Boeing has outlined plans to integrate and test the power upgrades at the heart of the Block III upgrade programme for the US Army AH-64D Apache Longbow.

Manned-unmanned teaming and avionics improvements have been the focus over the past year of flight tests for the Block III system, the first major Apache fleet upgrade since the Longbow version was introduced about 20 years ago.

But the Block III programme is also aimed at improving the engine's thrust by 20%. The new General Electric 701D will increase its thrust rating from 2,830shp (2,100kW) to 3,400shp.

Meanwhile, an all-new drive system, including the operational debut of a gearbox with split-torque face gear, will enable the currently limited transmission to handle the higher power levels.


Boeing is now validating in ground tests that the new face gear technology is meshing most efficiently and making refinements, says Scott Rudy, Boeing's Apache programme manager.

The face gear checks will be quickly followed by completing bench tests on the new drive system by end-May, Rudy adds. The new transmission will be tested on a ground test vehicle in July, and finally, the new power and drive systems will be installed on a structures vehicle that arrives in the flight-test fleet in August, he says.

The army will conduct a limited user test using two Block III test vehicles starting in November, but neither will include the power upgrades. Instead the test is focused on evaluating the manned-unmanned teaming, including full control of an unmanned aircraft and sensor from the Apache cockpit.

Immediately following the limited user test, the army will begin testing Block III test vehicles that have the full package of engine and avionics improvements, Rudy says.

The Block III programme then has two years to complete development before launching its graduation exercise - the initial operational test and evaluation - in the first quarter of fiscal year 2012.

The US Congress, meanwhile, is steadily expanding the programme. The army's initial requirement for Block III Apaches ranges from 224 to 236, but the Congress is adding up to 52 wartime replacements through FY2011 and convert four Army National Guard battalions from AH-64As to the D-model.

Boeing also believes the army has a long-term requirement to acquire nearly 400 more AH-64Ds from 2017 to 2040, raising the overall fleet to about 800 aircraft over that period.

Source: Flight International