MD-83
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown
Aircraft Equipment Problem Critical
Air Traffic Control Provided Assistance; Flight Crew Returned To Departure Airport; General Declared Emergency
Aircraft; Human Factors
I requested to be towed to the de-ice pad; the weather conditions at the time were light winds about 4 SM visibility with a broken layer at around 1;100 FT and OAT of 2 degrees C. The ATIS was calling light rain and drizzle but by the time we push it was a very light drizzle. I requested Type-1 [fluid] to remove the ice that I observed during the walk around. After the de-icing was done; and they confirmed the airplane was clear of all ice we started the engines; applied engine ant-ice and taxied to Runway 15. We used the wet runway engine ice 'On' numbers on the Thrust Lever Rating (TLR) which required air conditioning packs 'Off' and takeoff power. It was a five minute taxi; were cleared for takeoff.  We taxied into position; did the engine clearing run; released the brakes; applied takeoff power; all engine instruments were normal.  Minimum N1 was around 88%; we showed around 92% on both engines and EPR was at 2.02; which is what the TLR indicated. At 400 FT I asked for heading select and one Air Conditioning (A/C) pack 'ON'. Immediately we noticed the left EPR became erratic; oscillating between 2.02 and around 1.40; as well as the left N1. Moments later we heard the first of a few bangs; I thought we had a compressor stall on the left engine and brought the left throttle back towards idle; this stop the banging noise. Right about that time Tower told us to switch to Departure frequency. I asked the First Officer to declare an emergency; we were somewhere between 1;000 FT to 1;500 FT and climbing. I stopped the climb at 2;000 FT; did the Engine Out procedure and climbed to 3;000 FT. We turned the airfoil ice protection as well as the second A/C pack on sometime during this procedure. The Engine Out procedure for Runway-15 requires a right turn heading 260 at around 7 DME from ZZZ VOR; so we informed the Tower that we were turning to a 260 heading and would level at 3;000 FT. We performed the Compressor Stall procedure in the QRH. I decided to leave the left engine running at idle since the compressor stall had stopped and it would give us the benefit of having the Left Generator as well as Left Hydraulic System plus idle thrust; which even though is not much; is better than nothing. I talked to the flight attendants and did the T.E.S.T.; told them what was going on; that an evacuation was not necessary at the time but if needed the signal would be 'Standby' three times followed later by 'Evacuate' three times and would use the forward exits only and that they have about five minutes to get ready. I asked them for any abnormalities and they said the heard several loud bangs in the back but there was no smoke or anything else. I briefed the passengers; informed them that we had experience difficulties with our left engine and would be returning to our departure airport for landing. We read the Single Engine Approach in the QRH; did the Air Return Checklist; got the weather; briefed the approach and asked the Tower for a special missed approach; to be runway heading to 3;000 and asked the Tower about the emergency vehicles; which they informed us; were ready. We were vectored for ILS 15; we landed uneventfully; exit the runway at Kilo and taxied into the ramp. I shutdown the left engine and the firefighters inspected the aircraft. They said that the left engine bullet was detached; but otherwise there did not appear to be any other damage and was safe to taxi to the gate. We followed the 'Follow Me' vehicle to the gate and deplaned the passengers. I called Dispatch; Maintenance Control and the Duty Pilot and informed them of the events. On the post flight [walk around]; I found the bullet to be detached from the left engine and resting in the [intake] cowling; I did not find any leaks or any other damage.
Captain reports that after takeoff; at 400 FT; he noticed the left EPR became erractic and oscillating including the left N1 tach; followed by several bangs. Throttle reduced to idle and banging noise stopped. Air turnback accomplished. Left engine inlet bullet found separated from engine and resting in the inlet nacelle.