Automated Helicopter Vibration Diagnostics
for the US Army and National Guard
Paul Grabill, Intelligent Automation Corporation, San Diego, CA
Paul.Grabill@iac-online.com
Dr. John Berry, US Army AMCOM-AMRDEC, Redstone Arsenal, AL
John.berry@redstone.army.mil
CW5 Lem Grant, South Carolina Army National Guard, Columbia, SC
GrantLE@SC-ARNG.ngb.army.mil
Jesse Porter, US Army AMCOM-RTTC, Redstone Arsenal, AL
Jesse.Porter@rttc.army.mil
The US Army and South Carolina Army National Guard have developed an automated vibration
monitoring and fault diagnostic tool as part of the Vibration Management Enhancement Program (VMEP).
This paper outlines the VMEP system rationale, design and the vibration diagnostic algorithms used to find
faults in the helicopter rotors, engines, and drive train. The concepts that differentiate VMEP from
traditional Health and Usage Monitoring Systems (HUMS) implementations are described. Specifics of the
system implemented in the Apache and Black Hawk helicopters found in the National Guard are shown.
The software architecture used in the on-board component, the ground-based component, and the
development station is presented. The data collection effort during the initial field trials is described and
examples of vibration test data and algorithm processing results are presented. We believe that the system
presented here represents a way of meeting many of the integrated vibration diagnostics goals for Army
Aviation.
Historical Perspective
In Vietnam we used a tracking flag and the seat
of our pants to track, balance and reduce
vibrations on our Huey helicopters. In the early
1970s technology arrived in the form the
Chadwick-Helmuth, Vibrex. We could now
measure vibrations. In the 1980’s, with 54
helicopters to maintain, the South Carolina
Guard began using the “Vibrex” to measure the
vibration level of rotating components on the
Huey. The measurements resulted in several
time saving diagnoses. Over the past 15 years,
numerous examples of emanate failures that
were detected from vibrations, have occurred. A
dream of predicting problems before they
occurred, or scheduling “unscheduled
maintenance” was born and we named it VMEP.
VMEP Requirements/Objective
The VMEP system was intended primarily as an
aid to the Army aviation maintainer. The goal is
to reduce unscheduled maintenance and the total
Presented at the American Helicopter Society
57
th
Annual Forum, Washington, DC, May 9-11,
2001.
Copyright
©
2001 by the American Helicopter
Society International, Inc. All rights reserved
number of maintenance test flights required to
complete maintenance activities. In addition the
system should have a minimal impact on
operational crews. Army aircrews should not
endure additional workload from an embedded
maintenance system. The intent of this system is
to capture, during operational flight activities,
the vibration environment of the major
components of the helicopter. The vibration data
is analyzed by the embedded system to produce a
set of specific machinery health indicators.
These indicators are stored for post flight use by
the aircraft maintainers. Maintenance actions are
correlated to these health indicators and clearly
communicated so that actions can be scheduled.
Completion of these maintenance actions prior to
the requirement for unscheduled maintenance
both increases the productivity of the overall
aviation operation, but precludes very expensive
collateral damage resulting from component
failure.
During the initial fielding phase of the VMEP, a
statistically significant set of indicators will be
collected and used to establish nominal operating
limits for measurements that do not have
previously established limits. Only when these
limits have been technically demonstrated to
have clear operating bounds will this system be
used to provide aircrew warnings of impending
system trouble that requires crew action. The
