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| H598
SERIES |
The Howell Instruments H598 Series of
microprocessor-based engine monitors combine
accuracy and dependability with multi-channel
monitoring capability. Engine management with
state-of-the-art technology enhances fleet
operations and safety while reducing
cost.
In addition to allowing the operator to view
engine and airframe parameters in real time,
the unit can be programmed to display data in
any of the following modes.
- Identification and Usage Data
- Exceedance Monitoring
- Trend Monitoring
- Flight Profile Data
Display Controls
The digital display includes three lines (16
characters/line) of alphanumeric characters
that are available in red, yellow, or NVG. A
light-sensitive photo cell controls the
brightness for varying ambient light
conditions.
Exceedance Monitoring
The H598 can monitor selected parameters for
out-of-limit conditions. The engine
manufacturer's operating limits are
programmed into the unit, which tracks engine
operation in real time under operational
conditions. When an exceedance is detected,
the offending parameter is displayed in a
flashing mode. The unit also has the
capability of providing an output signal to a
cockpit Advisory/Warning Panel. The H598
normally records the date and time of the
event, a frame (or frames) of all parameters
pertinent to the event, the duration of the
exceedance, the peak value of the offending
parameter and, if applicable, the level of
maintenance required based upon the severity
of the event.
The H598 can also accumulate the time that
critical parameters operate above selected
levels and provide a warning if an
accumulated time exceeds a limit.
Flight Profile Data
Flight profile data can be collected in a
Timed Recording Mode or a Profile All Mode.
The Timed Recording Mode collects a frame of
data at a selectable fixed time interval. The
Profile All Mode collects start and shutdown
records at a rate of one per second. All
other operational data is gathered using data
compression techniques to minimize the space
of data collected.
Data Reduction
A menu-driven ground station software package
helps operators reduce flight data using an
IBM compatible PC. Data file management is
straightforward, easy to interpret, and it
provides storage for data records.
Modularity
All electronic circuits are on plug-in
circuit boards using DIN 41612 connectors for
reliability and maintainability. All cards of
like kind are interchangeable. Analog circuit
cards contain their own calibration so that
re-calibration is not required when boards
are exchanged. Each board contains its own
unique identification code that the system
uses to check functional capability.
Input Signals
Four cards are dedicated to the processing of
input signals.
- The frequency card can monitor up to
five frequency inputs. The frequency range
is 3.5 Hz to 30 KHz.
- The low level analog card is capable of
monitoring eight thermocouples and three
RTDs.
- The high level analog card can monitor
twelve high level DC analog signals.
- The discrete card monitors up to
sixteen discrete inputs. These discrete
inputs can be voltage or ground. This card
also has the capability of outputting four
28 VDC@1 Amp discrete signals that are
software programmable.
Expansion
There are two expansion slots available for
increasing the quantity of existing signal
types or for addition of other signal inputs
such as synchros, resolvers, mass flow
meters, LVTDs, and RVDTs.
One of the two slots is designed to
accommodate data buss interfaces such as
ARINC 429 and MIL-STD-1553. This capability
allows the H598 to interface with:
- Howell Automatic Engine Data
Acquisition System (AEDATS)
- Howell JETCAL2000® Analyzer
- Aircraft Air Data Computers
- Personal Computers
- Air Frame Data Buss
Vibration measurement capability is also
available as an option.
See article on health
usage monitoring with H598 EPAMS.
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| EPAMS POINT PAPER |
August 8, 2000 By James L. Pettigrew,
P.E.
SUBJECT: HEALTH USAGE MONITORING with
EPAMS
The H598 Engine Performance Assurance
Monitoring System (EPAMS) is a proven
off-the-shelf HUMS for installation in the
cockpit of an aircraft where it provides the
aircrew a multi-function digital display of
engine instrument parameters and records
engine data. Continuous engine performance
status is available to the aircrew as NG and
GT margins. Accurate inflight data is
recorded to a removable 512 K or 1 MEG memory
module. Each memory module can record 1.5 or
3 hours of data at a rate of a record per
second or 100 plus operations in overlimit
monitoring with trend data, high power
operation and usage.
Data recording can be selected to capture (1)
over limit operation with trend data, (2)
power changes with over limit and trend, (3)
stable power with over limit and trend or (4)
trouble-shooting and diagnostic data recorded
at a selectable interval between 0.25 and 255
seconds. Engine transmission usage with
threshold crossings and times above threshold
are stored in the EPAMS. After the flight,
the memory module easily transports the data
to a personal computer. The data can be
copied, sent by E-mail or modem, formatted
and analyzed to give engine and transmission
usage and relative health as a basis for
on-condition maintenance. Counting algorithms
are available to track life used.
HowellÂ's copyrighted software based on
the patented Referred Engine Diagnostic Data
(REDD) methodology provides the basis for
engine condition evaluation and diagnostics
for on-condition maintenance decisions. Usage
data is provided to support "life usage and
power by the hour" programs. Reports can be
viewed on the screen or printed to any
available printer.
EPAMS does the following:
- Provides backup digital display of
engine instruments readings
- Provides a quantified measure of engine
performance margins in real time
- Records exceedance data (magnitude and
duration above limit)
- Life Usage calculations (Provides
accumulated time above selected operating
levels with a count of the number of times
operated above the selected operating
levels).
EMI/EMC tests have shown compatibility
in the lab and operating environment. Navy
EMI test facilities at Patuxent River NAS
successfully tested an AH-1W aircraft with an
EPAMS installed at aircraft carrier radiation
levels. EPAMS has been approved for inflight
use by the FAA, the Navy, and the Army.
EPAMS operates on Navy Aircraft and
Helicopters as a flight profile data recorder
and as a real time detector of engine
performance degradation. The US Army
competitively selected and is using EPAMS,
NSN4920-01-342-0449, as a Portable Engine
Test Cell to establish engine condition and
diagnose faults in installed engines.
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