AJCPP 2008
March 6-8, 2008, Gyeongju,Korea
Sensor Fault Detection of Small Turboshaft Engine for Helicopter
Sangman Seong, Ihnseok Rhee
Korea University of Technology and Education
Hyeok Ryu
Korea Aerospace Research Institute
Abstract
Most of engine control systems for helicopter
turboshaft engines are equipped with dual sensors.
For the system with dual redundancy, analytic
methods are used to detect faults based on the
system dynamical model. Helicopter engine
dynamics are affected by aerodynamic torque
induced from the dynamics of the main rotor. In
this paper an engine model including the rotor
dynamics is constructed for the T700-GE-700
turboshaft engine powering UH-60 helicopter.
The singular value decomposition(SVD) method is
applied to the developed model in order to detect
sensor faults. The SVD method which do not
need an additional computation to generate
residual uses the characteristics that the system
outputs in direction of the left singular vector if
an input is applied in direction of the right
singular vector. Simulations show that the SVD
method works well in detecting and isolating the
sensor faults.
Nomenclature
: rotational speed of power turbine, rpm
: rotational speed of gas generator, rpm
: station 3 total pressure, psi
: station 4.5 temperature, degR
: fuel flow, lbm/sec
: moment of inertia of power turbine and
associated accessories, ft-lbf-sec
2
: torque produced by compressor/
gas-generator, lbf-ft
:torque produced by power turbine, lbf-ft
: external torque to engine, lbf-ft
: main rotor torque, lbf-ft
: gear ratio
: rotational speed of main rotor, rad/sec
: design rotational speed of main rotor,
rad/sec
: ratio of flapping and lagging hinge location
and blade length
: undamped natural frequency of flapping
motion, rad/sec
: damping ratio of flapping motion
: undamped natural frequency of lagging
motion, rad/sec
: damping ratio of lagging motion
1. Introduction
Gas turbine engines have been used for
propulsion systems of fixed wing and rotary wing
aircraft. Recent high performance gas turbine
engine is controlled by a full authority digital
engine control(FADEC) system. Because a
mechanical backup system is not employed for
the engine equipped with FADEC a failure of
FADEC system makes the engine uncontrollable
and thereby causes the loss of aircraft. Hence
the fault tolerance against FADEC failure is very
important.
Most of engine control systems for helicopter
turboshaft engines are equipped with dual sensors.
For the system with dual redundancy, analytic
methods are used to detect faults based on the
system dynamical model. The dynamics of small
turboshaft engines are described by power turbine
rotational speed and gas generator rotational
speed. While the gas generator speed is
independent of the power turbine speed the
dynamics of power turbine are coupled with the
gas generator speed and affected by external
