Control surfaces electric actuators stops.

[Macm_020171]

Hello community,

I wanted to know how electric actuators in light aircraft stops the rotation of the control surface to the motion limit +/- deg. Are actuators including an integrated stop system (electronic or mechanical)? Or this stopping feature has to be integrated into the airframe?

Thank you!

 

[rb1957]

so sort of how does a fly-by-wire system work (how does moving the stick command the control surface to deploy) ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[jaceb]

both solutions may be used - there is no restriction to use either of this mentioned by you. Everything comes to the cost/reliability/maintainability trade.

 

[BrianE22]

If you can find and watch the right episode of Air Disasters you'll see how it was done on one large commercial aircraft. I believe it was the stop for the aileron. A bolt in the wing was meant to be a stop for the hydraulic ram. The service guy missed putting on a washer that was used for the oversized hole. The bolt broke loose and got pressed by the ram and punctured a hole in the fuel tank - big fire.

I believe it had landed at an Asian destination but I can't remember which.

 

[Ng2020]

Brian I think you're thinking of 737 leading edge slat tracks.

An "electronic stop" would be more complex to get through certification.

Sometimes there may be more than one stop, some in the system, some on the airframe.

 

[rb1957]

there'd be hard stops for max deflection, but how does the side stick control the surface?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[WKTaylor]

This is a very odd question. As far as GA aircraft are concerned, I'm aware of electrical actuators used for trim-tab [crew command] actuation or stab-trim [electric motor jack-screw] or for flap extend-retract. These electrical actuators typically have 'return-to-off' springs that shut-off the actuator instantly... with/without position/extension sensors for instrument reading of position... and limit switches for 'hard-mechanical-stop'.

I am unaware of any GA Acft using electrical [fly-by-wire] actuation for flight control surfaces. OK, maybe autopilot servos driving trim tabs.

Trim tab(s) systems are typically light-weight flight control cable driven.

Flight control systems typically have 'stout' flight control cable systems or Push-Pull rods or torque-tubes connected to stick/yoke or pedals.

In every case, to limit control surface movement there are 'hard-stops' made from high bearing/wear strength materials [aluminum, steel, hard reinforced plastic, etc] and with fine +/- 'stop-movement' adjustments made using a crown-head 'adjusting screw' such as NAS428, with locking devices.

Regards, Wil Taylor
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