PPRuNe Forums - View Single Post - Jackstall: What is it? Any experiences?
View Single Post
Old 6th December 2006 | 22:37
  #51 (permalink)  
petitfromage
 
Joined: Feb 2005
Posts: 291
Likes: 0
From: Chamonix
So...we are all agreed then?

a. Jack Stall occurs when the limits of the designers chosen hydraulics jacks are exceeded by the aerodynamic forces of stalled rotor blades.

b. Both roll &/or pitch control (or both) are lost for the period of exceedence.

c. It is violent, potentially fatal & probably reduces the airframe & component fatigue life &....

d. Can, like LTE, be significantly reduced (even eliminated) with more robust design efforts.

**

My 2cents:

Risk management is the very essence of being a pilot (esp a helo pilot).
I agree with Nick entirely but the manufacturers also have valid points. Eg: Mr Robinson designed a the R22 to commute from A to B. If you're throwing it around mustering or deer hunting then you must bear some responsibility if things break.

RBS and Jack Stall are not always the result of deliberately being a cowboy. Scooting around a ridge into a string wind is a common cause.
(other factors are weight, blade angle, rate of control inputs, temperature/humidity/density altitude and TAS)

Perhaps the compromise is that if you're NOE at 8000ft, ISA+20 and dodging gunfire in the Afgan mountains......you surely deserve powerful hyd jacks.
If you're helo was designed for flying tourists on city tours of NYC, then I you should be flying within the most limiting factor (be that mechanical or crew experience).

So where does that leave us?
Should manufacturers be providing a comprehensive list of tasks, locations or environments that void the helos warranty?

btw: The Huey jackstalls with carefree abandon. (Euro vs USA isn't a rivalry worth anyones time/effort).

Nick...I can only agree with your points but following that same route:

a. We'd all be flying twin engined helos that can hover at MAUW on 1 at ISA+15 'just in case' the engineers failed us and,
b. We'd all have anti-icing and full IFR avionics just in case, in poor weather with poor airmanship, we failed ourselves?
petitfromage is offline  
Reply