SOURCE: AFI
Hindustan Aeronautics Limited (HAL) has announced plans to conduct an independent review and engage consultancy services aimed at modifying its prototype helicopters to reduce noise levels. The primary goal is to attenuate noise by at least 10 to 15 dB in the critical frequency range of 500 to 8000 Hz to comply with the MIL-STD-1474 D military noise specifications.
This move comes after noise level measurements were carried out inside the cockpit and cabin of one of HAL’s Light Utility Helicopter (LUH) prototypes during developmental flight tests. The tests revealed that the noise levels were exceeding MIL-STD-1474 D limits, particularly in the 500 to 8000 Hz frequency band, which is highly sensitive to the human ear and critical for both comfort and operational safety.
The LUH program is a key initiative by HAL to develop a new generation of lightweight, versatile helicopters for the Indian Armed Forces. These helicopters are expected to perform a variety of roles, including reconnaissance, search and rescue, and troop transport, often in challenging terrains. Ensuring that these helicopters comply with military standards for noise levels is a vital aspect of their design and operational effectiveness.
The MIL-STD-1474 D standard sets stringent limits on noise exposure for military personnel, ensuring that noise levels inside the aircraft do not exceed thresholds that could impair hearing or interfere with communication between crew members. Excessive noise in the cockpit and cabin can also lead to pilot fatigue, reduced situational awareness, and increased stress during long missions.