What should be the first step if an engine fire occurs while in flight?

In the event of an engine fire during flight, the first step should indeed be to open the cabin heat and prepare for autorotation. This action is crucial because it addresses the immediate necessity of maintaining control of the helicopter while you manage the emergency.

Opening the cabin heat performs two important functions. First, it can help to divert smoke and fumes away from the cabin, providing a clearer atmosphere for the pilot and any passengers, which is vital for maintaining situational awareness and ensuring safe handling of the aircraft. Second, preparing for autorotation is essential, as the engine may shut down due to the fire, and the pilot needs to establish a controlled descent. Being in the proper mindset to execute an autorotation allows for a better chance of landing safely.

While other options suggest taking action as well, they do not prioritize maintaining control and readiness for an emergency descent. Attempting to extinguish the fire manually could be risky and may not address the immediate threat to flight safety. Shutting off navigation systems is unnecessary at this stage, as the primary concern is ensuring control of the aircraft. Reducing speed and climbing may conflict with the need for a controlled descent in case of engine failure. Thus, focusing on cabin heat and preparing for autorotation is the most critical