Actuator fault is a prominent system's issue that attracts the researchers' attentions. One type of actuator fault is a constant Loss-of-Effectiveness (LoE). In this paper, two systematic algorithms are presented. The first algorithm is designed to detect and diagnosis the actuator fault. This Fault-Detection-and-Diagnosis (FDD) approach relies on an estimator design that is called intelligent Output-Estimator (iOE). The proposed iOE is intended to improve the estimation of the actuator fault based on the Model-Free technique. The second algorithm works online after detecting, isolating and estimating the actuator fault. This Active-Fault-Tolerant-Control (AFTC) algorithm will use the estimated actuator value in a reconfigured control design to compensate for the fault. Real-time flight tests are applied on the Qball-X4 quadrotor. Different LoE actuator-fault scenarios are presented in this paper to validate the proposed algorithms.