Narrative:

I was flying my 1957 beech D-50 (twin bonanza). I was alone in the plane. I was on an instrument flight plan. I was cleared for a visual approach to runway xx. The weather was clear. It was a moonless night; but visibility was good. The descent started late and I was a bit high for the visual. I turned to a course of 180 degrees to add distance to the runway. I needed to lose additional altitude so before turning onto the runway heading I slowed the aircraft into gear speed range and dropped the gear. The gear operated normally and I got a green indicator light and the down flag in the inspection window. I progressively added flaps. I flew a visual approach along the extended centerline of runway xx. I progressively reduced throttle to 15 inches/2500 RPM and added full flaps in order to lose altitude more quickly. At an AGL of 400 feet I was right on the border between 4 white PAPI's and 3 white/1 red; but I was about 10 mph over blue line. It was a salvageable landing; but west of runway xx at ZZZ is the national forest which is a 'black hole' at night that makes judging your glide slope difficult. I elected to go around. I added power then progressively raised the flaps. I got a positive rate and retracted the gear. Gear retraction seemed normal. I called the tower and told them I was going around because 'that was ugly' (referring to the approach to runway xx) and asked to join the left downwind for runway yy. The tower told me to join the left downwind for runway yy. I continued the climb back toward pattern altitude. About the time I crossed the centerline of runway yy I began to smell acrid smoke such as emitted by burning insulation. I then made a quick turn onto the downwind to runway yy; having decided to fly a tight pattern and get on the ground more quickly. About this time the tower cleared me to land on runway yy. On late downwind I actuated the gear switch to drop the gear. I heard the gear motor and felt the gear dropping. The acrid smell grew noticeably stronger and I decided to turn immediately onto base. As I was in the left turn and looking left I glanced to the right and saw the down flag in the inspection window. I looked back to the left and realized I was going to have to continue the left turn (without leveling) to avoid overshooting the centerline of runway yy. I did continue the turn but still overshot while staying within a maximum 30 degree bank. I had to continue the turn. Then I leveled out to re-intercept the centerline to runway yy. As I was leveling the wings I saw smoke in the cockpit. The cockpit lighting was dim and I could not tell where the smoke was coming from. I grabbed my flashlight off the copilot's seat and shined it around. I thought the smoke was coming from the area of the voltage regulator - low in the panel on the copilot's side. I banked right to join the centerline of runway yy. At this point I was about 400 feet AGL. The smoke grew worse. I pulled the throttles back to the bottom of the green to try to lose altitude as quickly as possible. I descended quickly but flared normally. I slowly pulled the throttles back in the flare. I got a chirp-chirp from the mains; and about 1 second later I got a chirp from the nose wheel. The plane then rolled normally for about 1 second with the smoke getting thick enough to be visible while looking ahead through the canopy. During this time I continued pulling the throttles back toward the closed position. Then the gear horn went off. Then the plane pitched up even though the speed was too slow to fly (in retrospect I think this was actually the rear of the plane starting to drop but my perception at the time was looking forward down the runway and seeing the runway start to descend out of my field of view). I relaxed some pressure on the yoke and the nose pitched down. Then the plane settled in a flat attitude to the surface of the runway. The props impacted the runway surface but the plane did not slow noticeably. The twinbonanza was rolling on its wheels in the retracted position. The throttles were being slowly pulled closed at the time of the prop strike and I expect the strike occurred at about 1;300 - 1;500 engine RPM with the props wind milling (these are geared engines so the props would have been considerably slower). I called the tower and told them I had had a gear up landing. I then applied the brakes. I saw a taxiway coming up and steered the plane off the runway onto the taxiway. Because the twin bonanza is designed to roll on its tires with the gear in a retracted state (while maintaining clearance for the airframe) steering and braking remained effective throughout. I braked to a stop. I shut off all power with the key switch and shut off the mags. I then removed my seat belt and grabbed the flashlight on my way out. The cockpit was very dark after shutting off all power. When I turned on the flashlight to find the door handle I saw that smoke was actually pouring up through the floorboards in front of the main spar. I opened the door and started to exit. I then remembered that I had shut off power before getting an acknowledgment from the tower (or at least if the tower did acknowledge I was too preoccupied to remember it). I was worried that nobody knew my situation and maybe there was somebody coming in behind me. I climbed back to the pilot position and turned on the key again. I made another call on tower frequency advising of the gear up landing. The smoke had dissipated a good bit after I opened the door but when I turned power back on the smoke returned - again coming from below the floorboards. I quickly turned the key back off and very rapidly exited the aircraft. I exited the back of the right wing and saw light coming from below the aircraft. I thought it was a fire; but in fact the plane had come to rest right over one of the flush taxiway/runway edge markers. The smoke exited through the open door. The smoke seemed to diminish as I watched. A helicopter began to circle over me at this point and I waved to the helicopter to let them know I was ok. I could see rescue vehicles approaching so I was then certain that my radio calls had been heard.

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Original NASA ASRS Text

Title: BE50 pilot reported landing gear up at night after experiencing smoke in the cockpit.

Narrative: I was flying my 1957 Beech D-50 (Twin Bonanza). I was alone in the plane. I was on an instrument flight plan. I was cleared for a visual approach to runway XX. The weather was clear. It was a moonless night; but visibility was good. The descent started late and I was a bit high for the visual. I turned to a course of 180 degrees to add distance to the runway. I needed to lose additional altitude so before turning onto the runway heading I slowed the aircraft into gear speed range and dropped the gear. The gear operated normally and I got a green indicator light and the down flag in the inspection window. I progressively added flaps. I flew a visual approach along the extended centerline of runway XX. I progressively reduced throttle to 15 inches/2500 RPM and added full flaps in order to lose altitude more quickly. At an AGL of 400 feet I was right on the border between 4 white PAPI's and 3 white/1 red; but I was about 10 mph over blue line. It was a salvageable landing; but west of Runway XX at ZZZ is the National Forest which is a 'black hole' at night that makes judging your glide slope difficult. I elected to go around. I added power then progressively raised the flaps. I got a positive rate and retracted the gear. Gear retraction seemed normal. I called the tower and told them I was going around because 'that was ugly' (referring to the approach to Runway XX) and asked to join the left downwind for Runway YY. The tower told me to join the left downwind for Runway YY. I continued the climb back toward pattern altitude. About the time I crossed the centerline of Runway YY I began to smell acrid smoke such as emitted by burning insulation. I then made a quick turn onto the downwind to Runway YY; having decided to fly a tight pattern and get on the ground more quickly. About this time the tower cleared me to land on Runway YY. On late downwind I actuated the gear switch to drop the gear. I heard the gear motor and felt the gear dropping. The acrid smell grew noticeably stronger and I decided to turn immediately onto base. As I was in the left turn and looking left I glanced to the right and saw the down flag in the inspection window. I looked back to the left and realized I was going to have to continue the left turn (without leveling) to avoid overshooting the centerline of Runway YY. I did continue the turn but still overshot while staying within a maximum 30 degree bank. I had to continue the turn. Then I leveled out to re-intercept the centerline to Runway YY. As I was leveling the wings I saw smoke in the cockpit. The cockpit lighting was dim and I could not tell where the smoke was coming from. I grabbed my flashlight off the copilot's seat and shined it around. I thought the smoke was coming from the area of the voltage regulator - low in the panel on the copilot's side. I banked right to join the centerline of Runway YY. At this point I was about 400 feet AGL. The smoke grew worse. I pulled the throttles back to the bottom of the green to try to lose altitude as quickly as possible. I descended quickly but flared normally. I slowly pulled the throttles back in the flare. I got a chirp-chirp from the mains; and about 1 second later I got a chirp from the nose wheel. The plane then rolled normally for about 1 second with the smoke getting thick enough to be visible while looking ahead through the canopy. During this time I continued pulling the throttles back toward the closed position. Then the gear horn went off. Then the plane pitched up even though the speed was too slow to fly (In retrospect I think this was actually the rear of the plane starting to drop but my perception at the time was looking forward down the runway and seeing the runway start to descend out of my field of view). I relaxed some pressure on the yoke and the nose pitched down. Then the plane settled in a flat attitude to the surface of the runway. The props impacted the runway surface but the plane did not slow noticeably. The TwinBonanza was rolling on its wheels in the retracted position. The throttles were being slowly pulled closed at the time of the prop strike and I expect the strike occurred at about 1;300 - 1;500 engine RPM with the props wind milling (These are geared engines so the props would have been considerably slower). I called the tower and told them I had had a gear up landing. I then applied the brakes. I saw a taxiway coming up and steered the plane off the runway onto the taxiway. Because the Twin Bonanza is designed to roll on its tires with the gear in a retracted state (while maintaining clearance for the airframe) steering and braking remained effective throughout. I braked to a stop. I shut off all power with the key switch and shut off the mags. I then removed my seat belt and grabbed the flashlight on my way out. The cockpit was very dark after shutting off all power. When I turned on the flashlight to find the door handle I saw that smoke was actually pouring up through the floorboards in front of the main spar. I opened the door and started to exit. I then remembered that I had shut off power before getting an acknowledgment from the tower (or at least if the tower did acknowledge I was too preoccupied to remember it). I was worried that nobody knew my situation and maybe there was somebody coming in behind me. I climbed back to the pilot position and turned on the key again. I made another call on tower frequency advising of the gear up landing. The smoke had dissipated a good bit after I opened the door but when I turned power back on the smoke returned - again coming from below the floorboards. I quickly turned the key back off and very rapidly exited the aircraft. I exited the back of the right wing and saw light coming from below the aircraft. I thought it was a fire; but in fact the plane had come to rest right over one of the flush taxiway/runway edge markers. The smoke exited through the open door. The smoke seemed to diminish as I watched. A helicopter began to circle over me at this point and I waved to the helicopter to let them know I was OK. I could see rescue vehicles approaching so I was then certain that my radio calls had been heard.

Data retrieved from NASA's ASRS site 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.