A Line Mechanic described the current and potential problems with deferring and disconnecting the Forward Passenger Door Power Assist Cable under MEL 52-11-1 for CRJ-200's and -900 aircraft.

Narrative

[We received a] pilot report (PIREP) for CRJ-900 passenger door very difficult to open and close. Removed jet bridge at gate. Found broken strands of cable wrapped around itself going to the Power Assist Motor. Mechanic Y cut the broken strands and then I disconnected Power Assist Cable. The cable then retracted into the motor housing. Placed the passenger door in the horizontal position with support and inspected [the] passenger door for any damage with Mechanic Y and crew members outside. Closed and opened the door [to check] for defects. The door operations checked good; no defects noted or any damage. [We] completed MEL procedure for Deactivation of Power Assist [Motor]. Four days later; third shift; working on MEL 52-11-1C Passenger Door Power Assist had trouble opening and closing the passenger door. I inspected the door and found a lot of damage to outer skin and surrounding structure (steps had buckles on either side of the steps). Supervisor said the door is hard to open and close and could not let it go on MEL. I did NOT have the problems that they were having or damage [when] I deferred the power assist. They also could not find any damage that I noted to them.The plane flew for four days with no problems. At sometime; no one caught the door [as it was opening] and it shows the door has impact damage from hitting the ground. I [had previously] installed the Placard outside of the door next to the handle. The cable slows the door down. When [the door is] on MEL and the cable disconnected; the door slams outward very hard and its very heavy; where it will bounce with the wheel out; then the door will bounce high enough where the wheel will go to the stow position then land on the ground. This has been a problem any time this MEL is applied to the CRJ-200's or the -900's. The placard doesn't do enough. There are ramp personal opening and closing the doors with crew not around [and] they might not see the placard at night. Take the MEL out or do a two-day flight MEL 'A'. [There will be] less of a chance to get damaged.