U.S. patent application number 11/281504 was filed with the patent office on 2006-07-06 for method and system for health monitoring of aircraft landing gear.
Invention is credited to Steven A. Gedeon, R. Kyle Schmidt.
Application Number | 20060144997 11/281504 |
Document ID | / |
Family ID | 36406130 |
Filed Date | 2006-07-06 |
United States Patent
Application |
20060144997 |
Kind Code |
A1 |
Schmidt; R. Kyle ; et
al. |
July 6, 2006 |
Method and system for health monitoring of aircraft landing
gear
Abstract
The invention relates to a new method and system for health
monitoring of aircraft landing gear. The system includes sensors
that are attached to the landing gear structure and equipment
(e.g., one or more of brakes, tires, hydraulics, electrical systems
and switches) and analyzed to report and alert personnel such as
pilots, maintenance personnel, airline operators, ground crew and
regulatory authorities of the health of the landing gear and the
potential need for service, maintenance or replacement. The system
monitors and reports critical health issues as real-time
information which can be analyzed in conjunction with an extensive
database of information and used to alert pilots or other relevant
personnel to the condition of the landing gear and actions that may
be required as a result.
Inventors: |
Schmidt; R. Kyle;
(Pickering, CA) ; Gedeon; Steven A.; (Toronto,
CA) |
Correspondence
Address: |
Gowling Lafleur Henderson LLP;Suite 1600
1 First Canadian Place
100 King Street West
Toronto
ON
M5X 1G5
CA
|
Family ID: |
36406130 |
Appl. No.: |
11/281504 |
Filed: |
November 18, 2005 |
Current U.S.
Class: |
244/100R ;
340/960 |
Current CPC
Class: |
G01G 19/07 20130101;
B64F 5/60 20170101; G07C 5/0808 20130101; B64D 2045/008
20130101 |
Class at
Publication: |
244/100.00R ;
340/960 |
International
Class: |
B64C 25/00 20060101
B64C025/00; G08B 21/00 20060101 G08B021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 18, 2004 |
CA |
2,487,704 |
Claims
1. An aircraft landing gear health monitoring system comprising: at
least one sensor coupled to at least one component of the aircraft
landing gear system for measuring and recording real-time data
associated with the status of at least one component; at least one
processor connected to the at least one sensor for receiving and
processing the real-time data to calculate the condition of the at
least one component of the landing gear system; and reporting means
operable to receive information from the at least one processor for
reporting at least one of the condition of the landing gear system
and the real-time data.
2. The health monitoring system according to claim 1 wherein the at
least one processor is operable to compare the real-time data to
pre-determined health data associated with each component to
calculate the condition of the at least one component.
3. The health monitoring system according to claim 1 wherein the at
least one component of the aircraft landing gear system is selected
from the group consisting of tires, brakes, hydraulics,
electronics, landing gear doors, oil pressure, oil temperature, oil
level, shock strut position, loads, strain gauges, structural
integrity, magnetic permeability, brake pressure, aircraft bus data
including airplane velocity, position, attitude and altitude.
4. The health monitoring system according to claim 1 wherein the
reporting means is selected from the group consisting of a display
screen located in the aircraft cockpit, a ground-based system, and
a display screen located within the aircraft and accessible by at
least one crew member.
5. The health monitoring system according to claim 1, further
comprising at least one self powered measurement and analysis unit
connected to and in communication with the at least one sensor and
connected to the aircraft avionics for receiving power therefrom
when the aircraft avionics are on, the measurement and analysis
unit further operable to supply power to the at least one sensor
and to receive and store real-time data from the at least one
sensor when the aircraft power is off and further operable to
transmit stored data received from the at least one sensor to the
at least one processor when the aircraft avionics are on.
6. The health monitoring system according to claim 1 further
comprises at least one electronic memory device connected to the at
least one component of the landing gear system for storing
pre-determined health data related to the structural integrity of
the at least one component, the at least one electronic memory
device being operable to communicate the stored data to the at
least one processor for comparison with the real-time data.
7. The health monitoring system according to claim 1, wherein the
at least one sensor and the reporting means are independently
connected to the aircraft power supply.
8. The health monitoring system according to claim 1, wherein the
at least one sensor and the reporting means each independently
further include a power supply.
9. The health monitoring system according to claim 1, wherein the
at least one sensor is connected to at least one memory device for
storing the recorded data thereon.
10. The health monitoring system according to claim 1, wherein the
at least one memory device is integral with the at least one
sensor.
11. The health monitoring system according to claim 1, further
comprising at least one signal conditioning device operable to
receive and process the real-time data from the at least one sensor
into a processor readable form and operable to transmit the
processed real-time data to the at least one processor.
12. The health monitoring system according to claim 11, wherein the
system comprises a plurality of sensors and one signal conditioning
device operable to receive real-time data independently from each
sensor and operable to transmit the real-time data to the at least
one processor.
13. The health monitoring system according to claim 11, wherein the
system comprises a plurality of sensors and a plurality of signal
conditioning devices, each signal conditioning device operable to
receive real-time data from one of the sensors.
14. A method for monitoring the health of an aircraft landing gear
system comprising the steps of: (i) collecting real-time data
associated with the condition of at least one component of the
aircraft landing gear system; (ii) analysing the real-time data to
assess the condition of the at least one component; and (iii)
reporting the condition of the at least one component.
15. The method according to claim 14 comprising the additional step
of comparing the real-time data with pre-determined data associated
with the at least one component to calculate the current landing
gear condition and to assess any action required prior to step
(iii).
16. The method according to claim 14, comprising the additional
step (iv) of reporting the current landing gear condition and any
required action associated therewith.
17. The method according to claim 14, comprising performing steps
(i) through (iv) while the aircraft is in flight.
18. The method according to claim 14, comprising performing steps
(i) through (iv) while the aircraft is on the ground.
19. An aircraft landing gear health monitoring system comprising: a
plurality of sub-systems each comprising: a plurality of sensors
each independently connected to separate components of a
pre-determined sub-system of the aircraft landing gear and operable
to measure and record real-time data associated with the status of
each component; and a processor connected to the plurality of
sensors for receiving the real-time data therefrom and operable to
analyse the real-time data to calculate the condition of the
sub-system; and a reporting device connected to each of the
sub-systems for receiving data therefrom and operable to report at
least one of the real-time data and the condition of each of the
sub-systems.
20. The health monitoring system according to claim 19, wherein the
processor of one sub-system is operable to receive real-time data
from at least one of a processor of another sub-system and a sensor
of another sub-system for use in the calculation of the condition
of the sub-system to which the processor relates.
21. The health monitoring system according to claim 19, further
comprising at least one communication device connected to the
plurality of sub-systems and to the reporting device to relay
information therebetween.
22. The health monitoring system according to claim 19, wherein the
processor is operable to compare the real-time data to
pre-determined health data to determine the condition of the
component associated with the real-time data.
23. The health monitoring system according to claim 19, wherein the
reporting device is operable to report the condition of each
component within each sub-system.
24. The health monitoring system according to claim 19, wherein the
reporting device is at least one of a display device located in the
aircraft cockpit, a ground-based system, and a display device
located within the aircraft and accessible by at least one crew
member.
25. The health monitoring system according to claim 19, wherein the
plurality of sub-systems are connected to the aircraft power for
recharging and are operable to transmit the recorded data to the
aircraft avionics system when the aircraft avionics system is
on.
26. The health monitoring system according to claim 19, wherein
each component of the landing gear structure includes an electronic
memory device attached thereto for storing data related to the
structural integrity of the component.
27. The health monitoring system according to claim 26, wherein
each electronic memory device is operable to transmit the stored
data to at least one of the sensor associated with the component
and the processor.
28. The health monitoring system according to claim 19, wherein
each of the plurality of sub-systems further comprise at least one
memory device for storing at least one of the real-time data and
the analysed data.
29. The health monitoring system according to claim 19, wherein the
at least one component of the aircraft landing gear system is
selected from the group consisting of tires, brakes, hydraulics,
electronics, landing gear doors, oil pressure, oil temperature, oil
level, shock strut position, loads, strain gauges, structural
integrity, magnetic permeability, brake pressure, aircraft bus data
including airplane velocity, position, attitude and altitude.
30. An aircraft landing gear health monitoring system comprising:
at least one sensor coupled to at least one component of the
aircraft landing gear system for recording real-time data
associated with the at least one component; and reporting means
connected to the at least one sensor for reporting the recorded
data.
31. The health monitoring system according to claim 30, further
comprising a processor operable to communicate with the at least
one sensor for receiving and analysing the real-time data to
calculate the condition of the at least one component.
32. The health monitoring system according to claim 31, wherein the
processor is operable to communicate with the reporting means and
the reporting means is operable to report the calculated condition
of the at least one component.
33. The health monitoring system according to claim 30, wherein the
reporting means is selected from the group consisting of a display
screen located in the aircraft cockpit, a ground-based system, and
a display screen located within the aircraft and accessible by at
least one crew member.
34. An aircraft landing gear health monitoring system comprising:
at least one sensor coupled to at least one component of the
aircraft landing gear system for recording real-time data
associated with the at least one component; a processor operable to
receive and compare the recorded real-time data with pre-determined
health data associated with the at least one component and to
calculate the condition of the at least one component; a
communication device operable to communicate with the at least one
sensor and the processor, and to receive information relating to
the real-time data, the analysed data and the calculated condition
of the at least one component; and reporting means connected to the
communication device and operable to receive and report information
received therefrom relating to at least one of the real-time data,
the analysed data and the condition of the at least one
component.
35. The health monitoring system according to claim 34, further
comprising at least one signal conditioning device operable to
receive and process the real-time data from the at least one sensor
into a processor readable form and operable to transmit the
processed real-time data to the processor.
36. The health monitoring system according to claim 34, wherein the
reporting means is selected from the group consisting of a display
screen located in the aircraft cockpit, a ground-based system, and
a display screen located within the aircraft and accessible by at
least one crew member.
37. The health monitoring system according to claim 34, wherein the
system is located inside an aircraft.
38. A method for monitoring and diagnosing the health of an
aircraft landing gear system comprising the steps of: (i) recording
real-time data associated with the status of at least one component
of the aircraft landing gear system; (ii) transmitting the
real-time data to a processor for processing; (iii) processing the
real-time data to calculate the current condition of the at least
one component and to determine if any maintenance is required; and
(iv) reporting at least one of the real-time data, the calculated
condition and any required maintenance.
39. The method according to claim 38, comprising the additional
step of recording the calculated condition of the at least one
component.
40. The method according to claim 38, further comprising the
additional step of transmitting at least one of the real-time data,
the calculated condition and any required maintenance to a
ground-based master landing gear database.
41. The method according to claim 38, wherein the reporting step
(iv) includes reporting the information to at least one of the
aircraft personnel and the ground-based personnel.
42. The method according to claim 38, comprising performing steps
(i) through (iv) while the aircraft is in flight.
43. The method according to claim 38, comprising performing steps
(i) through (iv) while the aircraft is on the ground.
44. A method for monitoring and diagnosing the health of an
aircraft landing gear system comprising the steps of: (i) recording
real-time data associated with the status of a plurality of
components contained within a pre-determined sub-system of the
aircraft landing gear system; (ii) transmitting the real-time data
to a processor for processing; (iii) processing the real-time data
to calculate the current condition of the sub-system and to
determine if any maintenance is required; and (iv) reporting at
least one of the real-time data, the calculated condition and the
required maintenance.
45. The method according to claim 44, comprising the additional
step of repeating steps (i) and (ii) for additional
sub-systems.
46. The method according to claim 45, wherein the processing step
(iii) comprises calculating the condition of each sub-system.
47. The method according to claim 44, comprising performing steps
(i) through (iv) while the aircraft is in flight.
48. The method according to claim 44, comprising performing steps
(i) through (iv) while the aircraft is on the ground.
49. The method according to claim 44, further comprising the
additional step of transmitting at least one of the real-time data,
the calculated condition and any required maintenance to a
ground-based master landing gear database.
50. The method according to claim 44, wherein the reporting step
(iv) includes reporting the information to at least one of the
aircraft personnel and the ground-based personnel.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to aircraft landing systems
and more particularly to a method and system for determining
whether the landing gear is healthy or whether it requires
maintenance, service and/or replacement. This invention will also
determine if the risk of a catastrophic failure of the landing gear
has changed as a result of its in-service operations.
BACKGROUND OF THE INVENTION
[0002] The goal of health monitoring technologies is to know at any
time, for any aircraft in the fleet, the structural integrity of
the landing gear, the amount of remaining fatigue life in the
landing gear, the landing gear servicing information (such as shock
strut pressure and fluid volume, tire pressure and temperature, and
brake condition), and the internal status of all on-board
electronics and systems related to the landing gear system.
[0003] Being able to measure and assess the safety and integrity of
the landing gear and landing gear system is of vital interest to
the public safety.
[0004] The current process for deciding that an airplane has had a
"hard landing", and thus has compromised the safety and integrity
of the landing gear, is based on a subjective assessment by the
flight crew. Because of the lack of reliable quantitative data,
errors are made in this assessment. As a result, an airplane may be
grounded unnecessarily, at a considerable cost of time and money,
or conversely, a damaged airplane can continue in service, thus
compromising public safety.
[0005] In addition to this current practice, servicing and
maintenance are scheduled to take place at pre-determined
intervals. This results in some servicing and inspections taking
place before it is required, thus resulting in considerable
additional cost of time and money. Conversely, in some cases, the
landing gear may be in need of servicing, maintenance or
replacement before the next scheduled time. In the interests of the
public safety, it is better to be safe than sorry and so
maintenance and servicing schedules tend to be very
conservative.
[0006] Landing gear health monitoring systems involve several
unique issues that differentiate it from all other airplane systems
and the airframe itself. Airframes are made from relatively ductile
aluminum alloys that can withstand relatively long cracks that grow
over time. These aluminum structures can sustain fairly significant
corrosion before the airplane's fitness for service is compromised.
In contrast, landing gears are made from very high strength (but
relatively low toughness) steel, aluminum, and titanium alloys with
critical defect sizes that are much smaller.
[0007] This significant difference is also reflected in the fact
that aircraft design and approval methodologies are quite different
between the airframe and the landing gear. For example, the
airframe uses "damage tolerant" design methodologies, which allow
cracks of known sizes to exist in structural members, applied to
fatigue dominated zones in the airframe compared to "safe life"
design methods, which do not permit cracks, used in the landing
gear.
[0008] As a result, many of the technologies and articles related
to health monitoring of the airframe, e.g. measuring the dynamic
characteristics of the structure and then inferring whether certain
joints have failed or cracks have grown, are of little interest
when considering health monitoring of the landing gear. Similarly,
the sensors and technology involved for airplane systems are not
sensitive enough to resolve the very small defects of interest or
displacements of interest for landing gear applications.
[0009] The present invention provides a system and method that
utilizes extensive destructive and non-destructive testing and
analysis of full-scale landing gear, extensive engineering modeling
of the landing gear design and modeling of the causes of failure,
and extensive experience with analysis of landing gears in-service.
This integrated system and method utilizes an arrangement of
sensors and sub-systems and an extensive database of information
such as the original manufactured condition of the landing gear,
amount and type of maintenance, in-service history of similar
landing gear, history of the specific landing gear of interest,
prior in-service loads, and number and type of hard landings; and
sophisticated analytical techniques in order to determine the
safety of the landing gear and/or need for service, maintenance or
replacement. The present invention can disseminate and report the
need for service, maintenance or replacement to a spectrum of
interested parties including: pilots and flight crews, maintenance
personnel, airline operators, ground crew and regulatory
authorities.
SUMMARY OF THE INVENTION
[0010] The present invention provides a system having a variety of
sensors attached to the landing gear structure and equipment, a
method and system to communicate the data measured by the sensors
to the monitoring system, a method to analyze the data to derive
relevant information about the health and safety of the landing
gear, and a method and system to report the potential need for
service, maintenance or replacement to pilots and flight crew,
maintenance personnel, airline operators, ground crew and
regulatory authorities.
[0011] In one embodiment the present invention provides an aircraft
landing gear health monitoring system comprising at least one
sensor coupled to at least one component of the aircraft landing
gear system for measuring and recording real-time data associated
with the status of at least one component. The system also includes
at least one processor connected to the at least one sensor for
receiving and processing the real-time data to calculate the
condition of the at least one component of the landing gear system
and reporting means operable to receive information from the at
least one processor for reporting at least one of the condition of
the landing gear system and the real-time data.
[0012] In another embodiment the present invention provides an
aircraft landing gear health monitoring system comprising a
plurality of sub-systems and a reporting device connected to each
of the sub-systems for receiving data from the sub-sytem. Each
sub-system comprises a plurality of sensors each independently
connected to separate components of a pre-determined sub-system of
the aircraft landing gear and operable to measure and record
real-time data associated with the status of each component and a
processor connected to the plurality of sensors for receiving the
real-time data therefrom and operable to analyse the real-time data
to calculate the condition of the sub-system. The reporting device
is operable to report at least one of real-time data and the
condition of each of the sub-systems.
[0013] In a further embodiment, the present invention provides an
aircraft landing gear health monitoring system comprising at least
one sensor coupled to at least one component of the aircraft
landing gear system for recording real-time data associated with
the at least one component, a processor operable to receive and
compare the recorded real-time data with pre-determined health data
associated with the at least one component and to calculate the
condition of the at least one component, a communication device
operable to communicate with the at least one sensor and the
processor, and to receive information relating to the real-time
data, the analysed data and the calculated condition of the at
least one component and reporting means connected to the
communication device and operable to receive and report information
received therefrom relating to at least one of the real-time data,
the analysed data and the condition of the at least one
component.
[0014] In an alternative aspect the present invention provides a
method for monitoring the health of an aircraft landing gear system
comprising the steps of (i) collecting real-time data associated
with the condition of at least one component of the aircraft
landing gear system, (ii) analysing the real-time data to assess
the condition of the at least one component and (iii) reporting the
condition of the at least one component.
[0015] In an alternative embodiment of the present invention
provides a method for monitoring and diagnosing the health of an
aircraft landing gear system comprising the steps of (i) recording
real-time data associated with the status of at least one component
of the aircraft landing gear system, (ii) transmitting the
real-time data to a processor for processing, (iii) processing the
real-time data to calculate the current condition of the at least
one component and to determine if any maintenance is required and
(iv) reporting at least one of the real-time data, the calculated
condition and any required maintenance.
[0016] In addition, the method described above may also include
repeating steps (i) and (ii) for additional sub-systems. The method
may occur while the aircraft is in flight or while it is on the
ground. The methods described above may also include the additional
step of transmitting at least one of the real-time data, the
calculated condition and any required maintenance to a ground-based
master landing gear database.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The present invention will be described in further detail
below with reference to the attached figures in which:
[0018] FIG. 1 is a schematic of one embodiment of the health
monitoring system of the present invention;
[0019] FIGS. 2A-2C are a series of graphs showing the
transformation of load data into load-damage data;
[0020] FIG. 3 is a graph showing damage versus life remaining;
[0021] FIG. 4 illustrates one embodiment as initial screen of a
user interface for the present invention;
[0022] FIG. 5 illustrates a query screen of a user interface for
the present invention;
[0023] FIG. 6 illustrates a bulletin screen of a user interface for
the present invention;
[0024] FIG. 7 illustrates a data accessing screen of a user
interface for the present invention;
[0025] FIG. 8 illustrates a multi-data display screen of a user
interface for the present invention; and
[0026] FIG. 9 illustrates a further query screen of a user
interface of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] The invention relates to a new method and system for health
monitoring of aircraft landing gear. The invention includes the use
of a plurality of sensors that are attached to separate components
of the landing gear structure and equipment (e.g., one or more of
brakes, tires, hydraulics, electrical systems and switches) and
analyzed to report and alert personnel such as pilots, maintenance
personnel, airline operators, ground crew and regulatory
authorities of the health of the landing gear and the potential
need for service, maintenance or replacement.
[0028] The individual sensors measure and record data related to
the component(s) to which it is attached, e.g. a sensor attached to
the shock strut may measure oil pressure, level, and/or
temperature; a sensor attached to a tire may measure the tire
pressure. The sensors that may be used are known in the art and may
be either releasably or permanently attached to the component after
manufacturing or may be connected to the component during the
original equipment manufacturing operations. The data collected
from the sensor(s) is then either directly or indirectly, through
analysis and/or manipulation, used to report a health issue which
may be directly connected to the component being monitored, e.g. a
flat tire, or indirectly related, e.g. low tire pressure that
affects the braking system.
[0029] The present system is operable to monitor and report
critical health issues associated with the landing gear such as the
in-service loads due to landing and taxiing, the presence of
structural defects such as cracks or pre-crack material damage,
tire pressure, tire temperature, brake wear, hydraulic pressure,
the status of on-board electronics, the status of the equipment and
wiring, and the overall condition of the landing gear and ability
to sustain another landing. This real-time information, also
referred to herein as real-time data, can be analyzed in
conjunction with an extensive database of information, also
referred to herein as pre-determined health data, such as the
original manufactured condition of the landing gear, amount and
type of maintenance, in-service history of similar landing gear,
history of the specific landing gear of interest, prior in-service
loads, and number and type of hard landings in order to determine
the safety of the landing gear and/or need for service, maintenance
or replacement. The real-time information and/or information
analyzed in conjunction with the database, can be used to alert
pilots using a cockpit display screen and/or to alert the aircraft
owners, operators, maintenance staff, ground crew and regulatory
authorities via remote transmission providing such personnel with
the option to take actions such as additional inspection, service,
maintenance and/or replacement of the landing gear.
[0030] The present invention will now be discussed in further
detail with reference to the attached FIGS. 1-9.
[0031] One embodiment of the health monitoring system 10 of the
present invention is illustrated in FIG. 1 and includes a plurality
of sensors 12 independently connected to separate components of the
landing gear structure and equipment of an aircraft, not shown. The
system 10 also includes a processor 16 to process and communicate
the data received from the sensors 12. The processor 16 analyses
the data received from the sensors 12 to ascertain the status of
the landing gear structure and may also compare the analysed data
to pre-determined health data to determine the current condition of
the landing gear relative to the historic condition. The processor
16 then reports the condition of the landing gear using a display
24 to at least one relevant personnel. The displaying of the
information may be in the form of a query and reporting system that
will be described in further detail below.
[0032] The system 10 may also include at least one signal
conditioning device 14 connected to the plurality of sensors 12 and
the at least one processor 16. In the illustrated embodiment, the
system 10 includes a plurality of signal conditioning devices 14
connected to the plurality of sensors 12. The plurality of signal
conditioning devices 14 are in turn connected to the processor
16.
[0033] It will be understood that the processor 16 and the
plurality of signal conditioning devices 14 may be separate
components or may be one unitary component, i.e. the processor 16
may be operable to receive data directly from the sensors 12.
Further the plurality of signal conditioning devices 14 may in fact
be one unitary signal conditioning device 14 that is connected to
each sensor 12 and to the processor 16. Further, each sensor 12 may
be connected to one signal conditioning device 14 or to several
signal conditioning devices 14 or alternatively each sensor 12 may
be directly connected to one central processor 16.
[0034] In one embodiment, the signal conditioning device 14 is
operable to receive data from the sensor(s) 12 and convert it into
a form that the processor is able to understand and analyse. As an
example, the signal conditioning device may be an analog to digital
converter to transfer the sensor information into a form that the
processor can understand.
[0035] In an alternative embodiment, the signal conditioning device
14 may include a component for conditioning the data received which
in turn is connected to a network bus or alternatively the data may
be transferred from the sensor 12 to the network bus and then be
converted into a form that the processor is able to understand and
analyse. It will therefore be understood that the signal
conditioning device 14 may be in the form of a distributed system
where the sensor data is communicated over a network or
communications bus, such as ARINC-429, AFDX, CANbus or Time
Triggered Protocol--or other similar devices known to a person
skilled in the art.
[0036] It will also be understood by a person skilled in the art
that each different type of sensor will require suitable interface
circuitry to adapt it to be read by the processor. For instance,
strain gauged based sensors need excitation, amplification,
filtering, and then conversion from the analog domain to the
digital domain. A capacitive fluid level sensor may require
conversion either using a direct to digital converter, or by using
a capacitive bridge circuit, excitation circuitry, an demodulation
circuitry. Preferably, the sensors will be of an analog nature,
with the exception of sensors that behave like a switch, e.g.
proximity sensors.
[0037] An appropriate number and type of sensors 12 are attached to
the components of the landing gear (not shown) in appropriate
locations for each component to be monitored which will be
described in further detail below. It will be understood that a
person skilled in the art will know where particular sensors 12
should be located and how to attach them to a component of the
landing gear. It will be understood that the choice of number and
type of sensor 12 may vary depending on the type and number of
components to be monitored. The minimum number of sensors 12 may
depend on both the geometry of the landing gear, and the
information desired. For example, the system may include only one
sensor if a small amount of specific data is required whereas other
systems will require additional sensors. The state of some
components may be assessed using data from one particular sensor or
from a combination of sensors.
[0038] Examples of the types of sensors 12 and components to which
the sensors 12 may be attached include, but are not limited to,
tires, brakes, hydraulics, electronics, landing gear doors, oil
pressure, oil temperature, oil level, shock strut position, loads,
strain gauges, structural integrity, magnetic permeability, brake
pressure, and aircraft bus data including airplane velocity,
position, attitude and altitude
[0039] As an example, in a system for measuring the servicing state
of the shock strut, a measurement of one of the following could be
used alone or in combination with the other measurements to assess
the servicing state: internal oil pressure, oil level, shock strut
extension, and oil temperature. Alternatively, one could not
measure the oil level and instead use a stored measurement that was
made with the aircraft in flight--two sets of data at known
conditions--strut position, temperature, and pressure can be used
to determine the service state. For the determination of the loads
through the landing gear, the landing gear geometry directly
affects how this can be achieved--there are three loading
directions of interest--vertical, side, and drag--these could
define a minimum.
[0040] This real-time data, i.e. the data recorded by each sensor
12, may be conditioned or transformed, by either the sensor itself
or the signal conditioning device 14 or the processor 16, into
information that is more directly relevant to a condition to be
monitored and reported (e.g. converting voltage to pressure). For
example, if a communications bus is used the sensors may be of the
`smart sensor` variety. Therefore, the sensors may employ a local
microprocessor, signal conditioning circuitry, and data conversion
circuitry to convert the measured signal to a digital signal, then
relay that signal over the communications bus to the processor
16.
[0041] This information may then be analysed in conjunction with an
on-board database 18, containing the pre-determined health data
associated with each component, by the processor 16 based on
pre-determined algorithms, heuristics, or alternative methodology
such as neural networks or fuzzy logic. This set of analytical
techniques may be referred to as the "Analysis Method Library" and
is indicated generally by numeral 20. It will be understood that
the analytical techniques may be stored in the processor 16 or may
be stored within a system with which the processor 16 is operable
to communicate to retrieve the required information. Likewise the
on-board database 18 may be part of the processor 16 or may be a
separate component in communication with the processor 16.
[0042] The resulting analysis determines the landing gear condition
and may be reported, along with any alerts deemed necessary as a
result of the analysis through a display 24 accessible by, for
example, the on-board crew including the pilot(s), co-pilot(s) and
flight crew. Alternatively, the display 24 may be part of a
ground-based system that is in communication with the processor 16
and is accessible by ground personnel.
[0043] In an alternative embodiment the system 10 includes a
communications sub-system 22 that receives the information relating
to the condition of the landing gear components from the processor
16 and in turn communicates the information to the display 24. The
communications sub-system 22 may be part of the processor 16 or may
be a co-processor. The sub-system 22 is operable to collect all
communications into and out from the processor 16, and optionally
all other components in the system 10. The sub-system 22 provides a
separate communication from the processor 16 if desired or
required.
[0044] Examples of the types of alerts that may be transmitted as a
result of the analysis include, but are not limited to: the
remaining life of the landing gear; the need for servicing; the
need for maintenance; the need for inspection and a calculated risk
of failure of the landing gear upon next landing.
[0045] The communications sub-system 22 and/or the processor 16 may
also be operable to communicate with a ground-based master landing
gear database 26. Therefore, all relevant information may be
transmitted between the communications sub-system 22/processor 16,
including the on-board database 18 and the ground-based master
landing gear database 26 which will allow for any updates of
information from the master landing gear database 26, for example
to the algorithms used to be made. The master landing gear database
26 may include information such as landing gear system information,
i.e. built in test results for each piece of avionics, reported
anomalies, brake system information, i.e. brake temperatures,
pressures, wear information, tire information, i.e. tire pressure,
tire wear information, tire temperatures and landing gear
information, i.e. landing gear usage including loads, forces, time
histories, individual part fatigue information and life consumed.
Preferably the master landing gear database 26 includes at least
the landing gear information.
[0046] When the information is communicated to the ground-based
master landing gear database 26, the status of the landing gear
and/or alerts can be sent through a reporting sub-system 28 to the
aircraft owners and operators, maintenance staff, ground crew, and
regulatory authorities, indicated generally at 30, who may decide
to take actions such as additional inspection, service, maintenance
and/or replacement of the landing gear. Any actions taken on the
landing gear, such as servicing, maintenance or inspection,
indicated generally at 32, can then be entered and uploaded back to
the master landing gear database 26, which can in turn update the
on-board database 18 in preparation for the next takeoff.
[0047] In an alternative embodiment of the invention, there are
multiple sub-systems that are included in the overall system. The
sub-systems each focus on one component of the aircraft, including
structural, tires, brakes, hydraulics, electronics, position,
communications, database, analysis, and reporting. Each modular
sub-system is dedicated to obtaining, conditioning and analyzing
information of interest regarding the component. However, the
information recorded by each sub-system can be shared between
sub-systems and used to assess the condition of other components in
the overall system.
[0048] In one example, a structural integrity sub-system is
provided in which the sensors 12 are attached directly onto the
structural portions of the landing gear, either during a retrofit
operation or during the original manufacture. These sensors 12 are
used to measure all relevant loads experienced by the structure
during taxiing, take-off and landing, including, but not limited
to, for example torsional, axial, fatigue and shock loads. The data
recorded by the sensors 12 of the system may then be processed to
calculate information related to the presence of defects,
discontinuities and/or pre-crack damage to the structure. This
information can then be used to calculate the current health of the
landing gear structure which in turn can be compared to the
original manufactured condition of the landing gear.
[0049] In another example, in order to monitor the tire pressure a
pressure sensor is attached to the tire in such a way as to obtain
and communicate the pressure information to the monitoring system
or brake monitoring sub-system. In order to monitor the loads on
the structure, load sensors are attached to the structure in the
appropriate locations so as to obtain and communicate the load
information to the monitoring system or structural integrity
monitoring sub-system.
[0050] The sensor information is analyzed in a variety of ways,
depending on the specific sub-system. For example, the tire
pressure sensor can measure the pressure directly. By knowing the
change in tire pressure over time, an assessment can be made
whether the tire is leaking air. Depending on rate of pressure
decrease, ambient temperature, prior service history, e.g. if a
valve has just been replaced, and correlation with tires in the
rest of the fleet, an assessment may be made to replace the tire,
fix a valve stem, simply re-inflate the tire, or leave the tire
alone because the pressure drop was caused by a drop in ambient
temperature.
[0051] Each sub-system will have its own method for analyzing the
raw sensor information, conditioning or converting the raw
information into more directly relevant information as appropriate,
e.g. converting voltage to pressure or converting the time rate of
voltage change to magnetic permeability to the presence of
pre-crack damage, analyzing the information in conjunction with a
database of information and reporting the need for service,
maintenance or replacement.
[0052] The real-time information from each sub-system can be
analyzed in conjunction with an extensive database of information
such as the original manufactured condition of the landing gear,
amount and type of maintenance, in-service history of similar
landing gear, history of the specific landing gear of interest,
prior in-service loads, and number and type of hard landings in
order to determine the safety of the landing gear and/or need for
service, maintenance or replacement.
[0053] The real-time information and/or information analyzed in
conjunction with the database, can be used to alert pilots using a
cockpit display screen, and/or remotely transmitted to the aircraft
owners and operators, maintenance staff, ground crew, and
regulatory authorities who may decide to take actions such as
additional inspection, service, maintenance and/or replacement of
the landing gear.
[0054] Determining the number, location and type of these sensors
12 requires engineering modeling and testing of the landing gear in
order to optimize performance and sensitivity. It should be noted
that the number, location, and type, e.g. number of windings, of
sensors 12 will be identical from one set of landing gear to
another within a given type of landing gear, but will vary from one
type of landing gear to another depending on the engineering design
analysis and full scale destructive testing results. The raw data
taken from the load sensor must be conditioned in order to
determine the actual load.
[0055] The following provides an example of the type of analysis
that may be performed. Analysis of the in-service loads measured
using the structural integrity sub-system can be used to determine
the weight and balance of the airplane, presence of hard landings,
and other loads that may contribute to a reduction in the remaining
useful life of the structure. Generally, the most common way for
engineers to measure the life of a structure is to construct a S-N
Curve showing the number of cycles to failure (N) for a given
applied load (S). Statistical analysis is used to predict the
probability of failure of a landing gear that has experienced a
certain number of cycles of a given load. However, if the landing
gear is subjected to several significantly higher loads than S, the
effect on the remaining number of cycles to failure (N) is far more
difficult to calculate. Furthermore, during the lifetime of a
landing gear there will be large fluctuations in the range of loads
(S), requiring a more sophisticated technique for assessing the
total amount of load-damage (e.g. a modification to the calculation
of S which we will name "D") and thus remaining useful life (a
modification to the calculation of N which we will name "L"). The
structural integrity sub-system must continually update the actual
D that the particular landing gear has been subjected to, so as to
continuously be calculating the remaining number of cycles to
failure (L) and probability of failure for any potential future
landing (e.g. the probability of failure during a hard landing will
be different than the probability of failure during a soft
landing).
[0056] As an example, FIG. 2 is a graphical illustration of how to
transform the load data (S) into more relevant information (D). As
can be seen, certain small loads may not affect the overall damage,
however, a large load may cause a significant increase in the
damage. In the example shown in FIG. 2, the first set of loads (S)
cause a slight increase in D. However, this slightly increased D
has almost no effect on the Life Remaining (L), as shown in the
lower arrow that points from the second graph to the third graph.
In contrast, a higher load, such as shown taking place at a later
time (t), can increase the damage further resulting in a
significant effect on the Life Remaining (L), as shown in the top
arrow that points from the second graph to the third graph.
[0057] As shown in FIG. 3, there may be significant scatter in the
experimental data when performing actual destructive tests on
full-scale landing gear. For example, seemingly identical specimens
may have a significant difference in the number of cycles to
failure or remaining life. This uncertainty is addressed using
statistical analyses as well as conservative projections. As can be
seen from FIG. 3, using a conservative remaining life projection
(the lower edge of the curve) may result in almost half of the
anticipated lifetime compared to using the projection from the
centre or top of the curve.
[0058] Therefore, using only the directly measured in-service loads
to predict remaining life will result in very conservative
predictions. However, these predictions can be significantly
improved, often resulting in a much higher calculated remaining
life, if the D-L curve can be modified based on additional sources
of information such as direct measurement of the damage, knowledge
of the original manufactured condition, and knowledge of the
service history of the landing gear. A system, as provided by the
present invention, that includes continual monitoring of the
landing gear components and a comparison of the monitored data with
pre-determined structural health measurements provides more
accuracy to such calculations.
[0059] In an alternative embodiment, the sensors 12 in the
structural integrity sub-system will also directly measure the
material properties in a way that will provide direct evidence of
the presence of defects and/or pre-crack damage. In one embodiment
of the invention, meandering winding magnetometer sensors are used
to measure the magnetic permeability of the material in such a way
as to be highly correlated with the presence of defects and/or
pre-crack damage. An example of the sensors that may be used are
the sensors manufactured by Jentek Sensors Inc.
[0060] Each landing gear has its own continuously updated D-L
curve, that calculates the remaining life (L) as a function of the
total spectrum of applied loads, which are used to calculate (D).
However, once a defect, crack or pre-crack defect has been found,
for example by measuring the magnetic permeability of the material,
the D-L curve will be shifted to a new D-L curve which shows a
lower remaining life, which will be named "Ld" for L in the
presence of a known defect.
[0061] In another embodiment, the original manufactured condition
of the landing gear is known. This is achieved by creating a "birth
certificate" or "fingerprint", indicated generally at 40 in the
schematic of FIG. 1, for each newly manufactured landing gear
composed of a three dimensional geometric inspection and
complemented with enhanced non-destructive inspection results, such
as magnetic permeability or Barkhausen noise inspection. The "birth
certificate" or "fingerprint" establishes the part's expected
fatigue and strength performance. The "birth certificate" includes
such data as non-destructive inspection results, surface
discontinuities, coating thickness, tube wall thickness, heat
treatment history, repair and rework occurring during
manufacturing. By comparing the in-service material properties,
e.g. magnetic permeability or Barkhausen noise, the "new
fingerprint"--to the original fingerprint, a better determination
can be made as to the presence of a defect and/or pre-crack damage.
Thus a better determination can be made as to the remaining useful
life (Ld) of the landing gear. This information may be stored in
the on-board database 18 along with the pre-determined health data
for each component. Alternatively, the "birth certificate" or
"fingerprint" for each component may be stored separately.
[0062] Using an array of information based on real-time data (e.g.
load and magnetic permeability), provided by the sensors 12 and/or
signal conditioning device 14 in conjunction with the on-board
database 18 (e.g. prior birth certificate fingerprint of magnetic
permeability) and sophisticated algorithms (e.g. the method for
transforming S into D to calculate L or Ld) or heuristics, neural
networks or fuzzy logic (e.g. the Analysis Method Library 20), the
processor 16 can determine the need for service, maintenance or
replacement.
[0063] The structural integrity sub-system can provide a plethora
of useful information including weight and balance information
(which is of immediate interest and concern to the pilot and flight
crew who may wish to move passengers or decline to take-off until
the weather has changed), hard landing indication (which may be
used for regulatory authority notification), and notification that
the remaining useful life has been compromised so that the landing
gear can be removed, inspected, or serviced.
[0064] If a hard landing has taken place, the structural integrity
sub-system can calculate the immediate effect of this on the
remaining life of the landing gear and the cost of this reduction
in life can be charged to the operator.
[0065] In a further embodiment, the sensors 12 in the health
monitoring system are connected to a plurality of measurement and
analysis units (not shown) (one per landing gear assembly) that are
in close proximity to the sensors, and that contain internal,
rechargeable power supplies. When the aircraft avionics are on
(such as when the aircraft is flying or taxiing) the remote
measurement and analysis unit(s), which are connected by electrical
cabling to the aircraft avionics, are recharged by the aircraft
electrical system and the measured data contained in the units are
transferred to the aircraft avionics. This system permits the
measurement of landing gear structural integrity when the aircraft
power is not on (during towing, parking, and storage or maintenance
activities). This facility provides the structural integrity
sub-system with capability to detect damage during these times when
conventional systems would not be operational. Considerable landing
gear damage can occur when the aircraft is not powered on.
[0066] Alternatively, each sensor 12 may include its own source of
power separate from the aircraft power system, which allows the
sensor to continue to monitor data even when the aircraft power is
switched off. In this embodiment, each sensor 12 for which
continual monitoring is required, is equipped with, or connected
to, a separate power supply/source.
[0067] In a preferred embodiment of the system, subsets of the
Master Landing Gear Database including accrued Damage (D)
information and available life (Ld) information will be stored
(along with fingerprint information) in an electronic memory that
is attached to components of the landing gear. As critical
components of a landing gear may be removed for maintenance and
replaced with other components from a rotatable pool of parts, a
means is required to track the current composition of the landing
gears on the airplane. By storing pertinent excerpts from the
Master Landing Gear Database on the actual landing gear components,
and by being able to retrieve them electronically (e.g. by using
RFID tags and scanners) the processor 16 will always be aware of
the exact damage status of the components on the aircraft. For
example, if a component in the landing gear is changed when the
aircraft is powered off, once the power is returned the processor
16 will automatically read and download the information about the
component contained on it. This information will provide the
processor 16 with all relevant damage information and the
information will be updated by the processor 16 during and after
flight. The central database can also be updated with the relevant
information relating to the parts in use and any damage applied
thereto.
[0068] In a preferred embodiment of the system, there will also be
sub-systems for the following: tires (pressure, temperature, wear
and remaining life), brakes (temperature, integrity, wear and
remaining life), hydraulics (pressure, temperature and viscosity),
electronics (power, integrity and status), position (of the landing
gear doors and landing gear), communications (between the sensors,
on-board systems, pilot cockpit display, on-board database, and
ground-based systems), Master Landing Gear Database (of the
maintenance history, in-service load history, similar landing gear
systems, and maintenance history), and analysis and reporting (to
show alerts, recommendations for servicing or maintenance, and
provision of information).
[0069] Each of the above named sub-systems can be implemented using
a similar methodology as described for the structural integrity
sub-system: taking key data from sensors attached in the
appropriate location, analyzing the data to determine critical
information of interest (e.g. the condition of the brakes), and
analyzing this information in conjunction with the on-board
database by the central processing unit to determine the need to
take actions such as alerting the pilot, performing additional
inspection, removing the landing gear, and/or performing servicing
or maintenance.
[0070] In another embodiment of the system, data collected from
each of the sub-systems is returned electronically from the
aircraft to an analysis center. Each report is accepted into a
database system (such as Teamcenter from UGS) that attaches the
data report to the data records for that part number and serial
number of part or assembly. In the case of data returned from the
structural integrity sub-system, data is electronically attached to
a top level landing gear assembly. The software aligns all data
records with original design specifications and as-built records.
For structural data on an assembly, the data is automatically
routed to individual data processing and analysis routines that
generate the damage and life information for each sub component.
This information is then automatically appended to the appropriate
part numbers and serial numbers within the database. Upon
completion, electronic messages are dispatched to the aircraft
avionics to update the onboard databases, and to operators and
customer service personnel.
[0071] FIGS. 4 through 9 demonstrate one embodiment of a user
interface to the Querying and Reporting Sub-System for the present
invention (in this example, using the trade name "SmartStrut--your
landing gear health monitoring system"). As shown in FIG. 4, the
system can be accessed using a standard web browser such as
Microsoft Explorer or Netscape Navigator and can be password
protected to restrict access to conduct queries and permission to
modify the database.
[0072] FIG. 5 demonstrates the ability to conduct a query for a
specific customer, aircraft and landing gear. FIG. 6 demonstrates
the ability to tie into other databases such as service bulletins
and news bulletins. FIG. 7 demonstrates the ability to directly
access the real-time data and/or most recently updated information
provided to the Master Landing Gear Database from the on-board
systems. FIG. 8 demonstrates the ability to access information
associated with several sub-systems at once, including a down-lock
sensor component fault, the oil level and nitrogen pressure. As can
be seen, simple heuristics can be used to determine the potential
need for servicing. In this case, the heuristic for oil level is
that the oil level is critically high when above one number and
critically low if the oil level is below another number.
[0073] In one embodiment of the invention, the oil level, rate of
change of oil level, nitrogen pressure, and rate of change of
nitrogen pressure (and/or other information) are used to report a
single value--"need to perform service", "no need to perform
service", or "service needed soon".
[0074] FIG. 9 demonstrates the ability to log the access to the
system, email alerts and conduct further queries. Additional
searching, querying, analysis and reporting functions are available
through this user interface.
[0075] While this invention has been described with reference to
illustrative embodiments and examples, the description is not
intended to be construed in a limiting sense. Thus, various
modifications of the illustrative embodiments, as well as other
embodiments of the invention, will be apparent to persons skilled
in the art upon reference to this description. It is therefore
contemplated that the appended claims will cover any such
modifications or embodiments. Further, all of the claims are hereby
incorporated by reference into the description of the preferred
embodiments.
[0076] All publications, patents and patent applications referred
to herein are incorporated by reference in their entirety to the
same extent as if each individual publication, patent or patent
application was specifically and individually indicated to be
incorporated by reference in its entirety.
* * * * *