Description:1 Title of invention
In-built telescopic retractable pilot step-way assembly for aircraft.
2 Field of invention
The present invention is related to aircraft structural engineering design in general and more particularly the design of mechanically retractable telescopic step-way with a redundant locking mechanism for entry of crew to the cockpit without any ground supporting equipment ladder.
3 Background of invention
A combat aircraft must be battle-ready all the time and should be prepared for flight within a short time and with less ground supporting equipment. One such requirement is to eliminate the need of an external ladder as a ground supporting equipment for entry of the pilot into the cockpit. Traditionally fighter aircraft were designed with a provision of hard points on the fuselage side shell to engage a ladder ground supporting equipment for entry of the pilot into the cockpit. The external ladder is carried manually by the ground crew and engaged onto the hard points on the fuselage. In larger air bases having more numbers of aircraft, handling the ladder ground supporting equipment becomes a tiresome activity and results fatigue of ground crew. Hence there is a need to provide in-built retractable pilot step-way on the aircraft itself, to eliminate the need for external ladder ground supporting equipment and reduce flight preparation time and ground crew fatigue. The prior arts on in-built telescopic step-way for aircraft uses either actuators or the assistance from ground crew for its operation by the pilot in the cockpit. Hence there is a need to develop a simple mechanically retractable in-built step way that can be operated by the pilot from the cockpit without any assistance from the ground crew and without any need for electrical power or electrical/hydraulic actuators to operate it. In-built retractable pilot step-way should be simple in terms of operation and not have external projections on the external surface of fuselage skin in a retracted condition.
4 Brief summary of invention
The primary objective of the present invention is to reduce the flight preparation time and enable flight operation from remote air bases as well. This invention reduces the fatigue of the ground crew, by eliminating the need to carry ladder ground supporting equipment to the bases. The present invention provides a simple mechanically retractable in-built step way that can be operated by the pilot inside the cockpit without any assistance from the ground crew and without any need for electric power or actuators to operate it.
The present invention of an in-built telescopic retractable pilot step-way assembly (100) is embodied as an integral system of a combat aircraft, operated on the ground for entry or exit of a crew into or from the cockpit. The assembly (100)is operated by the crew sitting inside the cockpit or by the crew on the ground. It is manually closed after the entry or exit of the crew. The in-built telescopic retractable pilot step-way assembly (100) is a simple conventional mechanical system, which is manually operated without any kind of electrical or hydraulic actuators, and it (100) comprises a step-way bar assembly (10), a double hook lock assembly (40), and a stowage bay (50).The two-stage telescopic step-way bar assembly (10) is made of an outer bar of a square hollow tube (31) and an inner bar of a circular hollow tube (21) with upper and lower footsteps (32)(22) attached at the bottom end. The upper and lower footsteps (32)(22) are contoured at the bottom to match the fuselage (200) surface in retracted condition, to avoid drag in flight. Since the system is compact in the retracted condition, it is feasible to be stowed onto the confined space of the cockpit side shell without blocking the looming and plumbing in the cockpit console.
5 Brief description of drawings
Fig-1 shows the step-way bar assembly (10) of the in-built telescopic retractable pilot step-way assembly (100), stowed and locked into an aircraft fuselage side structure (200).It also shows an external lock handle (41) and a plurality of footsteps(22)(32)flushed with the external surface of the fuselage side skin (200).
Fig-2 shows the step-way bar assembly (10) extended out of the fuselage structure(200). The upper footstep(32) and a lower footstep(22), part of the step-way bar assembly (10), are at a different height from the ground to suit the ergonomics of the crew for climbing.
Fig-3 shows a vertical section-AA from Fig-2of the step-way bar assembly (10) on the fuselage structure(200) in the deployed and down-locked condition. The outboard tilt of the step-way bar assembly(10)is shown in this figure. The outboard tilt helps in better ergonomics and reachability for the crew to step on from the ground.
Fig-4 shows a standalone view of the step-way bar assembly(10) in extended condition with an outer bar assembly (30) and an inner bar assembly (20).
Fig-5 shows a design of the outer bar assembly (30). It consists of the upper footstep (32) with a fairing (37), a bottom stopper (36) on the upper footstep (32),and a restraint bracket (33). The bottom stopper(36) is machined as an integral part of the upper footstep (32).The fairing (37) is a machined part bolted onto the upper footstep (32) and flushes with the fuselage side skin (200) contour in a closed condition. A plurality of bearings (34) is attached to the forward and aft sides of the restraint bracket (33), to facilitate sliding of the outer bar assembly (30) on a plurality of guide rails (51) on a stowage bay (50).
Fig-6 shows a design of the inner bar assembly (20). It consists of the lower footstep (22), a top stopper(23),and a locking spike (24).A circular hollow tube (21) is inserted into a grove on the lower footstep (22) and attached using a plurality of cross bolts (25).The lower footstep (22) is machined by aluminum alloy stock and provided with straight knurls on the top face for better foot grip. The locking spike (24) and the top stopper (23) are inserted on to the top side of the hollow tube (21) and bolted together with the cross bolts (25).
Fig-7 shows the stowage bay (50) of the in-built telescopic retractable pilot step-way assembly (100), that comprises of a plurality of guide rails (51), a down-lock arm (52), and a roller assembly (60). The stowage bay(50) is an enclosed pressure bay bounded by forward and aft cockpit frames (53) (54), the fuselage side skin (200), and a pressure sealing wall (55). The topology of the stowage bay(50) is decided so as to fit within the limited space available inside the cockpit. The guide rails (51) are loose parts attached to the forward and aft cockpit frames (53) (54).A spring-loaded down-lock arm (52) is hinged onto the forward and aft cockpit frames (53)(54). A stopper bolt (56) is provided on the forward and aft cockpit frames (53)(54) to limit the rotation of the down-lock arm(52) in a deployed condition. The stowage bay (50) structural assembly is pressure sealed using sealants.
Fig-8shows a double hook lock assembly (40) of the in-built telescopic retractable pilot step-way assembly (100), that comprises of an external lock handle (41), a link (42), torsion springs (45), and a housing (44).The external lock handle(41) is hinged onto a top cover (48) and connected to a yoke slider(43) through the link (42).The yoke slider(43) slides on a hole on the housing (44). Two swing hooks (46) are hinged onto the housing (44) using a plurality of pins (47). Two torsion springs (45) are used to hold the swing hooks (46) in a closed position by default. The pin-type projections on the yoke slider (43) are engaged onto the swing hook (46) arms to create a slider-type of interface.
Fig-9 shows the cut section of the double hook lock assembly (40) with step-way bar assembly (10) in retracted and locked condition. The locking spike (24) on the inner bar assembly (20) is engaged onto the swing hooks (46).
Fig-10 shows the cut section of the double hook lock assembly (40) in open condition. When the external lock handle (41) is pushed inside, the yoke slider(43) is pulled upwards which in turn rotates the swing hooks (46). The rotation of the swing hooks (46) releases the locking spike (24) and the step-way bar assembly (10) is deployed by gravity force. Once the external lock handle(41) is left free, the lock returns back to the default locked position.
6 Detailed description of invention
The present invention of in-built telescopic retractable pilot step-way assembly (100) is an integral system on aircraft that is designed to aid in entry or exit of the crew onto aircraft without the need for ladder ground supporting equipment. The in-built telescopic retractable pilot step-way assembly (100) is a simple conventional mechanical system, which is manually operated without any kind of electrical or hydraulic actuators and comprises a step-way bar assembly (10), a double hook lock assembly (40), and a stowage bay (50).
The in-built retractable pilot step-way assembly (100) is embodied as an integral system on the aircraft to facilitate the entry/exit of the crew without the aid of an external ground supporting equipment. Refer to Fig-1 for the retracted condition of the present invention (100). The Fig-1 describes that the external lock handle (41),the upper footstep (32), and the lower footstep (22) of the present invention (100) are flushed with the aircraft fuselage side skin(200). There are no external projections on the external surface of the fuselage skin (200) in the retracted condition of the in-built telescopic retractable pilot step-way assembly (100).
Refer to Fig-2 and Fig-3. For deployment or extension of the in-built retractable pilot step-way assembly (100), the external lock handle (41) is pushed inside, by which the double hook lock assembly(40) is opened to release the step-way bar assembly (10) and it extends down due to self-weight by gravity action, as shown in Fig.2.
Refer to Fig-4, Fig-5, and Fig-6. The step-way bar assembly (10) comprises of a two-stage telescopic extendable/collapsible unit that is further comprising of an inner bar assembly (20) and an outer bar assembly (30) made of hollow tubes. The Inner bar assembly (20) slides inside the outer bar assembly (30) during deployment/extension. The circular hollow tube (21)and square hollow tube(31) are made of corrosion resistant steel alloys for durability. A top stopper (23)and bottom stopper (36) are provided on the bar assemblies (20) (30) to restrict the movement within the designed limits. A locking spike (24) is added to the top end of the inner bar assembly (20).
Refer to Fig-7. The stowage bay (50) comprises a plurality of guide rails (51), a down-lock arm (52), and a roller assembly (60) for the operation of the step-way bar assembly (10) during extension/retraction. These are made of steel alloys for resisting wear and tear and supporting local reactions. The down-lock arm (52) and the bottom roller assembly (60) support the step-way bar assembly (10) in a deployed/extended condition. The stowage bay (50) is also closed by a pressure sealing wall (55) to seal the cockpit.
Refer to Fig-8, Fig-9, and Fig-10. The double hook lock assembly (40) is designed for holding the step-way bar assembly (10) in an up-locked position when stowed in flight condition. The double hook lock assembly (40) is a mechanical lock assembly with conventional swing hooks (46) held in closed position by torsion springs (45). The swing hooks (46) are operated by a yoke slider (43) pulled by a link (42) connected to the hinged external lock handle (41). With this scheme of double hooks and torsion spring lock arrangement, the inadvertent release of the step-way bar assembly (10) from the stowed condition in flight is not possible unless there is any mechanical failure.
Refer to Fig-3. In the deployed condition, the restraint bracket (33) on the step-way bar assembly (10) is engaged onto the down-lock arm (52) and supported by roller assembly (60) at the bottom. The rotation of the down-lock arm (52) is limited by the stopper bolts (56). The location of the down-lock arm (52) and the roller bearings (60) on the fuselage fixed structure are arranged in such a way that it ensures the outboard tilt of the step-way bar assembly (10) in the deployed/extended condition. The weight of the crew is supported by the down-lock arm (52) on the stopper bolt (56) and the swing is controlled by bearings(34).
Refer to Fig-4. The step-way bar assembly (10) is made of the outer bar assembly (30) and the inner bar assembly (20). The inner bar assembly (20) slides inside the outer bar assembly (30) and the limits of the movement are controlled by the bottom stopper (36) on the outer bar assembly (30).
Refer to Fig-5. The outer bar assembly (30) consists of a square hollow tube (31), upper footstep(32) with fairing (37), and restraint bracket (33). The fairing (37) is a machined part bolted onto the upper footstep (32). The upper footstep (32)together with the fairing(37)is attached to the square hollow tube (31)bottom end using the attachment bolts(35). The restraint bracket (33) is bolted to the square hollow tube (31) top end and it is a removable part. The restraint bracket (33) is provided with two integral shaft extensions on the sides for locking the bearings (34). The bearings (34) on the restraint bracket (33) facilitate frictionless sliding of the outer bar assembly (30) on the guide rails (51). All the parts except fairing (37)are made of steel alloys to withstand wear and tear and loads during the deployment. The fairing (37) on the upper footstep (32) is made of aluminum alloy. The restraint bracket (33) engages with the down-lock arm (52) in the extended condition.
Refer to Fig-6. The inner bar assembly (20) consists of a circular hollow tube (21), lower footstep (22), top stopper (23), and locking spike (24). The bottom end of the hollow tube (21)is inserted into the circular groove on the lower footstep (22) and secured using cross bolts (25). The top stopper (23) is bolted onto the circular hollow tube (21) top end together with the locking spike (24) inside the tube. All the parts except the lower footstep (22)are made of steel alloy. The lower footstep (22) is integrally machined from aluminum alloy bar. The locking spike (24) engages onto the swing hooks (46) on the lock assembly (40) for positive engagement in the retracted condition.
Refer to Fig-7. The stowage bay (50) for the in-built step-way system (100) consists of side frames (53) (54), a pressure sealing wall (55), guide rails (51), and a down-lock arm (52). The step-way bar assembly (10) is guided and supported by a set of guide rails (51) at the top and a roller assembly (60) at the bottom. The guide rails (51) are permanently attached to the forward and aft side frames (53) (54) with rivets. The roller assembly (60) is permanently attached to the cockpit side member (57). The bearings (34) on the outer bar assembly (30) slide on the guide rails (51) during the extension and retraction of the step-way bar assembly (10). The external surface of the outer bar (30) slides over the roller assembly (60) at the bottom. The guide rails (51) are positioned with a tilt so that the step-way bar assembly (10) extends and bottom end moves outboard laterally when deployed and in reverse retracts and top end moves inboard when stowed back. This arrangement helps in attaining a better position of the footsteps in the step-way bar (10) extended condition facilitating better human ergonomics for climbing. The down-lock arm (52) is spring-loaded with rotation limited by two stopper bolts (56) and engages with the hook projection on the restraint bracket (33) at a fully extended position. During retraction of the step-way bar assembly (10), the down-lock arm (52) tilts outboard thus clearing the path for stowage.
Refer to Fig-8. The double hook lock assembly (40) consists of the external lock handle (41) with a link (42), swing hooks (46), yoke slider (43), and housing (44). Two swing hooks (46) are hinged onto the housing (44) using pins (47) and held in a default closed position by the torsion springs (45). The external lock handle (41) is held flush with the aircraft fuselage skin(200) by the handle torsion spring(49). Pushing the lock handle (41) inside operates the link (42) and pulls up the yoke slider (43). The pin-type projections on the yoke slider (43) are engaged onto the swing hook (46) arms to create a slider type of interface. The upward movement of the yoke slider (43)rotates the swing hooks (46) in the opposite direction. The swing hooks (46) and link (42) are made of steel alloy to resist wear and tear due to cyclic operations. The lock housing (44) and the external lock handle (41) are machined from aluminum alloy bar to optimize the weight.
Refer to Fig-9. The locking spike (24) on the inner bar assembly(20) is engaged onto the swing hooks (46) in the closed position. Two swing hooks(46) provide scissor-type locking that ensures redundancy in case of any failure of one swing hook. The mating surfaces on the locking spike (24) and swing hooks (46) are provided with acute angle faces to ensure positive geometry locking. This feature of geometry locking eliminates any remote chances of inadvertent opening of hook locks. A spike is provided on the restraint bracket (33) which also gets engaged to swing hooks (46). This ensures that both inner and outer bar assemblies(20)(30) are locked onto the swing hooks(46), thereby increasing the redundancy of the system as a whole. The geometry of the spike on the restraint bracket (33) and locking spike (24) are made exactly the same to ensure proper and smooth locking.
Refer to Fig-10. The yoke slider (43) is pulled upwards by link (42) when the external lock handle (41) is pushed in. The pin-type projections on the yoke slider (43) convert linear motion into rotation of swing hooks (46), thereby releasing the locking spike (24) from the clutch. Once released, the step-way bar assembly (10) falls down by gravity due to self-weight.
OPERATION:
The operation for extension of the step-way assembly (100) from the stowed condition starts with pressing the external lock handle (41). This operates the link (42) and pulls up the yoke slider (43). Pin projections on the yoke slider arm (43)cause the swing hooks(46) to rotate and open. Once the swing hooks (46) open, the locking spike (24) is released from the double hook clutch, and the inner bar assembly (20) starts to slide down by gravity due to self-weight and in turn, pulling down the outer bar assembly (30) as well. The deployment/extension is complete when the restraint bracket (33) is fully engaged with the down-lock arm (52). The whole step-way bar assembly (10) is firmly held in the deployed position by combined reactions from the guide rails (51), roller assembly (60), and down-lock arm (52). The external lock handle (41) is located on the fuselage side skin(200) within the reach of the crew in the cockpit and makes it feasible to operate from the cockpit by extending the hands out. This ensures that ground crew is not required for deployment of in-built step-way assembly (100) after landing in remote bases or in an emergency.
Retraction of the step-way assembly(100) is done manually from the ground. The inner bar assembly (20) is pushed up first which collapses it into the outer square hollow tube (31) and further pushes them together into the stowage bay (50). The spike on the restraint bracket (33) and locking spike (24) on the inner bar assembly (20) push open the swing hooks(46) and after further pushing in, the swing hooks (46)engage again by spring force. This completes the retraction and both the footsteps (22)(32) become flushed with fuselage contour.
The present invention is designed for two times the crew weight for reliability and its elements are appropriately sized for optimal weight. Extension and retraction of in-built telescopic retractable pilot step-way assembly (100) are operated manually, without any kind of electrical or hydraulic actuators, assisted by gravity due to self-weight. Frictionless operation of the step-way bar assembly (10) is ensured by bearings(34) on the outer bar assembly(30) and roller assembly (60) on the stowage bay(50). Further, it reduces the flight preparation time and enables operation from remote bases as well. This invention also reduces fatigue of ground crew, by eliminating the need to carry ladder ground supporting equipment to bases.

7 Drawing numerals:
Item No. Description
100 In-built telescopic retractable pilot step-way assembly
200 Fuselage side skin
10 Step-way bar assembly
20 Inner bar assembly
21 Circular hollow tube
22 Lower footstep
23 Top stopper
24 Locking spike
25 Cross bolts
30 Outer bar assembly
31 Square hollow tube
32 Upper footstep with fairing
33 Restraint bracket
34 Bearings
35 Attachment bolts
36 Bottom stopper
37 Fairing
40 Double hook lock assembly
41 External lock handle
42 Link
43 Yoke slider
44 Housing
45 Torsion springs
46 Swing hooks
47 Pins
48 Top Cover
49 Handle torsion spring
50 Stowage bay
51 Guide rails
52 Down-lock arm
53 Forward cockpit frame
54 Aft cockpit frame
55 Pressure sealing wall
56 Stopper bolt
57 Cockpit side member
60 Roller assembly

, Claims:We claim:
1. An in-built telescopic retractable pilot step-way assembly (100) for aircraft is an integral system on the aircraft, that be a manually operated conventional mechanical system without any need for electrical or hydraulic actuators for its operation, to aid in the entry/exit of the crew onto/from the aircraft without any ladder ground supporting equipment, characterized in that, the assembly (100) comprising:
a step-way bar assembly (10), a double hook lock assembly (40), and a stowage bay (50) as main assemblies;
the step-way bar assembly (10) comprises: a two-stage telescopic extendable and collapsible unit consisting of an inner bar assembly (20) made of a circular hollow tube (21) and an outer bar assembly (30) made of a square hollow tube (31), such that the inner bar assembly (20) slides inside the outer bar assembly (30) during the deployment/extension;
the said inner bar assembly (20) comprises the circular hollow tube (21), a lower footstep (22), a top stopper (23), and a locking spike (24);
the bottom end of the hollow tube (21) is inserted into the circular groove on the lower footstep (22) and secured using cross bolts (25), and the top stopper (23) is bolted onto the circular hollow tube (21) top end together with the locking spike (24) inside the tube (21);
the said outer bar assembly (30) comprises the square hollow tube (31), an upper footstep (32) with a fairing (37), and a restraint bracket (33);
the fairing (37) is a machined part bolted onto the upper footstep (32), the upper footstep (32) together with the fairing (37) is attached to the square hollow tube (31) bottom end using a plurality of attachment bolts (35), the restraint bracket (33) is bolted to the square hollow tube (31) top end and it is a removable part, the restraint bracket (33) is provided with two integral shaft extensions on the sides for locking the bearings (34), the bearings (34) on the restraint bracket (33) facilitate frictionless sliding of the outer bar assembly (30) on a plurality of guide rails (51) of the stowage bay (50);
the stowage bay (50) comprises a plurality of side frames (53) (54), a pressure sealing wall (55), the guide rails (51), and a down-lock arm (52);
the step-way bar assembly (10) is guided and supported by the guide rails (51) at the top and a roller assembly (60) at the bottom, the guide rails (51) are permanently attached to the forward and aft cockpit frames (53) (54) with rivets, the roller assembly (60) is permanently attached to the cockpit side member (57), the bearings (34) on the outer bar assembly (30) slide on the guide rails (51) during the extension and retraction of the step-way bar assembly (10), the external surface of the outer bar assembly (30) slides over the roller assembly (60) at the bottom, the guide rails (51) are positioned with a tilt so that the step-way bar assembly (10) extends and bottom end moves outboard laterally when deployed and in reverse retracts and top end moves inboard when stowed back such that this arrangement provides a better position of the footsteps (22) (32) in the step-way bar (10) extended condition facilitating better human ergonomics for climbing, the down-lock arm (52) is spring-loaded with rotation limited by two stopper bolts (56) and engages with the hook projection on the restraint bracket (33) at a fully extended position, and the down-lock arm (52) tilts outboard during retraction of the step-way bar assembly (10) that clears the path for stowage;
the double hook lock assembly (40) comprises an external lock handle (41) with a link (42), a plurality of swing hooks (46), a yoke slider (43), and a housing (44) such that the swing hooks (46) are hinged onto the housing (44) using pins(47) and held in a default closed position by a plurality of torsion springs (45);
the external lock handle (41) is held flush with the aircraft fuselage skin (200) by the handle (41) torsion spring(49), pushing the lock handle (41) inside operates the link (42) and pulls up the yoke slider (43), the pin-type projections on the yoke slider (43) are engaged onto the swing hook arms (46) to create a slider type of interface, the upward movement of the yoke slider (43) rotates the swing hooks (46) in the opposite direction, the locking spike (24) on the inner bar assembly (20) is engaged onto the swing hooks (46) in the closed position, the two swing hooks (46) provide a scissor-type locking that ensures redundancy in case of any failure of one swing hook, the mating surfaces on the locking spike (24) and swing hooks (46)are provided with acute angle faces to ensure a positive geometry locking that eliminates any remote chances of inadvertent opening of hook locks, the spike provided on the restraint bracket (33) also gets engaged to the swing hooks (46) to ensures that both inner and outer bar assemblies (20)(30) are locked onto the swing hooks(46), thereby, increasing the redundancy of the system (100) as a whole, and the geometry of the spike on the restraint bracket (33) and the locking spike (24) are made exactly the same to ensure proper and smooth locking;
the yoke slider (43) is pulled upwards by the link (42) when the external lock handle (41) is pushed in, the pin-type projections on the yoke slider (43) convert linear motion into rotation of swing hooks (46), thereby, releasing the locking spike (24) from the clutch, and once released, the step-way bar assembly (10) falls down by gravity due to self-weight;
the operation for extension of the step-way assembly (100) from the stowed condition starts with pressing the external lock handle (41) that operates the link (42) and pulls up the yoke slider (43), the pin projections on the yoke slider arm (43) cause the swing hooks (46) to rotate and open, once the swing hooks (46) open, the locking spike (24) is released from the double hook clutch and the inner bar assembly (20) starts to slide down by gravity due to self-weight and in turn pulling down the outer bar assembly (30) as well, the deployment/extension is complete when the restraint bracket (33) is fully engaged with the down-lock arm (52), the whole step-way bar assembly (10) is firmly held in the deployed position by combined reactions from the guide rails (51), the roller assembly (60), and the down-lock arm (52);
the external lock handle (41) is located on the fuselage side skin (200) within the reach of the crew in the cockpit and makes it feasible to operate from the cockpit by extending the hands out which ensures that the ground crew is not required for deployment of in-built step-way assembly (100) after landing in remote bases or in an emergency; and
retraction of the step-way assembly (100) is done manually from the ground, the inner bar assembly (20) is pushed up first which collapses it into the outer square hollow tube (31) and further pushes them together into the stowage bay (50), the spike on the restraint bracket (33) and the locking spike (24) on the inner bar push open the swing hooks (46) and after further pushing in, the swing hooks (46) engage again by spring force, and this completes the retraction and both the footsteps (22)(32) become flushed with the fuselage skin (200) contour.
2. The in-built telescopic retractable pilot step-way assembly (100), as claimed in claim 1, wherein, locations of the guide rails (51), the down-lock arm (52), and the roller assembly(60) on the aircraft fuselage structure are arranged to ensure that top end of the step-way bar assembly (10) is tilted outboard in the retracted condition, thereby requiring lesser volume of the stowage bay (50) inside cockpit.
3. The in-built telescopic retractable pilot step-way assembly (100), as claimed in claim 1, wherein, arrangement of the guide rails (51) with the bearings (34) on the outer bar assembly (30) and the roller assembly (60) are enabling frictionless sliding of the step-way bar assembly (10) on the stowage (50).
4. The in-built telescopic retractable pilot step-way assembly (100), as claimed in claim 1, wherein, the locking spike (24), the restraint bracket (33), and the swing hooks (46) are fabricated from corrosion resistant steel alloy bars to resist wear and tear due to cyclic operations