OK, I have to ask (since no-one else has); In AlanM's pic, what are the pendulum type objects protruding from the top of the eng cowls?
Airspeed and Directional Sensors. Here's a cut and paste of the description of the one seen on the starboard side of the AH-1F's canopy:-
"Airspeed and Directional Sensor (AADS): The AADS is mounted on a boom to the right side of the airframe between the pilot and gunner stations. The purpose is to measure local airflow pitot and static pressure, the angle of the airflow relative to the helicopter, and the air temperature. The probe can swivel 360 degrees in pitch and 60 degrees plus or minus in yaw, accurately senses impact and static pressure up to 250 knots forward, 50 knots aft, 50 knots left and 50 knots right. The probe information is also used for rocket and automatic gun operations. A 115 VAC heater is contained within the probe which can be activated by the pilot during inclement weather."