# NTSB CEN15LA224: Enstrom F-28F, N8011Q, Argyle, TX, May 6, 2015 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: May 6, 2015, 14:26 local (19:26 UTC) - Place: Argyle, TX - Coordinates: 33.360713, -97.169937 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=33.3607&lon=-97.1699&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Defining event: [Takeoff: Settling with power/vortex ring state](https://openairdocs.org/ntsb-events/244) - Highest injury: Serious injuries - Injuries: 2 serious - Status: Completed, report September 12, 2016 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Federal Aviation Administration; NTX FSDO - NTSB case key (mKey): 91146 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN15LA224 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/91146/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=91146 - Page: https://openairdocs.org/ntsb/CEN15LA224 ## Probable cause The pilot and flight instructor's inadvertent encounter with settling with power during a confined area takeoff at an altitude that was too low for recovery. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Performance/control parameters: climb rate](https://openairdocs.org/ntsb-findings/01062035): Aircraft › Aircraft oper/perf/capability · Attain/maintain not possible (probable cause); cases with it: [Enstrom F-28F, 1 case](https://openairdocs.org/ntsb-findings/01062035/cases.md?model=3300412), [All aircraft, 265 cases](https://openairdocs.org/ntsb-findings/01062035/cases.md) - [Performance/control parameters: altitude](https://openairdocs.org/ntsb-findings/01062012): Aircraft › Aircraft oper/perf/capability · Not specified (probable cause); cases with it: [Enstrom F-28F, 1 case](https://openairdocs.org/ntsb-findings/01062012/cases.md?model=3300412), [All aircraft, 1,310 cases](https://openairdocs.org/ntsb-findings/01062012/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Takeoff: Settling with power/vortex ring state](https://openairdocs.org/ntsb-events/244) (defining event); cases with it: [Enstrom F-28F, 1 case](https://openairdocs.org/ntsb-events/244/sequence.md?model=3300412), [All aircraft, 52 cases](https://openairdocs.org/ntsb-events/244/sequence.md) - [Takeoff: Loss of control in flight](https://openairdocs.org/ntsb-events/240); cases with it: [Enstrom F-28F, 3 cases](https://openairdocs.org/ntsb-events/240/sequence.md?model=3300412), [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: [Enstrom F-28F, 5 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=3300412), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis According to the pilot receiving instruction, he and the flight instructor were performing the third in a series of confined area takeoffs in the helicopter. The previous two takeoffs were conducted with no anomalies observed. The pilot stated that, on the third takeoff, he performed a vertical climb to just above treetop level. As the helicopter transitioned to forward motion, it began to settle, and the flight instructor assumed the flight controls to attempt to return to the departure point. The helicopter continued to descend and subsequently impacted trees and terrain. Postaccident examination of the helicopter revealed no mechanical anomalies that would have precluded normal operation. ## Factual narrative On May 6, 2015 at 1426 central daylight time, an Enstrom F-28F, N8011Q, impacted trees while maneuvering over a field near Argyle, Texas. The helicopter sustained substantial damage. The private pilot and flight instructor sustained serious injuries. The helicopter was registered to US Aviation Group LLC and operated by Longhorn Helicopters under Code of Federal Regulations Part 91 as an instructional flight. Visual meteorological conditions prevailed the time of the accident. The local flight originated from DTO about 1330. According to a Federal Aviation Administration (FAA) inspector from the North Texas Flight Standards District Office, the pilot stated he and the flight instructor had flown for approximately 30 minutes prior to the accident. The pilot stated that the helicopter engine seemed to be functioning normally, and he did not recall any unusual power fluctuations or noises. The pilot and flight instructor were practicing confined area takeoffs and had accomplished two confined area takeoffs just preceding the accident with no abnormal issues. During the third confined area takeoff, the helicopter developed power up to 32 inches of manifold pressure and they began the vertical climb to just above tree top level. At that time he stated that they began transition to forward motion and the helicopter began to "settle with power". The pilot stated that as the helicopter began to descend, the flight instructor announced that she "had the controls" and began to attempt increasing power and immediately turned the aircraft around intending to return to the departure point, away from the trees. The helicopter continued to descend and impacted the trees in a slight nose down attitude. According to the FAA inspector, on-scene examination of the helicopter revealed that it made contact with a group of trees, approximately 10 feet from the pasture in which the confined area takeoff maneuver was initiated. The trees were estimated to be 30 feet in height. Debris was confined to the location in which the aircraft impacted. Fire/rescue personnel removed approximately 30 gallons of fuel from the helicopter, which had a fuel capacity of 40 gallons. The right side of the cockpit impacted a tree which penetrated up to the right side collective. The bottom of the cockpit area on both sides near the rudder pedals sustained major damage from impact with the ground. The tail boom and engine area sustained minor damage due to impact with trees and the helicopter remained intact although it was resting in approximately a 30 degree angle with the tail boom suspended in a tree to the rear of the crash site. The main rotors were in a high pitch setting and intact. One main rotor had substantial damage from impact with a tree the other two main rotors did have some bending suggesting a largely vertical descent. The flight instructor stated that she believed that the engine turbocharger waste gate malfunctioned, which prevented them from receiving the extra powerrequired. No mechanical anomalies that would have precluded normal aircraft operation were noted during the examination. The required National Transportation Safety Board Pilot/Operator Accident/Incident Report, form 6120, was not received from the private pilot. ## Aircraft - Registration: [N8011Q](https://openairdocs.org/deregistered/N8011Q-2021-07-20), registration cancelled 2021-07-20, S/N 732, built 1984 (OpenAirDocs) - Reported make and model: ENSTROM F-28F - Registry model: [Enstrom F-28F](https://openairdocs.org/model/enstrom-f-28f) (registry code 3300412) (OpenAirDocs) - Registry engine: [Lycoming I0360 series](https://openairdocs.org/engine/lycoming-i0360-series) (registry code 41515, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 732 - Engines: Lycoming IO360 reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: US Aviation Group LLC - Registered owner: US Aviation Group LLC - Airworthiness certificate: Standard, Normal - Departed: DTO, Denton, TX - Destination: DTO, Denton, TX ## Flight crew As NTSB recorded them. NTSB leaves out names. - Student pilot; age 23; injuries: serious; private; instrument ratings: helicopter; seat: right - Flight instructor; age 25; injuries: serious; seat: left ## Weather - Conditions: Visual (VMC), Day - Wind: 150° at 15 knots - Visibility: 10 statute miles - Lowest ceiling: 3,000 ft broken - Temperature: 77 °F, dew point 68 °F - Altimeter: 29.92 inHg - Observed at: DTO, 5 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 20150506008519A](https://openairdocs.org/incident/20150506008519A), May 6, 2015: Enstrom F-28F, Denton, TX, Destroyed. While conducting a confined area takeoff in helicopter N8011Q the aircraft failed to gain sufficient rotor speed to maintain lift as the aircraft began to… ## Docket (2 files) The files NTSB released with the investigation on July 28, 2016, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=91146. 5.9 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 5.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40442700&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Record of Correspondence - FAA (item 2, .PDF, 57 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40442701&FileExtension=.PDF&FileName=Record%20of%20Correspondence%20-%20FAA-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.