T A DEVICE FOR SEARCHING FOR DEFECTS ON PARTS BY ENDOSCOPY
The invention relates to a device for using
endoscopy to search for defects on parts that are masked,
i.e. that are not directly visible, e.g. such as parts
5 inside a turbine engine.
It is known to inspect the internal components of
equipment or of a machine with the help of an endoscope
which is an elongate optical instrument of small diameter
that is passed through a small orifice in a wall in order
10 to examine the appearance of components that are to be
found on the other side of the wall. The endoscope can
thus be used for inspecting blades of a turbine engine
such as an airplane turboprop or turbojet without it
being necessary to disassemble the engine.
15 In order to view defects of a part, it is known to
use a penetrant test technique that consists in
depositing organic materials on the surface under
examination of the part and in observing under
ultraviolet illumination the extent to which the organic
20 materials impregnate the surface of the part. The
presence of defects is revealed after drying the surface
of the part and depositing a developer material that
reveals the organic material that has infiltrated into
surface defects of the part when the part is illuminated
25 with ultraviolet light.
In order to facilitate the use of the penetrant
testing technique on an airplane engine while it is
attached under the wing of an airplane, proposals have
already been made in document US-A-4 273 110 to use an
30 endoscope incorporating penetrant test means. For that
purpose, the proposed instrument comprises an elongate
rigid cylindrical sheath of small diameter containing a
duct that is used for passing means for guiding
ultraviolet light and visible light towards an end of the
35 instrument that is close to the part for inspection. The
instrument also has an optical duct for integrating means
for transmitting and forming images in order to observe
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the illuminated zone, and a plurality of ducts, each used
for passing a respective penetrant test material.
That type of instrument is relatively easy to use
when it is desired to examine a masked part, i.e. a part
5 that is not directly visible and that is situated behind
a wall. For that purpose, it suffices to insert the
rigid sheath through an orifice in the wall and to
perform the inspection in the manner described above.
The Applicant has also made proposals in a prior
10 application FR 2 857 094 to perform the penetrant testing
and the observation with the help of two separate
endoscopes. In another prior application, FR 2 861 185,
the Applicant proposes using an endoscope with
ultraviolet illumination and deflected distal viewing,
15 the endoscope having a rigid tubular body.
Nevertheless, those prior devices require a
plurality of independent ducts for passing different
penetrant test materials, thereby requiring the endoscope
to have a section that is large and restricting its use
20 to orifices or passages that are sufficiently large.
A particular object of the invention is to provide a
solution to that problem that is simple, satisfactory,
and inexpensive.
To this end, the invention provides a device for
25 searching for defects on parts that are masked and
accessible via a passage that is not rectilinear inside a
turbine engine such as an airplane turboprop or turbojet,
the device comprising a tubular sheath and light-guide
means for guiding light and image-transmission means for
30 transmitting images housed in the sheath in order to
illuminate and observe a part for inspection, the device
being characterized in that it comprises an examination
head at the distal end of the sheath, the head having
illumination means and image-taking means connected to
35 the light-guide means and to the image-transmission means
housed in the sheath, means for spraying a succession of
•
penetrant test materials on the part for inspection, said
means comprising a capillary slidably guided inside a
duct housed in the sheath, and in that it includes means
for adjusting the orientation of the examination head at
the distal end of the sheath.
5 Integrating a duct inside the sheath makes it
possible to insert and withdraw a capillary for passing a
penetrant test material, which capillary is mounted to
slide inside the duct, thus making it possible to use a
plurality of capillaries in succession, each capillary
10 being dedicated to pass one particular penetrant test
material. The diameter of the tubular sheath can thus be
smaller than the diameter of a prior art sheath.
Slidably inserting the capillary inside the duct
also makes it possible to bring the distal end of the
15 capillary close to the zone of the part where it is
desired to apply the penetrant test material. In this
manner, the illumination means and the image-taking means
may be set back from the distal end of the capillary.
This avoids penetrant test material spray from becoming
20 deposited on the illumination means or on the image-
| taking means. When the operator desires to observe the
treated region, the operator pulls on the proximal
portion of the capillary in order to bring its distal end
closer to the distal end of the sheath.
25 According to another characteristic of the
invention, the device comprises air-blow means for
blowing air on the illumination means and image-taking
means located at the distal end of the sheath.
The air-blow means prevent the illumination means
30 and the image-taking means from being polluted by the
various penetrant test materials injected via the
dedicated capillaries that are inserted in succession
into the duct.
In a particular embodiment of the air-blow means,
35 they comprise means for feeding air under pressure that
are connected to a blow tube leading at its distal end to
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the vicinity of the illumination means and the imagetaking
means.
In a preferred embodiment of the invention, the
means for feeding air under pressure are connected to the
5 proximal end of the duct for passing the capillary in
order to feed the duct with a continuous stream of air
that leaves via its distal end.
In operation, the stream of air that blows
continuously between the inside surface of the duct and
10 the capillary prevent drops of penetrant test materials
such as acetone, a penetrant dye, an emulsifier, or a
developer, or indeed washing water, from becoming
deposited inside the duct.
According to another characteristic of the
15 invention, the proximal end of the flexible sheath is
connected to a handle for fastening to the engine and the
duct housing the capillary is extended inside the handle
and is connected to a rigid tube carried by the handle
and serving to insert the capillary into the inside of
20 the duct.
According to another characteristic of the
invention, the device comprises holder means for
preventing the capillary from sliding inside the duct,
constituted by an endpiece designed to be engaged and
25 held against the free end of the rigid tube, the endpiece
having means for clamping onto the capillary by pinching
it.
In a particular embodiment of the invention, the
endpiece includes a passage leading to the inside of the
30 tube and forming an inlet for connection to the means for
feeding air under pressure.
In this configuration, the endpiece with the
clamping means also serves to make a connection with the
means for feeding air under pressure.
35 According to another characteristic of the
invention, the orientation adjustment means comprise a
control member for controlling the angular orientation of
r
the examination head, which member is rotatably mounted
on the endoscope handle and is connected to transmission
means for transmitting the orientation control to the
examination head, these transmission means being housed
5 in the sheath.
Turning the control member in one direction or the
other serves to cause the examination head to tilt
relative to the remainder of the sheath.
In a particular embodiment of the invention, the
10 means for adjusting the orientation of the examination
| head comprise at least two cables guided inside the
sheath and fastened at their distal ends to the
examination head at two diametrically opposite points,
and wound under tension at their proximal portions in
15 opposite directions on a rotary control member situated
on the handle.
In another particular embodiment of the invention,
| the means for transmitting the orientation control
comprise at least one rod extending inside the sheath and
20 connected at its distal end to a mechanism for converting
rotary movement of the ring into movement in translation
of the rod, the rod being connected by its distal end to
a finger that is pivotally hinged to the distal end of
the sheath about an axis that is perpendicular to the
25 sheath.
Advantageously, the distal finger includes an axial
channel for passing the capillary and is hinged to pivot
between a position in which it is in alignment with the
axis of the sheath and a position in which it is oriented
30 perpendicularly to the axis of the sheath.
The pivoting of the hinge finger induces pivoting of
the distal end of the capillary, thereby enabling the
distal end of the capillary to be oriented angularly in
three dimensions in order to spray the penetrant test
35 materials on the part for inspection.
In a preferred configuration of the invention, the
tubular sheath is flexible and the capillary is flexible,
thereby making it possible to perform non-destructive
inspection of a part that is to be found inside a complex
three-dimensional structure and that is accessible solely
via a narrow and non-rectilinear passage, where this is
5 not possible using an endoscope of rigid structure.
According to another characteristic of the
invention, the distal end of the sheath is fitted with a
spray endpiece at its distal end.
Preferably, the spray endpiece at the distal end of
10 the capillary is removable and can be selected from a set
of spray endpieces for spraying radially, forwards, or
backwards.
In a practical embodiment of the invention, the
sheath is of circular section with a diameter lying in
15 the range 6 millimeters (mm) to 10 mm, and the duct for
passing the capillary has a diameter of about 1.2 mm, the
capillary having a diameter of about 0.8 mm.
According to another characteristic of the
invention,- the device has fastener means for fastening to
20 a portion of the engine, which means comprise a hinge arm
.connected to the handle.
The invention also provides a method of nondestructively
inspecting a masked part inside a threedimensional
structure by means of the above-described
25 device, the method consisting in:
• inserting and guiding the examination head inside
a three-dimensional structure to a position for examining
the part for inspection;
• with the examination head placed facing the part
30 for inspection, feeding the proximal end of the capillary
with a first penetrant test material and applying this
material via the distal end of the capillary to the part
for inspection;
• slidably withdrawing the capillary from the duct
35 in which it is housed; and
• slidably inserting a second capillary into the
duct and bringing its distal end into the vicinity of the
*
part for inspection, and then feeding the proximal end of
the second capillary with a second penetrant test
material and applying the second material to the part for
inspection.
5 Other advantages and characteristics of the
invention appear on reading the following description
made by way of non-limiting example and with reference to
the accompanying drawings, in which:
• Figure 1 is a diagrammatic view of a prior art
10 device for searching for defects;
• Figure 2 is a diagrammatic perspective view of a
device of the invention for searching for defects;
• Figure 3 is a diagrammatic section view of the
flexible sheath of the device of the invention;
15 • Figure 4 is a diagrammatic perspective view on a
larger scale of the proximal portion of the Figure 2
device;
• Figure 5 is a diagrammatic end view of an endpiece
having inserted therein a capillary for passing a
20 penetrant test material;
• Figure 6 is a diagrammatic view of the distal end
of the duct housing a capillary;
• Figure 7 is a diagrammatic view of the penetrant
test material being sprayed;
25 • Figure 8a is a diagrammatic section view of the
distal end of the flexible sheath of the device of the
invention;
• Figure 8b is a diagrammatic view in section of the
distal end of the examination head of the device of the
30 invention;
• Figure 9 is a perspective view of an orientable
examination head of the device of the invention;
• Figure 10 is a diagrammatic view of an arm for
holding the endoscope of the invention;
35 • Figures 11 to 13 are perspective views of
endoscopic equipment having a rigid inspection tube and
*
adapted to penetrant testing under ultraviolet
illumination in an embodiment of the invention;
• Figure 14 is a perspective view of the distal end
of the endoscope of Figures 11 to 13;
5 • Figure 15 is a view in perspective and in
longitudinal section of the endoscope of Figures 11 to
13;
• Figure 16 is an exploded perspective view of the
endoscope of Figures 11 to 13;
10 • Figure 17 is an exploded perspective view of the
distal end of the endoscope of Figures 11 to 13;
| • Figure 18 is a diagrammatic fragmentary axial
section view of an endoscope in a variant embodiment of
the invention; and
15 • Figure 19 is a perspective view of the distal end
of the Figure 18 endoscope.
Reference is made initially to Figure 1, which shows
a prior art device 10 for searching for defects, the
device comprising a rigid tubular cylindrical stick 12
20 for inserting via one end into an endoscopic orifice 14,
e.g. made in a wall of a casing 16 of a turbine engine
within which there is a part 18 that is to be examined,
such as a rotor blade, for example.
The cylindrical stick 12 has a duct receiving means
25 for guiding light and for transmitting images in order to
illuminate and observe the part. The cylindrical stick
12 also has a duct for spraying penetrant test materials,
such as acetone, a penetrant dye, an emulsifier, or
water. The end 20 of the stick 12 opposite from its end
30 for inserting in the orifice 14 is connected via a
circuit 22 to means 24 for feeding it with penetrant test
materials and to illumination and control means.
This type of device requires the use of a plurality
of independent ducts for passing the various penetrant
35 test materials, thereby increasing the diameter of the
endoscope and limiting its use to endoscopic orifices or
passages that are sufficiently large.
The device 26 of the invention provides a solution
to that difficulty by replacing the rigid cylindrical
stick with a flexible sheath 28 including an orientable
examination head 62 and incorporating a duct 30 in the
5 sheath 28, which duct houses a capillary 32 slidably
engaged inside the duct 30 (Figures 2 and 3). Figure 3
also shows a second duct 34 used for passing light-guide
means and image-taking and image-transmission means.
These means are described in greater detail below.
10 The device has an endoscope handle 36 of
substantially cylindrical shape with a first end that is
connected to the proximal end of the flexible sheath 28.
The second end of the handle 36 carries a bent rigid tube
38 leading to the inside of the handle 36 and
15 communicating with the duct 30 housing the capillary 32.
The device 26 has means for holding the capillary 32
stationary inside the duct 30. In a particular
embodiment (Figures 4 and 5), these means comprise an
endpiece 40 with a cylindrical or frustoconical skirt 42
20 engaged and clamped on the free end of the rigid tube 38.
The endpiece 40 has a central orifice 44 enabling a
capillary 32 to be inserted inside the rigid tube 38 and
consequently inside the duct 30 extending inside the
flexible sheath 28 (Figures 3 and 4).
25 The endpiece 40 includes means for clamping the
capillary 32 in such a manner as to prevent the capillary
32 from moving relative to the endpiece 40. By way of
example, these means are made by dimensioning the
diameter of the orifice 44 so that it is slightly smaller
30 than the outside diameter of the capillary 32. Thus, the
capillary can be moved manually to slide inside the tube
38 and each time the operator lets go of the capillary
32, the capillary is held in position. In order to
enable such clamping, the endpiece 40 is made of a
35 suitable plastics or elastomer material, such as rubber,
for example.
The device of the invention also has air-blow means
for blowing air from the distal end of the sheath. For
this purpose, the endpiece 40 includes a second orifice
46 formed in its front face and leading to the inside of
5 the rigid tube 38. This orifice 46 is connected to means
48 for feeding air under pressure and enabling the tube
38 and the duct 30 to be fed with a continuous stream of
air 50 that leaves via the distal end of the duct 30.
The exiting stream of air thus prevents the inside of the
10 duct 30 becoming polluted with drops of the various
penetrant test materials (Figure 5) and it limits the
spraying of penetrant test materials in the vicinity of
the illumination means and the image-taking means formed
at the distal end of the sheath.
15 When the pressure of the stream of air is at least
0.3 bars, it is possible to dry the part with the air
feed means, e.g. between two successive applications of
different penetrant test materials.
The proximal end of the capillary 32 is connected to
20 a supply of a given penetrant test material. The device
may then be used with a plurality of capillaries 32, each
of which is associated with a supply of a given penetrant
test material. Each capillary has a spray endpiece at its
distal end enabling the penetrant test material to be
25 sprayed in a particular direction. The endpiece is
advantageously removable and may be replaced at will with
endpieces of other types suitable for performing spraying
that is radial 52, forward 54, or backward 56 (Figure 6).
The device includes image-taking means and image-
30 transmission means as shown in Figure 8a. The imagetaking
means comprise an image-forming lens 64
transmitting the image onto a camera 66 such as a chargecoupled
device (CCD) camera having its output connected
to an analog-to-digital converter. The digitized image
35 is then transferred by a cable 68 to external display
means such as a monitor of a computer processor system.
In a particular configuration of the device of the
invention, the camera 66 has 500,000 pixels, each having
a side lying in the range 8 micrometers (urn) to 12 urn.
The device also has second image-transmission means
5 provided inside the sheath and comprising a set of
optical components (not shown) transmitting the image
formed by the lens to an eyepiece 58 carried by the
proximal end of the handle.
| The device also has light-guide means and
10 illumination means extending to the proximal end of the
sheath. By way of example, these means may comprise an
optical fiber cable 70 extending from the distal end of
the sheath to a connector 60 for coupling to a source of
visible or ultraviolet light.
15 In order to spray penetrant test materials in the
proper direction towards the part and in order to observe
the treated zone appropriately, the device includes means
for adjusting the orientation of the examination head 62
(Figures 8a and 8b).
20 By way of example, these adjustment means comprise
two cables that are guided inside the sheath and that
have their distal ends fastened to the examination head
62 at two diametrically opposite points 72 and 74. The
proximal portions of the cables are wound under tension
25 in opposite directions on a rotary control member 76 of
the handle (Figure 2). Thus, by turning the control
member 7 6 in a given direction, the examination head 62
can be tilted in a plane containing the two fastener
points 72 and 74, and also the central axis 76 of the
30 examination head.
It is possible to add two additional cables having
their distal ends fastened to the examination head 62 at
two diametrically opposite points 78 and 80 that are at
90° to the two fastener points 72 and 74 of the first two
35 cables. The proximal portions of these two additional
cables should likewise be wound onto a rotary member of
the handle. With such an arrangement, it becomes
possible to tilt the examination head 62 in two
orthogonal planes, one of which contains the points 72
and 74 and the other of which contains the points 78 and
80, thereby enabling the distal end of the sheath to be
5 oriented in four different directions.
i
In order to enable the examination head 62 to be
tilted, it may comprise non-touching metal annulus 82,
84, 86 (Figure 9). An annulus 84 is connected to a
downstream ring 82 by two blades 88 that are angularly
10 spaced apart by 180°, being pivotally hinged on the outer
periphery of the downstream annulus 82 and being fastened
on the annulus 84 at 180° from each other. The annulus
84 is fastened to an upstream annulus 86 by two blades 90
that are likewise angularly spaced apart by 180°, and
15 that are pivotally hinged at one end to the outer
I periphery of the annulus 84. The second ends of the two
blades 90 are fastened on an upstream annulus 86 at 180°
to each other. The blades 88 joining the annulus 84 to
the downstream annulus 82, and the blades 90 joining the
20 annulus 84 to the upstream annulus 86 are spaced apart at
! 90° from one another (Figure 9).
Each annulus has four bridges (not shown) that are
I spaced apart at 90° in pairs for slidably guiding cables
fastened to the distal end of the examination head 62.
25 In a variant embodiment of the invention, the cables
for controlling the orientation of the examination head
are wound under tension on a motor-driven rotary member
that may be housed in the handle.
Figure 10 shows an arm 92 for holding the handle of
30 the endoscope. This holding arm 92 has two rods 94 and
96 that are pivotally hinged relative to each other at 98
at a first one of their ends. A respective clamp 100,
102 is pivotally hinged to the other end of each of the
rods 94, 96. A first clamp 100 is for clamping onto the
35 handle of the endoscope 36 and the other clamp 102 is for
fastening on a portion of the turbine engine so as to
enable the endoscope to be used in a static position.
In a variant embodiment of the invention (not
shown), the means for feeding air under pressure are
connected to a coupling leading with the rigid tube into
a common cavity formed inside the handle, the proximal
5 end of the duct leading to the inside of this cavity so
as to allow the capillary inserted from the free end of
the rigid tube to pass through and so as to allow the
stream of air under pressure to flow to the distal end of
the sheath. In this configuration, the endpiece has a
10 single central orifice into which a capillary is
inserted.
In a practical embodiment of the invention, the
sheath 28 is of circular section with a diameter lying in
the range 6 mm to 10 mm, the duct 30 for passing the
15 capillary 32 has a diameter of about 1.2 mm, and the
capillary 32 has a diameter of about 0.8 mm. The
flexible sheath may have a length of about 1.5 meters
(m) .
In another embodiment of the invention, the sheath
20 may be rigid and the capillary may be flexible or indeed
rigid. Nevertheless, a rigid sheath in the form of a
stick as in the prior art does not make it possible to
take action in zones inside a turbine engine that are
accessible only via passages that are curved or not
25 rectilinear.
Thus, using a flexible sheath with a flexible
capillary makes it possible to perform non-destructive
testing of zones that are difficult to access without
requiring the engine to be taken to a maintenance
30 workshop, thereby reducing the time required for
maintenance and the costs of operating the engine.
Reference is made below to Figures 11 to 19 which
show other embodiments of the invention.
The endoscope 104 has a handle 105 with a proximal
35 portion 106 and a distal portion 124, and a sheath
forming a rigid distal inspection tube 108. In
Figure 11, the tube 108 is engaged in an inspection tube
g 14
110. The handle 106 has a focusing ring 112 and an
eyepiece 114 housed in a proximal eyecup 116 suitable for
being connected to an endoscopic camera. The endoscope
104 has a path for transmitting illumination light
5 comprising a bundle of illumination fibers (not shown)
extending in an illumination cable 118 secured to the
handle 106. The distal portion of the tube 108 includes
a porthole 120 at the distal end of an image optical path
of the endoscope 104, and a window 122 behind which it is
10 possible to stick the previously-polished distal end of
the bundle of illumination fibers.
The endoscope has a tube 126 with a distal lateral
opening 128 under which there are positioned the viewing
window or porthole 120 and the illumination window 122 of
15 the endoscope 104 (Figure 11). The distal end of the
tube 110 is secured to a hinge finger 130 having an
internal channel 132 leading at one end to an orifice 134
and at an opposite end into a working channel or duct 136
housed in the tube 110. In the handle 124., the working
20 channel 136 leads into a socket 138 leading to the
proximal end of the working channel 124. The working
channel 124 is designed to enable a flexible capillary
tube 32 to be slidably inserted (Figure 15), which tube
can enter via the socket 138 and leave via the orifice
25 134. Such a capillary tube is for spraying penetrant
test materials onto the part to be inspected. The handle
124 also has a control ring 140 making it possible to
adjust the angle of the hinge finger 130 manually. The
handle 124 may also have a socket 142 connectable to a
30 source of compressed air, in communication with an airblow
tube 144 leading into the opening 128, parallel to
the porthole 120 and the illumination window 122.
In Figures 13, 15, and 16, the distal portion^ 124 of
the handle 105 includes a cylindrical proximal housing
35 146 for receiving the cylindrical distal end 148 of the
proximal portion 106 of the handle 105 of the endoscope
104. The housing 146 has a distal partition 150 provided
with an axial orifice constituting the proximal end of an
internal cylindrical tube 152 for receiving the tube 108
of the endoscope 104. Means for assembling and fastening
the handle 105 in the housing 146 may include an indexing
5 and locking device (not shown) enabling the distal end of
the tube 108 of the endoscope to be properly positioned
under the distal-opening 128 of the endoscope 104.
The distal portion 124 of the handle 105 has a
proximal cylindrical part 154 with a proximal portion
10 forming the cylindrical housing 146 and with a tubular
distal portion 155 having a longitudinal slot 156.
The endoscope has a ring 140 for controlling the
angle of the distal hinge finger 130. A cylindrical ring
158 is mounted stationary inside the control ring 140 and
15 has a helical slot 160 formed in its periphery. A
tubular couple 162 is slidably mounted around the
I internal tube 152 and has a radial finger 164 on its
| outer periphery. The shuttle 162 is secured to two
longitudinal maneuvering rods 166, 168 extending inside
20 the tube 126 and serving to control the angle of the
; distal hinge finger 130.
The control ring 140 and the cylindrical ring 158
are mounted around the tubular distal portion 155 of the
proximal cylindrical part 154. The tubular shuttle 162
25 is mounted inside the tubular distal portion 155 of the
proximal cylindrical part 154 and the radial finger 164
passes through the longitudinal slot. 156 of the tubular
distal portion 155 of the proximal cylindrical part 154,
and its radially outer end is received in the helical
30 slot 160 of the cylindrical ring 158.
The distal portion 124 of the handle 105 also has a
central part 170 and a distal part 172 which in
association with the proximal cylindrical part 154 serves
to block movement in translation of the distal portion
35 124 of the handle 105 and the cylindrical ring 158 around
the tubular distal portion 155 of the proximal
cylindrical part 154, while forming two lateral orifices
that allow sockets 138 and 142 to pass and be fastened.
The parts 154, 170, and 172 can thus be secured, e.g. by
means of two screws 174a, 174b that are engaged in
orifices provided for this purpose in the part 172 and
5 that are screwed into the part 154.
In operation, turning the control ring 140 about the
tubular distal portion 155 of the proximal cylindrical
part 154 causes the radial finger 130 to move in
translation in the longitudinal slot 156, thereby causing
10 the tubular shuttle 162 to move axially.
The distal portion of the tube 124 has a distal part
176 comprising:
• a proximal tubular cylindrical portion 178 with an
internal orifice 180 provided for receiving the distal
15 end of the internal tube 152;
• a middle tubular housing 182 presenting a lateral
opening 128 and a distal partition 184, the housing 182
being designed to receive the distal end of the tube 108
of the endoscope .104 inserted into the internal tube 152;
20 • two distal longitudinal lugs 18 6, each having a
transverse orifice 188;
• a longitudinal channel with a proximal end that
receives the blow.tube 144 and a distal end leading to
the housing 182;
25 • a longitudinal channel having a proximal end that
receives the working channel 136 and having a distal
portion leading to between the two lugs 186; and
• two longitudinal channels leading to between the
two distal lugs 186 and slidably receiving the
| 30 maneuvering rods 166 and 168.
The distal portion of the internal part 176 is
associated with an internal pulley 190 having an axial
orifice 192 perpendicular to the axis of the tube 126 and
an annular groove 194 provided for guiding the capillary
35 tube 32 inserted into the working channel 136 via the
socket 138. The hinge finger 130 has two lugs 196 at its
proximal end, each lug presenting a distal transverse
orifice 198 and a proximal transverse orifice 200.
The part 176, the pulley 190, and the hinge finger
130 are assembled together by a cylindrical pin 202
5 passing successively through the orifice 188 in one of
the distal lugs 186 of the part 176, the orifice 198 in
one of the proximal lugs 196 of the finger 130, the
orifice 192 in the pulley 190, the orifice 198 in the
other proximal lug 196, and finally the orifice 188 in
10 the other distal lug 186 of the part 176.
The hinge finger 130 is assembled with the
maneuvering rods 166 and 168 separately for each of the
rods with the help of a respective transverse cylindrical
pin 204 inserted into the proximal orifice 200 of one of
15 the two lugs 196 of the finger 130, and then in an
orifice 206 provided at the distal end of the
corresponding maneuvering rod 166, 168.
In operation, the finger 130 can thus be tilted and
I positioned angularly between an axial position in which
20 it is in alignment with the axis of the tube 126
(Figure 13) and a position in which it is oriented
perpendicularly to the axis of the tube 126 (Figure 14).
A capillary tube 32 can be inserted into the working
channel 136 and then into the channel 132 while the hinge
25 finger 130 is in its axial position. The positioning of
the distal outlet from the capillary 32 on the part for
inspection is performed by turning the control ring 140
so as to orient the finger 130 towards a direction that
is perpendicular to the axis of the tube 126 with the
30 length of the distal portion of the capillary tube 32
that projects beyond the finger 130 being adjusted under
visual monitoring with the help of the endoscope 104.
Figures 18 and 19 show a flexible video endoscope
probe adapted to penetrant testing under illumination by
35 ultra-violet (UV) light, and adapted to accessing
internal zones of a turbine engine.
The video endoscope probe has a control handle with
a distal end that is secured to a flexible inspection
tube 208, and a proximal end that is generally secured to
an umbilical cable (not shown) enabling the probe to be
5 connected to operating devices, such as a light
generator.
For penetrant testing, the control handle of the
probe is fastened to a specific part 210 having a distal
end secured to a distal sleeve 212. The part 210 is a
10 tubular part having an axial proximal housing within
which the control handle is fastened. The part 210 has
i
| an oblique lateral tubular inlet 216 with an outside end
that presents internal tapping 214.
The sleeve 212 may be made of a flexible material,
15 and it surrounds the proximal end of the inspection tube
208. The inspection tube 208 includes a flexible distal
angulation 218 and a distal examination head 220 housing
an optoelectronic device having illumination means and
image-taking means analogous to those described with
20 reference to Figures 8a and 8b. A nut ring 222 is
fastened on an outside thread 224 at the distal axial end
of the part 210 in order to secure the part 210 in
leaktight manner with the sleeve 212.
The part 210 has an axial tubular channel 226
25 housing the following connections:
• a bundle of illumination fibers 228;
• four flexible sheaths 230; and
• a multiconductor electric cable 232.
The bundle of illumination fibers 228 connects an
30 axial illumination window 234 situated on a distal face
of the distal head 220 without discontinuity to the
proximal end of the umbilical cable of the video
endoscope probe. The proximal end of the umbilical cable
may be connected to an illumination generator suitable
35 for delivering equally well white light or UV light.
The four sheaths 230 are designed to guide four
flexible control cables whose distal ends are secured to
the distal angulation 218 and whose proximal ends are
actuated by a manual or motor-drive control member, which
may be housed in the control handle. The control cables
and the control member may be similar to those described
5 with reference to Figures 8b and 9.
The multiconductor electric cable 232 connects the
image sensor housed in the distal head 220 to a video
i processor that may be housed in the control handle. The
main functions of the video processor are to synchronize
I 10 the distal image sensor and to transform the electric
| signal delivered by the sensor into a standardized video
signal. The image sensor is associated with a lens 235
forming a viewing window that is likewise located in the
distal face of.the head 220.
15 The oblique tubular inlet 216 of the part 210 is
designed to receive the proximal portion 236 of a working
channel or duct, which proximal portion is fastened in
the oblique tubular inlet 216, e.g. by adhesive. The
proximal portion 236 may be made of a rigid material,
20 e.g. a metal. The distal end of the proximal portion 236
of the working channel is secured (with the help of a
releasable device for maintenance purposes that is not
shown) to the proximal end of a flexible proximal portion
238 of the working channel as received in the inspection
25 tube 208. The distal end 238 of the proximal portion of
the working channel leads to an orifice 241 formed in the
distal face of the distal head or examination head 220
(Figure 5A).
The distal end of an intermediate tubular part 240
30 is screwed (or adhesively bonded) in the oblique tubular
inlet 216 of the part 210 by means of a distal outside
thread.
A coupling part 246 including a lateral inlet 242
and a proximal axial inlet may be associated in leaktight
35 manner with the part 240 by means of a ring 244 screwed
onto the periphery of the intermediate part 240 and held
axially against an annular rim of the coupling part. A
£ 20
sealing O-ring is clamped at the interface between the
I coupling part 242 and the intermediate tubular part 240.
The proximal axial inlet of the coupling part 246
presents a diameter that is slightly greater than the
5 diameter of a flexible capillary 32 suitable for being
inserted therein. The proximal axial inlet of the part
246 may be fitted with a removable sealing cap 248 made
of a flexible material and presenting an axial orifice
into which the operator can insert a capillary tube 32
10 that is capable of sliding in the working channel 236,
238 until its distal portion emerges from the orifice 241
in the distal face of the distal head 220. The lateral
inlet 242 of the part 246 is connected to means for
feeding air under pressure. Under such conditions, the
15 air injected via the inlet 242 flows in the annular space
between the outside surface of the capillary tube 32 and
the inside surface of the working channel 236, 238 until
it exits via the orifice 241 in the distal head 220. In
this way, the air as injected in this way via the inlet
20 242 can prevent the penetrant test materials sprayed by
the remote outlet of the capillary tube 32 from becoming
deposited on the viewing window 235 and the illumination
window 234 on the distal face of the head 220, thereby
serving to clean these windows. The air injected into
25 the working channel also avoids the working channel being
polluted by drops of the penetrant test material.
The ability to disconnect the coupling device 246
directly constitutes an important advantage in terms of
maintenance, insofar as it makes it easier to clean the
30 working channel 236, 238 periodically.
In another embodiment, the illumination device of
the video endoscope probe may comprise at least two
light-emitting diodes (LEDs), one emitting white light
and the other emitting UV light, these two LEDs being
35 installed in the distal end of the probe.
In embodiments that include a bundle of illumination
fibers, the bundle of illumination fibers may be replaced
by a liquid light guide suitable for transmitting UV
light and white light, or it may be associated with such
a liquid light guide that may be removable.
It can clearly be seen by the person skilled in the
5 art that the present invention may be subjected to a wide
variety of embodiments and applications. In particular,
the above-described video endoscope probe may include an
air-blow tube that is distinct from the working channel
and that leads to the distal head 220 of the probe so as
10 to deliver air onto the illumination and viewing windows.
The endoscope of the invention may be used with
inspection tubes that are flexible or rigid. In an
endoscope or a video endoscope having a flexible
inspection tube fitted with a distal angulation, the
15 viewing and illumination windows may be lateral or axial.
When these windows are axial, the tube 126 has an opening
enabling these windows to be oriented laterally with the
help of the angulation. When the windows are lateral,
the angulation may be omitted.
i
20 In the various embodiments of the invention as
described above, the illumination fibers are made of a
material suitable for transmitting both visible light and
UV light, e.g. they are made of quartz or of a polymer
that is suitable for transmitting both white light and UV
25 light.
By blowing air over the illumination means and the
image-taking means, there is no need at any time to
remove the inspection tube from the endoscopic inspection
i
I orifice, in particular during or after spraying penetrant
30 test materials onto the part for inspection, and the tube
can remain in place until the end of visually inspecting
the part under illumination with UV light, thereby
reducing the time needed for endoscopic inspection
operations.
35 Injecting air into the working channel 236, 238
while injecting penetrant test materials, in combination
with the fact that the capillary tube immerses from the
«k 22
distal end of the working channel, contributes to greatlyreducing
the amount of pollution both in the working
channel and on the examination head.
It may be preferable to avoid mixing penetrant test
5 materials. Under such circumstances, a different
capillary tube 32 may be used for injecting each
penetrant test material. The capillary tubes that are
used may thus be single-use tubes.

£ 23
CLAIMS
1. A device for searching for defects on parts that are
masked and accessible via a passage that is not
rectilinear inside a turbine engine such as an airplane
5 turboprop or turbojet, the device comprising a tubular
sheath (28, 126, 208) and light-guide means for guiding
light and image-transmission means for transmitting
images housed in the sheath in order to illuminate and
observe a part for inspection, the device being
10 characterized in that it comprises an examination head
(62, 220) at the distal end of the sheath (28, 126, 208),
the head having illumination means and image-taking means
connected to the light-guide means and to the imagetransmission
means housed in the sheath (28, 208), means
15 for spraying a succession of penetrant test materials on
the part for inspection, said means comprising a
capillary (32) slidably guided inside a duct (30) housed
in the sheath (28, 126, 208), and in that it includes
means for adjusting the orientation of the examination
20 head at the distal end of the sheath.
2. A device according to claim 1, characterized in that
it includes air-blow means for blowing air on the
illumination means and on the image-taking means located
25 at the distal end of the sheath.
3. A device according to clam 2, characterized in that
the air-blow means comprise means (48) for feeding air
under pressure that are connected to a blow tube (30)
30 leading at its distal end to the vicinity of the
illumination means and the image-taking means.
4. A device according to claim 3, characterized in that
the means for feeding air under pressure are connected to
35 the proximal end of the duct (30, 236) for passing the
capillary (32) in order to feed the duct (30, 236) with a
continuous stream of air that leaves via its distal end.
-
•
A 24
5. A device according to any one of claims 1 to 4,
characterized in that the proximal end of the sheath (28,
208) is connected to a handle (36) for fastening to the
5 engine, and in that the duct (30, 136, 241) housing the
capillary (32) is extended inside the handle (36) and is
connected to a rigid tube (38) carried by the handle (36)
and serving to insert the capillary (32) into the inside
of the duct (30).
10
6. A device according to claim 5, characterized in that
it includes holder means for preventing the capillary
(32) from sliding inside the duct (30).
15 7. A device according to claim 5 or claim 6,
characterized in that the holder means comprise an
endpiece (40) including means for clamping onto the
capillary (32) and designed to be engaged and held on the
free end of the rigid tube (38).
20
8. A device according to claims 4 and 7 taken together,
characterized in that the endpiece (40) includes a
passage (46) leading to the inside of the tube (38) and
forming an inlet for connection to the means (48) for
25 feeding air under pressure.
9. A device according to any preceding claim,
characterized in that the orientation adjustment means
comprise a control member (76, 140) for controlling the
30 angular orientation of the examination head, which member
is rotatably mounted on the endoscope handle and is
connected to transmission means for transmitting the
orientation control to the examination head, these
transmission means being housed in the sheath (28, 126,
35 230).
f
^ 25
10. A device according to claim 8, characterized in that
the means for adjusting the orientation of the
examination head comprise at least two cables guided
inside the sheath and fastened at their distal ends to
5 the examination head (62, 220) at two diametricallyopposite
points, and wound under tension at their
proximal portions in opposite directions on a rotarycontrol
member situated on the handle (36).
10 11. A device according to claim 9, characterized in that
the means for transmitting the orientation control
comprise at least one rod (166, 168) extending inside the
sheath (126) and connected at its distal end to a
mechanism for converting rotary movement of the ring into
15 movement in translation of the rod, the rod being
connected by its distal end to a finger (130) that is
pivotally hinged to the distal end of the sheath (126)
about an axis that is perpendicular to the sheath.
20 12. A device according to claim 11, characterized in that
the distal finger (130) includes an axial channel (132)
for passing the capillary (32) and is hinged to pivot
between a position in which it is in alignment with the
axis of the sheath (126) and a position in which it is
25 oriented perpendicularly to the axis of the sheath (126).
13. A device according to any preceding claim,
characterized in that the tubular sheath (28, 218) is
flexible, and in that the capillary (32) is flexible.
30
14. A device according to any preceding claim,
characterized in that the distal end of the sheath (28)
is fitted with a spray endpiece at its distal end.
35 15. A device according to claim 14, characterized in that
the spray endpiece at the distal end of the capillary
^ 26
(32) is removable and can be selected from a set of spray
endpieces for spraying radially, forwards, or backwards.
16. A device according to any preceding claim,
5 characterized in that the sheath (28) is of circular
section With a diameter lying in the range 6 mm to 10 mm,
and the duct (30) for passing the capillary (32) has a
diameter I of about 1.2 mm, the capillary (32) having a
diameter •• of about 0.8 mm.
10
17. A method of non-destructive penetrant testing of a
part that is masked, by using a device according to any
one of claims 1 to 16, the method being characterized in
that it consists in:
15 • inserting and guiding the examination head inside
a three-dimensional structure to a position for examining
the part for inspection;
• with the examination head placed facing the part
for inspection,- feeding the proximal end of the capillary
20 with a first penetrant test material and applying this
first material via the distal end of the capillary to the
part for.inspection;
• slidably withdrawing the capillary from the duct
in which|it is housed; and
25 • slidably inserting a second capillary into the
duct and;bringing its distal end into the vicinity of the
part for inspection, and then feeding the proximal end of
the second capillary with a second penetrant test
material and applying the second material via the distal
30 end to the part for inspection.