Helicopter Crash Inside View

Inside view of helicopter crash due to LTE

Category:

Science & Technology

Tags:

• Helicopter
• crash
• accident
• helicopter accident

[lukefled]

Tail rotor vortex ring state? Mountain flying is a bitch!

[mushatrusha]

Yes, causing the LTE

[obese1konobe]

Poster please can you provide further info please.

Dramatic footage.

Initially I would doubt LTE, as the airspeed is too high. Appears more like a tail rotor failure.

[mushatrusha]

This and the other video you commented about, were shown by Bell Helicopter Textron as examples of LTE on a operation and maintenance conference to helicopter pilots and mechanics. Therefore I took it to be true, but who knows, maybe you are right.

[mushatrusha]

I'm just now seeing these comments on the video I posted. If you check out the other videos I posted you'll find a visual example of a simmilar situation as the one nais very clearly explained.

Suprafrase, yes there are ways to prevent and recover from these situations, but I will leave it for nais to explain them. He'll do it much better than I can.

[nais26]

LTE is Loss of tail rotor effectiveness, it is a condition where the tail rotor thrust can't oppose the yaw produced from the main rotor due to a few possible reasons.. One of the most common is a vortex ring state situation, where the airframe yaw stability is lost due to the horizontal stabilizer becoming erroneous when the aircraft slows for landing, loss of translational lift demands more power on landing and the mix of slow airspeed and increased power presented in a turbulent environment

[nais26]

@Deinacrida Everything control wise is mechanically sound, but it doesn't effectively do what it should. As far as a loss of translational lift is concerned, at low airspeed or in hover (anything below translational lift) you need more power as the effectiveness of airflow over the disc is reduced. So more power pulled means more torque between the main rotor and airframe, which needs more pitch on the tail rotor to counteract it, which means more chance for tailrotor VRS.

[nais26]

@Deinacrida I stated that horizontal stabilizers lose authority and you're right, it's the vertical stabilizers that do, not horizontal, I don't know what I was smoking that day, i was probably reading something else while I was writing. But their loss of effectiveness in hover or low airspeed can accelerate the yaw, increasing the speed of the tail rotor VRS situation. This is when there is a total loss of effectiveness. Notice theres no loss of control, but control effectiveness.

[nais26]

@Deinacrida No probs mate, basically in the event of a LTE, theres a few different nasties that can affect how the tail rotor works, whether that be mechanical or an effect of how the outside forces can change in different circumstances during flight. But as a main rotor can lose effectiveness due to VRS during flight, so can a tail rotor. In gusty conditions wind gusts can travel through the tail rotor in the direction of thrust causing a VRS situation if the heli is moving too slow

[Deinacrida]

This is grim but very interesting. See at 0:32 main rotor sheared off and went skyward - with the mainshaft attached by the looks. There was a person on the summit near the start - hope they didn't get clobbered by bits! It's obviously a Bell Jet Ranger by the shadow and sound.

[Deinacrida]

@nais26 Thanks for that comment, interesting. I'm not quite clear on the loss of tail rotor command: So is it only the 'bleed' of power (due to landing power increase) ? How does the 'vortex ring' part work? Is this the main rotor down wash interfering with the tail rotor thrust projection? Doesn't the horizontal stabiliser help with pitch not yaw? Cheers

[JWTackle]

Perfect example of loss of tailrotor drive. You actually can see the helicopter yaw and the pilot almost emmediatelly does what the emergency checklist tells: collective pitch reduce to stop yawing. You can hear the N1 turbine speed down, when you listen closely to it. He just is to Slow n low to recover the chopper. Bad Luck beeing in the dead mans curve when tailrotor quits service.

[Jackismycopilot]

Everyone is an expert.

[ibtm]

definitely LTE----at the crest the mountain, mountain roll wind is a bitch!!!

[bill4long]

How come the pilot doesn't cuss?

[DiamondPilotDan]

LTE? someone please explain this for me?:)