The US Federal Aviation Administration is expected to "sign off" on a performance improvement programme for the Boeing MD 600N helicopter by the end of July.

The year-long effort will result in clearance for take-off and landing at 7,000ft (2,130m) density altitude at all-up weights of up to 1,750kg (3,850lb), and at 4,000ft altitude at 1,860kg.

Other upgrades will allow operators to fly the MD 600N with doors off at speeds up to 115kt (212km/h), operate at temperatures up to 52°C, and lift up to 970kg on its external hook. The aircraft has also been certified to land on slopes of up to 10°.

Boeing says the improvements are aimed at expanding the operating envelope and were not introduced because of the three flight test incidents in 1996/7 which delayed certification of the helicopter by about six months.

The incidents, in which a prototype MD 600N was destroyed by the resulting bush fire, forced Boeing to strengthen the gear strut and skid. The new upgrades "-will be handled as a revision to the rotorcraft flight manual, and allow the operator to expand the envelope", says Boeing.

The revised manual will apply to 21 MD 600Ns now operated in Africa, Europe and the USA, as well as to 20 others due for delivery by the end of this year. It will also apply to the 45 MD 600Ns due to begin deliveries to the US Border Patrol at the end of this month.

Boeing says "other certification tests" have also been approved that allow the helicopter to be operated in temperatures down to -40°C and enable it to use emergency floats and a wire strike protector.

Other new certified add-ons include executive seats in the rear cabin, bubble windows, a moveable landing light and a 127 litre (33.5 USgal) auxiliary fuel tank.

Source: Flight International