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Aviation History
2004
2004-09 - 1064.PDF
Flight test AB139 The preliminary .hyilllllJnu.l |' shows no weight restriction for an in-g round-effect twin-engine hover at maximum continuous power guard against overtorquing the gearbox, although this might be difficult anyway with the helicopter's full-authority digital engine controls (FADEC). All transients are recorded by the stan dard health and usage monitoring system, which records over 40 parameters. The gearbox is designed to run without oil for at least 30min, enough time to get to a proper landing site. This is one of many safety requirements manufacturers now have to comply with to achieve European and US certification. The high-mass com ponents mounted overhead, such as the main gearbox and engines, are designed to stay in place in a crash or heavy landing and not penetrate the cabin structure. The initial impact is taken by the energy- absorbing undercarriage, then by the crashworthy subfloor. All seats and fuel tanks are crashworthy. The tanks are behind the cabin, hence the low floor. The main rotor blades have swept tips, and all flapping, dragging and feathering movements are accommodated by one elastomeric bearing for each of the five blades so no lubrication is required at the hub. The main and tail rotors are mounted high enough to stay out of the way of pas sengers and others. A unique feature is the horizontal stabiliser with its upturned tips. These help to offload the tail rotor and assist with stabilisation at high speed, espe cially after an autopilot failure. Although Agusta still has to explore hot, high and heavy performance, the AB139 has been to 17,000ft (5,200m) density altitude and the company is confident that there will always be plenty of tail rotor power available. Impressive hover The rotors and engines give impressive per formance. The preliminary flight manual which, at the moment goes only to 10,000ft, shows no weight restriction for an in-ground-effect twin-engine hover at maximum continuous power, nor for an out-of-ground-effect hover at standard- atmosphere outside air temperature (OAT). Single-engine hover performance is also impressive. The aircraft can hover on one engine at maximum weight at sea level using 2.5min power in ground effect up to an OAT of 40°C. This means that, if the air craft is engaged in a rescue operation winching someone up, it can suffer an engine failure and remain in the hover, even at maximum weight. My own unoffi cial interpolation of the graph suggests that the AB139 will probably do likewise at the increased weight to 6,400kg to a maxi mum OAT of 25°C (77°F). OAT was 25°C for our test flight, so we used the aircraft's air conditioning system. If engaged in a resc FH 4 r«i tmvj i ii*< ii i iii i someone up, the aircraft can suffer an engine failure and remain in the hover Windspeed was lOkt (18km/h), density alti tude 1,500ft, and the centre-of-gravity posi tion was mid-aft. At my request, the aircraft was at its 6,000kg maximum gross weight. As well as Bellucci in the left-hand seat, there was a photographer in the jump seat. Initial impressions of the cockpit are of its user friendly and ergonomically pleasing design. The production aircraft will have plenty of space to install pockets and other receptacles for stowing the pilots' gear. This is important, as the AB139 will eventually be certificated for single-pilot instrument flight rules. Honeywell Primus Epic inte grated avionics are standard. Our prototype had three 150 x 205mm (6 x 8in) multi function displays (MFD), but production aircraft will be fitted as standard with the www.fliqhtinternational.com FLIGHT INTERNATIONAL 22-28 JUNE 2004 29
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