# NTSB CHI99TA232: Hughes OH-6A, N911EP, Chesterfield, MO, July 13, 1999

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Final report
- Date: July 13, 1999, 09:13 local (14:13 UTC)
- Place: Chesterfield, MO
- Coordinates: 38.650569, -90.579338 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=38.6506&lon=-90.5793&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report June 22, 2000
- Report: Approved by Office Director
- NTSB case key (mKey): 46779
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI99TA232
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/46779/pdf
- Page: https://openairdocs.org/ntsb/CHI99TA232

## Probable cause

the pilot-in-command's improper autorotational landing.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Hard landing, landing
  - autorotation - improper, pilot in command (cause)

## Analysis

A rated helicopter pilot was acting as pilot-in-command with a check pilot.  According to the check pilot who was interviewed after the accident, the pilot-in-command had accomplished several autorotational landings to a hover and he asked the pilot on the next one to 'demonstrate a full touchdown.'  He said that the helicopter landed hard and received damage.

## Factual narrative

On July 13, 1999, at 0913 central daylight time, a Hughes OH-6A, N911EP, sustained substantial damage during an autorotational landing to the surface.  The pilot and check pilot reported no injuries.  The public use flight was operating under provisions of 14 CFR Part 91 in visual meteorological conditions.  No flight plan was on file.  The local flight departed at 0830.

The flight was for the purpose of the pilot-in-command receiving a check ride from a check pilot (flight instructor). In a verbal statement given to a Federal Aviation Administration inspector, the check pilot said that the pilot had been practicing various landings including autorotational landings to a hover.  He said that on the seventh landing he told the pilot to "demonstrate a full touchdown."  He said the helicopter touched down hard and the main rotor blade contacted and cut through the tail boom.

A post accident examination failed to reveal any pre-existent mechanical anomalies.

## Aircraft

- Registration: N911EP (not matched to a registry record)
- Reported make and model: Hughes OH-6A
- Category: Helicopter
- Serial number: 591176
- Airframe hours: 5072
- Engines: Allison 250-C10-D 317 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Public aircraft, Part 91
- Registered owner: St Louis County Police Dept
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, June 22, 1999, 49 hours before
- Departed: SUS
- Airport: SUS, Spirit Of St Louis

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 40; private; medical: class 2, valid medical--no waivers/lim.; seat: right; flight hours: 268 total, 268 in this make and model, 215 as pilot in command, 88 in the last 90 days, 12 in the last 30 days, 3 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 70 °F, dew point 63 °F
- Altimeter: 30.00 inHg
- Observed at: SUS

## 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 19990713008949A](https://openairdocs.org/incident/19990713008949A), Jul 13, 1999: Hughes OH6A, Chesterfield, MO, Substantial damage. St. louis county police public use Hughes OH6A helicopter was involved in auto-rotation practice when the main rotor blades flexed down on landing and struck…

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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