Hope that makes sense. this may have already happened and I am well behind aviation doors but I am under the impression that a system like this doesn't exist?
Also having an entirely manual latch is significantly more reliable in case of the need for emergency evacuation.
Imagine a plane had to ditch into a river, the plane slowly starts to fill with water, the Air stewards can't get the door open as the electrics have gone out!
Also saves weight by not having to fit an actuator to open/close the doors, which hopefully are only open at the start and end of the journey?
Actually, power-operated doors do exist - they were quite common in the 1970s and 1980s; they're fitted to some or all doorways on Lockheed L-1011s, Douglas DC-10s, McDonnell-Douglas MD-11s, and Boeing 767s. The commonality in the systems is that the doors are mounted on runners that carry them
up into the ceiling space above the doorway, so in effect they are quite like the plug doors you see on a train.
The system has a number of advantages; chief amongst them being that the door never has to pass through the doorway as an outward-opening one does, so it can be made physically larger than the doorway and this simplifies pressure-sealing it. Secondly, since there's no external protrusion, there is nothing to be damaged or removed from the aircraft entirely by gusts of wind or badly-aimed pieces of ground equipment. They were also a response to the increasing weight and unwieldiness of early outward hinged designs, which were starting to cause strain injuries to crew opening them and sometimes even more serious injuries to crew trying to close them (the 737 and 757 in particular were quite notorious for this at times).
The actual power assistance techniques varied by manufacturer: on the L-1011 the door was closed against a number of titanium springs with the assistance of an electric motor, with a hand crank provided in case the motor failed. In normal situations the door would be opened by releasing the latches that held it against the spring, with a governor controlling the rate of opening. In an emergency open the governor was disengaged, the slide/raft pack was released, and the door was effectively launched into the ceiling by the full force of springs.
On DC-10s and MD-11s the doors were effectively winched up and down by an electric motor in a windlass-style arrangement, which was more simple to design and maintain than Lockheed's spring-loaded design, but made opening the door very difficult if the motor failed because there was no counterweighting. For emergency opening a bottle of pressurised air or nitrogen (depending on fitout) would "fire" the door up the runners, again aided by weight lost in releasing the slide/raft pack.
Boeing's design was perhaps the most elegant - the door was fully counterweighted and so actually didn't
need the power assistance, so much so that the power-assistance package was only fitted as a standard feature to the front-left door. Without the assistance it could be both closed and opened by one person, although obviously some strength was required to overcome the inertia of the door and the mechanical resistance of the runners. In any case power assistance was preferred for doors in regular use 1) because when opening the door the assistance system automatically disarmed the slide/raft firing system, and 2) when closing the door it meant the staff member didn't need to be tall enough to actually reach the door handles. In an emergency opening the slide/raft pack is released from the door and the counterweight easily carries the door up the runners on its own.
In time though all of the designs fell out of favour for a number of reasons: 1) the systems are very heavy, 2) they take up a lot of ceiling space, which is why they were never used on narrowbodies and which is at a premium even in newer widebodies, and 3) Airbus came up with a decent design for an outwards-opening door that was both lighter and easier to use, and that didn't need space inside the airframe, which Boeing promptly adopted for the 777 and 787.
It was also felt in some quarters that the need for runners to guide the door through its travel made the system more vulnerable to jamming in the event of fuselage distortion, although I don't believe this was ever objectively validated.
Now the fun part:
A DC-10 emergency door opening:
And the same on an MD-11:
And one here on a 767:
For those of you wanting a more in-depth understanding, I'll leave you in the capable hands of Canadian Airlines;
For the DC:10:
And for the 767:
Note: I believe that some companies employed various inward-opening and/or power assistance door concepts before the examples I've given above - the Sud Aviation Caravelle and Lockheed Electra come to mind - but they're not discussed because there's a limit to my willingness to do research for you lot
