A319 flight crew reported a Flight Control/Slat anomaly when Flaps were selected to position 3. This resulted in several associated flight control issues; and the aircraft reverted to Direct Law; then Alternate Law; before a landing at the destination airport was accomplished.
Synopsis
A319 flight crew reported a Flight Control/Slat anomaly when Flaps were selected to position 3. This resulted in several associated flight control issues; and the aircraft reverted to Direct Law; then Alternate Law; before a landing at the destination airport was accomplished.
Narrative
I was the Pilot Flying. The flight was uneventful until the approach phase. During the ILS approach to Runway XX; at approximately 2;000 feet and about one mile from the FAF (ZZZZZ); I called for 'gear down' and shortly after; 'flaps 3.' The Captain moved the flap lever to position 3; and immediately we received multiple ECAM alerts; including an F/CTL SLATS LOCKED message; and master caution warnings. Simultaneously; the autopilot; flight directors; and auto thrust disengaged; and the aircraft transitioned into direct law with an amber 'man pitch trim' message displayed on the PFD (primary flight display).I immediately took manual control of the aircraft; hand-flying while the captain began troubleshooting the issue. A glance at the Upper ECAM confirmed a slat malfunction; the slats were amber and not extending. As we processed the failures; it became clear that continuing the approach was unsafe. After a brief discussion; the Captain and I agreed to execute a go-around; which commenced at approximately 1;000 feet. During the go-around; we selected flaps 2; maintained a speed of 190 knots; and were assigned runway heading and 3;000 feet by ATC. Additionally; the aircraft transitioned into alternate law at some point during the subsequent approach and go-around phase.The Captain informed ATC of the malfunction; and requested terrain clearance and vectors. The Captain faced significant task saturation. He worked through the slats locked checklist; coordinated with dispatch via ACARS; and briefed the flight attendants to prepare for a potential evacuation. My sole focus was flying the aircraft; given the loss of automation; while monitoring the situation closely.Fuel became a concern due to delays at ZZZ and the additional time spent in the air managing the issue. We determined that diverting to our alternate (ZZZ2) was not a viable option; and the decision was made to return to ZZZ1. There was an initial discussion about returning to flaps 3; as prescribed in the checklist; but we agreed to remain in flaps 2 given that the transition to flaps 3 had triggered the direct law condition. The Captain recalculated our landing distance; which was approximately 6;800 feet; and adjusted Vref by +10 knots to account for the configuration. I suggested using medium autobrakes; and the Captain concurred.While on the downwind leg; the Captain requested that I verify the slats locked checklist. The Captain assumed control of the aircraft; becoming the Pilot Flying; while I became the Pilot Monitoring. I reviewed the slats locked checklist and confirmed our configuration. We were cleared for the ILS but transitioned to a visual approach for Runway XX as we had the runway in sight. Captain recalls not receiving any ILS data on his PFD; but I recall having the raw data on my side. At 500 feet; the Captain instructed me to issue PA to the cabin.The Captain executed a textbook landing within the touchdown zone. After [advising ATC]; I made a 'remain seated' PA as we came to a full stop on the runway. ARFF (airport fire and rescue) units inspected the aircraft before we taxied safely to the gate. The passengers and cabin crew remained calm and followed instructions; contributing to the overall safe resolution of the situation.
Second reporter narrative
Normal night flight from ZZZ to ZZZ1. A little bit late due to delays out of ZZZ. Weather in ZZZ1 was light winds out of north and light snow. FO briefed ILS to runway XX. We got vectors to final. Approaching the FAF of ZZZZZ he asked for gear down flaps 3 and managed the speed and this is when we got the F/CTL SLATS LOCKED ECAM. We also reverted to direct law and all of the automation came off including flight directors; autopilot; and auto thrust. We stayed in direct law for a period of time but I don't recall how long. It was a fairly startling event. PF continued to fly while I pondered whether we should go around or attempt to land. We elected to go around and performed a normal go around and climbed out to 3000 feet on runway heading. I told tower we had a malfunction and she sent us back to approach. Approach gave us a heading east then to downwind. PF continued flying while I tried to decipher what we had. We kept the speed at 190 with flaps at 2 and slats locked at the number 2 position. There were no action items on the ECAM other than the speed limit so I got into the flight manual and started running the procedure. Fuel was becoming an issue because we sat on the ground with two engines running for quite a time in ZZZ. We decided we did not have the option to divert to another airport (our alternate was ZZZ2). I talked to the flight attendants and went through the briefing with them and told them to prep the cabin for an evacuation. I shot a ACARS message off to dispatch and continued to run through the procedure in the book which is pretty involved. I also briefly talked to the passengers and told them we had a problem but we're going to come back and land at ZZZ2 At this point the PF is flying with no autopilot; auto thrust or flight directors. I'm unclear if we were in alternate law because the PF recalls we had no speed protections but I can't remember. Approach queried about nature of situation and at that point I was prompted to [advise ATC] and get vectors for an ILS to runway XX. I looked at our landing distance given our configuration of slats between 1 and 3 and flaps at 2. We were both hesitant to put the flaps back at 3 as the procedure in the book calls for and left them at 2. I looked up a landing distance and got about 6;800 for our configuration and a VREF add of 10. We turned base with PF still flying and I told him I would land so I took the aircraft and he reverted to pilot monitoring. We got a vector to intercept and we could not arm approach and we were getting no LOC or glideslope. I knew we could manually tune the ILS through the radios but at this point we were late in the game to get into that and we could see where the runway was and continued visually to the runway configured at flaps two with the gear down. We elected to have the fire trucks rolled and PF gave the call on short final over the PA. I got a little low and we subsequently got a too low flaps GPWS due to the flaps being at 2. I chopped the power fairly early and landed in the zone and came to a stop half way down the runway. We go on the PA and gave the remain seated call as we came to a full stop. We had responders give us a once over then continued uneventfully to the gate. The flight attendants did a great job as the passengers followed all their instructions and stayed calm.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.