Narrative:

Cessna 310G. About 10 mins from gck, I turned on the heater. Between 2 and 5 mins later, we noticed a strange acrid smell in the cabin. It smelled of burning electrical insulation. I had also pulled the forward cabin air and cabin air knobs out. Very soon after we noticed the smell, we saw smoke enter the cabin. I immediately turned the heater off. We turned around and began to descend. Pilot turned off the battery and generator switches and the smoke and smell began to slowly disappear. I then realized that the landing gear was electric. So I asked pilot to turn on the battery master to see if we would get the smell and smoke again. He did so and we got no smell. So we decided to put the landing gear down to get it out of the way. When we lowered the landing gear, I felt the gear fall out and the extension seemed to begin normally, then we heard a strange sound come from the gear motor. It was a high pitched whine. We didn't get a green light. We pushed both the red and green lights to see if they would light and they did. We then agreed that the electrical failure somehow affected the landing gear motor. So we decided to extend the gear manually. Mr X went through the procedure but he never got a green light and never felt any resistance in the handle. When we turned on the radio, we got the smell and more smoke. We tried putting 7700 in the transponder and when we turned it on, we got the smell and more smoke. So we stowed the gear handle, turned on the master and tried to lower the gear again. We got the high pitched whine again and so mr X turned off the master switch. However, the motor didn't stop running. It seemed to continue at a higher and higher pitch and then it stopped. The outside air temperature gauge, the fuel quantity indicators and cylinder head temperature were working. Mr X then noticed that the fuel gauges had condensation on the inside of the glass. I touched them and they were hot to the touch. So we decided that the gear down green light was not reliable and decided to try a real softlndg to see if the gear was down and locked. I came down on final at about 100 mph IAS and settled gently onto the runway. We felt the gear touch and it felt solid. Just as I was about to reduce power, the right side landing gear began to collapse, I put in full throttle and took off. We decided to read the flight manual again and try to get a better picture of the gear system and try the emergency extension system again. I read and then performed the procedure. Again I felt no resistance to the emergency gear extension handle. I placed the gear handle in the 'up' position. Nothing happened. So I placed it back into the neutral position and tried the manual extension again. We then decided to 'bounce the landing gear on the runway to lock it. Throughout our efforts, the acrid smell would come and go and the fuel gauges were still hot to the touch adding to our urgency. We decided to go ahead and land on the next pass. We agreed that if the plane started to fall right after touchdown we would go around again and if it rolled out ok, I would kill the mixtures. We came in at about 100 mph IAS and touched down. All 3 wheels supported the airplane and so I pulled the mixtures. We rolled about 500-1000 ft and then the right main collapsed taking the left main down and we slid another 2000 ft and slid off the runway to the left side. Probably, the gear wouldn't lock because of air loads on the nosewheel. When the right main collapsed, it pulled the rods to the other 2 landing gear. That pulled the left main under. The gear didn't fold completely up into the wells because the nosewheel was at such an angle that it wouldn't fold back under. This held the rods on the other 2 wheels so they stayed partially extended. I believe that something is broken inside the gear transmission. I believe that some part of the heater electrics shorted. We talked with FAA inspector out of wichita. It would be classified as an aircraft incident. Throughout we were worried about an electrical fire because the electrical short left some equipment on even with the battery and generators off. Also the hot faces of the fuel quantity indicators made us very nervous. Mr X also thought he saw a spark when he turned the transponder on and I thought I saw a spark behind the panel. Supplemental information from acn 397326: mr Y took the controls as I slowly went through the emergency gear extension procedure as written in the poh. I was dismayed to find there was no 'pressure' on the emergency gear crank. I have gone through the procedure many times in the past in another 310 with students (only in practice!) and am intimately familiar with the procedure. After cranking the gear down, the crank should be impossible to move as the gear is moved by push rods. I rotated the crank 90 times (30 more than normal) feeling no pressure in the handle at all. Mr Y climbed into the back to attempt to unscrew the floorboards and inspect the gear mechanism. He saw that there were many screws to undo and while he was working on the second one I heard several loud 'pops' from the instrument panel and saw some more smoke. I called mr Y up front and we decided the time had come to land. I am reviewing our actions but at present I am happy with our actions. I am very glad we could work as a crew and work through the options available. It was important to me that we had crash assistance before we landed and I was upset (perhaps irrationally, given the situation) that there was none. Ultimately a crash fire rescue equipment truck would not have changed the course of events during our landing, but it would have provided me some peace of mind. I would be happy to (and look forward to) talk with someone to figure out how a crash truck would be available to someone in a similar situation in the future.

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Original NASA ASRS Text

Title: A C310 HAS MASSIVE ELECTRICAL PROBS CREATING SMOKE AND POSSIBLE FIRE. THE LNDG GEAR JAMMED PARTLY EXTENDED AND FOLDED UPON MAKING THE EMER LNDG ATTEMPT.

Narrative: CESSNA 310G. ABOUT 10 MINS FROM GCK, I TURNED ON THE HEATER. BTWN 2 AND 5 MINS LATER, WE NOTICED A STRANGE ACRID SMELL IN THE CABIN. IT SMELLED OF BURNING ELECTRICAL INSULATION. I HAD ALSO PULLED THE FORWARD CABIN AIR AND CABIN AIR KNOBS OUT. VERY SOON AFTER WE NOTICED THE SMELL, WE SAW SMOKE ENTER THE CABIN. I IMMEDIATELY TURNED THE HEATER OFF. WE TURNED AROUND AND BEGAN TO DSND. PLT TURNED OFF THE BATTERY AND GENERATOR SWITCHES AND THE SMOKE AND SMELL BEGAN TO SLOWLY DISAPPEAR. I THEN REALIZED THAT THE LNDG GEAR WAS ELECTRIC. SO I ASKED PLT TO TURN ON THE BATTERY MASTER TO SEE IF WE WOULD GET THE SMELL AND SMOKE AGAIN. HE DID SO AND WE GOT NO SMELL. SO WE DECIDED TO PUT THE LNDG GEAR DOWN TO GET IT OUT OF THE WAY. WHEN WE LOWERED THE LNDG GEAR, I FELT THE GEAR FALL OUT AND THE EXTENSION SEEMED TO BEGIN NORMALLY, THEN WE HEARD A STRANGE SOUND COME FROM THE GEAR MOTOR. IT WAS A HIGH PITCHED WHINE. WE DIDN'T GET A GREEN LIGHT. WE PUSHED BOTH THE RED AND GREEN LIGHTS TO SEE IF THEY WOULD LIGHT AND THEY DID. WE THEN AGREED THAT THE ELECTRICAL FAILURE SOMEHOW AFFECTED THE LNDG GEAR MOTOR. SO WE DECIDED TO EXTEND THE GEAR MANUALLY. MR X WENT THROUGH THE PROC BUT HE NEVER GOT A GREEN LIGHT AND NEVER FELT ANY RESISTANCE IN THE HANDLE. WHEN WE TURNED ON THE RADIO, WE GOT THE SMELL AND MORE SMOKE. WE TRIED PUTTING 7700 IN THE XPONDER AND WHEN WE TURNED IT ON, WE GOT THE SMELL AND MORE SMOKE. SO WE STOWED THE GEAR HANDLE, TURNED ON THE MASTER AND TRIED TO LOWER THE GEAR AGAIN. WE GOT THE HIGH PITCHED WHINE AGAIN AND SO MR X TURNED OFF THE MASTER SWITCH. HOWEVER, THE MOTOR DIDN'T STOP RUNNING. IT SEEMED TO CONTINUE AT A HIGHER AND HIGHER PITCH AND THEN IT STOPPED. THE OUTSIDE AIR TEMP GAUGE, THE FUEL QUANTITY INDICATORS AND CYLINDER HEAD TEMP WERE WORKING. MR X THEN NOTICED THAT THE FUEL GAUGES HAD CONDENSATION ON THE INSIDE OF THE GLASS. I TOUCHED THEM AND THEY WERE HOT TO THE TOUCH. SO WE DECIDED THAT THE GEAR DOWN GREEN LIGHT WAS NOT RELIABLE AND DECIDED TO TRY A REAL SOFTLNDG TO SEE IF THE GEAR WAS DOWN AND LOCKED. I CAME DOWN ON FINAL AT ABOUT 100 MPH IAS AND SETTLED GENTLY ONTO THE RWY. WE FELT THE GEAR TOUCH AND IT FELT SOLID. JUST AS I WAS ABOUT TO REDUCE PWR, THE R SIDE LNDG GEAR BEGAN TO COLLAPSE, I PUT IN FULL THROTTLE AND TOOK OFF. WE DECIDED TO READ THE FLT MANUAL AGAIN AND TRY TO GET A BETTER PICTURE OF THE GEAR SYS AND TRY THE EMER EXTENSION SYS AGAIN. I READ AND THEN PERFORMED THE PROC. AGAIN I FELT NO RESISTANCE TO THE EMER GEAR EXTENSION HANDLE. I PLACED THE GEAR HANDLE IN THE 'UP' POS. NOTHING HAPPENED. SO I PLACED IT BACK INTO THE NEUTRAL POS AND TRIED THE MANUAL EXTENSION AGAIN. WE THEN DECIDED TO 'BOUNCE THE LNDG GEAR ON THE RWY TO LOCK IT. THROUGHOUT OUR EFFORTS, THE ACRID SMELL WOULD COME AND GO AND THE FUEL GAUGES WERE STILL HOT TO THE TOUCH ADDING TO OUR URGENCY. WE DECIDED TO GO AHEAD AND LAND ON THE NEXT PASS. WE AGREED THAT IF THE PLANE STARTED TO FALL RIGHT AFTER TOUCHDOWN WE WOULD GO AROUND AGAIN AND IF IT ROLLED OUT OK, I WOULD KILL THE MIXTURES. WE CAME IN AT ABOUT 100 MPH IAS AND TOUCHED DOWN. ALL 3 WHEELS SUPPORTED THE AIRPLANE AND SO I PULLED THE MIXTURES. WE ROLLED ABOUT 500-1000 FT AND THEN THE R MAIN COLLAPSED TAKING THE L MAIN DOWN AND WE SLID ANOTHER 2000 FT AND SLID OFF THE RWY TO THE L SIDE. PROBABLY, THE GEAR WOULDN'T LOCK BECAUSE OF AIR LOADS ON THE NOSEWHEEL. WHEN THE R MAIN COLLAPSED, IT PULLED THE RODS TO THE OTHER 2 LNDG GEAR. THAT PULLED THE L MAIN UNDER. THE GEAR DIDN'T FOLD COMPLETELY UP INTO THE WELLS BECAUSE THE NOSEWHEEL WAS AT SUCH AN ANGLE THAT IT WOULDN'T FOLD BACK UNDER. THIS HELD THE RODS ON THE OTHER 2 WHEELS SO THEY STAYED PARTIALLY EXTENDED. I BELIEVE THAT SOMETHING IS BROKEN INSIDE THE GEAR TRANSMISSION. I BELIEVE THAT SOME PART OF THE HEATER ELECTRICS SHORTED. WE TALKED WITH FAA INSPECTOR OUT OF WICHITA. IT WOULD BE CLASSIFIED AS AN ACFT INCIDENT. THROUGHOUT WE WERE WORRIED ABOUT AN ELECTRICAL FIRE BECAUSE THE ELECTRICAL SHORT LEFT SOME EQUIP ON EVEN WITH THE BATTERY AND GENERATORS OFF. ALSO THE HOT FACES OF THE FUEL QUANTITY INDICATORS MADE US VERY NERVOUS. MR X ALSO THOUGHT HE SAW A SPARK WHEN HE TURNED THE XPONDER ON AND I THOUGHT I SAW A SPARK BEHIND THE PANEL. SUPPLEMENTAL INFO FROM ACN 397326: MR Y TOOK THE CTLS AS I SLOWLY WENT THROUGH THE EMER GEAR EXTENSION PROC AS WRITTEN IN THE POH. I WAS DISMAYED TO FIND THERE WAS NO 'PRESSURE' ON THE EMER GEAR CRANK. I HAVE GONE THROUGH THE PROC MANY TIMES IN THE PAST IN ANOTHER 310 WITH STUDENTS (ONLY IN PRACTICE!) AND AM INTIMATELY FAMILIAR WITH THE PROC. AFTER CRANKING THE GEAR DOWN, THE CRANK SHOULD BE IMPOSSIBLE TO MOVE AS THE GEAR IS MOVED BY PUSH RODS. I ROTATED THE CRANK 90 TIMES (30 MORE THAN NORMAL) FEELING NO PRESSURE IN THE HANDLE AT ALL. MR Y CLBED INTO THE BACK TO ATTEMPT TO UNSCREW THE FLOORBOARDS AND INSPECT THE GEAR MECHANISM. HE SAW THAT THERE WERE MANY SCREWS TO UNDO AND WHILE HE WAS WORKING ON THE SECOND ONE I HEARD SEVERAL LOUD 'POPS' FROM THE INST PANEL AND SAW SOME MORE SMOKE. I CALLED MR Y UP FRONT AND WE DECIDED THE TIME HAD COME TO LAND. I AM REVIEWING OUR ACTIONS BUT AT PRESENT I AM HAPPY WITH OUR ACTIONS. I AM VERY GLAD WE COULD WORK AS A CREW AND WORK THROUGH THE OPTIONS AVAILABLE. IT WAS IMPORTANT TO ME THAT WE HAD CRASH ASSISTANCE BEFORE WE LANDED AND I WAS UPSET (PERHAPS IRRATIONALLY, GIVEN THE SIT) THAT THERE WAS NONE. ULTIMATELY A CFR TRUCK WOULD NOT HAVE CHANGED THE COURSE OF EVENTS DURING OUR LNDG, BUT IT WOULD HAVE PROVIDED ME SOME PEACE OF MIND. I WOULD BE HAPPY TO (AND LOOK FORWARD TO) TALK WITH SOMEONE TO FIGURE OUT HOW A CRASH TRUCK WOULD BE AVAILABLE TO SOMEONE IN A SIMILAR SIT IN THE FUTURE.

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.