ALH Dhruv problems: Helicopters crashes HAL doesn't want you to know about

[Echo419]

I've been following the ALH Dhruv helicopter crashes for a while now. I've noticed there has always been a pattern of denial by HAL.The investigations are also shrouded in mystery. There was an air crash near Ranchi on 19 October 2011. Though it opened up an enquiry from DGCA, the AFCS data was apparently missing. Is this a cover up?

ALH Dhruv problems: Helicopter crashes HAL wants you to forget | George Kottakal (http://georgekottakal.com/2017/02/alh-dhruv-problems-helicopter-crashes-hal/)

I've put up some of the information here. If there is any ALH Dhruv pilot out there who can give me clarity on the subject do reach out to me. Even if you have a basic understanding of helicopter crash reports do let me know. The links for the report is given in the article.

Thanks and Regards

[Echo419]

I came across this article from India where the manufacturer of the helicopter (Hindustan Aeronautics Limited) kept lying about the safety issues with its helicopter. It resulted in a series of crashes over the years in India and Ecuador.


ALH Dhruv problems: Helicopter crashes HAL wants you to forget | George Kottakal (http://georgekottakal.com/2017/02/alh-dhruv-problems-helicopter-crashes-hal/)

Question 1: How big is the problem of cyclic saturation with a rigid rotor system? Can a rotor actually break mid-air because of it?

Question 2: Is there a Standard Operating Procedure when one enters into a situation of cyclic saturation? The correct response according to some is to lower the collective and then turning cyclic to the right. But that sounds a bit vague. :oh:

Question 3: There is mention of a warning system that would provide visual and audio warnings. How long would it take to retrofit one into said chopper?

On a separate note, I came across 2 different versions for the same crash ( Ecuador FAE 603 ALH Dhruv)

Version 1: HAL manufacturer says that the crash took place due to Pilot Associated Oscillations (Human error).

India looks at European safety certification for Dhruv choppers | Business Standard News (http://www.business-standard.com/article/news-ians/india-looks-at-european-safety-certification-for-dhruv-choppers-116112501002_1.html)


Version 2: Military Accident Investigation Board says that crash took place due to the presence of oscillations as the autopilot had malfunctioned.


Tres naves Dhruv dejarán de volar en Ecuador (http://www.eltelegrafo.com.ec/noticias/politica/1/tres-naves-dhruv-dejaran-de-volar-en-ecuador)

Are they both right? Is one of them lying?

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Perhaps you should look at the Bo105 which I believe had similar handling qualities in a hard left turn.

[JohnDixson]

Is the term " cyclic saturation " used to mean overload/stall of a control system hydraulic actuator?

[skadi]

Perhaps you should look at the Bo105 which I believe had similar handling qualities in a hard left turn.

No, that was in a hard and slow right turn,when the BO could reach the left lateral cyclic stop. That in combination with unsufficent altitude could end bad...

skadi

[[email protected]]

Yes and the 105 ISTR has an anti clockwise rotation of the MR when viewed from above whereas, if i read it correctly, the DHruv has a clockwise rotation.

So the Dhruv has the problem in a left turn and the 105 has the problem in a right turn.

Both the Lynx and the Sea King (to a much lesser degree) has the same problem in a right turn (anti-clockwise rotation) where an acceleration cross-couple caused more right turn when you loaded the rotor.

Not sure saturation is the right term since you simply run out of cyclic control to oppose the turn.