Accident mars AB139 progress

 - October 9, 2007, 8:58 AM

Before suffering a fatal crash April 22, the joint Bell/Agusta AB139 helicopter was enjoying a notably trouble-free development program that was at times well ahead of its original development schedule, and being warmly received by its target markets, both rarities in commercial aviation today and nearly miracles in the helicopter business. Three preproduction development prototypes were in flight test, with the first making its maiden flight on February 3 last year, followed by the second on June 4 and the third on October 22.

According to preliminary reports, the aircraft lost in the April 22 accident was the first preproduction prototype. Flying the aircraft at the time of the accident was test commander Pietro Vananzi, assisted by flight-test engineer Vincenzo Iellamo. The two were reportedly practicing high-altitude autorotations at 6,000 ft near the northern Italian air force base at Rimini, some 25 mi from Bologna. Following a malfunction of as yet undetermined nature, eyewitnesses said they saw both men exit the airborne helicopter safely. However, engineer Iellamo’s chute fouled in the AB139’s tail rotor and he was swept to his death and killed.

Italian aeronautical investigators are looking into the matter, and there is a nearly complete news blackout on the accident, reminiscent of the kind formerly favored by the U.S. government’s NTSB. Agusta, likewise, has maintained a low profile since the tragedy.

Steady Progress

Announced at the 1998 Farnborough Air Show as a joint venture of the newly formed Bell/Agusta Aerospace Co., the AB139 was proceeding through its design, fabrication and flight-test programs at a refreshingly brisk pace when the project tripped. Under the joint-production agreement, 75 percent of the AB139’s project responsibility has been shouldered by Agusta, which plans to produce the helicopter at its Frigate plant outside Milan, with the remaining 25 percent left for Bell Helicopter to fulfill.

The flight-test program had been heading toward certification of the 13,227-lb mtow rotorcraft by the third quarter of this year. Flight-test objectives already met include a maximum continuous speed of 185 kt, making it one of the fastest civil helicopters ever built.

A conventionally configured helicopter, the AB139 at mtow has demonstrated a cruise speed in excess of 157 kt, a maximum ceiling of 20,000 ft and a hover out of ground effect at 12,000 ft. The maximum rate of climb achieved has exceeded 2,200 fpm.

Like nearly every other major commercial helicopter program under development today, the AB139 program includes an assortment of international risk-sharing companies, among them Pratt & Whitney Canada, Honeywell, PZL Swidnik of Poland, Liebherr of Germany, Japanese industrial conglomerate Kawasaki and a host of lesser players.

A Quiet Technological Tour de Force
In its civil edition, the AB139 can tote a internal useful load, which cubes out to mean seating for as many as 15 passengers in utility-style accommodations. In its military edition, the AB139 is capable of carrying up to 15 troops and their equipment, or six stretchers with four medical attendants. The helicopter can be fitted with gun pods, rocket launchers and air-to-air missiles attached to two removable weapons sponsons.

Driving all this cargo capacity are a pair of P&WC PT6C-67C turboshaft engines with Fadec. The engines provide a maximum continuous power of 1,531 shp each and a maximum range (without reserves) of 400 nm. Thanks to the power reserve of the engines, safe flight is ensured with one engine inoperative (OEI) at mtow, in compliance with ICAO/JAA regulations.

Up Front
It’s uncommon to talk much about fancy avionics included on a new helicopter, but the AB139 represents the first time that such an ambitious package flew on any aircraft. The suite has since gone on to become standard equipment for the Raytheon Hawker Horizon and proposed Hawker 450, Cessna Citation Sovereign, Gulfstream GV-SP, Dassault Falcon 900EX, Embraer 170/190 and Fairchild Dornier 728/928.

The AB139’s Honeywell Primus Epic avionics suite is offered in four configurations: basic VFR, IFR three-axis automatic flight control system (AFCS), IFR four-axis digital AFCS and a search-and-rescue version. The IFR versions have three or four Honeywell 8- by 10-in. active-matrix liquid crystal displays. The Honeywell flat-panel displays provide advanced graphics generation capabilities, and two cursor control devices (CCDs) act as a “computer mouse” for the system.

The system architecture is built on two modular avionics units (MAUs) that house the processing functions within the system. By integrating the functions into an MAU, powerful computer processing can be shared to do multiple tasks that previously required individual computer platforms.

The system features a powerful central maintenance computer function that will provide operators with a high level of troubleshooting and system maintenance support. Maintenance personnel may use the cockpit displays or a laptop computer to perform aircraft rigging, sensor calibration and avionics systems diagnostics.

Despite its recent setback, Bell/ Agusta Aerospace remains committed to the AB139 program. Production had begun before the accident, but has reportedly been slow-tracked since.

Certification is still expected this year, although slippage of this self-imposed deadline is likely. Deliveries of the $6.98 million (equipped) rotorcraft will follow.

Inside and out, the AB139 is a functional, no-nonsense design, which has attracted its 50 or so advance buyers of the machine. “It fills a niche in between light singles such as the EC 135 and larger Bells such as the 412,” said one commercial operator. “If Bell/Agusta can bring it to the market at the advertised price and performance, I think it has got a winner.”