MIA99LA070
MIA99LA070

On January 30, 1999, at about 0841 eastern standard time, a Robinson R22, N4046H, registered to Comprador Helicopter Inc., operated by Heliflite as a 14 CFR Part 91 instructional flight crashed while conducting a 180 autorotation with turn to runway 10 at Pompano Beach Airpark, Pompano Beach, Florida. Visual meteorological conditions prevailed and no flight plan was filed. The helicopter was destroyed. The commercial pilot/certified flight instructor, and commercial pilot receiving instruction sustained serious injuries. The flight originated about 3 minutes before the accident

Two witnesses who are Robinson R22 instructor pilots stated they observed the helicopter in right closed traffic for runway 10. They observed the helicopter conduct a 180 autorotation before the accident, which resulted in a termination with power to the numbers on runway 10. They stated the autorotation did not look right, so they decided to watch the helicopter. The helicopter remained in right closed traffic and was at about 500 feet as it was abeam the numbers of runway 10. They entered the auto and turned left about 20 degrees. The helicopter was observed to turn a very steep right turn (90 degrees) with a steep nose low/down attitude (60 degrees). Between 100 to 150 feet they started to roll out of the turn, but not all of the way out. One of the witnesses stated, "the dive looked to steep to recover from." At contact with the ground they appeared to still have had a nose low attitude of 5 to 10 degrees. The helicopter crashed short of the numbers.

The pilot stated in an initial interview that he was demonstrating the 180 autorotation to the rated student pilot. He entered the maneuver at 500 feet and 60 knots. He lowered the collective pitch to the full down position, applied right anti torque pedal, reduced the throttle to split the needles, and adjusted his airspeed to a 60 knot attitude, and began a right turn towards his intended touchdown point. The airspeed decreased a little so he lowered the nose. As they were going through 100 feet he started to level off. The rotor was in the green arc, airspeed 60 knots, they were in a high rate of descent, and the airframe started to vibrate. The helicopter collided with the ground in a nose low attitude. When asked why he did not initiate a power recovery when he knew he was in a high rate of descent and would not reach his intended touchdown point, he kept referring to the airframe vibration. When asked if he experienced any low rpm after he went through 100 feet he said no.

The pilot stated in the NTSB Pilot/Operator Aircraft Accident Report, "As we came on downwind I took the controls from Mr. Perez and positioned the aircraft abeam the proposed landing spot at +/- 500 AGL and +/- 60 kts Through out the turn rpm was in the green. But as airspeed was a little low (+/- 55 kts) I lowered the nose a little bit to maintain 60 kts. Upon leveling off out of the turn at around 100" AGL I performed the 100' check. As I recall rpm was slightly above the green (106-107% rpm) and airspeed was +/- 60 kts. At that very instant the entire helicopter began vibrating violently and the rate of descent increased dramatically. I can also recall very high control forces as I attempted to pull aft cyclic and up collective. As I recall it took about 3 seconds from the time I came out of the turn and the vibrations started to the time of impact."

The commercial pilot receiving instruction stated the CFI stated, "Jasper Blotkamp was in command of the helicopter as he was showing me 180 degree auto rotations when I felt the helicopter vibrate and heard the warning alarm of the low rotor rpm in the cockpit. Immediately after this the helicopter hit the ground."

The Robinson R22 Maneuver Guide states the following entry procedures for a 180 (Autorotation) with power recovery: Establish the aircraft on a downwind at 75 KTS and 700 feet AGL. When abeam the intended touchdown point, enter the autorotation by smoothly, but firmly, lowering the collective full down without reducing the throttle. Usually the needles will split establishing an autorotation. If the needles do not split, reduce the throttle slightly. Apply right pedal and aft cyclic to maintain the attitude. Crosscheck attitude, trim, rotor, RPM, and airspeed. It states that the turn should be completed and the helicopter aligned with the intended touchdown area prior to passing through 100 feet AGL. If the collective has been increased to load the rotor during the turn, it may have to be lowered on roll out to prevent a decay in RPM. As the aircraft descends through 100 feet AGL, make an immediate power recovery if the following conditions do not exist:

1. Aircraft aligned with the touchdown point.

2. Rotor RPM in the green.

3. Airspeed 60 to 70 KTS.

4. Rate of descent less than 1500 FPM.

The maneuver guide defines the symptoms of low rotor rpm as:

1. A noticeable decrease in engine noise.

2. Aircraft vibration and cyclic stick shake at higher airspeeds.

3. The low rotor RPM warning horn and light at approximately 95% RPM.

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