A B737-400 crew detected a flap asymmetry at flaps 15 after flaps 30 was selected and so executed a ...

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.

Original NASA ASRS Text

Title: 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.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	986703
Time
Date	201112
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Make Model Name	B737-400
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Flight Plan	IFR
Component
Aircraft Component	Trailing Edge Flap
Person 1
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Critical Inflight Event / Encounter Weather / Turbulence

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.