Date: 201411
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Takeoff / Launch
ATC / advisory: Tower ZZZ
Aircraft component: Elevator Trim System
Component problem: Improperly Operated; Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Workload; Troubleshooting; Situational Awareness; Human-Machine Interface; Confusion; Distraction
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Weight And Balance
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Returned To Departure Airport; General Declared Emergency
Contributing factors: Aircraft; Procedure
Primary problem: Aircraft

Narrative: The weight and balance calculations begin 5 [minutes] prior to scheduled push. After completion of the first calculations on the WB; me and the First Officer (FO) realized that the stab trim was marked on the max forward CG line. I then told the Flight Attendants to move 4 passengers aft from Z1 to Z3. I then re-calculated the weight and balance; subtracted -7 off the index for the passenger re-location. The paperwork was complete; the aircraft was late because of the weight and balance re-calculations. We had a normal taxi and about a 10 minute wait for takeoff. Upon cleared for takeoff the before takeoff checklist was performed. I do remember checking the stab trim indicator; it read 4.8. The beginning of the takeoff roll was normal; after the 80kt. cross check I noticed that the nose wheel was pre-maturely wanting to lift off the ground. I increased forward pressure slightly knowing I would have to forward trim upon rotation. The aircraft became airborne with little back pressure at VR. Increased forward pressure was applied after liftoff; I was preparing to apply forward trim when I ask for gear up. Once the gear up transition occurred I knew we had a big problem. I immediately had to go full forward on the control column. I can't remember if I was trying to work the trim switch or not. The incredible forces I was trying to fight might not have allowed me to work my thumb up to it. I do remember looking at the trim indicator and it did not appear to be a runaway trim; but my glance was short as my attention went to the EICAS for a Bleed Air 2 Fail; Bleed Air 2 Overpressure caution. At that point in time I assumed we had an improperly loaded aircraft that was aft CG. During this time I alerted my FO that we had a pitch problem and to notify ATC for a return to the field. I still had incredible forward control input on the control column. Thinking we had an aft CG load problem; I then ask the FO to call the flight attendants in the back of the aircraft to move all passengers forward to relieve some control pressure. The aircraft was still climbing slightly; and I was trying to get more control of the aircraft by using different thrust settings with the engines. All the while holding continuous full forward pressure to the stops on the control column. I begin making a continuous turn for a downwind to return to the field. Once on the downwind; I was finally able to get some forward pressure relief; I assume due to the passengers now seated in the forward seats. I then got my thumb on the electric trim switch and began running the trim forward. We then had a normal landing back at our departure airport. After landing I noticed the trim indication at 2.3. When at the gate my FO stated the trim was at 10.1 at one point. I was not notified during the emergency sequence; nor can I confirm this.Not sure what the problem actually was. If it was a trim runaway; there was no notification aural or EICAS with the autopilot off and the pilot not working the trim switch. At my first glance; I did not see the trim running; although it was a very short glance. Due to other distractions and the stressful situation of encountering an un-controllable pitch up situation. Not sure if I missed it. I do not re-call it running. But it could have ran for the 3 second interval already; then cut off. We will have to see when the Flight Data Recorder is released to see what the actual cause of this incident was.This is to add to our previous report for an un-commanded pitch up. The First Officer had used summer weights for passengers on the weight and balance form. The event occurred the first day of winter weights usage. I signed off on this WB form. This did not cause an overweight condition. The trim setting was only a .1 trim difference with winter weights.


Second narrative: On takeoff off of runway 17; right at 400 feet we had a master caution (amber) ICAS message for bleed 1 fail and over pressure. I was really confused when the Captain asked me to advise ATC. Then I realized he was having a very tough time keeping the airplane from pitching up; he pushed on the yoke full forward to the stop and the airplane kept pitching up. On the right crosswind; I noticed the trim indication at 10.1 degrees; which led me to believe it was a pitch trim runaway; nevertheless the movement of the passengers saved our situation in my opinion; the captain got positive control on the trim after turning downwind.


Synopsis: Upon takeoff the Captain of an EMB-175 found it necessary to maintain full down elevator deflection to prevent over rotation. The condition continued until flight attendants were able to move passengers forward. The Captain recalled noting the trim set at 4.8 units ANU during preflight and the First Officer noted 10.1 ANU during the struggle to maintain a safe attitude.