- Date
- August 6, 2020, 15:15 local (20:15 UTC)
- Place
- St Louis, MO
- Injuries
- 2 uninjured
- Damage
- Substantial damage
- Phase of flight
- Landing
- Aircraft
- N911EPHughes 369A
- Defining event
- Landing: Hard landing
- Weather
- Visual (VMC) · Day
- Status
- Completed
- Report
- Approved by Office Director
- Investigation class
- Class 4 - Basic report with no Prelim publish
- NTSB office
- Central Region
- Parties
- FAA FSDO
- FAA report
- 20200806008229A
- Case key
- 101751
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
Probable cause
The flight instructor's failure to maintain helicopter control which resulted in a hard landing while preforming a practice autorotation.
Findings · 3
NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.
Sequence of events
The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.
Analysis
The instructor reported that during the instructional flight, he was manipulating the controls and accepted the option to land on the taxiway; he decreased the throttle for a full touchdown auto rotation. About 50 ft above the ground (agl), he flared the helicopter and leveled off about 5 to 10 ft agl. The instructor reported that everything seemed "normal" at this point. He then raised the collective, but the descent was not arrested, so he raised the collective full up. The helicopter landed hard and shook violently. The instructor closed the throttle to which stopped the fuel supply. The tailboom was substantially damaged. The flight instructor reported that there were no mechanical anomalies with the helicopter that would have precluded normal operation. The instructor added that he felt a slight tailwind after exiting the helicopter and that the tail wind caused a "vortex ring state" which stalled the main rotor blades.
Aircraft
- Registration
- N911EP
- Reported as
- Hughes 369A (No Series)
- Category
- Helicopter
- Serial number
- 591176
- Airframe hours
- 1,229.4
- Engine
- Rolls Royce 250-c20C, turbo shaft
- Damage
- Substantial damage
- Flight
- Public aircraft · Public use
- Operator
- St Louis County Police Department
- Registered owner
- St Louis County Police Department
- Airworthiness certificate
- None
- Last inspection
- 100 hour · August 4, 2020
- Departed
- KSUS · St Louis, MO
- Destination
- KSUS · St Louis, MO
- Airport
- KSUS · Spirit of St Louis Airport
- Equipment
- ADS-B
Flight crew · 2
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 51
- Injuries
- None
- Certificates
- Flight instructor, Commercial
- Instrument ratings
- Helicopter
- Medical
- Class 2, With waivers/limitations
- Seat
- Left
- Restraint
- 4-point
- Flight hours
- 6,814 total · 6,814 in this make and model · 6,338 as pilot in command
- Role
- Pilot
- Age
- 39
- Injuries
- None
- Certificate
- Commercial
- Medical
- Class 2, Without waivers/limitations
- Last flight review
- June 18, 2020
- Seat
- Right
- Restraint
- 4-point
- Flight hours
- 635 total · 91 in this make and model · 585 as pilot in command
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- Variable at 3 knots
- Visibility
- 10 statute miles
- Temperature
- 81 °F, dew point 55 °F
- Altimeter
- 30.09 inHg
Docket · 2
The files NTSB released with the investigation on October 9, 2020, on NTSB’s docket system: statements, records, photos and specialists’ reports. 1.5 MB in all.
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.