Pratt & Whitney (P&W) claims it has developed more than 300 new repairs through the Scrap Avoidance and Value Engineering (SAVE) program, an initiative designed to repair or reuse engine parts that have been deemed unserviceable.
Since its introduction in 2002, the program has saved customers more than $100 million, according to P&W. Savings in 2007 (through mid-October), as measured in terms of cost avoidance, totaled $10.6 million in commercial airline clinics.
“The key value of a program like this is that it reduces cost of ownership for our customers,” said Lynn Gambill, Director of Global Services Engineering. “We take parts that are determined to be unserviceable [and] evaluate and assess them with our engineering knowledge.
“We will help with inspection interpretation that might enable the part to be used longer. We look at what is currently published on the use of the part, and then look to see what we can expand upon. In some circumstances, we are able to develop a new repair that didn’t previously exist.”
Most of the parts in the program are from the engine hot section, as well as turbine parts, vanes, blades, and cases. When an airline maintenance staff determines that such a part has reached its operational life span based on criteria in the manufacturer’s engine service manual, the part is typically stored or discarded. Over time, a pretty sizeable stash of unusable parts begins to build up.
At that point an airline calls in P&W to conduct a SAVE clinic. These on-site salvage clinics typically require four weeks of preparation, followed by three weeks of on-site work with the customer. During the clinic, a team of P&W hardware experts works side by side with the customer to designate parts as “save,” “study,” or “scrap,” and then choose corrective action. This could include researching approved technical data for a given part, creating a new repair, or assisting with inspection interpretation.
P&W had conducted 16 SAVE clinics in 2007 (through mid-October), and more than 100 since the program’s inception about five years ago.
“A customer could have multiple engines torn down over time and have accumulated material,” said Gambill. “They will send us a parts list, we evaluate the type of parts on the list, and assemble a team of one to four people based on the parts group. If there are multiple parts across the engine, then we’ll send more people.”
The team physically examines each part and determines whether it is truly unserviceable, or finds an existing repair through a technical data search, or develops a wholly new repair. In some instances, the information gleaned during inspection leads to development of a new part.
“An airline operator will classically follow parts limits as written in an engine manual developed by the OEM,” said Gambill. “They have the latitude to work outside the manual and they have capable engineering teams to do that.
“But at the point where they see something they haven’t seen before, they need to bring in an OEM who has certain analytical capabilities that maybe they don’t have. Sometimes there is a level of complexity that goes beyond them, and we have that skill set.”
As an engine racks up flight hours, it is fairly common for both airline operators and the OEMs to witness engine-life issues that were not anticipated when the original maintenance manual was written. The SAVE program specifically addresses those operational realities.
“When you first introduce an engine into service, you publish an engine manual around what you would expect to see so you can evaluate parts when the engine is brought in for overhaul,” explained Gambill. “As an engine remains in service longer, operators continually bring forward new learning about the engine that was not identified in the manual. You start to see trends over time, and with your engineering knowledge you can come up with a way to reuse parts.”
Such a program is of value to the airline because it gets to reuse parts that were thought to have outlived their life, and also to P&W because the work is typically done in its maintenance shops. And in this time of greater environmental awareness, reusing a part instead of manufacturing a new one preserves natural resources, according to Gambill..
“Materials used in gas turbine engines include complex nickels and titanium,” he said. “Finding a way to reuse that material actually preserves raw materials and resources. It is a little less tangible, but nonetheless important.”