WHITTIER, AK, USA
N2622M
ROBINSON R-22
THE PILOT ENTERED AN OUT OF GROUND EFFECT HOVER OVER A RAVINE DUE TO DETERIORATING WEATHER. THE HELICOPTER BEGAN TO SETTLE AND HE APPLIED FULL THROTTLE AND ATTEMPTED TO MAINTAIN ALTITUDE WITH COLLECTIVE. THE ROTOR RPM BEGAN TO DECAY AND HE ATTEMPTED TO ACCELERATE TO ATTAIN TRANSLATIONAL LIFT. HE DID NOT HAVE SUFFICIENT ALTITUDE IN WHICH TO RECOVER SO HE ATTEMPTED TO LAND IN THE BOTTOM OF THE RAVINE. DURING THE DESCENT THE ROTOR BLADES STRUCK THE RAVINE'S WALLS. THE PILOT NOTED A 3 TO 4 KNOT TAILWIND AFTER THE CRASH.
On August 2, 1994, at 1430 Alaska daylight time, a float/skid equipped Robinson R-22 helicopter, N2622M, registered to Donald Ross of Ketchikan, Alaska, and operated by Pollux Aviation LTD., of Anchorage, Alaska, crashed in the east end of Portage Pass located near Whittier, Alaska. The ferry flight, operating under 14 CFR Part 91, departed Merrill Field, Anchorage, and the destination was Cordova, Alaska. A visual flight rules flight plan was filed and visual meteorological conditions prevailed for a helicopter operating in class G airspace. The Commercial Certificated Pilot and the passenger were not injured and the helicopter received substantial damage. According to the pilot, upon reaching Portage Pass, near Whittier, the headwinds had subsided to 25 knots. The pass had limited visibility and precipitation. He applied 1/2 carburetor heat as a precaution and the carburetor heat gauge showed that the temperature was out of the caution range. He entered an out of ground effect hover (approximately 35 to 40 feet above ground level), prior to entering the pass to make sure he had sufficient power. He stated all the helicopter's gauges were in the green. He proceeded forward slowly to check the conditions in the pass. After he entered the pass, the weather deteriorated and he came to an out of ground effect hover over a small ravine. The helicopter began to settle and he was unable to maintain altitude by applying full throttle and the rotor RPM began to decay. He attempted to accelerate to attain translational lift but was unable to achieve translational lift in the altitude remaining. He pulled the nose up and set up for a landing in the bottom of the ravine. The ravine walls narrowed and the helicopter's blades struck the ravine walls prior to landing. After the crash, the pilot noticed that there was a tailwind of 3 to 4 knots at the base of the ravine. The pilot was unable to recall if he lowered the collective when he began to accelerate, nor could he recall the actual rotor RPM during the landing attempt prior to the rotor blades striking the ravine walls. Visual examination of the engine by an Airframe and Powerplant mechanic showed no mechanical reason for a loss of power. According to Lycoming Service Division, the overhaul for the engine was a normal overhaul. According to the records, the engine had a total time of 4385.8 hours and had 511.7 hours since it was overhauled. According to the helicopter logbook records, the engine was last inspected on June 10, 1993. Examination of the Helicopter logbook records show that the helicopter received an annual inspection on June 10, 1993, and had a total time of 2079.8 hours. The helicopter had a total of 2492.2 hours at the time of the accident. According to Brian Cox, A&P and IA for Flight Safety Alaska, he performed an annual inspection in June 1994, however, the operator did not have the logbooks and no entry was made. The operator did not produce the logbooks until the helicopter wreckage was shipped to Robinson Helicopter Company. According to the Robinson, R22, Pilot's Operating Handbook, under the section titled "Safety Tips," item number 11 states the following: " A vertical descent or steep approach downwind can result in "settling-with-power." This happens when the rotor is settling in its own down wash and additional power won't stop the descent. Should this occur, reduce collective and lower the nose to increase airspeed. This can be very dangerous near the ground as the recovery results in a substantial loss of altitude."
THE PILOT'S FAILURE TO MAINTAIN ROTOR RPM. FACTORS WERE THE RAVINE AND THE TAILWIND.
Source: NTSB Aviation Accident Database
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