ASN Wikibase Occurrence # 141912
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| Date: | Monday 16 January 2012 |
| Time: | 06:15 |
| Type: |  Bell 214ST |
| Owner/operator: | AAR Airlift |
| Registration: | N5748M |
| MSN: | 28102 |
| Year of manufacture: | 1981 |
| Total airframe hrs: | 11538 hours |
| Engine model: | General Electric CT7-2A |
| Fatalities: | Fatalities: 3 / Occupants: 3 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | 7 mi S of Camp Bastion, Helmand Province -
 Afghanistan
|
| Phase: | En route |
| Nature: | Passenger - Non-Scheduled/charter/Air Taxi |
| Departure airport: | Camp Bastion, Helmand |
| Shindand Air Base, Helmand | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
Witness accounts from the flight crew of the helicopter flying behind the accident helicopter indicated that, after both helicopters had climbed to an altitude between about 800 to 1,000 feet, the accident helicopter rolled sharply to the right and entered a steep, nose-down pitch, at which time the aft tailboom separated from the helicopter. The helicopter's nose-down pitch attitude continued until ground impact.
There was no evidence of abnormal engine operation at the time of the accident or a failure of the tail rotor system or a major airframe structural component before the in-flight breakup. The damage observed on the right collective lever arm, idler link, and collective sleeve bearing support assemblies were consistent with an overtravel of the collective sleeve, which resulted in a severe and sudden reduction in main rotor collective pitch. Also, the damage to the left and right sides of the idler link showed that the left and right collective lever arms were in their installed position at the time of the collective sleeve overtravel.
Bell Helicopter Textron's math model simulation of the Bell 214 helicopter's response to a sudden and severe reduction of main rotor collective pitch (resulting from a failure of the collective flight control system) showed that the helicopter would respond with a severe right roll and a simultaneous nose-down pitch attitude. The math model simulation also showed that a sudden and severe reduction of main rotor collective pitch would cause the main rotor hub to exceed its flapping angle and the main rotor blade tips to deflect downward and possibly contact the tailboom due to the reduced amount of clearance.
The results of the math model simulation were closely aligned with the witness accounts from the flight crew of the helicopter behind the accident helicopter and the damage observed on the helicopter wreckage. For example, the nose-down pitch and right roll observed in the math model simulation was similar to the reported pitch and roll of the accident helicopter when the accident sequence began. Also, the main rotor mast showed damage consistent with mast bumping that resulted when the main rotor hub significantly exceeded its flapping angle. Thus, the evidence showed that, when the accident helicopter's main rotor hub exceeded its flapping angle, the resulting loss of clearance between the main rotor system blades and the tailboom caused the main rotor blades to contact the tailboom. This contact was severe enough to cause the aft tailboom section to completely separate from the rest of the tailboom, leading to a loss of pitch control.
Probable Cause: the overtravel of the collective sleeve, which led to a severe and sudden reduction in main rotor blade collective pitch, resulting in a loss of control of the helicopter. The reason for the collective sleeve overtravel could not be determined since much of the collective control system was consumed in the post crash fire.
Sources:
NTSB
http://aerossurance.com/helicopters/aar-214st-afghanistan-2012/
Location
Media:
OTD in 2012: AAR Bell 214ST Accident in Afghanistanhttps://t.co/LUNz3cQld0#NTSB #flightsafety #airworthiness pic.twitter.com/yScAgZqxdZ
— Aerossurance (@Aerossurance) January 17, 2020
#OTD in 2012: AAR Bell 214ST Accident in Afghanistanhttps://t.co/LUNz3cQld0#NTSB #helicopter #accident #flightsafety #aviationsafety #airworthiness pic.twitter.com/H5S7zijHwZ
— Aerossurance (@Aerossurance) January 17, 2021
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 16-Jan-2012 02:20 | gerard57 | Added |
| 16-Jan-2012 04:51 | gerard57 | Updated [Operator, Total fatalities, Total occupants, Source, Narrative] |
| 16-Jan-2012 08:54 | gerard57 | Updated [Operator, Source] |
| 16-Jan-2012 11:06 | marko | Updated [Time] |
| 17-Jan-2012 00:39 | harro | Updated [Aircraft type, Operator] |
| 17-Jan-2012 16:14 | Geno | Updated [Aircraft type, Registration, Cn, Operator, Source] |
| 17-Jan-2012 16:55 | RobertMB | Updated [Time, Location, Source, Narrative] |
| 17-Feb-2012 10:34 | Geno | Updated [Time, Location, Source] |
| 20-Feb-2013 09:04 | TB | Updated [Time, Operator, Location, Source, Narrative] |
| 20-Feb-2013 09:07 | TB | Updated [Source] |
| 20-Aug-2014 20:46 | Aerossurance | Updated [Narrative] |
| 22-Mar-2015 16:15 | Aerossurance | Updated [Narrative] |
| 21-Nov-2015 17:01 | Aerossurance | Updated [Operator, Location, Nature, Departure airport, Destination airport, Narrative] |
| 21-Dec-2016 19:26 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 18-Aug-2017 17:54 | ASN Update Bot | Updated [Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative] |
| 18-Aug-2017 17:58 | harro | Updated [Departure airport, Destination airport, Narrative] |
| 18-Aug-2017 18:32 | ASN Update Bot | Updated [Departure airport, Destination airport] |
| 23-Jan-2020 22:41 | Aerossurance | Updated [Source, Embed code, Narrative] |
| 23-Jan-2020 22:43 | Aerossurance | Updated [Other fatalities, Nature, Departure airport, Destination airport, Embed code] |
| 17-Jan-2021 10:15 | Aerossurance | Updated [Embed code] |
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