NASA Finds Cause of Craft’s Wreck : Aviation: Faulty gyroscope is blamed for Nov. 22 breakup of unpiloted research plane high above the desert.

A faulty gyroscope sent an unpiloted NASA research airplane into a steep dive last month that caused the $1.5-million craft to break up high above this desert base, the space agency said Thursday.

The aircraft, dubbed Perseus, is designed to carry instruments into the stratosphere to measure erosion of Earth’s vital ozone layer. Perseus is expected to fly thousands of feet higher than piloted aircraft, such as converted U-2 spy planes, that now are the workhorses of stratospheric research.

NASA said the Nov. 22 breakup of one of two Perseus A aircraft it is testing will not cause cancellation of the high-altitude drone program.

“It’s been a setback but it’s not a showstopper,” said Don Haley, a spokesman for NASA’s Dryden Flight Research Center at Edwards. “It’s the type of program where you can expect incidents like this to happen with much greater frequency than with traditional aircraft, because of the tender nature of these machines.”

The aircraft that broke up was struggling in hurricane-force winds nearly seven miles above Edwards when controllers on the ground decided to bring it home. As the craft descended, it began pitching and rolling uncontrollably.

A NASA investigation team headed by former astronaut Vance Brand determined that the failed gyro plunged Perseus into a dive during which its 59-foot wing snapped off its fuselage. Although Perseus is designed to maneuver at speeds not exceeding 70 m.p.h., it was diving at 92 m.p.h. when its wing separated.

Ground handlers then deployed a parachute on the craft, bringing its pieces back to Earth safely. NASA officials said the badly damaged plane will not be rebuilt but can be used for spare parts for the second Perseus vehicle.

The Perseus program has been plagued by mechanical and weather difficulties since NASA began test flights a year ago at Edwards. The plane is intended to soar to 82,000 feet but so far has not exceeded 50,000 feet.

While some atmospheric scientists support Perseus as a low-cost, low-risk way to push higher into the stratosphere, others say NASA should build bigger aircraft that can loft larger packages of scientific instruments.

Haley said Brand’s team pinpointed the gyroscope as the cause of Perseus’ breakup after studying recorded flight data. The team later confirmed its finding by re-creating the Nov. 22 flight in an electronic flight simulator.

The wrecked craft was on its 16th test flight. The second Perseus craft has flown only five times.