SEA02FA035

History of flight

On January 31, 2002, approximately 1004 mountain standard time, a Robinson R-22 Beta, N7507G, registered to and being operated by a private pilot, accompanied by an airline transport rated Federal Aviation Administration (FAA) inspector, was substantially damaged during an in-flight collision with terrain during descent at Silver City, Montana. Both pilots sustained serious injuries, and there was no post crash fire. Visual meteorological conditions prevailed at the time of the accident and no flight plan had been filed. The purpose of the flight was to build flight time for the FAA pilot. The aircraft was being operated under 14CFR91, and had just departed from the Helena Regional airport (HLN), Helena, Montana, at 0948.

The FAA inspector reported that the flight was the second of two three-hour flights in the helicopter, the purpose of which was to build his flight time to 50 hours experience in this make/model. The FAA had rented the helicopter and one three-hour flight had been completed the day previous to the accident.

On the day of the accident the owner flew the helicopter from Bozeman to Helena where the FAA inspector boarded. The helicopter departed and proceeded northwest to the vicinity of the accident site (Silver City airstrip) and the FAA inspector executed a 180-degree autorotation maneuver. He discussed the maneuver with the owner during its execution and recovered to a five-foot hover at which time he turned the controls over to the owner suggesting he try the same autorotation maneuver.

According to an interview with the FAA inspector conducted on the morning of February 6, 2002, the owner took the controls, climbed to 900-1,000 feet above ground level (agl) to a position abeam (180 degrees from the intended landing area), lowered the collective and applied abrupt, full left (anti-torque) pedal at which time the helicopter entered into an uncoordinated turn, began to vibrate violently and the airspeed dropped off down to between 30 to 20 knots. The inspector further stated that he called for "Governor ON" as the owner was rolling the throttle on, and although the rate of descent was approximately 2,500 feet/minute the airspeed was recovering. The inspector called to make a power recovery and the owner began to apply collective decelerating about 250 feet agl at which time, the inspector got on the controls to stop the recovery, which he believed was initiated at an altitude higher than desired. Both pilots were on the controls and the owner had full throttle with normal rotor RPM about 150 feet agl, however the helicopter landed hard and rolled on to it's right side (refer to attached statements).

According to an interview with the owner conducted shortly after noon on February 5, 2002, the owner reported that at the time the (accident) maneuver was initiated the governor was off, throttled rolled off and collective reduced simultaneously. He further reported that during the maneuver rotor RPM was coming up fine, but when he went to apply power (recovery) the helicopter began vibrating and there was no power available. He reported that the inspector had taken the controls and the helicopter landed hard (refer to attached statements).

Personnel information

Left seat pilot

The privately certificated left seat pilot/owner held airplane single-engine land and helicopter ratings. A review of his personal flight log showed the first entry logged on February 16, 2000, in a Bell 47G2 helicopter. The last entry logged was on January 14, 2002. The total flight time accrued in this logbook was 827 hours of which 693 hours were in the R-22 helicopter (681 pilot-in-command). The pilot possessed a second class medical issued February 16, 2000, with no waivers or limitations.

Right seat pilot

The airline transport rated right seat pilot held airplane single/multi-engine land/instrument and helicopter/instrument ratings, as well as a flight instructor certificate with the same ratings. The pilot reported a total of approximately 10,000 hours of flight time of which 26 hours were in the R-22 helicopter (no reported R-22 pilot-in-command time). He reported approximately 8,000 hours of total helicopter time of which 6,000 hours were pilot-in-command and 5,000 were as an instructor. The pilot possessed a second class medical issued May 3, 2001, with the restriction that the holder must wear corrective lenses and possess glasses for near and intermediate vision.

Aircraft information

Not less than 11 gallons of fuel were drained from the helicopter's main and auxiliary fuel tanks immediately following the crash. The estimated weight of this fuel was 67 pounds. The left seat pilot weighed 240 pounds and the right seat pilot weighed 200 pounds. The helicopter's two wheels and attach struts were observed in place in the left seat baggage compartment with the struts facing up directly beneath the seat pan/cushion.

These items from under the left seat weighed 9 pounds. The weight of fuel that leaked out subsequent to the accident, as well as those items stowed under the right seat were not known. Refer to attachment RHC-I for additional weight and center of gravity information.

The left seat baggage compartment contained a placard, which read in part:

"Caution

Do not exceed any of the following:

Compartment capacity: 50lb max

Each seat plus compartment: 240lb max"

And

"Avoid placing objects in compartment which

Could injure occupant if seat collapses during

Hard landing"

Meteorological information

The aviation weather surface observation taken at the Helena Regional airport at 0953 reported in part: winds calm, temperature -3 degrees C., and an 11,000 foot scattered sky condition. Helena Regional bears 12 nautical miles east-southeast of the accident site.

A private pilot flying a Cessna 172 who, at the request of Helena Regional air traffic control tower, proceeded to the accident site and reported that he encountered moderate (intermittent) turbulence close to the ground. He reported that the turbulence was light at 6,500 feet above ground increasing at lower altitudes.

Wreckage and impact information

The aircraft crashed on the Silver City private airstrip on flat, low grass and shallow snow covered terrain. The accident site was approximately 46 degrees 44.97 minutes north latitude and 122 degrees 10.82 minutes West longitude approximately 4,380 feet above mean sea level (MSL) (refer to CHART I). The wreckage was confined to an area approximately 300 feet in diameter (refer to diagram in attachment CIB-I).

All components from the helicopter were found within this 300-foot diameter area. The majority of the helicopter (fuselage, pylon, right skid and main rotor including both blades was observed at rest with the nose of the helicopter oriented generally north (refer to photographs 1 and 2).

Both main rotor blades remained attached to the rotor hub assembly. One blade displayed minimal deformation and damage. The opposing blade displayed noticeable downward bending deformation and a split along the chordline from the trailing edge forward approximately 75% outboard of the hub attach point (refer to photograph 3).

The left skid was observed a short distance north of the fuselage and the vertical/horizontal stabilizer was observed roughly midway between the two previous components. Several sections of tail boom were noted lying on the ground as well as the 90-degree tail rotor gearbox and rotor minus both rotor blades (refer to photograph 4). The tail rotor blades were recovered in the general crash site area referenced in attachment CIB-I.

Tests and research

The airframe and engine were examined at the facilities of Arlin's Aircraft Service, Inc., Bozeman, Montana, on February 6, 2002. No pre-impact mechanical anomalies were n