Narrative:

I, the instructor, departed sbm in a piper aztec PA23 with pilot (newly certificated private multi engine rated) and 2 passenger for the purpose of gaining flight time for insurance solo signoff. Morning preflight and WX-mation showed VFR for entire route sbm-3WO-W147-sbm. First leg sbm-3WO uneventful and normal. Stopped for breakfast. Departed sbm approximately XA30 from airport. Landed 3WO approximately XB00 hours. Departed on second leg XD15. Preflight and walkaround normal before departure from 3WO. Climbed to 5500 ft MSL cruise altitude en route to W147, wi. On leveloff, both engines began to surge and roughness in RPM noticed. I, PNF, instructed the PF to turn on boost pumps as a precautionary measure. I also applied carburetor heat to both engines. No change or improvement occurred. I, non flying instructor, advised PF in left seat I would next try leaning mixtures to see if I could get engines to smooth out. This measure appeared to alleviate problem. We started down out of altitude for descent into W147. Called on CTAF to advise traffic of our position and intent to land. PF left seat completed descent and approach checklist. As he advanced mixtures to full rich for landing, engine roughness occurred. I, being PNF, advised him that I would assume command as PIC because of experience level and that he would assist me in PNF duties. Turned downwind with engines intermittently running rough. Asked the left seat pilot to extend the gear, followed by flaps first position. PNF called 'coming gear down.' I looked and saw 3 green lights, called for final flaps as I turned final and had runway made and closed throttles for flare. Airplane came to rest on runway 14, favored runway at time, approximately 1/4 or 600 ft down from approach end on runway centerline. Followed emergency shutdown and evacuate/evacuation procedures. No personal injuries were sustained. Minimal damage to underbelly of fuselage. With only visual damage to propellers, believe incident occurred because I was consumed with engine problem and relied on rated PNF to back me up while I tried to get aircraft safely on ground. Several distrs contributing to gear up: 1) engine roughness and surging. 2) inbound traffic. 3) bright sunlight in cockpit which appeared to give illusion of 3 green light. 4) poor sound-deading in cockpit and cabin and use of headsets which masked gear warning horn. 5) newly rated multi pilot.

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Original NASA ASRS Text

Title: AN INSTRUCTOR PLT IN A PA23 MADE A PRECAUTIONARY LNDG GEAR UP. HE WAS CONCENTRATING ON MAKING THE LNDG AND FAILED TO NOTE THE GEAR POS.

Narrative: I, THE INSTRUCTOR, DEPARTED SBM IN A PIPER AZTEC PA23 WITH PLT (NEWLY CERTIFICATED PVT MULTI ENG RATED) AND 2 PAX FOR THE PURPOSE OF GAINING FLT TIME FOR INSURANCE SOLO SIGNOFF. MORNING PREFLT AND WX-MATION SHOWED VFR FOR ENTIRE RTE SBM-3WO-W147-SBM. FIRST LEG SBM-3WO UNEVENTFUL AND NORMAL. STOPPED FOR BREAKFAST. DEPARTED SBM APPROX XA30 FROM ARPT. LANDED 3WO APPROX XB00 HRS. DEPARTED ON SECOND LEG XD15. PREFLT AND WALKAROUND NORMAL BEFORE DEP FROM 3WO. CLBED TO 5500 FT MSL CRUISE ALT ENRTE TO W147, WI. ON LEVELOFF, BOTH ENGS BEGAN TO SURGE AND ROUGHNESS IN RPM NOTICED. I, PNF, INSTRUCTED THE PF TO TURN ON BOOST PUMPS AS A PRECAUTIONARY MEASURE. I ALSO APPLIED CARB HEAT TO BOTH ENGS. NO CHANGE OR IMPROVEMENT OCCURRED. I, NON FLYING INSTRUCTOR, ADVISED PF IN L SEAT I WOULD NEXT TRY LEANING MIXTURES TO SEE IF I COULD GET ENGS TO SMOOTH OUT. THIS MEASURE APPEARED TO ALLEVIATE PROB. WE STARTED DOWN OUT OF ALT FOR DSCNT INTO W147. CALLED ON CTAF TO ADVISE TFC OF OUR POS AND INTENT TO LAND. PF L SEAT COMPLETED DSCNT AND APCH CHKLIST. AS HE ADVANCED MIXTURES TO FULL RICH FOR LNDG, ENG ROUGHNESS OCCURRED. I, BEING PNF, ADVISED HIM THAT I WOULD ASSUME COMMAND AS PIC BECAUSE OF EXPERIENCE LEVEL AND THAT HE WOULD ASSIST ME IN PNF DUTIES. TURNED DOWNWIND WITH ENGS INTERMITTENTLY RUNNING ROUGH. ASKED THE L SEAT PLT TO EXTEND THE GEAR, FOLLOWED BY FLAPS FIRST POS. PNF CALLED 'COMING GEAR DOWN.' I LOOKED AND SAW 3 GREEN LIGHTS, CALLED FOR FINAL FLAPS AS I TURNED FINAL AND HAD RWY MADE AND CLOSED THROTTLES FOR FLARE. AIRPLANE CAME TO REST ON RWY 14, FAVORED RWY AT TIME, APPROX 1/4 OR 600 FT DOWN FROM APCH END ON RWY CTRLINE. FOLLOWED EMER SHUTDOWN AND EVAC PROCS. NO PERSONAL INJURIES WERE SUSTAINED. MINIMAL DAMAGE TO UNDERBELLY OF FUSELAGE. WITH ONLY VISUAL DAMAGE TO PROPS, BELIEVE INCIDENT OCCURRED BECAUSE I WAS CONSUMED WITH ENG PROB AND RELIED ON RATED PNF TO BACK ME UP WHILE I TRIED TO GET ACFT SAFELY ON GND. SEVERAL DISTRS CONTRIBUTING TO GEAR UP: 1) ENG ROUGHNESS AND SURGING. 2) INBOUND TFC. 3) BRIGHT SUNLIGHT IN COCKPIT WHICH APPEARED TO GIVE ILLUSION OF 3 GREEN LIGHT. 4) POOR SOUND-DEADING IN COCKPIT AND CABIN AND USE OF HEADSETS WHICH MASKED GEAR WARNING HORN. 5) NEWLY RATED MULTI PLT.

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.