# NTSB WPR17LA158: Enstrom F 28C, N5697B, Ontario, CA, July 19, 2017

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Limited investigation · Final report
- Date: July 19, 2017, 10:10 local (17:10 UTC)
- Place: Ontario, CA
- Coordinates: 33.971389, -117.635276 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=33.9714&lon=-117.6353&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Defining event: [Approach-VFR pattern downwind: Loss of control in flight](https://openairdocs.org/ntsb-events/240)
- Highest injury: Serious injuries
- Injuries: 1 serious
- Status: Completed, report January 25, 2018
- Report: Approved by Office Director
- NTSB office: Western Pacific Region
- Parties: Federal Aviation Administration, Enstrom Helicopter Corporation, Lycoming Engines
- NTSB case key (mKey): 95623
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR17LA158
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/95623/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=95623
- Page: https://openairdocs.org/ntsb/WPR17LA158

## Probable cause

The student pilot's mismanagement of the main rotor rpm, which resulted in low rotor rpm, a high descent rate, and a subsequent hard landing.

## 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 · Student/instructed pilot (probable cause); cases with it: [Enstrom F-28C, 5 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=3300407), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md)
- [Use of equip/info: use of equip/system](https://openairdocs.org/ntsb-findings/02063015): Personnel issues › Task performance · Student/instructed pilot (probable cause); cases with it: [Enstrom F-28C, 2 cases](https://openairdocs.org/ntsb-findings/02063015/cases.md?model=3300407), [All aircraft, 1,391 cases](https://openairdocs.org/ntsb-findings/02063015/cases.md)
- [Main rotor system: main rotor blade system](https://openairdocs.org/ntsb-findings/01046210): Aircraft › Aircraft propeller/rotor · Incorrect use/operation (probable cause); cases with it: [Enstrom F-28C, 2 cases](https://openairdocs.org/ntsb-findings/01046210/cases.md?model=3300407), [All aircraft, 60 cases](https://openairdocs.org/ntsb-findings/01046210/cases.md)
- [Performance/control parameters: descent rate](https://openairdocs.org/ntsb-findings/01062037): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Enstrom F-28C, 1 case](https://openairdocs.org/ntsb-findings/01062037/cases.md?model=3300407), [All aircraft, 242 cases](https://openairdocs.org/ntsb-findings/01062037/cases.md)
- [Performance/control parameters: prop/rotor parameters](https://openairdocs.org/ntsb-findings/01062052): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Enstrom F-28C, 3 cases](https://openairdocs.org/ntsb-findings/01062052/cases.md?model=3300407), [All aircraft, 182 cases](https://openairdocs.org/ntsb-findings/01062052/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Approach-VFR pattern downwind: Loss of control in flight](https://openairdocs.org/ntsb-events/240) (defining event); cases with it: [Enstrom F-28C, 4 cases](https://openairdocs.org/ntsb-events/240/sequence.md?model=3300407), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md)
- [Approach-VFR pattern downwind: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Enstrom F-28C, 3 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=3300407), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md)

## Analysis

The solo student pilot reported that he entered the downwind leg to set up for the helicopter's first landing of the day. When abeam the touchdown location, he conducted the prelanding checks with no anomalies noted. Before turning onto the base leg, the pilot lowered the collective, reduced the throttle, and started to descend about 100 ft per minute. During the descent, he observed that the engine rpm was slightly above 2,900 rpm. He reduced the throttle, and the rpm reduced slightly; however, it again increased to 2,900 rpm, and the manifold pressure was about 10 inches of mercury. When the helicopter was about 400 ft above ground level, the pilot heard the engine sound increase, and he observed that the engine rpm had increased to between about 3,300 and 3,500 rpm. The helicopter was unable to reach the runway, so the pilot continued to descend it toward a pasture, and it landed hard in the dirt. A postaccident airframe and engine examination and subsequent engine run revealed no preimpact anomalies that would have precluded normal operation. The observed damage to the main rotor blades was consistent with blade coning, a condition indicative of low main rotor rpm. It is likely that the student pilot mismanaged the main rotor rpm during the descent, which resulted in a low rotor rpm and a high descent rate during landing.

## Factual narrative

On July 19, 2017, about 1010 Pacific daylight time, an Enstrom F28-C rotorcraft, N5697B, descended rapidly and landed hard in a dirt pasture about 1/2-mile northeast of the Chino Airport (CNO), Ontario, California. The student pilot, sole occupant, was seriously injured and the helicopter sustained substantial damage to the tailboom and main rotor blades. The helicopter was registered to Dubois Aviation Inc and operated by the pilot as a 14 Code of Federal Regulations Part 91 solo instructional flight. Visual meteorological conditions prevailed and no flight plan was filed. The flight originated from CNO about 1005. The student pilot reported he entered the downwind leg to set up for the first landing of the day. When abeam his touchdown location, he conducted the prelanding checks with no anomalies noted. Prior to turning base he lowered the collective, reduced the throttle, and started to descend at about 100 feet per minute. During the descent, he observed the engine RPM to be slightly above 2,900 RPM, and he reduced the throttle. The RPMs reduced slightly, however, went back to 2,900 RPM, and the manifold pressure was about 10 inches of Hg. About 400 feet above the ground, he heard the engine sound increase and he observed 3,300-3,500 RPM. Unable to make the runway, he continued to descend towards a pasture and landed hard in the dirt. A postaccident airframe and engine examination revealed no preimpact anomalies that would have precluded normal operation. Flight control continuity was established from the cockpit controls to the main rotorhead. The tailrotor driveshaft was turned and rotation was observed from the tail rotor gear to the main rotor mast. The main rotor blades remained intact and exhibited signatures consistent with coning. The lower spark plugs were removed from the engine and the engine was rotated from the cooling fan. Thumb compression was obtained on all cylinders in proper firing order, and the impulse coupling was heard clicking from the left magneto. The spark plugs were reinstalled, and the engine was prepared for an engine run. The engine ran normally for several minutes at various RPMs. Normal operating pressures and temperatures were observed, and there were no fuel or oil leaks observed. The engine was shutdown normally with no anomalies noted.

## Aircraft

- Registration: [N5697B](https://openairdocs.org/deregistered/N5697B-2018-07-20), registration cancelled 2018-07-20, S/N 505-2 (OpenAirDocs)
- Reported make and model: ENSTROM F 28C
- Registry model: [Enstrom F-28C](https://openairdocs.org/model/enstrom-f-28c) (registry code 3300407) (OpenAirDocs)
- Category: Helicopter
- Serial number: 505-2
- Airframe hours: 3715
- Engines: Lycoming HIO-360-E1AO 200 horsepower reciprocating
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, May 5, 2017, 20 hours before
- Departed: CNO, Ontario, CA
- Destination: CNO, Ontario, CA
- Airport: CNO, Chino Airport

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 37; injuries: serious; student; medical: class 2, without waivers/limitations; seat: left; restraint: 3-point; flight hours: 33 total, 33 in this make and model, 1 as pilot in command, 30 in the last 90 days, 8 in the last 30 days, 0 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 280° at 7 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 84 °F, dew point 61 °F
- Altimeter: 30.01 inHg
- Observed at: CNO, 1 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 20170719009939A](https://openairdocs.org/incident/20170719009939A), Jul 19, 2017: Enstrom F-28C, Ontario, CA, Substantial damage. The pilot was on final approach to Chino Airport (cno). The pilot established a 100 foot descent rate and noticed the engine RPM was slightly above 2900 rpm's.…

## Docket (4 files)

The files NTSB released with the investigation on November 2, 2017, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=95623. 3.0 MB in all.

- Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 348 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457669&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF
- Airframe and Engine Examination (item 2, .PDF, 8 photos, 2.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457670&FileExtension=.PDF&FileName=Airframe%20and%20Engine%20Examination-Master.PDF
- Statement of Party Representatives to NTSB Investigation (item 3, .PDF, 362 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457671&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Master.PDF
- Release of Aircraft Wreckage, NTSB Form 6120.15 (item 4, .PDF, 59 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457672&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-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.

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