This article deals with a new Quality of Service (QoS) aware Two-Level Scheduler (TLS) for real-time (RT) data flows in downlink transmission of Long Term Evolution (LTE) cellular networks. It consists of two distinct scheduler levels. At the upper-level scheduler, the Potential Feedback Controller (PFC) determines the quota of data to transmit in order to meet the delay constraints of RT data flows while, at the lower-lever scheduler, the Proportional Fair (PF) scheduler is used to reach a high fairness among Users (UEs). The PFC is well suited for the upper-level scheduler since it maintains the queue length as close as possible to zero which leads to a low Packet Loss Ratio (PLR). A comparison, by using LTE-Sim simulator, with well-known QoS aware scheduling methods Frame Level Scheduler (FLS), Exponential (EXP)-rule and Logarithmic (LOG)-rule has been provided which shows that our proposed TLS outperforms the EXP-rule and LOG-rule scheduling methods and it slightly decreases the PLR of RT data flows compared to the FLS scheduling method while it significantly reduces the computation time.