INSTRUCTOR WITH 2 STUDENTS ABOARD HAS ENG FAILURE. EMER LNDG.

Narrative

I WAS INSTRUCTING 2 STUDENTS; A AND B. THE STUDENTS WERE SON AND FATHER; AND THE PLAN WAS TO HAVE 1 PERSON OBSERVE IN THE BACK WHILE THE OTHER ONE FLIES. A AND I HAD FLOWN ABOUT 1.3 HRS ON THE FLT; UNEVENTFUL; WE DID SLOW FLT AND MEDIUM TURNS AND BASIC ENG OUT PROCS ALSO ONE TOUCH-AND- GO AT ARB AND THEN LAND THERE TO SWITCH STUDENTS. B IS NOW THE STUDENT. WE BOTH WENT THROUGH THE PREFLT PROCS AND ALL LOOKED NORMAL. WE HAD DEPARTED ARB TO THE N TO DO MANEUVERS. THE WX WAS ABOUT 3000 OVCST WITH SOME SHOWERS IN THE AREA; THE TEMP WAS IN THE 70'S AND VERY HUMID; THE WIND WAS ABOUT 250 AT 13 KTS; AND THE PRESSURE WAS 29.71. WE WERE ABOUT 2500 FT MSL AND JUST STARTED TO DO SOME TURNS AT A SLOW SPD (75 MPH). THE ENG BEGAN TO RUN ROUGH INSIDE OF A SECOND. THE ENG WAS APPROX 2250 RPM BEFORE THE TROUBLE AND THEN REDUCED TO ABOUT 1900-2000 RPM'S AND VERY ROUGH AFTER. I TOOK THE CTLS FROM THE STUDENT; WENT THROUGH THE ENG OUT CHKLIST. I SUSPECTED CARB ICE AND PROMPTLY APPLIED THE CARB HEAT. IT SEEMED TO HELP FOR A LITTLE BIT; BUT ENG IMPROVEMENT DID NOT HOLD. I LOOKED FOR A FIELD; AND THERE WERE MANY. I DECIDED TO HEAD TO YIP ARPT BECAUSE WE WERE ABOUT 1/2 WAY BTWN YIP AND ARB; ARB ALSO A CITY BEFORE IT; AND YIP WAS THE ACFT HOME BASE AND HAD MORE RESCUE FACILITIES. I INFORMED YIP OF OUR INTENTIONS WITH THE ENG PROBS; AND ASKED TO BE LET DIRECTLY IN TO THE FIELD. THEY ACKNOWLEDGED AND ASKED HOW MANY PEOPLE WERE ON BOARD; I INFORMED THEM 3. THE ENG WOULD NOT RESPOND TO A THROTTLE ADJUSTMENT (ADVANCEMENT) AND WAS SET ABOUT 3/4 OPEN. I DID NOT WANT TO TRY ANYTHING OUT OF THE NORMAL TO TRY AND FIX THE ENG BECAUSE WE WERE ONLY ABOUT 1000 AGL AND I DID NOT WANT TO MAKE THE SIT WORSE; THE ENG FELT VERY WEAK. AFTER A COUPLE OF MINS; THE ENG HAD GOTTEN WORSE. I HAD KEPT FLYING OVER FIELDS AND ROADS; TO LEAVE MYSELF AN OUT. THEN ENG HAD GOTTEN A LOT WORSE AND I FELT LIKE THE AIRPLANE WOULD NOT MAKE IT TO THE ARPT. I STARTED TO CIRCLE A FIELD I HAD DECIDED TO LAND ON; IF THE ENG DID NOT GET BETTER. WHEN I BEGAN TO CIRCLE; THE ENG EFFECTIVELY QUIT AND I HAD TO LAND IN ANOTHER FIELD. I TOLD MY STUDENTS TO MAKE SURE THAT THEY WERE STRAPPED IN AND THAT WE WERE GOING TO LAND. THE LNDG WAS NICE; BUT THERE WAS AN UNAVOIDABLE PUDDLE IN THE WAY. THE L MAIN GEAR CAUGHT THE PUDDLE FIRST (AT ABOUT 40 MPH) AND THIS CAUSED THE AIRPLANE TO SWERVE L AND THE R WING CAUGHT THE GND. THE WING GRABBING THE GND CAUSED THE NOSE TO DIG IN AND THE PLANE TIPPED UP ON THE NOSE AND ALMOST TIPPED OVER; BUT IT JUST HUNG THERE FOR ABOUT A SECOND; AND THEN PLOPPED DOWN ON THE MAINS. I SHUT OFF THE MAGNETOS AND THE MIXTURE AND THE MASTER; ASKED IF MY STUDENTS WERE ALRIGHT; AND EXITED THE ACFT. THE RESCUE PERSONNEL ARRIVED SOON AFTER AND NO ONE WAS INJURED. THE AIRPLANE HAD A DAMAGED R WING; PROP; SPINNER; AN THE FRONT NOSE GEAR WAS BENT TO THE SIDE ABOUT 20 DEGS. I AM NOT SURE WHAT CAUSED THE FAILURE OR WHAT COULD BE DONE TO PREVENT IT; BUT I CREDIT MY TRAINING FOR NOT LETTING THE SIT COME OUT MORE TRAGIC.