Date:	06-AUG-2020
Time:	15:15
Type:	Hughes OH-6A
Owner/operator:	St Louis County Police Department
Registration:	N911EP
C/n / msn:	591176
Fatalities:	Fatalities: 0 / Occupants: 2
Other fatalities:	0
Aircraft damage:	Substantial
Category:	Accident
Location:	Spirit of St. Louis Airport, Chesterfield, MI -   United States of America
Phase:	Landing
Nature:	Training
Departure airport:	Saint Louis-Spirit of St. Louis Airport, MO (SUS/KSUS)
Destination airport:	Saint Louis-Spirit of St. Louis Airport, MO (SUS/KSUS)
Investigating agency:	NTSB

Narrative:
The flight instructor and pilot were conducting a helicopter training flight. Each pilot had performed several maneuvers, such as confined approach, slope landing, settling with power, and maximum performance takeoffs. They then flew to another airport where they conducted several practice emergency procedures; quick stops, stuck pedals, and auto rotations. They then returned to their home airfield, where they contacted the tower controller, who reported calm wind and cleared them to land. The instructor reported 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 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.

NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20200806X70122&key=1
https://callnewspapers.com/st-louis-county-officers-uninjured-as-helicopter-rotor-breaks-off-in-training-flight/
https://helihub.com/2020/08/06/06-aug-20-n911ep-hughes-oh-6-chesterfield-us-missouri/
http://www.slmpd.org/Aviation_unit.shtml
helis.com
c/n 591176
Helicopter Hughes OH-6A Cayuse Serial 591176 Register N911EP 68-17216 used by State of Missouri US Army Aviation.
68-17216 usa US Army Aviation US Army
N911EP
usa State of Missouri
1997-04 St Louis County Police Department (SLCPD) at Chesterfield, MO from Apr97
Jan20 still SLCPD

source joe baugher.com
17216 (MSN 1176) Registered N911EP to St Louis County Police Department, Chesterfield, MO, 11Apr 11, 1997; current On July 13, 1999 the aircraft sustained substantial damage during an auto-rotational landing to the surface

Date/time	Contributor	Updates
07-Aug-2020 06:01	HeliHub	Added
07-Aug-2020 12:14	francois	Updated [Source]
07-Aug-2020 13:17	Aerossurance	Updated [Operator, Location]
16-Sep-2020 08:30	ASN Update Bot	Updated [Cn, Operator, Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative, Accident report]
16-Sep-2020 08:32	ASN Update Bot	Updated [Source, Narrative]
16-Sep-2020 08:36	harro	Updated [Nature, Source, Narrative]