A B757 captain noticed a flap asymmetry on the flap gauge with no EICAS annunciation and no flight c...

Attributes
ACN	867252
Time
Date	200912
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Flight Plan	IFR
Component
Aircraft Component	Flap/Slat Indication
Person 1
Function	Captain Pilot Not Flying
Person 2
Function	Pilot Flying First Officer
Events
Anomaly	Aircraft Equipment Problem Less Severe

Narrative:

When about to configure to flaps 30 degrees at 1300 ft AGL we noticed that we had a flap asymmetry indicated on the flap position indicator gauge; left at 25 degrees; right at 20 degrees with no amber te message or EICAS message and no lateral control problem. We set flaps to 20 degrees and increased approach speed to 20 degree setting from the FMC to 137+5 KTS and continued visually; with ample dry runway available; to a normal landing. We declared an emergency on short final and determined that airport rescue and fire fighting equipment was not needed upon clearing the runway. Was later informed by maintenance that the flaps functioned normally but that a flap transmitter was replaced.

Original NASA ASRS Text

Title: A B757 Captain noticed a flap asymmetry on the Flap Gauge with no EICAS annunciation and no flight control displacement. Flaps 20 were selected; an emergency declared and a normal normal landing completed. The Flap Gauge malfunctioned.

Narrative: When about to configure to flaps 30 degrees at 1300 FT AGL we noticed that we had a Flap Asymmetry indicated on the Flap Position Indicator gauge; left at 25 degrees; right at 20 degrees with no amber TE message or EICAS message and no lateral control problem. We set flaps to 20 degrees and increased approach speed to 20 degree setting from the FMC to 137+5 KTS and continued visually; with ample dry runway available; to a normal landing. We declared an emergency on short final and determined that Airport Rescue and Fire Fighting equipment was not needed upon clearing the runway. Was later informed by Maintenance that the flaps functioned normally but that a Flap Transmitter was replaced.

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.

A B757 captain noticed a flap asymmetry on the flap gauge with no EICAS annunciation and no flight control displacement. Flaps 20 were selected; an emergency declared and a normal normal landing completed. The flap gauge malfunctioned.