An interesting story at the link below describes the kind of real-world flight tests that a recent class of Test Pilot School students performed. This is not just fluff. As a former Deputy Commandant of the USAF Test Pilot School, I can tell you that the services are wringing every last dollar out of their training by putting them to work answering real-world questions while they train. An interesting list of projects is provided in the article, and while the risk is generally low, it is NOT zero.
http://www.edwards.af.mil/news/story.asp?id=123330597
Hello!
ReplyDeleteI’m sorry for disturbing. I am a PPL pilot and I need some advice from someone with technical knowledge on flight controls systems.
Assuming a conventional flight control system on a light airplane (cable operated, pushrods or other variation) do you figure out an internal failure causing the actuated surface to deflect and jam beyond current position? That is, is there a way to fail (bellcrank, pulley, I don’t know) in which the surface might jam to an extreme position, beyond the position that was when the failure occurred?
I figure out the only possibility is the surface jams in current position or becomes freefloating due to linkage/cable failure and in this case it returns to neutral position because of airflow acting and neutralizing the surface.
Basically, as an example, if the pilot haven’t use more than one third control deflection, can you figure out a control system failure which results in surface being jammed more beyond that position?
Could it jam towards an extreme due to flapping or fluttering or when it breaks could it slam and jam in an unfavorable position to recover?
What do you think?
Thank you very much!
PLEASE REPLY AT rich_swave@yahoo.com
Typically, for a reversible flight control system, parts 23 and 25 require that there be very limited stick force reversal as controls are deflected. I bring this up because stick force reversal implies a flight control surface that is trying to deflect farther than it has been intentionally deflected by the pilot. If a control system DOES have such force reversal, then you could probably expect that upon failure of certain mechanical components, the surface will keep going, perhaps to the stop. So the typical answer to your question would be "No if the system is well-designed, but yes if it is not."
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