WPR11LA356

NTSB accident investigation · Sikorsky S-55B · Brewster, WA · July 25, 2011

Accident · No injuriesLimited investigationFinal report
Date
July 25, 2011, 11:45 local (18:45 UTC)
Place
Brewster, WA
Injuries
2 uninjured
Damage
Substantial damage
Phase of flight
Maneuvering
Aircraft
N855TCSikorsky S-55B
Defining event
Maneuvering-hover: Loss of control in flight
Weather
Visual (VMC) · Day
Status
Completed · report April 20, 2012
Report
Approved by Office Director
NTSB office
Western Pacific Region
Parties
FAA FSDO
FAA report
20110725015669A
Case key
81354

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 did not maintain main rotor rpm while hovering in gusting wind conditions.

Findings · 3

NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.

WindEnvironmental issues › Conditions/weather/phenomena · Contributed to outcomeSikorsky S55B: 1 caseAll aircraft: 110 cases
Performance/control parameters: prop/rotor parametersAircraft › Aircraft oper/perf/capability · Not attained/maintainedSikorsky S55B: 1 caseAll aircraft: 182 casesProbable cause
Use of equip/info: use of equip/systemPersonnel issues › Task performance · PilotSikorsky S55B: 1 caseAll aircraft: 1,391 casesProbable cause

Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.

Analysis

The helicopter pilot was conducting a low-level flight over orchards for the purpose of drying cherry trees. The orchard was bordered by a series of power lines, and a gusting, variable wind was present at the time of the flight. During a low hovering pass over the orchard, a gust of wind pushed the helicopter toward power lines. In an attempt to avoid the power lines, the pilot increased collective pitch, and the helicopter began to climb. During the climb, the main rotor rpm decayed and the nose of the helicopter yawed to the right. The pilot lowered the collective and increased the engine power in an effort to regain main rotor rpm; however, the helicopter descended into the orchard. The pilot reported no preimpact mechanical malfunctions or failures with the helicopter that would have precluded normal operations, and that the accident could have been prevented if the flight had been conducted after the wind diminished.

Factual narrative

On July 25, 2011, about 1145 Pacific daylight time, a Sikorsky S-55B helicopter, N855TC, sustained substantial damage after impacting terrain near Brewster, Washington. The private pilot and pilot rated passenger were not injured. The helicopter sustained substantial damage to the fuselage, tail boom and main rotor drive system. The helicopter was registered to Golden Wings Aviation and operated under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the flight. The local flight originated from Brewster about 45 minutes prior to the accident. The private pilot reported that he was conducting a low level flight, for hire, over cherry orchards for the purpose of drying cherry trees. He reported that the orchard was bordered by a series of power lines and that gusty variable winds, with peak gusts to 30 knots, were present at the time of the flight. The pilot reported that during a low hovering pass over the orchard, a gust of wind from the left pushed the helicopter to the right, and towards the power lines. In an attempt to avoid the power lines, the pilot increased collective pitch and the helicopter began to climb. During the climb, the main rotor rpm decayed, and the nose of the helicopter yawed to the right. The pilot lowered the collective and increased the engine power in an effort to regain main rotor rpm; however, the helicopter descended into the orchard. The pilot reported no preimpact mechanical malfunctions or failures with the helicopter that would have precluded normal operations. The pilot further reported that the accident could have been prevented if the flight had been conducted after the wind diminished.

Aircraft

Registration
N855TC
Reported as
Sikorsky S-55B
Category
Helicopter
Serial number
551005
Airframe hours
7,314
Engine
Curtis - Wright R1300, 690 horsepower, reciprocating
Damage
Substantial damage
Flight
Other work use · Part 91
Operator
Golden Wings
Registered owner
Smith David C
Airworthiness certificate
Standard, Normal
Last inspection
Annual · May 23, 2011
Departed
Brewster, WA
Destination
Brewster, WA

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
42
Injuries
None
Certificate
Private
Medical
Class 2, Without waivers/limitations
Last flight review
June 1, 2010
Seat
Right
Flight hours
318 total · 109 in this make and model · 192 as pilot in command · 25 in the last 90 days · 22 in the last 30 days

Weather

Conditions
Visual (VMC) · Day
Wind
Variable at 10 knots, gusting 30
Visibility
10 statute miles
Lowest ceiling
4,000 ft broken
Temperature
70 °F

Docket · 3

The files NTSB released with the investigation on March 15, 2012, on NTSB’s docket system: statements, records, photos and specialists’ reports. 448 KB in all.

FAA reports on this event · 1

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