Small aircraft lost power due to ice that formed in the carburetor induction tube.

Attributes
ACN	234268
Time
Date	199302
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : hvn
State Reference	CT
Altitude	agl bound lower : 0 agl bound upper : 1000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : hvn
Operator	general aviation : instructional
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Fixed Gear
Flight Phase	other
Flight Plan	None
Person 1
Affiliation	Other
Function	instruction : instructor
Qualification	pilot : commercial pilot : cfi pilot : instrument
Experience	flight time last 90 days : 40 flight time total : 1050 flight time type : 400
ASRS Report	234268
Person 2
Affiliation	Other
Function	instruction : trainee
Qualification	pilot : student
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa
Resolutory Action	flight crew : declared emergency other
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

Preflight inspection (student and CFI) -- no discrepancies noted. Run-up normal. Takeoff and climb -- normal engine power output. First touch-and-go normal. Second takeoff and climb, normal operations. Throttle reduction on downwind from 2500-2100 rpms rough running engine aircraft 'shaking'. Power loss checklist accomplished. Carburetor heat -- unable to open lever fully (approximately 1/3 travel obtained). Condition worsened. More loss of power and more vibration noted. Contacted tower for full stop landing -- no emergency declared. Adjusted throttle slightly. No change in performance. Closed and tried to obtain carburetor heat. Conditions worsened (with 0 carburetor heat). Landed uneventfully. Taxi was uneventful. Engine still vibrating and RPM's decreased slightly. Tried to open carburetor heat (with force) and succeeded. Engine ran smoothly. Resistance noted while attempting the above, the a 'snap.' then engine ran well. Taxied to maintenance facility. A&P listened to the event. Noted water in carburetor. Removed tubing from induction air filter (foam type) to air box. Large chunk of ice fell out. Run-up and subsequent operations all okay. Prior to flight we had heavy rain and snow during the preceding day. Temperatures never got over 0 degrees C.

Original NASA ASRS Text

Title: SMA LOST PWR DUE TO ICE THAT FORMED IN THE CARB INDUCTION TUBE.

Narrative: PREFLT INSPECTION (STUDENT AND CFI) -- NO DISCREPANCIES NOTED. RUN-UP NORMAL. TKOF AND CLB -- NORMAL ENG PWR OUTPUT. FIRST TOUCH-AND-GO NORMAL. SECOND TKOF AND CLB, NORMAL OPS. THROTTLE REDUCTION ON DOWNWIND FROM 2500-2100 RPMS ROUGH RUNNING ENG ACFT 'SHAKING'. PWR LOSS CHKLIST ACCOMPLISHED. CARB HEAT -- UNABLE TO OPEN LEVER FULLY (APPROX 1/3 TRAVEL OBTAINED). CONDITION WORSENED. MORE LOSS OF PWR AND MORE VIBRATION NOTED. CONTACTED TWR FOR FULL STOP LNDG -- NO EMER DECLARED. ADJUSTED THROTTLE SLIGHTLY. NO CHANGE IN PERFORMANCE. CLOSED AND TRIED TO OBTAIN CARB HEAT. CONDITIONS WORSENED (WITH 0 CARB HEAT). LANDED UNEVENTFULLY. TAXI WAS UNEVENTFUL. ENG STILL VIBRATING AND RPM'S DECREASED SLIGHTLY. TRIED TO OPEN CARB HEAT (WITH FORCE) AND SUCCEEDED. ENG RAN SMOOTHLY. RESISTANCE NOTED WHILE ATTEMPTING THE ABOVE, THE A 'SNAP.' THEN ENG RAN WELL. TAXIED TO MAINT FACILITY. A&P LISTENED TO THE EVENT. NOTED WATER IN CARB. REMOVED TUBING FROM INDUCTION AIR FILTER (FOAM TYPE) TO AIR BOX. LARGE CHUNK OF ICE FELL OUT. RUN-UP AND SUBSEQUENT OPS ALL OKAY. PRIOR TO FLT WE HAD HVY RAIN AND SNOW DURING THE PRECEDING DAY. TEMPS NEVER GOT OVER 0 DEGS C.

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.