# NTSB ERA17LA168: Robinson R44, N728CB, Newton, NC, April 27, 2017 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: April 27, 2017, 13:30 local (17:30 UTC) - Place: Newton, NC - Coordinates: 35.633335, -81.243888 - Nearby events: https://openairdocs.org/map.md?lat=35.6333&lon=-81.2439&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Loss of tail rotor effectiveness](https://openairdocs.org/ntsb-events/242) - Highest injury: Minor injuries - Injuries: 2 minor - Status: Completed, report March 5, 2018 - Report: Approved by Office Director - NTSB office: Eastern Region Aviation - Parties: FAA/FSDO, Robinson Helicopter Company, Lycoming Engines - NTSB case key (mKey): 95069 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA17LA168 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/95069/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=95069 - Page: https://openairdocs.org/ntsb/ERA17LA168 ## Probable cause The pilot's failure to maintain an adequate airspeed during out-of-ground-effect maneuvering at a low airspeed with a tailwind, which resulted in a loss of helicopter control due to a loss of tail rotor effectiveness. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Robinson Helicopter R44 II, 99 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=7640122), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Performance/control parameters: airspeed](https://openairdocs.org/ntsb-findings/01062010): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Robinson Helicopter R44 II, 6 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md?model=7640122), [All aircraft, 1,681 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md) - [Wind: tailwind](https://openairdocs.org/ntsb-findings/03034015): Environmental issues › Conditions/weather/phenomena · Effect on operation (probable cause); cases with it: [Robinson Helicopter R44 II, 13 cases](https://openairdocs.org/ntsb-findings/03034015/cases.md?model=7640122), [All aircraft, 594 cases](https://openairdocs.org/ntsb-findings/03034015/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-low-alt flying: Loss of tail rotor effectiveness](https://openairdocs.org/ntsb-events/242) (defining event); cases with it: [Robinson Helicopter R44 II, 9 cases](https://openairdocs.org/ntsb-events/242/sequence.md?model=7640122), [All aircraft, 100 cases](https://openairdocs.org/ntsb-events/242/sequence.md) - [Maneuvering-low-alt flying: Loss of control in flight](https://openairdocs.org/ntsb-events/240); cases with it: [Robinson Helicopter R44 II, 74 cases](https://openairdocs.org/ntsb-events/240/sequence.md?model=7640122), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) - [Uncontrolled descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Robinson Helicopter R44 II, 95 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=7640122), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The commercial helicopter pilot and a crewmember were conducting a pipeline patrol when they noticed a right-of-way infraction (construction work) that they wanted to photograph. The pilot then entered a left circuit at 500 ft above ground level. The pilot reported that he subsequently felt a shudder in the controls and that the helicopter began to yaw right and spin. Although the pilot reported that he maintained an airspeed of 70 knots while maneuvering, GPS data revealed that the loss of yaw control occurred at the completion of the first left circuit and the beginning of the second left circuit as the helicopter slowed to a groundspeed of about 1 mph. Weather data indicated that, at this point, the helicopter was experiencing an 8-knot tailwind. The pilot lowered the helicopter's nose but was unable to correct the spin. He entered an autorotation and maneuvered to avoid residences and utility poles, and the helicopter then impacted the ground. Examination of the helicopter did not reveal any evidence of preimpact mechanical malfunctions that would have precluded normal operation. It is likely that the low-airspeed condition combined with a tailwind during out-of-ground-effect maneuvering resulted in a loss of helicopter control due to a loss of tail rotor effectiveness. ## Factual narrative On April 27, 2017, about 1330 eastern daylight time, a Robinson R44 II, N728CB, operated by Chesapeake Bay Helicopters, was substantially damaged during a collision with terrain while maneuvering near Newton, North Carolina. The commercial pilot and crewmember sustained minor injuries. The local aerial observation flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and a company flight plan was filed for the flight that originated from Concord Regional Airport (JQF), Concord, North Carolina, about 1225.The pilot reported that he was performing a pipeline patrol at 500 ft above ground level and an airspeed of 70 knots. During the patrol, the crew observed a right-of-way infraction and circled the location at the same airspeed and altitude. While extending the circling pattern, the pilot felt a shudder in the controls while at the same time, the nose of the helicopter yawed right and the helicopter began to spin. He immediately lowered the nose in an attempt to increase forward motion, but the rate of spin increased. He then attempted to set up for an autorotation and avoid residences and utility wires. The helicopter subsequently impacted the ground and the pilot was able to shut down the engine and exit the helicopter. The crewmember reported that while on pipeline patrol, they circled to photograph construction work. While circling, the helicopter lost control and spun two or three times before impacting the ground. Examination of the wreckage revealed substantial damage to the helicopter. Tail rotor driveshaft continuity was confirmed from the tail rotor blades to the main rotor. Continuity was also confirmed from the left anti-torque pedal to the tail rotor. A section of right anti-torque pedal control tube was found bent and separated. The separated section of control tube was retained for metallurgical examination, which revealed that the separation was consistent with overstress due to impact forces. No preimpact mechanical malfunctions were identified. The helicopter's most recent 100-hour inspection was completed on March 10, 2017. At that time, the airframe and engine had accumulated 1,873.6 total hours of operation. The helicopter had flown an additional 43.6 hours from the time of the inspection, until the accident flight. The recorded wind at an airport located about 10 miles northwest of the accident site, at 1253, was from 190° at 8 knots. Review of GPS data provided by the operator revealed that after completion of the first left circuit and the beginning of the second left circuit, the helicopter's ground speed slowed to about 1 mph at a GPS altitude of 1,223 ft (about 500 ft above ground level). At that time, the GPS track was indicating a northerly course, with an approximate 8-knot tailwind. The track subsequently indicated transition from a left circuit to a right turn. The Federal Aviation Administration issued advisory circular (AC)-90-95,Unanticipated Right Yaw in Helicopters during February 1995. The AC stated that the loss of tail rotor effectiveness (LTE) was a critical, low-speed aerodynamic flight characteristic which could result in an uncommanded right yaw rate that did not subside of its own accord and, if not corrected, could result in the loss of aircraft control. It also stated, "LTE is not related to a maintenance malfunction and may occur in varying degrees in all single main rotor helicopters at airspeeds less than 30 knots." Paragraph 9 of the AC covered reducing the onset of LTE. It stated: "In order to reduce the onset of LTE, the pilot should: ... c. When maneuvering between hover and 30 knots: (1) Avoid tailwinds. If loss of translational lift occurs, it will result in an increased high power demand and an additional anti-torque requirement. (2) Avoid out of ground effect (OGE) hover and high power demand situations, such as low speed downwind turns. (3) Be especially aware of wind direction and velocity when hovering in winds of about 8 - 12 knots (especially OGE). There are no strong indicators to the pilot of a reduction of translation lift... (6) Stay vigilant to power and wind conditions." Paragraph 10 of the AC addressed recovery techniques. It stated: "a. If a sudden unanticipated right yaw occurs, the pilot should perform the following: (1) Apply full left pedal. Simultaneously, move cyclic forward to increase speed. If altitude permits, reduce power. (2) As recovery is effected, adjust controls for normal forward flight. b. Collective pitch reduction will aid in arresting the yaw rate but may cause an increase in the rate of descent. Any large, rapid increase in collective to prevent ground or obstacle contact may further increase the yaw rate and decrease rotor rpm. c. The amount of collective reduction should be based on the height above obstructions or surface, gross weight of the aircraft, and the existing atmospheric conditions. d. If the rotation cannot be stopped and ground contact is imminent, an autorotation may be the best course of action. The pilot should maintain full left pedal until rotation stops, then adjust to maintain heading." Additionally, Robinson Safety Notice SN-34 addressed aerial survey and photography flights, and provided cautions about such flights below 30 knots airspeed. ## Aircraft - Registration: [N728CB](https://openairdocs.org/deregistered/N728CB-2019-02-04), registration cancelled 2019-02-04, S/N 12899, built 2010 (OpenAirDocs) - Reported make and model: ROBINSON R44 (II) - Registry model: [Robinson Helicopter R44 II](https://openairdocs.org/model/robinson-helicopter-r44-ii) (registry code 7640122) (OpenAirDocs) - Registry engine: [Lycoming IO-540-AE1A5](https://openairdocs.org/engine/lycoming-io-540-ae1a5) (registry code 41899, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 12899 - Year built: 2010 - Airframe hours: 1917 - Engines: LYCOMING IO-540-AE1A5 245 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial observation, Part 91 - Operator: Chesapeake Bay Helicopters - Registered owner: Bulanov Galis LLC - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, March 10, 2017, 43 hours before - Departed: JQF, Concord, NC - Destination: JQF, Concord, NC - Flight plan: Company VFR - Equipment: Electronic flight bag or handheld device, Onboard weather, Satellite tracking device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 34; injuries: minor; commercial; airplane ratings: single-engine land; instrument ratings: helicopter, airplane; medical: class 2, without waivers/limitations; last flight review November 22, 2016; seat: right; restraint: 3-point; flight hours: 1,529 total, 207 in this make and model, 111 in the last 90 days, 14 in the last 30 days, 9 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 190° at 8 knots - Visibility: 8 statute miles - Lowest ceiling: 4,600 ft overcast - Temperature: 70 °F, dew point 55 °F - Altimeter: 29.87 inHg - Turbulence: Unknown - Observed at: HKY, 10 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20170427005959A](https://openairdocs.org/incident/20170427005959A), Apr 27, 2017: Robinson Helicopter R44 II, Newton, NC, Substantial damage. Narrative: On April 27, 2017, about 1330 eastern daylight time, a Robinson R44 ii, N728CB, operated by chesapeake bay helicopters, was substantially damaged… ## Docket (9 files) The files NTSB released with the investigation on December 21, 2017, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=95069. 7.5 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 3.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40458980&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - GPS Plots (item 2, .PDF, 588 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40459025&FileExtension=.PDF&FileName=GPS%20Plots-Master.PDF - Weather Report (item 3, .PDF, 40 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40459026&FileExtension=.PDF&FileName=Weather%20Report-Master.PDF - Interview Summary (item 4, .PDF, 26 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40459027&FileExtension=.PDF&FileName=Interview%20Summary-Master.PDF - Photo Array (item 5, .PDF, 1.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40459028&FileExtension=.PDF&FileName=Photo%20Array-Master.PDF - Materials Laboratory Factual Report (item 6, .PDF, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40459029&FileExtension=.PDF&FileName=Materials%20Laboratory%20Factual%20Report-Master.PDF - Robinson SN-34 (item 7, .PDF, 312 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40459030&FileExtension=.PDF&FileName=Robinson%20SN-34-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 8, .PDF, 280 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40459031&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Master.PDF - Evidence Control Form (item 9, .PDF, 142 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40459032&FileExtension=.PDF&FileName=Evidence%20Control%20Form-Master.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.