Monday, November 14, 2016

Robinson R44 Raven II, S M Hentges & Sons Inc., N744JS: Accident occurred in Stone Lake, Washburn County, Wisconsin (and) Accident occurred June 09, 2012 in Santa Teresa, Doña Ana County, New Mexico

S M HENTGES & SONS INC:   http://registry.faa.gov/N744JS

FAA Flight Standards District Office: FAA Milwaukee FSDO-13


N744JS ROBINSON R44 ROTORCRAFT ON DEPARTURE FROM PRIVATE RESIDENCE, STRUCK TREES AND ROLLED OVER, STONE LAKE, WISCONSIN. 


Date: 12-NOV-16

Time: 17:30:00Z
Regis#: N744JS
Aircraft Make: ROBINSON
Aircraft Model: R44
Event Type: Accident
Highest Injury: Minor
Damage: Substantial
Flight Phase: TAKEOFF (TOF)
City: STONE LAKE
State: Wisconsin






Washburn County Sheriff's Office Press Release


At approximately 11 AM this morning Washburn County Sheriff's Dispatch received a 911 call of a helicopter crash in Birchwood Township, on County B and Bobby Schmidt's Drive.


The operator of the helicopter, and the only occupant, tried to take off from his home on Long Lake. For reasons unknown to this office at this time, the helicopter hit a pine tree and the crashed on the owners property.


The pilot was taken to Spooner Hospital where he was treated and released. Stone Lake Fire and Ambulance were called to the scene.


The NTSB was notified and will have the responsibility for the investigation.


We are very thankful the pilot only suffered minor injuries and that the helicopter did not catch on fire.


Sheriff Dryden


Source:   http://www.drydenwire.com 


National Transportation Safety Board - Aviation Accident Final Report: http://app.ntsb.gov/pdf

National Transportation Safety Board -  Docket And Docket Items:   http://dms.ntsb.gov/pubdms

National Transportation Safety Board  -  Aviation Accident Data Summary:   http://app.ntsb.gov/pdf

NTSB Identification: CEN12LA359
14 CFR Part 91: General Aviation
Accident occurred Saturday, June 09, 2012 in Santa Teresa, NM
Probable Cause Approval Date: 11/06/2013
Aircraft: ROBINSON HELICOPTER COMPANY R44 II, registration: N744JS
Injuries: 3 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The helicopter was about 76 pounds under its maximum gross weight for the takeoff at a density altitude of about 6,800 feet. The pilot lifted the helicopter into a hover 2 feet above ground level (agl) and departed into the wind, which was variable from 210-260 degrees at 10 knots, gusting to 18 knots. After the helicopter entered translational lift, the pilot accelerated the helicopter to 30-35 knots and climbed to about 10-20 feet agl. The helicopter suddenly started to settle, the low rotor rpm warning light illuminated, and the warning horn sounded. The left seat passenger, who was a flight instructor, took control of the helicopter and attempted to recover rotor rpm. Unable to regain enough rotor rpm to maintain flight, he decided to land under control rather than continue to an uncontrolled crash. He was only able to slow the helicopter to about 15-20 knots before leveling the helicopter to land. The helicopter touched down in rough, uneven terrain, and substantial damage was incurred to the fuselage and tailboom. Examination of the helicopter did not show any evidence of preimpact mechanical malfunctions or failures that would have resulted in the loss of main rotor rpm and settling. 

The pilot and the left seat passenger stated that they could have operated the helicopter at a lighter takeoff weight for greater performance or waited until early morning to depart when the cooler temperatures would have reduced the density altitude. Further, they stated that the wind gusts resulted in the loss of some of the headwind component. Additionally, the left seat passenger reported that at the time the helicopter began to settle, a freight train was crossing about 30 to 50 yards in front of the takeoff flight path of the helicopter. He stated that he believed the train probably blocked some of the headwind component as it passed. A reduction in the headwind component would have resulted in the helicopter settling at a critical point during the takeoff. The pilot and the left seat passenger stated that the collective was probably raised slightly to compensate for the settling, which caused the decay of main rotor rpm, and once that happened, the helicopter was in a position that was not recoverable.

Given that the settling was sudden during an otherwise routine takeoff, it is likely that a wind gust, the blocking of the wind by the passing train, or a combination of the two resulted in an abrupt decrease in headwind, which caused the helicopter to lose lift and descend. Because the helicopter was already operating near its maximum performance capability (high gross weight at high density altitude), there was not enough reserve power available to stop the descent and maintain rotor rpm.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The sudden decrease in headwind during takeoff in a gusty wind and near a passing train, which resulted in a loss of lift and main rotor rpm. Contributing to the accident was the pilot's decision to operate the helicopter near its maximum performance capability (near gross weight at high density altitude), which resulted in a lack of reserve power available to compensate for the wind change.

On June 9, 2012, approximately 1900 mountain daylight time, a Robinson R44 II helicopter, N744JS, registered to S M Hentges & Sons of Jordan, Minnesota, was substantially damaged when it impacted terrain after a loss of lift during takeoff/initial climb from the Dona Ana County Airport (5T6), Santa Teresa, New Mexico. All 3 occupants, the private helicopter pilot and his 2 passengers (who both held helicopter pilot certificates), were not injured. Visual meteorological conditions prevailed in the area and a flight plan was not filed. The cross country flight was being conducted under the provisions of 14 Code of Federal Regulations Part 91. The flight's intended destination for this leg of the trip was Roswell, New Mexico. 

The helicopter had just been refueled at Santa Teresa after an uneventful flight leg from Chino, California. One of the passengers, who was a certified flight instructor (CFI) and seated in the left seat for the flight, stated that the helicopter was about 76 pounds under its maximum gross weight after the refueling. He stated that the density altitude was about 6,800 feet, with wind of 210 to 260 degrees at 10 to 18 knots at the time of takeoff. 

The pilot, who was also the owner of the helicopter, lifted the helicopter into a 2-foot hover and departed into the wind. The helicopter entered translational lift, accelerated to about 30 to 35 knots, and 10 to 20 feet of altitude. Unexpectedly, the helicopter suddenly started to settle and the low rotor RPM warning light illuminated and warning horn sounded. The CFI came onto the controls and announced that he had control of the helicopter. In an attempt to recover main rotor RPM, he slightly lowered the collective, increased throttle, and added slight aft cyclic. He was not able to increase the main rotor RPM enough to maintain flight, so attempted to land under control rather than continue to an uncontrolled crash. He made a cyclic flare to reduce the airspeed as much as possible. Due to the low main rotor RPM, low altitude, and low airspeed, he was only able to slow the helicopter to about 15 to 20 knots, before leveling the helicopter to land. 

The helicopter touched down in rough terrain, (gravel, sand, sage brush, and small mounds of dirt). The skids broke off when they hit a mound of dirt and the helicopter pitched forward. The main rotor struck the ground and broke off and the tail boom was severed. The helicopter spun slightly right, struck a mound of dirt and rolled onto its left side. Initial touchdown to the final point of rest was about 75-80 feet. The helicopter was secured and the 3 occupants evacuated.

NOTE: The flight was not instructional. The CFI was a friend of the pilot/owner and was along as a passenger on the flight.

After the accident, the CFI provided statements to the NTSB describing the event and offered more details. He stated that he had never experienced a helicopter lift off, enter translational lift almost immediately, accelerate through 30 knots, appear to be making a normal takeoff, and then suddenly begin to settle so abruptly. 

He stated that the pilot/owner and his wife were fairly new helicopter pilots, but had attended a very reputable training facility to get their licenses. During the various flights that he had flown with them prior to this trip, he thought that they were very competent helicopter pilots. The owner/pilot had asked the CFI to go on the trip with them due to the length of the trip and they wanted the CFI to teach them more about the operation of the Garmin 430 in their helicopter. The pilot/owner and his wife alternated legs as PIC on the trip, with the CFI in the left seat. 

The CFI stated that when he returned to the accident site after the accident, he discussed the accident with the owner of the fuel service where the helicopter refueled. During that discussion, the owner of the fuel service asked the CFI if the "whirlwinds (dust devils) had gotten us." The CFI stated that he had observed many whirlwinds that day during the flight across the southwest desert areas, and had turned to avoid several. He stated that he did not observe whirlwinds in the takeoff path during the accident flight, but that's not to say that one was't starting, or ending. He said that the helicopter could have passed near an unseen whirlwind, which could have contributed to the rapid decay in rotor RPM and settling that was experienced at a critical time during takeoff.

Initially, the accident was reported by a freight train engineer. The train was crossing in front of the takeoff flight path of the helicopter, about 30 to 50 yards away. The CFI had noticed the train in his peripheral vision during the takeoff attempt. The CFI stated that perhaps the freight train crossing in front of the takeoff path could have blocked enough of the relative headwind component to affect the takeoff. The train was basically traveling from west to east, and passed in front of the takeoff path about the time that the helicopter began to settle. The CFI stated that he believes that the train probably blocked some of the headwind component as it passed, causing the air flow to burble and settle into a downdraft. He believes that this could be what caused the loss of rotor RPM and started the helicopter to settle.

Examination of the helicopter (engine, airframe, and flight controls) after the accident did not show any evidence of preimpact mechanical malfunction or abnormalities that may have contributed to the loss of main rotor RPM and settling. The refueling source was tested and found to be within specifications and clear of contaminants. The fuel filter screens on the helicopter were clean.

On the submitted NTSB Form 6120, Recommendation Section, the CFI and pilot offered how this accident could have been prevented. They offered that they could have operated the helicopter at a lighter takeoff weight for greater performance (less fuel), or waited until early morning to depart in cooler temperatures and lower density altitude. They stated that the helicopter was within operating and gross weight limits for takeoff, but close to the maximum. They stated that the wind gusts were definitely a factor, and that the loss of some of the headwind component, caused the helicopter to settle at a critical time during takeoff. They stated that the collective was probably raised slightly to compensate for the settling, which caused the loss of main rotor RPM and the corresponding loss of power. They said that, once that happened, the helicopter was in a position that was not recoverable.

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