A C172 private pilot aborts his takeoff at 30 ft AGL when he encounters turbulence and perceives a r...

Attributes
ACN	394679
Time
Date	199802
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : ovo
State Reference	IN
Altitude	agl bound lower : 20 agl bound upper : 30
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : enw
Operator	general aviation : instructional
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	climbout : takeoff landing other other
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private
Experience	flight time last 90 days : 3 flight time total : 156 flight time type : 34
ASRS Report	394679
Person 2
Affiliation	Other
Function	other personnel other personnel other
Qualification	other other : other
Events
Anomaly	aircraft equipment problem : critical inflight encounter : weather other anomaly other anomaly other other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : rejected takeoff flight crew : regained aircraft control flight crew : declared emergency other
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

Occurrence was on return trip to home base after a stop of about 1/2 hour at ovo airport. After takeoff from runway 5, aircraft rolled about 15 degrees right due to turbulence at about 20-30 ft, recovered immediately to level flight. Just then, engine sounds and vibration suggested a rough running engine. Pilot determined there was sufficient runway left to land safely and decision was made immediately to abort takeoff. Power was pulled to idle and aircraft side slipped to above runway, aircraft centered and touchdown made on runway. Aircraft was slowed considerably on runway surface and came to a safe stop in soft wet ground and grassy area at the end of the runway. There was no damage to aircraft and no personal injury. Aircraft examined by a&P mechanic at field and also by owner's (rental) a&P who flew in at pilot's request. Magneto check, full power run-up, fuel sumps, visual structure, etc, showed ok to a&P's. After examination on the ground, a&P flight tested aircraft and flew it back to base. Aircraft log showed 100 hour had been completed in last 4 hours. No fuel was purchased during trip. Pilot during chkout had drained sumps -- no water. Magneto check at run-up before takeoff ok, also had run carburetor heat for about 5-10 seconds at 1700 RPM and idle during run-up with no roughness. Mixture full rich for takeoff. Field elevation 758 ft. Wind 090 degrees, 120 KTS, gusting at 8-12 KTS. Temperature about 10 degrees C, dewpoint about 3-5 degrees. Carburetor ice unlikely -- full power. Then sudden, not gradual, roughness. Exact cause undetermined. Possibility -- sudden windshear or turbulence from crosswind over adjacent trees, produced propeller cavitation vibration or other rapid vibration or chop that was perceived by pilot as engine roughness. Possibility of water in engine sump being ingested after sudden roll, but sumps drained -- very slight chance. Continue pilot education and dual training and experience -- wings ii, instrument instruction.

Original NASA ASRS Text

Title: A C172 PVT PLT ABORTS HIS TKOF AT 30 FT AGL WHEN HE ENCOUNTERS TURB AND PERCEIVES A ROUGH ENG. UPON LNDG HE ROLLS OFF THE END OF THE RWY, SOFTLY, INTO THE GRASS.

Narrative: OCCURRENCE WAS ON RETURN TRIP TO HOME BASE AFTER A STOP OF ABOUT 1/2 HR AT OVO ARPT. AFTER TKOF FROM RWY 5, ACFT ROLLED ABOUT 15 DEGS R DUE TO TURB AT ABOUT 20-30 FT, RECOVERED IMMEDIATELY TO LEVEL FLT. JUST THEN, ENG SOUNDS AND VIBRATION SUGGESTED A ROUGH RUNNING ENG. PLT DETERMINED THERE WAS SUFFICIENT RWY LEFT TO LAND SAFELY AND DECISION WAS MADE IMMEDIATELY TO ABORT TKOF. PWR WAS PULLED TO IDLE AND ACFT SIDE SLIPPED TO ABOVE RWY, ACFT CTRED AND TOUCHDOWN MADE ON RWY. ACFT WAS SLOWED CONSIDERABLY ON RWY SURFACE AND CAME TO A SAFE STOP IN SOFT WET GND AND GRASSY AREA AT THE END OF THE RWY. THERE WAS NO DAMAGE TO ACFT AND NO PERSONAL INJURY. ACFT EXAMINED BY A&P MECH AT FIELD AND ALSO BY OWNER'S (RENTAL) A&P WHO FLEW IN AT PLT'S REQUEST. MAGNETO CHK, FULL PWR RUN-UP, FUEL SUMPS, VISUAL STRUCTURE, ETC, SHOWED OK TO A&P'S. AFTER EXAMINATION ON THE GND, A&P FLT TESTED ACFT AND FLEW IT BACK TO BASE. ACFT LOG SHOWED 100 HR HAD BEEN COMPLETED IN LAST 4 HRS. NO FUEL WAS PURCHASED DURING TRIP. PLT DURING CHKOUT HAD DRAINED SUMPS -- NO WATER. MAGNETO CHK AT RUN-UP BEFORE TKOF OK, ALSO HAD RUN CARB HEAT FOR ABOUT 5-10 SECONDS AT 1700 RPM AND IDLE DURING RUN-UP WITH NO ROUGHNESS. MIXTURE FULL RICH FOR TKOF. FIELD ELEVATION 758 FT. WIND 090 DEGS, 120 KTS, GUSTING AT 8-12 KTS. TEMP ABOUT 10 DEGS C, DEWPOINT ABOUT 3-5 DEGS. CARB ICE UNLIKELY -- FULL PWR. THEN SUDDEN, NOT GRADUAL, ROUGHNESS. EXACT CAUSE UNDETERMINED. POSSIBILITY -- SUDDEN WINDSHEAR OR TURB FROM XWIND OVER ADJACENT TREES, PRODUCED PROP CAVITATION VIBRATION OR OTHER RAPID VIBRATION OR CHOP THAT WAS PERCEIVED BY PLT AS ENG ROUGHNESS. POSSIBILITY OF WATER IN ENG SUMP BEING INGESTED AFTER SUDDEN ROLL, BUT SUMPS DRAINED -- VERY SLIGHT CHANCE. CONTINUE PLT EDUCATION AND DUAL TRAINING AND EXPERIENCE -- WINGS II, INST INSTRUCTION.

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.

A C172 private pilot aborts his takeoff at 30 ft AGL when he encounters turbulence and perceives a rough engine. Upon landing he rolls off the end of the runway, softly, into the grass.