ASN Wikibase Occurrence # 186773
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| Date: | Monday 25 April 2016 |
| Time: | 18:45 |
| Type: |  Bell 206L-4 LongRanger IV |
| Owner/operator: | Methodist Air Care |
| Registration: | N435AE |
| MSN: | 52446 |
| Year of manufacture: | 2012 |
| Total airframe hrs: | 963 hours |
| Engine model: | Rolls Royce 250-C30P |
| Fatalities: | Fatalities: 0 / Occupants: 3 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Memorial Hermann Hospital Helipad (1TE6), Memorial City, TX -
 United States of America
|
| Phase: | Take off |
| Nature: | Ambulance |
| Departure airport: | Houston, TX (8TS4) |
| Victoria, TX (VCT) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The commercial pilot was departing for a positioning flight from a helipad bordered on three sides by buildings and parking structures. The pilot reported that, after lifting off, as he translated the helicopter from behind one of the buildings and into the prevailing wind, the nose began yawing right. He applied full left pedal, but the helicopter may have fully rotated once while moving back toward the helipad before the rotation stopped. The low rotor speed warning sounded, and the helicopter then began rotating rapidly right. The pilot lowered the collective and maneuvered toward the helipad. He subsequently raised the collective while at 25 ft above ground level, but the helicopter landed hard. A postaccident examination of the helicopter revealed no preimpact mechanical failures or malfunctions that would have precluded normal operation.
A loss of tail rotor effectiveness can be encountered while hovering under certain wind conditions, which may be encountered unexpectedly near buildings due to rapidly changing wind conditions. However, the pilot’s report that the low rotor speed warning sounded and engine data provided by the operator indicated that the main rotor speed decayed during the takeoff with a corresponding decrease in the tail rotor speed. A significant reduction in the tail rotor speed could result in an uncommanded yaw and a loss of directional control. The investigation was unable to determine if the pilot’s loss of directional control was due solely to the decrease in rotor speed during takeoff, the varying wind conditions, or a combination of both.
Probable Cause: The pilot's failure to maintain directional control during takeoff in varying wind conditions, which resulted in a hard landing.
Accident investigation:
 |
|
Sources:
NTSB
FAA register: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=435AE
https://flightaware.com/photos/view/241789-fbbea3e0d62a0a04e9b85bac2a73d26db90d89c1
Location
Media:
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 26-Apr-2016 05:29 | Aerossurance | Added |
| 26-Apr-2016 06:55 | Geno | Updated [Aircraft type, Location, Phase, Departure airport, Destination airport, Source, Narrative] |
| 26-Apr-2016 14:24 | Chieftain | Updated [Narrative] |
| 26-Apr-2016 15:11 | Geno | Updated [Time, Source] |
| 09-May-2016 13:42 | Aerossurance | Updated [Departure airport, Destination airport, Source, Embed code, Narrative] |
| 21-Dec-2016 19:30 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 11-Oct-2017 07:36 | ASN Update Bot | Updated [Operator, Other fatalities, Departure airport, Destination airport, Source, Narrative] |
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