Comtran and Jet Engineering, the Texas-based developers of a Stage 4-compliant jet nozzle for the Boeing MD-80, have won US Federal Aviation Administration certification for an advanced kit which now embraces all versions of the twinjet family, including the heavier MD-83 variant, and increases margins across the board.

Two supplemental type certificates (STC) have been awarded for the parts that make up the kit - one for a new turbine exhaust cone mixer for the Pratt & Whitney JT8D-200, and the other for incorporation of the new cone mixer with the previously certificated jet nozzle. The combined STCs now give a Stage 4 compliance margin of 1.2dB to the MD-83 at maximum take-off weight, and a margin of up to 5.8dB over Stage 4 for an MD-87 at typical operating weights, says the company.

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The upgrade from Comtran and Jet Engineering "improves fuel burn efficiency through remixing"

The upgrade, which builds on Comtran's earlier Super Q MD-80 development demonstrated at last year's Farnborough air show, "basically improves the efficiency of fuel burn through remixing", says Comtran director Dalton Kaye. The advanced jet nozzle therefore does not increase fuel consumption, and does not require a fan blade containment ring, he says.

Comtran and Jet Engineering have yet to announce any customers for the upgrade, but "we are in negotiation with a number of airlines at the moment", says Kaye, who adds that European operators are among the leading candidates.

The upgrade is also aimed at US operators, says Kaye, who adds that the potential market includes more than 900 MD-80s still in worldwide service.

The kit is also expected to be offered in conjunction with a winglet design, which Comtran plans to have available before the end of 2007. The original winglet, which appeared in mock-up form at the Farnborough show last year, has been enlarged and has an increased dihedral.

Source: Flight International