Bell 214 N5748M

Summary

On 16 January 2012 at about 06:15 local time, a Bell 214 registered N5748M, operated by AAR Airlift, was involved in an accident near Camp Bastion, Afghanistan. 3 people were on board and 3 died. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

16 January 2012 at 06:15

Classification

Accident

Location

Camp Bastion, Afghanistan

Coordinates

31.7836, 64.2103

Aircraft

Bell 214

Registration

N5748M

Category

Helicopter

Engines

2

Operator

AAR Airlift

Operating rule

Part 135: Air Taxi & Commuter

Phase of flight

Not recorded

Route

Camp Bastion → Unknown

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

DCA12FA024

3 people died.

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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

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.

Quoted verbatim from the NTSB record.