# NTSB DEN01LA154: McDonnell Douglas 369E, N440TJ, Kemmerer, WY, September 2, 2001

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: September 2, 2001, 11:50 local (17:50 UTC)
- Place: Kemmerer, WY
- Coordinates: 41.779228, -110.549385 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.7792&lon=-110.5494&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report February 20, 2002
- Report: Approved by Office Director
- Parties: FAA Flight Standards Field Office
- NTSB case key (mKey): 53163
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN01LA154
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/53163/pdf
- Page: https://openairdocs.org/ntsb/DEN01LA154

## Probable cause

loss of tail rotor effectiveness while hovering. A contributing factor was the wind gust.

## Sequence of events

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

- Loss of control - in flight, hover
  - loss of tail rotor effectiveness - encountered, pilot in command (cause)
  - weather condition - gusts (contributing factor)
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

The pilot was transporting bags of seismic equipment by long line to a remote site. While he hovered into the wind waiting for a flagger, the helicopter was struck by a wind gust and started turning right. The pilot applied left pedal, but was unable to stop the rotation. The helicopter struck terrain, breaking off both skid legs, tail rotor blades, and tail rotor gearbox. FAA's Advisory Circular 90-95 defines the loss of tail rotor effectiveness as "a critical, low-speed aerodynamic flight characteristic that can result in an uncommanded rapid yaw rate which does not subside of its own accord and, if not corrected, can result in the loss of aircraft control." Some of the conditions conducive to LTE include (1) a high power setting, (2) low airspeed, and (3) a tailwind or left crosswind.

## Factual narrative

On September 2, 2001, approximately 1150 mountain daylight time, a McDonnell Douglas 369E helicopter, N440TJ, operated by Omni Aviation of Carencro, Louisiana, was substantially damaged when it collided with terrain while hovering near Kemmerer, Wyoming. The commercial pilot, the sole occupant aboard, was not injured. Visual meteorological conditions prevailed, and no flight plan had been filed for this work use flight being conducted under Title 14 CFR Part 133. The helicopter departed a nearby landing zone approximately 1145.

According to the pilot, he was transporting bags of seismic equipment by long line to a remote site. He said while he hovered into the wind and waited for a flagger, "a [wind] gust caused the helicopter to start to turn right." He applied "more left pedal," but was unable to stop the rotation. He jettisoned the external load, lowered the collective control, and attempted to fly out of the condition. He was able to stop most of the rotation but not before the helicopter struck the terrain. Both skid legs, tail rotor blades, and tail rotor gearbox broke off. The left horizontal stabilizer was struck by one of the blades, and the tail boom buckled when it struck the ground. The pilot said the winds were "generally light and variable, with [an] occasional gust."

According to FAA's Advisory Circular (AC) 90-95, loss of tail rotor effectiveness (LTE) "is a critical, low-speed aerodynamic flight characteristic that can result in an uncommanded rapid yaw rate which does not subside of its own accord and, if not corrected, can result in the loss of aircraft control. Some of the conditions conducive to LTE include (1) a high power setting, (2) low airspeed, and (3) a tailwind or left crosswind

## Aircraft

- Registration: N440TJ (not matched to a registry record)
- Reported make and model: McDonnell Douglas 369E
- Category: Helicopter
- Serial number: 0442E
- Airframe hours: 8234
- Engines: Allison 250-C20B 420 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Other work use, Part 133
- Operator: Omni Aviation Services
- Registered owner: Textron Financial Corp.
- Airworthiness certificate: Standard, Normal; Special, Restricted (Special)
- Last inspection: AAIP, August 28, 2001, 67 hours before
- Departed: NONE, Kemmerer, WY

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 37; injuries: none; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; last flight review July 30, 2001; seat: left; flight hours: 1,584 total, 66 in this make and model, 1,491 as pilot in command, 31 in the last 90 days, 8 in the last 30 days, 3 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 160° at 6 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 73 °F, dew point 43 °F
- Altimeter: 30.21 inHg
- Observed at: BPI, 65 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 20010902025099A](https://openairdocs.org/incident/20010902025099A), Sep 2, 2001: Hughes 369E, Kemmerer, WY, No damage. (-23) Pilot lost control of the helicopter while hovering to deploy an external load.

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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