Residual thrust

[TAC u/s]

On a recent trip to BKK we parked on stand and shutdown, and, after receiving the 'chocks-in-place' signal from the marshaller, I released the park-brake as per our SOP (although I will admit that I was somewhat quicker than normal because of the amount of scribbling I now have to do at the end of every flight; I would normally wait for contact from the engineer). After a few seconds of writing I sensed the terminal moving towards me and jumped on the brakes. We missed the jetway by not very much and were pushed back to our rightful position before the post mortem started.
The stand in question has a slight slope towards the terminal building and on this occasion the apron was wet but nevertheless the brakes were only released when the aircraft was fully at rest and the chocks were in place (though my inspection revealed that only one, rather pathetic chock was used ahead of the right truck).
The engineer said that having placed the chock the aircraft started to aquaplane, pushing the chock ahead of it. But how?
Does anyone have any experience of such a thing? Is there any residual thrust generated by big-fan engines (in this case GE-115) unpowered but still rotating? We have been in contact with Boeing but the emphasis seems to be directed towards the issue of setting the park-brake rather than trying to understand why it happened and I would like to use the enormous experience out there to help me get a better knowledge of this.
Thanks for any offerings.

[TopBunk]

(1) I would imagine that the definition of aquaplaning would be when the wheel rotation rate is less than the rate of aircraft forward movement.

I would very much doubt that aquaplaning took place, I'm 99% sure that the wheel would have been rotating, so I think the engineers description is technically incorrect.

(2) If engines have been shut down and the N1 rotation is merely due to wind flow, I don't believe there can be any noticeable thrust from the engine.

(3) Re chocking and releasing brakes....if you're going to chock the aircraft do it properly, with sufficient number and quality of chocks to hold the aircraft in position in case the brake accumulator is depleted / brake fails etc!

Why you would want to routinely release the parking brake is beyond me - the name of the device says what it is for - to PARK. In that I agree with Boeing. In my company we used to release the brakes when parked but imho properly stopped that procedure about 16 years ago. WHat is the downside - the chance of a stuck brake unit - not known that happen to an extent that it has prevented pushback.

[vapilot2004]

Why you would want to routinely release the parking brake is beyond me - the name of the device says what it is for - to PARK.

Releasing hot brakes will assist cooling and also minimises disc warping.

[Swedish Steve]

Im with Topbunk on this. My airline has a policy of always keeping the Park brake set when parked. I have never known this to cause any problems with the brakes since it was introduced many years ago.
An Asian airline I work for always releases the park brake on arrival as soon as I have called up on the headset that the chocks are in. This causes us to rush out and place the chocks, so we can get the brake off before the jetty is in place, because on the very slight slope, the B777 moves a few inches as it compresses the chocks.

[CV880]

Unless brakes are in the overheat range it is better to leave them parked. 777 has carbon brakes so there is no risk of brake discs sticking together and in fact carbon brakes work better when warm as long as they are in the normal range at the next TO. Asian carrier I worked for stopped routinely releasing the park brake years ago after a couple of unchocked roll away incidents and never had a problem with the brakes.