Raptor engine completes initial service release testing

The F119 engine is prepared for testing in the center's propulsion development test cell C-1.

Required testing for the Initial Service Release (ISR) of the F-22 Raptor's F119 powerplant has been completed at the U.S. Air Force's Arnold Engineering Development Center (AEDC) in Tennessee. While at AEDC, the engine achieved 4330 total accumulated cycles (TAC) and underwent more than 1037 engine-operating hours in the center's altitude test cell C-1 and sea-level test facility SL-2. It also set a new test pace record of 28 days while in C-1. The tests were conducted to provide information on engine performance after 4330 cycles.

The engine began its accelerated testing at Pratt & Whitney's West Palm Beach, FL, test facility where it accomplished 750 TACs in 246 engine run hours. Following that phase, the engine was shipped to AEDC in July 2000 and installed in C-1, where it underwent performance calibrations and established a baseline for the upcoming tests.

Following the C-1 testing, crew members installed the engine into SL-2 for accelerated testing. While accumulating test cycles in SL-2, operators simulated in-flight mission cycles the aircraft would experience over a period of six to eight years. At the completion of the SL-2 testing, the engine had met a criteria established by the Defense Acquisition Board for ISR.

Pratt & Whitney's F119 engine that powers the USAF F-22 Raptor undergoes performance testing in AEDC's Propulsion Test Cell C-1 in preparation for Initial Service Release.

In November 2000, the F-22 test team removed the engine from SL-2, and an Executive Independent Review Team reviewed the results of the testing. Following the review, the test team refurbished, reassembled, and reinstalled the engine in SL-2, where it underwent more than 400 RAM (air) and 3180 sea-level TACs and achieved the required 4330 total accumulated cycles.

The team once again transferred the engine and reinstalled it in C-1 for final performance calibrations. Once installed, the engine underwent additional performance calibrations to validate engine performance, durability, stability and tracking, and high-cycle fatigue testing. At test completion, the engine had met final ISR-milestone requirements and was shipped to the Pratt & Whitney East Hartford, CT, facility for a complete teardown, inspection, and review.

- Frank Bokulich

A long bed at Airbus

Airbus UK is using a long-bed Alumax machine to help reduce cycle time.

Airbus UK, the designer and manufacturer of wings for all Airbus aircraft, is using an Alumax long bed gantry machine at its Broughton facility to help significantly reduce product cycle times. It is being used to produce the four aluminum panels that comprise the underside or "bottom skin" of the A340-500/600 wings. Built by AB Marwin, the twin-bed Alumax has an x-axis of 3-m cast-iron sections totaling 40.5 m, two y-axes of 3 m, and a z-axis of 600 mm. The main application of the machine is for high-speed milling of the wing's surfaces, but its roles also include various drilling and profiling operations on the massive 2024 aluminum billets, which are typically 32 m long, 3 m wide, and 35 mm thick.

The machining operation forms part of a tightly controlled manufacturing process that also includes deburring, inspection, anodizing, crack detection, painting, and final delivery. The machining center works in conjunction with a dedicated material-handling system featuring an overhead monorail and vacuum lift for transporting the billets. The Alumax's main task is precision milling of intricate internal structures on the inside face of each panel to make way for stringers, spars, ribs, and other components.

According to AB Marwin, consistent panel thickness is a crucial requirement of wing-skin production, and despite the enormous size of the components machined on it, Renishaw part probing and x-axis laser feedback enable the Alumax to produce components within a thickness tolerance of +0.13 and -0.08 mm. The machine's dual y-axis allows the simultaneous machining of both port and starboard wings, resulting in significant reductions in product cycle time. In an application that involves the removal of 80% of the billet's original material volume, the ability to machine a pair of wings simultaneously has proved beneficial by helping to streamline manufacturing operations considerably.

The company underlines the importance of high metal-removal rates, explaining that a typical "roughing" rate approaching 6554.8 cm³/min has resulted in an increase in machining feed rates from 5 m/min to 7.5 m/min on the Alumax. Finishing rates have undergone an even greater improvement, increasing from 8 m/min to approximately 20 m/min. The Alumax has two 85-kW Weiss spindles. Machine operation is from a remote control booth, obviating the need for users to work from the moving gantry. The Alumax is controlled via a Fanuc 15-MB system with Windows-based software.

- Stuart Birch