Flight Crew reported being removed from a test flight due to complications in the maintenance actions that reoccurred during the first test flight.
Synopsis
Flight Crew reported being removed from a test flight due to complications in the maintenance actions that reoccurred during the first test flight.
Narrative
Upon waking up in ZZZ1 I saw that I had been assigned a ZZZ-ZZZ flight for Date. I called scheduling and inquired as to what this was. They advised me that it was a test flight. I let them know that I needed to call the Union because I wasn't sure if I could perform that flight. After talking to the Union; they advised me to contact a Duty Pilot and inquire what type of test was being performed. The call to the Duty Pilot was at approximately XApm Local time in ZZZ1. I was told it was a simple check of the center autopilot. It was considered a Normal flight; that I shouldn't be concerned. I then called the Union and they concurred that as long as it was just turning on the AP; that is considered Normal Flight operations; and that I should perform the flight. That was all the information I was given. Flight Day. The Captain was commercialing in from ZZZ2; and did not arrive till about 20 minutes prior to departure. I arrived on time; completed the power up; preflight; loading of route; and logbook inspection. When I began to look that the logbook is I was surprised to see multiple entries showing various parts that had been replaced in that past days. Stab Trim Modules; Actuators; FCCs; and a new MCP; all in that last few days with no flights in between. Since I was told it was just a Normal Flight per the Duty Pilot and Union; I did not call to get clarification or more info. I did review the Stab Trim; and Stab Trim Runaway QRH checklist after looking at the logbook. Once the Captain arrived and was settled; we where given a basic Maintenance brief. The airplane had a daily that was done that morning and all we needed to do was just use the center AP; simple enough. I did my crew brief as Pilot Flying; and did bring up the logbook; the various Stab Trim equipment replacement; etc.; since they were new equipment; they would be the most likely to have issues. Also two Maintenance representatives were on board for the flight. Taxi; takeoff were uneventful. HDG select was commanded at 400 ft.; followed be VNAV at approximately 1;500 ft. and Center AP shortly after. ATC had just given us a turn to 330 when I began to notice a sharp increase in speed. I began to pull back power but it kept increasing. Then I noticed we weren't climbing; and that is when the Center AP failed; and we shortly got the first EICAS Message. I disconnected and began to correct when I realized how heavy the controls felt. I began to trim but got no relief; I looked down to the Stab Trim indicator to see if it was moving; and it was not. Shortly after that we see the STAB TRIM EICAS message. I call for the checklist and as we ran through it; during that time ATC climbs us and the Captain tells them we are running a Checklist and that we would like some altitude and stay nearby. We are given a climb to 11;000 ft. and vectors. During this climb we also tried the R and L Autopilots; both failing as well. We elected to try the other Autopilots as the ZZZ/ ZZZ3 is very congested and busy; we were trying to reduce our workload; but to no avail. But I would like to point out that these 2 were failing because they couldn't make turns. The flight director would command a turn; but the Autopilot would have degraded performance during the turn or it would to just not turn. Nearly the entire flight ended up being hand flown. As per the checklist; we would have to us the alternate trim. I remembered that the I would not go at the same speed as normal electric trim; but this was painfully slow during some trim commands and then would speed up during other times I would trim. We advised ATC that we wanted to return to ZZZ; and vectors and descent where quickly given. Performance data was obtained via software program; and all checklists where completed. We shot the ILS XX back in. I elected to fly a little faster on the approach to relieve the back pressure since I did not want to be constantly reaching over and trimming in this situation. The landing and taxi back wasuneventful except for the fact that now the electric trim began to work again. After block in Maintenance was waiting for us and came to speak with us. They put Maintenance Control on speaker and asked me to describe what happened. After a few minutes they said that they are going to put in a new MCP to troubleshoot the problem and that they would like us to go up again. At this point I put my foot down and said that I was not going to do this; I am not a test pilot. I called the Union who was able to put in touch with Name of the safety committee. The Captain and I spoke to Name and told him everything including the recent maintenance performed on the aircraft. At this point he was able to get hold of the company and remove us from further test flying of Aircraft X.One thing that I feel that we should have done was without a doubt declare a 'PAN PAN' instead of just asking to go back to the airport. Though we had the situation under control; we could have easily gotten overwhelmed if anything major happened and being that close to ZZZ3; it would have been the smarter decision. Now on the subject of the flight itself; multiple break downs in the system happened leading to 2 line pilots flying an airplane that should have been flown by test pilots or Check Pilots that are trained for this. We were able to hold our own but if the situation would have been worse; there could have been a much more serious outcome. I trust the training that I have received; but normal line pilots are there to solve issues when the happen on the line. Not to go find out what issues a plane that has just come out of a significant amount of maintenance has.
Second reporter narrative
I was assigned to operate Aircraft X ZZZ to ZZZ on Date as a functional test flight to verify operation of the Center Auto Pilot. First Officer had already spoken with both Duty Pilot and Union about the flight the day before. I requested a detailed briefing of the aircraft status and reason for the flight the aircraft was released from Maintenance and all the required checks were done and recorded in the logbook. We also had on board two Mechanics. First Officer Name was the Pilot Flying. We proceed to taxi and take off and everything was normal. After take off the Center Auto Pilot was engaged;and we noticed degraded performance with the associated message Auto Pilot and immediately after an EICAS message STAB TRIM . We performed appropriate checklists and requested to stop climbing. ATC gave us vectors. We tried the R and L Auto Pilots as well and they failed to operate. First Officer flew manually the entire flight and we returned back safely to ZZZ with no further incident. On the ground the Stab Trim started to working normally. We spoke to Maintenance Control and Company. We were asked to stay on the aircraft for another flight. First Officer called union due to legally concerns. Company subsequently released us from duty.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.