A B737-400 crew detected a Flap Asymmetry at flaps 15 after flaps 30 was selected and so executed a go around; declared an emergency; completed the QRH and conducted another ILS in overcast turbulent weather.

Narrative

The event took place during an ILS to 18 inside the outer marker. The Captain called for flaps 25 and a few seconds later he called for flaps 30 complete the landing checklist. The weather conditions at the time was right in the middle of a passing cold front with a cloud layer between 6;000 FT and about 500 FT overcast; turbulence in the clouds was steady moderate chop. As I completed the checklist and cross referenced the flap indicator with the selected flaps 30 we both noticed the flap indicator was still indicating flaps 15. Being this close to landing and not certain what kind of malfunction we had; the Captain choose to go around and ask for a vector and a possible hold to verify the problem and work through our QRH procedures. Given the weather/turbulence conditions it was impossible to tell what flap setting we actually had i.e. pitch/power; we could possibly also have some asymmetry without us sensing/noticing it in the turbulence. We both agreed to declare an emergency with ATC who then gave us a long vector around back to ILS 18. We completed the QRH procedure and landed with flaps 15. There was no further incident and no more assistance was needed. The flap malfunction was written up in the log book and handed over to Maintenance.