Narrative:

I was demonstrating a short field landing to a student in his small aircraft which resulted in a hard landing which damaged his firewall. I used 70 mph, which is what the pilot manual suggested, full flaps, power was cut to idle over an imaginary 50 ft obstacle. After power was cut, I pitched forward to maintain proper airspeed, which resulted in the increased rate of sink desired after passing the obstacle. In this case, due to the density altitude and possible gusty winds (10 KTS maximum) the rate of sink was much greater than desired. At this point, I began the flare and added full power only to impact very hard with the runway. I believe some of the factors in this extremely poor landing was the warm conditions and too slow of an airspeed. The pilot manual for the small aircraft suggests 70 mph power off approach for a short field landing. My experience in the past doing many short field lndgs in small aircraft types has always been that the min airspeed in the pilot manuals gives plenty of extra energy at the flare. The airspeed in the manual and my past experience in other smas lead me to incorrectly believe that even with the warm temperature, the landing at worst would be firm. The winds that afternoon were slightly gusting. I believe this could, maybe, have played a small part in not enough airspeed for a proper flare. As for the weight of the aircraft, 1 hour of fuel was burned, 3 adults weighing 185 pounds, 180 pounds, 125 pounds and a child, no baggage. I immediately after landing realized 70 mph was much too slow for an 'over the obstacle' short field landing and will, in the future for any plane, use a greater buffer of airspeed for these lndgs. In addition, it may be helpful to know I saw the owner make a short field landing at 80 mph just prior to my attempt at 70 mph, the short field speed in the small aircraft's manual.

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Original NASA ASRS Text

Title: HARD LNDG. FIREWALL DAMAGE.

Narrative: I WAS DEMONSTRATING A SHORT FIELD LNDG TO A STUDENT IN HIS SMA WHICH RESULTED IN A HARD LNDG WHICH DAMAGED HIS FIREWALL. I USED 70 MPH, WHICH IS WHAT THE PLT MANUAL SUGGESTED, FULL FLAPS, PWR WAS CUT TO IDLE OVER AN IMAGINARY 50 FT OBSTACLE. AFTER PWR WAS CUT, I PITCHED FORWARD TO MAINTAIN PROPER AIRSPD, WHICH RESULTED IN THE INCREASED RATE OF SINK DESIRED AFTER PASSING THE OBSTACLE. IN THIS CASE, DUE TO THE DENSITY ALT AND POSSIBLE GUSTY WINDS (10 KTS MAX) THE RATE OF SINK WAS MUCH GREATER THAN DESIRED. AT THIS POINT, I BEGAN THE FLARE AND ADDED FULL PWR ONLY TO IMPACT VERY HARD WITH THE RWY. I BELIEVE SOME OF THE FACTORS IN THIS EXTREMELY POOR LNDG WAS THE WARM CONDITIONS AND TOO SLOW OF AN AIRSPD. THE PLT MANUAL FOR THE SMA SUGGESTS 70 MPH PWR OFF APCH FOR A SHORT FIELD LNDG. MY EXPERIENCE IN THE PAST DOING MANY SHORT FIELD LNDGS IN SMA TYPES HAS ALWAYS BEEN THAT THE MIN AIRSPD IN THE PLT MANUALS GIVES PLENTY OF EXTRA ENERGY AT THE FLARE. THE AIRSPD IN THE MANUAL AND MY PAST EXPERIENCE IN OTHER SMAS LEAD ME TO INCORRECTLY BELIEVE THAT EVEN WITH THE WARM TEMP, THE LNDG AT WORST WOULD BE FIRM. THE WINDS THAT AFTERNOON WERE SLIGHTLY GUSTING. I BELIEVE THIS COULD, MAYBE, HAVE PLAYED A SMALL PART IN NOT ENOUGH AIRSPD FOR A PROPER FLARE. AS FOR THE WT OF THE ACFT, 1 HR OF FUEL WAS BURNED, 3 ADULTS WEIGHING 185 POUNDS, 180 POUNDS, 125 POUNDS AND A CHILD, NO BAGGAGE. I IMMEDIATELY AFTER LNDG REALIZED 70 MPH WAS MUCH TOO SLOW FOR AN 'OVER THE OBSTACLE' SHORT FIELD LNDG AND WILL, IN THE FUTURE FOR ANY PLANE, USE A GREATER BUFFER OF AIRSPD FOR THESE LNDGS. IN ADDITION, IT MAY BE HELPFUL TO KNOW I SAW THE OWNER MAKE A SHORT FIELD LNDG AT 80 MPH JUST PRIOR TO MY ATTEMPT AT 70 MPH, THE SHORT FIELD SPD IN THE SMA'S MANUAL.

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.