Pilot of small aircraft had gear unsafe light. Followed all procedures to lock gear. Unable. Declare...

Attributes
ACN	178670
Time
Date	199105
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : fcm airport : msp
State Reference	MN
Altitude	msl bound lower : 2500 msl bound upper : 2500
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : msp tower : bna
Operator	common carrier : air taxi
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Retractable Gear
Flight Phase	descent : approach landing other
Flight Plan	None
Person 1
Affiliation	company : air taxi
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : instrument pilot : private pilot : cfi
Experience	flight time last 90 days : 80 flight time total : 1875 flight time type : 20
ASRS Report	178670
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other other : unspecified cockpit
Resolutory Action	flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

After dropping off passenger and a careful preflight, I departed stp (under radar control) for a reposition flight to flying cloud airport. I noticed a gear unsafe indication when I lowered the gear. I departed the traffic area and recycled the gear a # of times unsuccessfully. I then lowered the gear and yawed the aircraft and jerked on the yoke in an attempt to dislodge the gear and snap it into a locked position. Again I was not getting gear safe (green) or the gear unsafe light to go out. At that point I went through the afm emergency gear extension procedure and the indications didn't change. I called msp approach and advised them of my problem. I requested they contact our maintenance chief via phone. Approximately 2 weeks earlier the same situation developed on a training flight, but after recycling the gear the system was checked and returned to service by our maintenance department. I confirmed what I had done with maintenance via approach. I requested a fly-by at msp. The tower indicated the gear appeared normal, so I requested the emergency trucks and landing clearance. Approach vectored me for a landing. About 1 min before landing, the gear indicated safe (right main indicator light came on) and the unsafe indicator went out. (I had previously tested to see if the light had just burned out, but it tested operational.) I advised tower of the change, but still continued with the emergency procedures advising them of my plans for evacuate/evacuation should the gear collapse and I requested a mechanic to check the gear before we turned the aircraft. This aircraft has off-center locks and the gear can collapse if a side load is induced west/O full lock. I landed west/O incident, advised the tower to release the trucks and waited for a ground tow. A mechanic examined the gear and he said the micro switch on the gear may have been mounted too far back to give a positive indication. A complete maintenance and flight check was performed before the aircraft was returned to service. I feel this is an unfortunate but unpredictable incident. The experience supports my belief in knowing my aircraft systems and reviewing my options in advance.

Original NASA ASRS Text

Title: PLT OF SMA HAD GEAR UNSAFE LIGHT. FOLLOWED ALL PROCS TO LOCK GEAR. UNABLE. DECLARED EMERGENCY AND ON FINAL FOR LNDG MSP UNSAFE LIGHT WENT OUT. NORMAL LNDG, BUT PLT WAITED FOR TOW AND MAINT INSPECTION.

Narrative: AFTER DROPPING OFF PAX AND A CAREFUL PREFLT, I DEPARTED STP (UNDER RADAR CTL) FOR A REPOSITION FLT TO FLYING CLOUD ARPT. I NOTICED A GEAR UNSAFE INDICATION WHEN I LOWERED THE GEAR. I DEPARTED THE TFC AREA AND RECYCLED THE GEAR A # OF TIMES UNSUCCESSFULLY. I THEN LOWERED THE GEAR AND YAWED THE ACFT AND JERKED ON THE YOKE IN AN ATTEMPT TO DISLODGE THE GEAR AND SNAP IT INTO A LOCKED POS. AGAIN I WAS NOT GETTING GEAR SAFE (GREEN) OR THE GEAR UNSAFE LIGHT TO GO OUT. AT THAT POINT I WENT THROUGH THE AFM EMER GEAR EXTENSION PROC AND THE INDICATIONS DIDN'T CHANGE. I CALLED MSP APCH AND ADVISED THEM OF MY PROB. I REQUESTED THEY CONTACT OUR MAINT CHIEF VIA PHONE. APPROX 2 WKS EARLIER THE SAME SITUATION DEVELOPED ON A TRNING FLT, BUT AFTER RECYCLING THE GEAR THE SYS WAS CHKED AND RETURNED TO SVC BY OUR MAINT DEPT. I CONFIRMED WHAT I HAD DONE WITH MAINT VIA APCH. I REQUESTED A FLY-BY AT MSP. THE TWR INDICATED THE GEAR APPEARED NORMAL, SO I REQUESTED THE EMER TRUCKS AND LNDG CLRNC. APCH VECTORED ME FOR A LNDG. ABOUT 1 MIN BEFORE LNDG, THE GEAR INDICATED SAFE (RIGHT MAIN INDICATOR LIGHT CAME ON) AND THE UNSAFE INDICATOR WENT OUT. (I HAD PREVIOUSLY TESTED TO SEE IF THE LIGHT HAD JUST BURNED OUT, BUT IT TESTED OPERATIONAL.) I ADVISED TWR OF THE CHANGE, BUT STILL CONTINUED WITH THE EMER PROCS ADVISING THEM OF MY PLANS FOR EVAC SHOULD THE GEAR COLLAPSE AND I REQUESTED A MECH TO CHK THE GEAR BEFORE WE TURNED THE ACFT. THIS ACFT HAS OFF-CENTER LOCKS AND THE GEAR CAN COLLAPSE IF A SIDE LOAD IS INDUCED W/O FULL LOCK. I LANDED W/O INCIDENT, ADVISED THE TWR TO RELEASE THE TRUCKS AND WAITED FOR A GND TOW. A MECH EXAMINED THE GEAR AND HE SAID THE MICRO SWITCH ON THE GEAR MAY HAVE BEEN MOUNTED TOO FAR BACK TO GIVE A POSITIVE INDICATION. A COMPLETE MAINT AND FLT CHK WAS PERFORMED BEFORE THE ACFT WAS RETURNED TO SVC. I FEEL THIS IS AN UNFORTUNATE BUT UNPREDICTABLE INCIDENT. THE EXPERIENCE SUPPORTS MY BELIEF IN KNOWING MY ACFT SYSTEMS AND REVIEWING MY OPTIONS IN ADVANCE.

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.

Pilot of small aircraft had gear unsafe light. Followed all procedures to lock gear. Unable. Declared emergency and on final for landing msp unsafe light went out. Normal landing, but pilot waited for tow and maintenance inspection.