# NTSB FTW99TA183: McDonnell Douglas 500-E, N686F, Oklahoma City, OK, July 1, 1999

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Final report
- Date: June 30, 1999, 23:30 local (Jul 1, 1999, 04:30 UTC)
- Place: Oklahoma City, OK
- Coordinates: 35.430568, -97.519905 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=35.4306&lon=-97.5199&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 1 minor, 2 uninjured
- Status: Completed, report November 30, 2000
- Report: Approved by Office Director
- NTSB case key (mKey): 46725
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW99TA183
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/46725/pdf
- Page: https://openairdocs.org/ntsb/FTW99TA183

## Probable cause

During a practice autorotation, the pilot flared the helicopter too low, which resulted in the tailboom contacting the ground.  A factor was the dark night light conditions.

## Sequence of events

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

- Dragged wing,rotor,pod,float or tail/skid, landing - flare/touchdown
  - emergency procedure - simulated, pilot in command
  - flare - low, pilot in command (cause)
  - light condition - dark night (contributing factor)

## Analysis

During a night practice autorotation, after reapplying power, the pilot flared the helicopter too low, and the tailboom contacted the ground.  Tail rotor control was lost, and the helicopter came to rest on its right side.

## Factual narrative

On June 30, 1999, at 2330 central daylight time, a McDonnell Douglas 500-E helicopter, N686F, owned and operated by the Oklahoma City Police Department, was substantially damaged during a night practice autorotational landing at the Downtown Airpark Airport, Oklahoma City, Oklahoma.  The commercial pilot and observer were not injured, and the passenger received minor injuries.  Dark night visual meteorological conditions prevailed, and a flight plan was not filed for the 14 Code of Federal Regulations Part 91 public use flight.  The local flight departed the Downtown Airpark Airport, about 40 minutes prior to the accident.

The pilot reported that after completing patrol duties, the flight returned to the airport.  He proceeded to practice some quick stop maneuvers, slope landings, and a hovering autorotation.  The pilot further reported that he then entered the traffic pattern and "once [on] downwind ... entered a 180 degree autorotation" for the area east of runway 16 on the north end of the field.  During the approach, and "after reapplying power, the flare was executed at too low of an altitude, and the tail boom made contact with the ground."   The pilot added that "tail rotor use was lost," and the helicopter came to rest on its right side.

The operator reported that an examination of the helicopter revealed that the tailboom was partially separated about three feet aft of its fuselage attaching point.  The main drive shaft was damaged, the tail rotor drive shaft was separated at its aft flex coupling, and the right skid was separated.

## Aircraft

- Registration: N686F (not matched to a registry record)
- Reported make and model: McDonnell Douglas 500-E
- Category: Helicopter
- Serial number: E-524
- Airframe hours: 3676
- Engines: Allison 250C-20B 420 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Public aircraft, Part 91
- Registered owner: Oklahoma City Police Dept.
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, June 17, 1999, 81 hours before
- Departed: 2DT
- Airport: 2DT, Downtown Airpark

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 29; commercial, private; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 400 total, 130 in this make and model, 105 in the last 90 days, 36 in the last 30 days, 4 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Night/dark
- Wind: 120° at 9 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 79 °F, dew point 73 °F
- Altimeter: 29.00 inHg
- Observed at: OKC, 5 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 19990630007959A](https://openairdocs.org/incident/19990630007959A), Jun 30, 1999: Doug MD500E, Oklahoma City, OK, Substantial damage. (Tty) Oklahoma City police department 1995 Mcdonnell Douglas ME-500E helicopter crashed in the grass adjacent to rwy 16, the tail rotor struck the ground, and…

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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