Max Kingsley-Jones/LONDON

Omega-led Seven Q Seven will begin proof-of-concept flight-testing of its Boeing 707-300 re-engining programme in May, with certification expected by early next year.

The Pratt & Whitney JT8D-200 re-engining programme for the 707, first revealed by Flight International in 1997, is being developed by Irish leasing specialist Omega and its Seven Q Seven partners Ed Swearingen and Douglas Jaffe, along with suppliers Pratt & Whitney (engine) and BFGoodrich (nacelle).

Omega director and Seven Q Seven vice-president Ulick McEvaddy says the company recently purchased a 30-year-old 707-300C from Challenge Air Cargo. The aircraft is becoming the prototype.

"The aircraft recently underwent fit-checks with a JT8D-217 installed on the No 1 position," says McEvaddy. "It will be flown in May with one of the four JT3Ds replaced by a JT8D -200 for some brief proof-of-concept testing," he adds. The modification work is being undertaken at Seven Q Seven's site in San Antonio, Texas.

McEvaddy says that the 707 will then be grounded to enable four JT8D-219 engines to be installed, and will begin a 400 hour flight test programme by September. "We expected [US Federal Aviation Administration] certification late this year or early next," he says.

Omega has specified the most powerful (21,500lb/96kN thrust) -219 variant of JT8D-200,which will be derated on its civil conversions to 19,000lb thrust. This is the first underwing application for the JT8D-200, which is normally side-mounted on the aft fuselage of Boeing MD-80s and re-engined 727s. Omega says the switch has required P&W to make some minor changes to the engine primarily concerning the oil, fuel and anti-ice systems. The engine's angle of attack has also been changed, so that on the 707 the inlet is angled 2.5¼ nose down.

As well as bringing the 707 well within the Stage 3 noise limits, the modification will also provide a significant boost in performance. While the final figures will not be known until flight-testing begins, the aircraft is expected to offer a 30%increase in range.

McEvaddy claims that the JT8D-powered 707 will be able to carry "42t of cargo on 11h non-stop missions, giving us 'Europe to South America' capability, at a lower cost than the [McDonnell Douglas] DC-8-73F".

Seven Q Seven has made some significant gains in drag reduction, particularly on the wing/pylon interface, which combined with the higher cruise thrust of the new engines, is expected to provide a Mach 0.05 increase in cruise speed to M0.83. The programme will initially be applied to Omega's own fleet of 12 707-300s, and the leasing company has identified a potential market for at least 100 further conversions of military operated 707s.

Source: Flight International