ASN Wikibase Occurrence # 169329
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| Date: | Thursday 28 August 2014 |
| Time: | 10:55 |
| Type: |  Eurocopter AS 350B3 Ecureuil |
| Owner/operator: | Riverside County |
| Registration: | N991SD |
| MSN: | 3325 |
| Year of manufacture: | 2000 |
| Total airframe hrs: | 6312 hours |
| Engine model: | Turbomeca Ariel 2B |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Hemet-Ryan Airport, Riverside County, CA -
 United States of America
|
| Phase: | Landing |
| Nature: | Unknown |
| Departure airport: | Hemet-Ryan Field, CA (HMT/KHMT) |
| Hemet-Ryan Field, CA (HMT/KHMT) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The flight instructor and pilot receiving instruction toward his commercial certificate worked for the Riverside County Sheriff's Department (RCSD) and were conducting a local instructional flight in the helicopter. However, the helicopter remained on alert status in the event of a need for response. The instructor reported that they started a maneuver to simulate a governor failure at 500 ft above ground level (agl) by switching the auto/manual switch to manual. With the switch in manual, the full authority digital engine control governor was disengaged, which required the pilot to use the twist grip throttle control on the collective to increase and decrease power. They then proceeded on an extended left downwind for 2.5 miles, and the pilot practiced manipulating the twist grip. The pilot then turned onto the base leg, turned from the base to final leg, started descending, and reduced the throttle input (rolled off the throttle). As the helicopter approached the runway threshold about 50 to 100 ft agl, the instructor noticed that the rotor rpm was decreasing a little more than he expected. He rolled the throttle on but noticed that the rotor rpm was not increasing. While the helicopter was about 50 ft agl and over the runway threshold, the flight instructor noticed that it was quickly descending and that the rotor rpm was continuing to decrease. His attempts to increase the rotor rpm by pulling aft cyclic and lowering the collective were unsuccessful. The helicopter then impacted the runway surface hard, rotated left 180 degrees, rolled over, and came to rest on its left side facing northeast. A postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.
The pilot was the first RCSD pilot to obtain only a private certificate from an outside vendor and then work on getting a commercial certificate with an RCSD flight instructor. There was no formal training syllabus, and the pilot did not know before the flight what maneuvers were to be performed. After completing in-flight simulated instrument work and with the helicopter still running on the ground, the instructor briefed the private pilot on the simulated governor failure maneuver; however, he did not demonstrate the maneuver in flight before he had the pilot perform it. Further, the instructor did not provide the pilot with an opportunity to adequately practice coordinating movements of the collective and the twist grip throttle before attempting a landing, likely because he had been talking to dispatch since the beginning of the maneuver.
It is likely that the instructor's failure to demonstrate the maneuver and to provide the pilot with adequate opportunity to practice manipulating the twist grip throttle before attempting a landing resulted in the pilot mismanaging the twist grip throttle during the final approach, which led to a decay in rotor rpm. Further, it is likely that the instructor's inadequate supervision and delayed remedial action during the final approach resulted in the unsuccessful performance of the maneuver.
Probable Cause: The flight instructor's failure to adequately brief and demonstrate the simulated emergency procedure to the pilot under instruction and his delayed remedial action and inadequate supervision during the maneuver, which resulted in an excessive sink rate and a hard landing.
Accident investigation:
 |
|
Sources:
NTSB
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 29-Aug-2014 09:49 | HeliNews+ | Added |
| 29-Aug-2014 09:49 | harro | Updated [Aircraft type] |
| 29-Aug-2014 13:21 | Aerossurance | Updated [Source, Narrative] |
| 29-Aug-2014 13:27 | Aerossurance | Updated [Narrative] |
| 29-Aug-2014 14:53 | Aerossurance | Updated [Time, Registration, Cn, Source] |
| 30-Aug-2014 07:10 | Anon. | Updated [Aircraft type] |
| 30-Aug-2014 18:59 | Anon. | Updated [Aircraft type] |
| 05-Sep-2014 17:16 | Aerossurance | Updated [Source, Narrative] |
| 05-Oct-2015 16:30 | Aerossurance | Updated [Time, Aircraft type, Source] |
| 24-Apr-2016 15:58 | Aerossurance | Updated [Time, Narrative] |
| 21-Dec-2016 19:28 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 19-Aug-2017 13:31 | ASN Update Bot | Updated [Operator, Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative] |
| 31-May-2023 05:47 | Ron Averes | Updated [[Operator, Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative]] |
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