First Such Tests Ever Done For Tiltrotors

Sources with Bell Helicopter and Boeing tell ANN the Bell Boeing V-22 Osprey program's Airframe Fatigue Test Program surpassed the 20,000 Effective Flight Hour (EFH) milestone on February 22, 2007. The Fatigue Test Program, involving a full-size V-22 aircraft, began in June 1998, and is the first ever conducted for a tiltrotor-type aircraft.

To reach the 20,000-hour mark, the Test Team conducted 60,000 simulated flights that included takeoffs, airplane and helicopter maneuvers, landings and ground maneuvers during the 20,000 flight hours of low-cycle load testing, covering the equivalent of two lifetimes on control surfaces and aft fuselage structures.

The team conducted fatigue tests in a 250,000-lb steel fixture holding the fuselage and wing structure of the V-22. The test article has 127 computer controlled, hydraulic cylinders and 418 sensors to record up to two billion data points for each 10,000-hour lifetime. The test fixture contains 5.25 miles of wire and two miles of hydraulic hose all subject to intense inspection.

The Fatigue Test Team members included Werner Idler, Dr. Chang Hong and Mark Southard of Bell and Doug Rhodes, Gary Bachman and Dave Parente of Boeing Rotorcraft Systems comprised the front line of testing with dozens of other Bell and Boeing personnel to demonstrate the V-22 airframe durability.

Next, the program soon will begin a block of high cycle loading equivalent to 30,000 flight hours applying up to 18 million load conditions. Bell Boeing fatigue test team and NAVAIR engineers are reviewing the flight load level survey data to evaluate the high cycle testing.

Since the V-22 combines the vertical lift of a helicopter and the speed of an airplane, the test must simulate loads in both air­plane and helicopter modes with no fatigue damage from rotor-induced high cycle loads.

"The test is a durability test, but the purpose is to identify areas we have issues with and either design production repairs or allow redesign of components for future aircraft," said Idler.

FMI: www.bellhelicopter.com, www.boeing.com/ids