B737-400 has unsafe indication when landing gear extended.

Attributes
ACN	311212
Time
Date	199507
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : lga
State Reference	NY
Altitude	agl bound lower : 0 agl bound upper : 2000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : n90 tower : lga
Operator	common carrier : air carrier
Make Model Name	B737-400
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent : approach landing other other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : atp pilot : commercial
Experience	flight time last 90 days : 100 flight time total : 10000
ASRS Report	311212
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : declared emergency flight crew : overcame equipment problem other
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

On final approach, landing gear handle was lowered with no gear down and safe indications. A go around was initiated, gear handle was raised but would not come above 'off.' crew, passenger, ATC, company was notified. ATC placed aircraft (B737- 400) in an extended/vectoring holding pattern while the flight crew referred to the aircraft manual and abnormal checklists. Prior to manual extension of gear, all circuit breakers were checked with none to be found popped. The manual gear extension procedure resulted in no safe indications. Visual verification of 3-DOWN-and-locked was made through the gear ports, by an aircraft vectored in by ATC, and by tower (tower had checked on the initial go around and on the subsequent fly-by requested by the local authority/authorized). An approach was made to a safe landing, on final the circuit breakers were rechked and the landing gear air and ground relay and lights circuit breaker was popped. It was reset providing normal indications prior to landing. The aircraft was pinned by maintenance after landing and taxied to the gate. It is not known if the circuit breaker was popped the whole time or popped after the initial search, it is a difficult area to see.

Original NASA ASRS Text

Title: B737-400 HAS UNSAFE INDICATION WHEN LNDG GEAR EXTENDED.

Narrative: ON FINAL APCH, LNDG GEAR HANDLE WAS LOWERED WITH NO GEAR DOWN AND SAFE INDICATIONS. A GAR WAS INITIATED, GEAR HANDLE WAS RAISED BUT WOULD NOT COME ABOVE 'OFF.' CREW, PAX, ATC, COMPANY WAS NOTIFIED. ATC PLACED ACFT (B737- 400) IN AN EXTENDED/VECTORING HOLDING PATTERN WHILE THE FLC REFERRED TO THE ACFT MANUAL AND ABNORMAL CHKLISTS. PRIOR TO MANUAL EXTENSION OF GEAR, ALL CIRCUIT BREAKERS WERE CHKED WITH NONE TO BE FOUND POPPED. THE MANUAL GEAR EXTENSION PROC RESULTED IN NO SAFE INDICATIONS. VISUAL VERIFICATION OF 3-DOWN-AND-LOCKED WAS MADE THROUGH THE GEAR PORTS, BY AN ACFT VECTORED IN BY ATC, AND BY TWR (TWR HAD CHKED ON THE INITIAL GAR AND ON THE SUBSEQUENT FLY-BY REQUESTED BY THE LCL AUTH). AN APCH WAS MADE TO A SAFE LNDG, ON FINAL THE CIRCUIT BREAKERS WERE RECHKED AND THE LNDG GEAR AIR AND GND RELAY AND LIGHTS CIRCUIT BREAKER WAS POPPED. IT WAS RESET PROVIDING NORMAL INDICATIONS PRIOR TO LNDG. THE ACFT WAS PINNED BY MAINT AFTER LNDG AND TAXIED TO THE GATE. IT IS NOT KNOWN IF THE CIRCUIT BREAKER WAS POPPED THE WHOLE TIME OR POPPED AFTER THE INITIAL SEARCH, IT IS A DIFFICULT AREA TO SEE.

Data retrieved from NASA's ASRS site as of July 2007 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.