ANC94LA096

NTSB accident investigation · Robinson R-22 · Whittier, AK · August 2, 1994

Accident · No injuriesLimited investigationFinal report
Date
August 2, 1994, 14:30 local (22:30 UTC)
Place
Whittier, AK
Injuries
2 uninjured
Damage
Substantial damage
Phase of flight
Maneuvering
Aircraft
N2622MRobinson R-22
Weather
Instrument (IMC) · Day
Status
Completed · report May 9, 1995
Report
Approved by Office Director
NTSB office
Alaska Regional Office
FAA report
19940802019949A
Case key
2533

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

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Probable cause

The pilot's failure to maintain rotor RPM. Factors were the ravine and the tailwind.

Sequence of events

NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.

Loss of control - in flightHover
Rotor rpm - not maintainedPilot in commandCause
In flight collision with terrain/waterDescent - uncontrolled
Terrain condition - ravineFactor
Weather condition - tailwindFactor

Analysis

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.

Factual narrative

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."

Aircraft

Registration
N2622M
Reported as
Robinson R-22
Category
Helicopter
Serial number
735M
Airframe hours
2,492
Engine
Lycoming O-320, 160 horsepower, reciprocating
Damage
Substantial damage
Flight
Ferry · Part 91
Operator
Pollux Aviation, Ltd
Registered owner
Donald Ross
Airworthiness certificate
Standard, Normal
Last inspection
Annual · June 10, 1993 · 413 hours before
Departed
MRI · Anchorage, AK
Destination
CDV · Cordova, AK
Flight plan
VFR

Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.

Flight crew

As NTSB recorded them. NTSB leaves out names.

Role
Pilot
Age
25
Certificates
Private, Commercial, Flight instructor
Airplane ratings
Single-engine land
Medical
Class 2, Valid Medical--w/ waivers/lim
Seat
Right
Flight hours
1,450 total · 1,385 in this make and model · 1,350 as pilot in command · 200 in the last 90 days · 75 in the last 30 days · 1 in the last 24 hours

Weather

Conditions
Instrument (IMC) · Day
Visibility
0.25 statute miles
Lowest ceiling
100 ft
Temperature
52 °F

FAA reports on this event · 1

The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.