization Control System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Commercial; Flight Crew Instrument; Flight Crew Multiengine
Human factors: Workload; Time Pressure; Communication Breakdown
Anomaly: Aircraft Equipment Problem Critical; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Aircraft Aircraft Damaged; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action; Flight Crew Overcame Equipment Problem
Contributing factors: Aircraft; Equipment / Tooling; Company Policy; Human Factors; Procedure
Primary problem: Aircraft

Narrative: Climbing through 16;000 feet to FL 200 we experienced a high whistle sound from the front of the airplane. I felt pressure on my ears; nose; and head and had the air pushed out of my lungs. We identified a cabin depressurization and I reached for my O2 mask. I took a long inhale from the oxygen and then proceeded with additional memory items. The Captain began an priority descent. I reached for the Pax oxygen switch with my right hand and the PA button with my left hand. I communicated with the Captain that I was going off comms to tell Pax to put on oxygen masks. The Captain stated 'Wait. They are going to be fine here in 2-3 seconds and I don't want to replace the masks.' This occurred around 13;500 feet. So I did not complete memory items per the Captain's instruction. I contacted ATC and advised we were on an priority descent because of depressurization. We received a new assigned altitude of 10;000 feet. The Cabin started to repressurize around 11;000. ATC asked if we wished to declare priority handling and the Captain declined. We were able to continue to ZZZ without incident.There were several deviations from our normal operating procedures that concern me. First the disregard from memory items on the checklist. Second; the captain did not have his O2 mask plugged in. He believed he could plug it in fast enough if needed and that he doesn't plug it in because he forgets to unplug it after a flight. This caused a delay in performing a memory item. The Captain was able to plug his oxygen mask in but never donned it during controlled handling decent. Also; we did not formally ask for priority handling with ATC. We could not diagnose the problem for the rapid depressurization so we were unaware of what triggered it. I suggested declaring priority handling to cover our bases if anything else occurred. This flight had already been abnormal with the priority descent. The Captain disagreed saying the problem is over. Lastly; I do not believe the cockpit acceptance was completed for this flight. It is typical that the FO (First Officer) does the walk around and security check while the Captain is completing the acceptance. While doing the walk around it is very apparent that the shaker pusher test is being tested from outside the airplane. You can hear the shaking on the horizontal stabilizer. I did not hear it that morning. Also upon startup; the Captain found a popped circuit breaker on his side for De-Ice. I'm not sure when the circuit breaker popped but no de-icing equipment was on so I assume it was before startup. This is another missed item on the acceptance checklist. Now; these deviations did not cause the priority handling to occur but they could have added on to make the event worse.




Synopsis: SA-227 AC Metro First Officer reported deviations from SOP during a Cabin Pressurization Event.