Paul Lewis / FORT WORTH
Small arms fire, sand ingestion and brown-outs have emerged as the chief challenges facing the US Army's fleet of more than 700 Bell OH-58D Kiowa Warrior, Boeing AH-64 Apache, CH-47D Chinook and Sikorsky UH-60 Black Hawk helicopters operating in Iraq. They have prompted several modifications being rushed to the field while planners are looking at long-term fixes as part of a comprehensive upgrade of the entire rotorcraft inventory.
US Army aviation appears to have emerged from the war relatively unscathed, but facing a hefty repair and overhaul bill. The army to date has lost one UH-60 and one AH-64D, but hard landings in brown-outs have badly damaged two Black Hawks and five Apaches, two of which are write-offs. At least one CH-47D has been hit by a rocket-propelled grenade, forcing it to drop its underslung load.
Col Bill Lake, US Army UH-60 project manager, says sand has been a "significant problem" for engines and avionics. The army is working on a barrier filter for the machine's General Electric T700 engines and auxiliary power unit (APU). The army is planning a "triage" inspection of the 250 deployed Black Hawks after they return, but the cost of repairing and replacing components is already estimated at $500,000 per helicopter.
Over half the initial deployment of 76 OH-58Ds were already equipped with engine barrier filters through a safety enhancement programme. "This is really saving the engine and we not had to replace a single one," says scout/attack project officer Lt Col Jeffrey Crabb. Ground fire has taken its toll on the OH-58D's mast-mounted sight, however.
Engine particle separators and APU filters have helped sustain the 150 AH-64A/Ds in Iraq, but combating brown-outs will require longer-term investment in a new generation forward-looking infrared imager and enhanced flight controls, says Col Ralph Palotta, Apache programme manager. TheUH-60M upgrade, meanwhile, will include a fully coupled flight director allowing step-down landing approaches and, from 2009 a fly-by-wire flight-control system permitting hands off flying.
The US Army has accelerated some Apache improvements, including a new internal auxiliary fuel system trading a 1,200-round 30mm magazine for 380 litres (100USgal) of extra fuel and a 300- round magazine. The first AH-64s equipped with new air transportablility kits have also been deployed, including folding main rotor blades, a quick-fit removable horizontal stabiliser and Longbow radar self-stowage system.
The war has included some firsts, with the opening shot of the ground offensive being the first combat firing of a radar-guided Lockheed Martin AGM-114 Longbow Hellfire by an AH-64D against an Iraqi T-55 main battle tank.
Source: Flight International
