The single most important function of an aircraft flight information
system is the display of an artificial horizon (attitude indicator)which
allows the pilot to control the aircraft's attitude (i.e. pitch andbank).
In a conventional attitude indicator this information is provided
mechanically by a gyroscope (a spinning mass, similar to a child'stop).
The (vertical) spinning mass rotates on suspension bearings located
above and below the mass on the axis of rotation. These suspension
bearings are mounted in a gimbal mechanism which is further mounted
in a protective case. The gimbal mechanism allows the gyroscope to
remain spinning vertically while the case is rotated freely in space.

The power source for such a gyroscope is typically an integral electric
motor but may also be a stream of air. Regardless of the power source,
a figure of merit for a gyroscope is what is known as ``coast time'',the
time for a gyroscope spinning at full speed to slow to a stop whenits
power source is removed. For example, a 16 minute coast time is
considered excellent.

B. F. Goodrich manufactures a wide variety of flight information systems,
among which are gyroscope based attitude indicators; typical of these
is the Model XYX.

Recently the suspension bearings of the Model XYX were improved,
increasing the life expectancy of the XYX from 3000 hours to 20,000
hours.

The goal of this project is to predict the remaining useful life of
new and/or used gyroscopes.

A variety of data taken from new and used gyroscopes are available for
analysis. Some of this data is life test data used to predict the lifeexpectancy
of the original and improved XYX gyroscopes by simple rules of thumb.
In addition, the customer service department tests and records thelow
speed torque requirement and the 22,000 RPM vibration spectrum of
gyroscopes returned for service (returns are not necessarily prompted
by time in service or gyroscope mechanical problems).

The ideal completed project deliverable would be a test specification
and algorithm for predicting the remaining useful life of an XYX model
gyroscope from spectral and torque data.


This summary prepared with the assistance of K. Devarasettyand G. Watson
of B. F. Goodrich Aerospace.