General aviation research is leading to major advances
in internal combustion engine control systems for single-engine,
single-pilot aircraft. These advances promise to increase engine
performance and fuel efficiency while substantially reducing pilot
workload and increasing flight safety. One such advance is a single-lever
power control (SLPC) system, a welcome departure from older, less
user-friendly, multilever engine control systems. The benefits
of using single-lever power controls for general aviation aircraft
are improved flight safety through advanced engine diagnostics,
simplified powerplant operations, increased time between overhauls,
and cost-effective technology (extends fuel burn and reduces overhaul
costs). The single-lever concept has proven to be so effective
in preliminary studies that general aviation manufacturers are
making plans to retrofit current aircraft with the technology
and are incorporating it in designs for future aircraft.
To aid in this effort, nine industry members of the Advanced General Aviation Transport Experiment (AGATE) consortium have teamed together to further develop SLPC technology. This consortium consists of Government, industry, and academia members who are joining forces to revitalize the nation's general aviation sector by designing integrated advanced flight systems that will improve safety and reduce the cost and time for learning to fly. SLPC technology is a vital element of this effort. SLPC team members range from aircraft manufacturers to suppliers, with the propulsion control system specialists at the NASA Lewis Research Center managing the effort.
A single lever is used in tandem with a digital engine
control system known as full-authority digital engine control.
The combined system controls engine power on an airplane much
like an automobile accelerator provides speed. Movement of the
power lever automatically sets the amount of fuel flow, air flow,
ignition timing, and propeller pitch to achieve requested thrust
levels from the engine and propeller during the takeoff, cruise,
and landing phases of flight. The single-lever power control increases
fuel efficiency, decreases the time between overhauls, and ensures
the best engine/propeller performance for all flight phases. SLPC
greatly simplifies engine control in comparison to older systems-which
use a 50-year-old technology and require the use of as many as
five levers for power control.
Mechanical versions of single-lever power control
were developed 15 years ago for light aircraft engines. However,
their implementation was limited because of their complexity and
inability to compensate for variations in air density. Later,
researchers found that digital computer technology greatly enhances
the accuracy and usefulness of the system as standalone equipment
or integrated with an advanced cockpit display system. Single-lever
power systems are commonly found today on turbine engines that
use NASA-developed fly-by-wire digital control technology. This
technology is used in present-day, high-performance military jet
fighters and commercial transports.
Thanks to the establishment of the AGATE consortium
in the spring of 1995, companies are now heavily engaged in single-lever
development for light aircraft, working together to eliminate
any remaining glitches and to further refine the technology. Work
is underway to include engine monitoring and diagnostic capability
in the full-authority digital engine control to enhance pilot
awareness of engine status during flight and to provide a postflight
diagnostic capability.
The team effort has led to reduced development risks
and costs, which are shared equally between NASA and industry
partners. Pooling of team members' resources and sharing of development
costs have also dramatically speeded the development of this technology
and are helping to bring new engine controls to market rapidly.
SLPC developers plan on developing guidelines, standards, and
certification methods for future technology applications. They
foresee the day when all general aviation engines will be completely
operated by electronic systems, helping to fulfill the broader
AGATE vision of creating "highways in the sky."
For additional information, visit the AGATE homepage.
And write for
The AGATE Flier
, vol. II, issue
1, May 1996:
c/o Office of Communications, RTI
P.O. Box 12194
Research Triangle Park, NC 27709-2194
Lewis contact: Jeffrey
L. Musgrave, (216) 433-6472,
Jeffrey.Musgrave@grc.nasa.gov
Author: Jeffrey L. Musgrave
Headquarters program office: OA
Previous articleLast updated April 29, 1997
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