Seawolves or a helicopter crash question

[GlennH]

midnightprowler

Yeah the ground would pop smoke and the aircraft would confirm color. Ground never said what color because Charlie would pop the same color.

and yeah, if the rotor seized, the chopper would fall like a anvil.

Exactly, ground announces pop smoke. Aircraft confirms the color of smoke they see.

Yep.

Only saw one go down thankfully about a hundred feet away. They were coming in for a medevac and not very high fortunately, maybe a couple hundred feet, when there was an explosion and it knocked out the tail rotor.

[midnightprowler]

The last pic looks like a BELL 206 or Kiowa, the rotorblades on the mast are fully articulated. By that I mean there are many more pitch links involved in operating the rotors, it is possible those were damaged in the crash and the “lead” blade simply turned over on impact.

I also agree with the other posts about the transmission seperating from the aircraft in the event of a siezure, most definitely. The cause of the rotor stoppage and blade siezure could be a combination of a broken main driveshaft from the engines to tranny and a defective OR improperly applied rotor brake.

No, it is clearly a Huey.

[midnightprowler]

During my 1/2 helicopter flight instruction we did a short auto rotation. In involved pulling down a lever that disconnected the rotor from the engine. The instructor pointed out the difference in rotor rpm and engine rpm. Based on this interesting thread I assume the transmission is still involved, yes?

That lever is called the collective, it changes the pitch of the main rotor. When autorotating the pitch is lowered and the rotor freewheels, by the air rushing thru the underside of the rotor and the helicopter acts like a quickly falling autogyro.So in a way the transmission is involved. If it seized the rotors would still stop.

[stikpusher]

armornut

The last pic looks like a BELL 206 or Kiowa, the rotorblades on the mast are fully articulated. By that I mean there are many more pitch links involved in operating the rotors, it is possible those were damaged in the crash and the “lead” blade simply turned over on impact.

I also agree with the other posts about the transmission seperating from the aircraft in the event of a siezure, most definitely. The cause of the rotor stoppage and blade siezure could be a combination of a broken main driveshaft from the engines to tranny and a defective OR improperly applied rotor brake.

No, it is clearly a Huey.

I was gonna say that the 206/OH-58 does not have that cross bar across the top of the main rotor…

[armornut]

Yep, my bad took a second better look, yes a Heuy. Can anyone identify the long straight thing coming out of what is left of the engine deck? My first thought was the tail rotor drive shaft but given the angle the fuselage is laying??? Could it have been a collision with a high raised object? Radio antenna, cell tower?

[midnightprowler]

Can’t be the drive shaft its facing forward. Very strange.

[Strongeagle]

Can’t be the drive shaft its facing forward. Very strang

It appears to be one of the huey’s skid landing gear. You can see the other one at the bottom of the pile if you follow the skid cross member down to the ground. The crash really scrambled up the pieces.

[midnightprowler]

You may be correct.

[armornut]

Not sure why I’m so intent on trying to solve the question…sorry thinking out loud…

Yes it could be one of the skids, most likely explanation, it truly is a pile of parts.

[jeaton01]

There is a clutch in the transmission that operates automatically to disconnect the main shaft from the gear section of the transmssion. This is true of all helicopters that I know of. If the engine fails, or is simply throttled back, this clutch will disengage and then rotor rpm is determined by airflow up through the rotor system. When you autorotate, you manage rotor rpm by maintaining the right combination of forward speed and rate of descent, forward speed with the cyclic stick primarily, and rotor speed with the collective. RPM of the engine is controlled with the grip of the collective, rotating the grip will add or reduce power, in combination with the governor on turbine engines or a correlation box on piston powered helicopters. To start an intentional autorotation the pilot rolls the power off and applies the proper cyclic and collective controls. If the collective is dropped all the way the rotor blades reach a pitch stop that limits the top rpm the rotor system can reach. If too much pitch is pulled, rotor rpm falls off and that can be a very bad thing because the only way you can get it back is to increase the rate of descent. The blades don’t have to come to a complete stop for the helicopter to fall like a rock. Just how a transmission might fail surely depends on where the damage occurs, but I would suspect that gear and bearing damage and oil loss would be as big a factor as actual system lockup from the initial impact.