air transport Guy Norris / Stavanger

Pratt & Whitney is completing design and development work on the first set of alternative parts for the CFM56-3, and plans to begin test runs in an engine in January.

The engine maker, which announced its controversial "Global Material Solution" (GMS) alternative parts plan for the CFM56 in February, says it is on track to complete certification of the first set, or block, of 11 new parts by the end of the first quarter of 2007. A second block of life-limited parts will be certificated and available for delivery by the end of the first quarter of 2008.

Certification will be completed using one of two CFM56 engines bought by P&W to verify and characterise the baseline performance and operating conditions of the original engine. The two have so far amassed more than 166h and almost 615 cycles between them. One engine is used for telemetry tests to "thermally map" the life limited hardware and identify the "thermal boundaries". The other "performance" engine is being used to assess overall operating performance and will be used to test the new parts themselves.

"We will run with our parts, OEM [original equipment manufacturer] parts, repaired parts and used serviceable parts to measure the interchangeability of our parts," says P&W. Initial castings include first- to fourth-stage low-pressure turbine (LPT) blades, LPT first-stage vane clusters, high-pressure turbine (HPT) first-stage vane assemblies and the HPT shroud.

P&W emphasises that unlike traditional parts manufacturing approval items that are basic replicas of the original, the GMS initiative uses company know-how to develop all-new, but completely interchangeable parts, which it says will offer longer life and better overall performance.

"In the engine at 35,000ft [10,680m] you won't know the difference, but when it comes to the repair bill you'll definitely notice something," says Graeme Crawford, managing director of P&W's Norway Engine Centre, which he says "quite likely will be one of the first places where we will have them installed". Although only United Airlines has so far been announced as a customer for GMS on the -3, Crawford says: "We have several other customers interested."

Standard OEM and other parts will continue to be offered alongside the new-build P&W parts. "Our position is 'if you want them you can have them'," says Crawford. "It's fair to say there's a high amount of interest".

To date, P&W is targeting solely the 4,000-plus CFM56-3 market, and is keeping quiet on any plans to advance to the -5 or -7 variants. "We've got to walk before we can run. But if we're successful on the -3 then I guess its possible," adds Crawford, who cautions: "But it all depends on the business case."

Source: Flight International