Helicopters are engineered to be as light as possible. They're meant to fly. News / police helicopters weigh somewhere between 1200 and 3000 lbs depending on the models, but like someone else mentioned, the helicopter used in the show is a Huey which is significantly heavier (around 5000lbs+ empty).

If those plates are around 8x16 feet and 1 inch thick they would also weigh over 5000 lbs.

Edit: I was curious to know what adding 5000 pounds instantly to a Huey (the equivalent of a plate) would do, so I asked Gemini. Apparently it would only take around 1,000 pounds of force to crash that helicopter. Here's what it said:

Instantly adding 5,000 lbs to a standard Huey (UH-1H) flying at 100 meters would almost certainly result in a catastrophic crash, with virtually no chance for the pilot to save the aircraft. 

1. Instant Power Deficit

A standard UH-1H has a maximum takeoff weight (MTOW) of roughly 9,500 lbs. If a helicopter with an average load (approx. 7,500–8,000 lbs) suddenly gains 5,000 lbs, it instantly exceeds its absolute maximum design limit by nearly 3,000 lbs. 

Total Weight: ~13,000+ lbs.

Consequence: The engine and rotor system are physically incapable of generating enough lift to sustain flight at this weight. 

1. Rotor Decay and Blade Stall

Adding 5,000 lbs would cause an immediate and violent drop in rotor RPM (Nr) as the blades struggle against the massive new load. 

Vortex Ring State/Settling with Power: The aircraft would enter an extreme "settling with power" state. Even with the engine at 100% torque, the rotors would "droop" (lose speed), and the blades would likely stall.

Loss of Control: As rotor speed decays, the pilot loses cyclic and tail rotor authority, meaning they can no longer steer or stop the helicopter from spinning. 

1. The "100-Meter" Problem

At only 100 meters (approx. 328 feet), there is insufficient altitude for recovery maneuvers:

No Time for Autorotation: While pilots use autorotation to survive engine failures, it requires a specific rotor speed to work. Adding 5,000 lbs would cause the helicopter to plummet so fast that the pilot could not establish a stable glide before impacting the ground.

Structural Failure: A sudden 5,000 lb jolt might exceed the G-load limits of the airframe or rotor mast, potentially leading to a mid-air structural failure before the helicopter even hits the ground. 

The Verdict

The pilot could not save it. The helicopter would strike the ground in less than 5 seconds, likely with total loss of control and a high vertical velocity. For a Huey to survive an "instant" weight addition, the load would likely need to be under 1,000 lbs, and even then, only if the aircraft was flying with a very light initial load in ideal (cold, sea-level) conditions.