BOEING IS PUSHING A service-life extension of its CH-46 to the US Navy as an alternative to procuring a new helicopter to fulfil the vertical-replenishment (vertrep) role.

It has proposed a basic CH-46 fleet-sustainment plan to the US Naval Air Systems Command, under which the safe and economical operation of the aging helicopter will be extended to 2025 .

The company believes that the plan will be the most cost-effective option for the USN, which recently extended the evaluation of commercially operated helicopters for vertrep of warships as an alternative to the CH-46 (Flight International, 21-27 February).

The proposal also addresses the requirements of the US Marine Corps, which is not expected to have sufficient V-22 Osprey capacity to enable the retirement of its last machines until 2017. The prototype Model 107 was flown in 1958 and has been consistently upgraded in an attempt to keep pace with requirements. Although even Boeing sources agree that "...the Navy would prefer something new for most of the roles", the dual-rotor configuration of the CH-46 makes it ideal for vertrep.

Much of the proposal builds on the platform of a dynamic component upgrade (DCU) modification kit entering service this month on the first modified CH-46.

The helicopter was fitted with the kit at the Naval Aviation Depot at MCAS Cherry Point, North Carolina. The work was being undertaken as part of routine depot-level maintenance. The aircraft, is the first of more than 400 H-46s expected, eventually to receive the upgrade.

Boeing is contracted to supply 342 DCU kits, some 261 for the USMC CH/HH-46 fleet and 81 for the USN's remaining 81 HH/UH-46s.

The DCU attacks problems of reliability and restricted flight-envelopes, which have been caused by rotor-related endurance and fatigue issues. The kit includes a stainless-steel rotor-head assembly, drive shaft, control system and transmission parts.

Concurrently with the first installations, a kit-equipped Navy H-46 is also being flight tested by Boeing pilots at the company's Wilmington flight-test site in Delaware.

The 17h programme, which was started in the middle of November 1995, and is scheduled to be completed, by late January has been disrupted by bad winter weather. The programme, is now expected to be completed in March.

Source: Flight International