Narrative:

During approach, we performed the before landing checklist. All of the gear indicated that the gear was down and locked. Then we got a gear unsafe light on the right gear. We then told tower we needed to go around and work on the problem. We did not raise the gear because we originally had 3 gear down and assumed it was a sensor problem. By raising the gear, we did not want to jeopardize what we had. We then tried manual extension to see if that would help since there is not a specific checklist addressing only one gear unsafe condition. Knowing it would not come down, we declared an emergency and prepared the cabin for a possible gear up landing and evacuate/evacuation. We landed on runway 7 at den with no problem. We stopped on the runway because we felt it would be safer to have the gear pins installed. It would have helped to have a specific checklist for our situation. With our fuel getting low, we did not have time to call maintenance control to try alternate procedures. Callback conversation with reporter revealed the following information: the reporter stated maintenance reported the cause of the right main gear unsafe light was contamination of the hydraulic fluid. The reporter said maintenance was pressed to describe how contaminated fluid could cause this incident but have released no further details. The reporter stated this was a new B737-800.

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Original NASA ASRS Text

Title: A B737-800 AT 7000 FT DECLARED AN EMER DUE TO R MAIN GEAR UNSAFE INDICATION, CAUSED BY HYD FLUID CONTAMINATION.

Narrative: DURING APCH, WE PERFORMED THE BEFORE LNDG CHKLIST. ALL OF THE GEAR INDICATED THAT THE GEAR WAS DOWN AND LOCKED. THEN WE GOT A GEAR UNSAFE LIGHT ON THE R GEAR. WE THEN TOLD TWR WE NEEDED TO GO AROUND AND WORK ON THE PROB. WE DID NOT RAISE THE GEAR BECAUSE WE ORIGINALLY HAD 3 GEAR DOWN AND ASSUMED IT WAS A SENSOR PROB. BY RAISING THE GEAR, WE DID NOT WANT TO JEOPARDIZE WHAT WE HAD. WE THEN TRIED MANUAL EXTENSION TO SEE IF THAT WOULD HELP SINCE THERE IS NOT A SPECIFIC CHKLIST ADDRESSING ONLY ONE GEAR UNSAFE CONDITION. KNOWING IT WOULD NOT COME DOWN, WE DECLARED AN EMER AND PREPARED THE CABIN FOR A POSSIBLE GEAR UP LNDG AND EVAC. WE LANDED ON RWY 7 AT DEN WITH NO PROB. WE STOPPED ON THE RWY BECAUSE WE FELT IT WOULD BE SAFER TO HAVE THE GEAR PINS INSTALLED. IT WOULD HAVE HELPED TO HAVE A SPECIFIC CHKLIST FOR OUR SIT. WITH OUR FUEL GETTING LOW, WE DID NOT HAVE TIME TO CALL MAINT CTL TO TRY ALTERNATE PROCS. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING INFO: THE RPTR STATED MAINT RPTED THE CAUSE OF THE R MAIN GEAR UNSAFE LIGHT WAS CONTAMINATION OF THE HYD FLUID. THE RPTR SAID MAINT WAS PRESSED TO DESCRIBE HOW CONTAMINATED FLUID COULD CAUSE THIS INCIDENT BUT HAVE RELEASED NO FURTHER DETAILS. THE RPTR STATED THIS WAS A NEW B737-800.

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.