Helicopter Blades Damaged by Storm Otto

[212man]

Hard to understand how it could have been in limits if the brake was unable to stop the rotation. How was that certified? Shutting down outside limits with another technical problem is an ever present dilemma, with no guarantees how it will go. But, in limits? You would reasonably expect to be able to stop the rotor!

[ShyTorque]

I’ve seen a situation where the wind was so strong that after shutting down the engines the blades continued to autorotate well above the maximum rpm for the use of the rotor brake.

[steve_oc]

Interesting. Sikorsky rotor brakes (S61, S76, S92) may be applied in emergency immediately after engine shutdown with NR still at 100% / 107%, and the AW139 permits application at 90% NR in that situation.

[Blackhawk9]

Originally Posted by steve_oc

Interesting. Sikorsky rotor brakes (S61, S76, S92) may be applied in emergency immediately after engine shutdown with NR still at 100% / 107%, and the AW139 permits application at 90% NR in that situation.

Yes but they work...

[212man]

Originally Posted by steve_oc

Interesting. Sikorsky rotor brakes (S61, S76, S92) may be applied in emergency immediately after engine shutdown with NR still at 100% / 107%, and the AW139 permits application at 90% NR in that situation.

They can also be applied with the engines running (as you know)

[Variable Load]

Originally Posted by 212man

Hard to understand how it could have been in limits if the brake was unable to stop the rotation. How was that certified? Shutting down outside limits with another technical problem is an ever present dilemma, with no guarantees how it will go. But, in limits? You would reasonably expect to be able to stop the rotor!

Perhaps it would be more accurate to state that the wind strength reported to the crew was within the shut down limits. As PlasticCabDriver mentions, the rotor brake itself on the H175 isn't the best. Sometimes you select it on and don't perceive any change in the rate of Nr decay!

[campbeex]

Apologies if this can't be viewed without a subscription:

Video: Footage shows moment Storm Otto rips blades off helicopter

[212man]

Originally Posted by campbeex

Apologies if this can't be viewed without a subscription:

Video: Footage shows moment Storm Otto rips blades off helicopter

I’m guessing it’s the same video I posted earlier?

[jimf671]

Originally Posted by 212man

Pretty sure it doesn’t. CF is an inertial, or pseudo force

Newton Three!