What happens to the pitch of the aircraft if there is a loss of the accelerated slip stream over the horizontal stabilizer when an engine fails?

When an engine fails on a multi-engine aircraft, its loss results in a reduction of the accelerated slipstream over the horizontal stabilizer. This accelerated slipstream plays a crucial role in providing the necessary aerodynamic forces that influence the control surfaces, particularly the horizontal stabilizer which affects pitch.

In particular, the loss of engine power from one side typically results in a yawing moment towards the inoperative engine. This yaw is combined with the aircraft's tendency to pitch nose down due to the diminished airflow over the horizontal stabilizer. Without the smooth and effective airflow that the slipstream provides, the pitch of the aircraft tends to decline, leading to a pitch down condition.

This interaction highlights the importance of maintaining adequate control inputs and understanding how changes in engine power and airflow can affect aircraft dynamics, especially during critical phases like an engine failure scenario. Thus, recognizing that the loss of an engine results in decreased lift at the tail due to reduced slipstream effects is key in understanding why the pitch will decrease in such situations.