Instructor with spi has engine vibration and loss of power. Forced landing in field.

Attributes
ACN	208491
Time
Date	199204
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : abb
State Reference	IN
Altitude	agl bound lower : 0 agl bound upper : 2300
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sdf tower : ord
Operator	general aviation : instructional
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other
Flight Plan	None
Person 1
Affiliation	Other
Function	instruction : instructor
Qualification	pilot : atp pilot : cfi
Experience	flight time last 90 days : 279 flight time total : 2150 flight time type : 200
ASRS Report	208491
Person 2
Affiliation	Other
Function	flight crew : single pilot instruction : trainee
Qualification	pilot : student
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other other : unspecified cockpit
Resolutory Action	flight crew : declared emergency none taken : unable
Consequence	other
Supplementary
Primary Problem	Aircraft

Narrative:

After preflting an small aircraft for a flight to the practice area for some instruction, we departed bowman to the north. We climbed to 2500 MSL, once clear of standiford's arsa. We did some clearing turns, medium bank turns, power off stalls. Approach to landing stalls. The carburetor heat was on at all times during the maneuvers, except after the stall recovery. After a standard stall recovery we noticed that the engine had a noticeable vibration and was only producing 1500-1600 RPM. It seemed like it was a stuck valve. We went through the checklist. I tried to radio bowman on 119.5 and emergency on 121.50, no one responded. Picked a field and made a landing into the wind with full flaps. There were no injuries to the student or I. The aircraft propeller and right wingtip were slightly damaged.

Original NASA ASRS Text

Title: INSTRUCTOR WITH SPI HAS ENG VIBRATION AND LOSS OF PWR. FORCED LNDG IN FIELD.

Narrative: AFTER PREFLTING AN SMA FOR A FLT TO THE PRACTICE AREA FOR SOME INSTRUCTION, WE DEPARTED BOWMAN TO THE N. WE CLBED TO 2500 MSL, ONCE CLR OF STANDIFORD'S ARSA. WE DID SOME CLRING TURNS, MEDIUM BANK TURNS, PWR OFF STALLS. APCH TO LNDG STALLS. THE CARB HEAT WAS ON AT ALL TIMES DURING THE MANEUVERS, EXCEPT AFTER THE STALL RECOVERY. AFTER A STANDARD STALL RECOVERY WE NOTICED THAT THE ENG HAD A NOTICEABLE VIBRATION AND WAS ONLY PRODUCING 1500-1600 RPM. IT SEEMED LIKE IT WAS A STUCK VALVE. WE WENT THROUGH THE CHKLIST. I TRIED TO RADIO BOWMAN ON 119.5 AND EMER ON 121.50, NO ONE RESPONDED. PICKED A FIELD AND MADE A LNDG INTO THE WIND WITH FULL FLAPS. THERE WERE NO INJURIES TO THE STUDENT OR I. THE ACFT PROP AND R WINGTIP WERE SLIGHTLY DAMAGED.

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.