Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 200; Flight Crew Total 20000; Flight Crew Type 18000
Aircraft Equipment Problem Critical
Flight Crew Returned To Departure Airport; Flight Crew Landed As Precaution; General Maintenance Action; General Declared Emergency
Aircraft
Day VFR takeoff. Around 100 KTS I noted an amber speed brake 'Do not Arm' light. After takeoff I called for Flaps 1 and started to accelerate; this is when I noticed my main electric trim from the yoke switch was not responding. I started using the manual trim (the auto trim feature was kicking against my inputs). I asked the First Officer to try his pickle switch and it was inoperative as well. I stabilized the aircraft and handed the controls to the First Officer. I used the newly formatted checklist and completed it to the phase line. Our altitude was still low (around 10;000 FT). I told the First Officer to tell Center I did not want to go above FL200 with possible multiple problems in the flight controls. The flight eventually leveled off at FL190. Having past difficulties with VHF AIRINC phone patches (usually dropped calls) I elected to call Maintenance at [departure station].  I explained the situation to them and they had me check and reset the stab trim breaker behind the Captain seat. It was in and I reset it per their request. No help.I realized our fuel situation would not be prudent to continue and the possible problem of the main electric trim. I elected to air return to [departure airport]. I did not want to stay in the air any longer than I needed to with this problem. Additional warnings were the 'Speed Brake do not arm' and the 'Speed Trim' lights on the overhead.  I noted [an] accident from years ago.During descent we descended through a cloud deck with icing conditions so we used Vref ice numbers. The flight landed without incident. Threats I noted were the new checklist format; mainly this is the first time I have used the new checklist in a truly an abnormal situation. The 737 fleet has no other way to contact Dispatch/Maintenance other than VHF phone patch. I sent a message to Dispatch using ACARS which is slow and time consuming. It was noted after landing another STAB breaker behind the First Officer was out. (The First Officer never released his shoulder straps). It was later found when the trim was inspected the cannon plug; after one half turn; fell off. The maintenance manual stated it should take about 15 turns. Although I like the NAV kits I considered it a threat since it is not the usual format I fly with and the manuals are bulky to use during such a busy time. Also; I [am] still getting used to what I need with me from my old flight kit; i.e.; a circuit breaker location guide; a 1 inch binder vs. the bulky binders. With all the changes to both the flight manual; FOM and the QRH added to the threat level of a non-normal flight.
The trim failure resulted in considerable nose up trim as the flaps were move to up. Also; the speed trim was trimming for; as designed; airspeed considerably slower than Clean Maneuvering Speed. 3/4 to 2/3 yoke nose down from neutral was required to maintain Clean Maneuvering Speed until the QRH was accomplished.
B737 flight crew reported abnormalities with the primary electric pitch trim system. They declared an emergency and returned to departure airport.