Narrative:

Departed monument state airport a newly paved 2200 ft airport on runway 32. Runway 32 has a 3-7% slope downward. Conditions at the time had a quartering tailwind of 6-8 KTS out of the west. I checked performance data against the conditions with an OAT of 12 degrees C and calculated a takeoff could be made in an adjacent ground roll. I did not factor the down slope in the calculation but mentally thought it would add to my performance in a positive fashion. I also figured if I was approximately 500-800 ft in the ground roll because of the steep runway gradient I was committed to take off. I performed a full power hold the brakes takeoff and at around a quarter of the way down the runway got an erratic manifold pressure indication surging above redline and back down. The waste gate had recently been replaced on the left engine the one with erratic indication. I was balancing my attention between engine instrument and airspeed indication and outside. I tried to stretch the takeoff roll maximum and at approximately 95 KIAS rotated. On rotation I clipped a fence at the end of the runway. I put a hole approximately 1 1/2 inch X 7 inch in the left side belly of the plane and also caught the fence on the right propeller and right horizontal stabilizer. The airplane had no apparent malfunctions except a lack of pressurization. I return to my home base. My rotation was what I would consider normal for a runway with no gradient. I did not factor the steep gradient for takeoff which I believe made the transition from runway to airborne delayed because of the downward momentum of the plane. The plane has been inspected and an estimate of damage by an a/I. I was operating in a narrow margin of safety and failed to consider the negative aspect of the downward momentum on the liftoff transition.

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Original NASA ASRS Text

Title: A CESSNA 340 CONTACTS A FENCE ON TKOF AT 12S.

Narrative: DEPARTED MONUMENT STATE ARPT A NEWLY PAVED 2200 FT ARPT ON RWY 32. RWY 32 HAS A 3-7% SLOPE DOWNWARD. CONDITIONS AT THE TIME HAD A QUARTERING TAILWIND OF 6-8 KTS OUT OF THE W. I CHKED PERFORMANCE DATA AGAINST THE CONDITIONS WITH AN OAT OF 12 DEGS C AND CALCULATED A TKOF COULD BE MADE IN AN ADJACENT GND ROLL. I DID NOT FACTOR THE DOWN SLOPE IN THE CALCULATION BUT MENTALLY THOUGHT IT WOULD ADD TO MY PERFORMANCE IN A POSITIVE FASHION. I ALSO FIGURED IF I WAS APPROX 500-800 FT IN THE GND ROLL BECAUSE OF THE STEEP RWY GRADIENT I WAS COMMITTED TO TAKE OFF. I PERFORMED A FULL PWR HOLD THE BRAKES TKOF AND AT AROUND A QUARTER OF THE WAY DOWN THE RWY GOT AN ERRATIC MANIFOLD PRESSURE INDICATION SURGING ABOVE REDLINE AND BACK DOWN. THE WASTE GATE HAD RECENTLY BEEN REPLACED ON THE L ENG THE ONE WITH ERRATIC INDICATION. I WAS BALANCING MY ATTN BTWN ENG INST AND AIRSPD INDICATION AND OUTSIDE. I TRIED TO STRETCH THE TKOF ROLL MAX AND AT APPROX 95 KIAS ROTATED. ON ROTATION I CLIPPED A FENCE AT THE END OF THE RWY. I PUT A HOLE APPROX 1 1/2 INCH X 7 INCH IN THE L SIDE BELLY OF THE PLANE AND ALSO CAUGHT THE FENCE ON THE R PROP AND R HORIZ STABILIZER. THE AIRPLANE HAD NO APPARENT MALFUNCTIONS EXCEPT A LACK OF PRESSURIZATION. I RETURN TO MY HOME BASE. MY ROTATION WAS WHAT I WOULD CONSIDER NORMAL FOR A RWY WITH NO GRADIENT. I DID NOT FACTOR THE STEEP GRADIENT FOR TKOF WHICH I BELIEVE MADE THE TRANSITION FROM RWY TO AIRBORNE DELAYED BECAUSE OF THE DOWNWARD MOMENTUM OF THE PLANE. THE PLANE HAS BEEN INSPECTED AND AN ESTIMATE OF DAMAGE BY AN A/I. I WAS OPERATING IN A NARROW MARGIN OF SAFETY AND FAILED TO CONSIDER THE NEGATIVE ASPECT OF THE DOWNWARD MOMENTUM ON THE LIFTOFF TRANSITION.

Data retrieved from NASA's ASRS site as of January 2009 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.