Lord has received its first production contract for active vibration control systems on the Hindustan Aeronautics (HAL) Dhruv Advanced Light Helicopter. The first production helicopter with the anti-vibration system is scheduled to enter service in the third quarter.
Production of the twin-turboshaft Dhruv was launched in 2001, deliveries to the Indian armed forces began in March 2002 and HAL obtained Indian civil certification in October last year. The company is aiming for European certification this year.
Cary, North Carolina-based Lord, which supplies the Dhruv's current pylon-isolation system as well as elastomeric rotor bearings, began working with HAL in mid-2002 on an 18-month "fast-track" effort to reduce vibration in the 12-passenger helicopter.
The system uses actively controlled Frahm dampers to reduce fuselage vibration generated by the four-blade main rotor. The vibration control system can be switched between two to four active Frahms, depending on the Dhruv's mission, says Lord.
After diagnostic testing on the ground and in the air at HAL, Lord delivered the first prototype in November 2002. The Indian manufacturer began flying two helicopters equipped with demonstration systems early last year. Lord says flight tests showed the desired vibration reduction in the cockpit as well as reductions throughout the aircraft for almost all flight conditions.
Lord, meanwhile, has introduced a new line of noise and vibration isolation systems specifically designed for the aircraft interiors market. The elastomeric isolators can reduce transmitted vibration by 15dB compared with a conventionally mounted interior panel, the company says, and are intended as drop-in replacements for existing designs.
Source: Flight International
